xref: /frameworks/base/docs/html-intl/intl/vi/guide/topics/providers/content-provider-basics.jd

page.title=Ni dung C bn v Trnh cung cp Ni dung
@jd:body
<div id="qv-wrapper">
<div id="qv">
<!-- In this document -->
<h2>Trong ti liu ny</h2>
<ol>
    <li>
        <a href="#Basics">Tng quan</a>
        <ol>
            <li>
                <a href="#ClientProvider">Truy cp mt trnh cung cp</a>
            </li>
            <li>
                <a href="#ContentURIs">URI Ni dung</a>
            </li>
        </ol>
    </li>
    <li>
        <a href="#SimpleQuery">Truy xut D liu t Trnh cung cp</a>
        <ol>
            <li>
                <a href="#RequestPermissions">Yu cu quyn truy cp c</a>
            </li>
            <li>
                <a href="#Query">Xy dng truy vn</a>
            </li>
            <li>
                <a href="#DisplayResults">Hin th cc kt qu truy vn</a>
            </li>
            <li>
                <a href="#GettingResults">Ly d liu t cc kt qu truy vn</a>
            </li>
        </ol>
    </li>
    <li>
        <a href="#Permissions">Quyn ca Trnh cung cp Ni dung</a>
    </li>
    <li>
        <a href="#Modifications">Chn, Cp nht, v Xa D liu</a>
        <ol>
            <li>
                <a href="#Inserting">Chn d liu</a>
            </li>
            <li>
                <a href="#Updating">Cp nht d liu</a>
            </li>
            <li>
                <a href="#Deleting">Xa d liu</a>
            </li>
        </ol>
    </li>
    <li>
        <a href="#DataTypes">Cc Kiu D liu ca Trnh cung cp</a>
    </li>
    <li>
        <a href="#AltForms">Cc Hnh thc Truy cp Trnh cung cp Thay th</a>
        <ol>
            <li>
                <a href="#Batch">Truy cp hng lot</a>
            </li>
            <li>
                <a href="#Intents">Truy cp d liu thng qua  nh</a>
            </li>
        </ol>
    </li>
    <li>
        <a href="#ContractClasses">Cc Lp Hp ng</a>
    </li>
    <li>
        <a href="#MIMETypeReference">Tham kho Kiu MIME</a>
    </li>
</ol>

    <!-- Key Classes -->
<h2>Lp kha</h2>
    <ol>
        <li>
            {@link android.content.ContentProvider}
        </li>
        <li>
            {@link android.content.ContentResolver}
        </li>
        <li>
            {@link android.database.Cursor}
        </li>
        <li>
            {@link android.net.Uri}
        </li>
    </ol>

    <!-- Related Samples -->
<h2>Cc Mu Lin quan</h2>
    <ol>
        <li>
        <a href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/view/List2.html">
        Con chy (Danh b)</a>
        </li>
        <li>
        <a href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/view/List7.html">
        Con chy (in thoi)</a>
        </li>
    </ol>

    <!-- See also -->
<h2>Xem thm</h2>
    <ol>
        <li>
            <a href="{@docRoot}guide/topics/providers/content-provider-creating.html">
            To mt Trnh cung cp Ni dung</a>
        </li>
        <li>
            <a href="{@docRoot}guide/topics/providers/calendar-provider.html">
            Trnh cung cp Lch</a>
        </li>
    </ol>
</div>
</div>

    <!-- Intro paragraphs -->
<p>
    Trnh cung cp ni dung qun l truy cp vo mt kho d liu tp trung. Trnh cung cp
    l b phn ca mt ng dng Android, n thng cung cp UI ca chnh mnh  lm vic cng
    d liu. Tuy nhin, trnh cung cp ni dung c thit k ch yu cho cc ng dng khc
    s dng, gip truy cp trnh cung cp bng cch s dng mt i tng my khch cung cp. Cng nhau, trnh cung cp
    v my khch cung cp s mang n mt giao din nht qun, tiu chun cho d liu, giao din ny
    cng ng thi x l truyn thng lin tin trnh v bo mt truy cp d liu.
</p>
<p>
    Ch  ny  cp n nhng ni dung c bn sau y:
</p>
    <ul>
        <li>Cch trnh cung cp ni dung hot ng.</li>
        <li>API bn s dng  truy xut d liu t mt trnh cung cp ni dung.</li>
        <li>API bn s dng  chn, cp nht, hoc xa d liu trong mt trnh cung cp ni dung.</li>
        <li>Cc tnh nng API khc to iu kin lm vic cng cc trnh cung cp.</li>
    </ul>

    <!-- Basics -->
<h2 id="Basics">Tng quan</h2>
<p>
    Trnh cung cp ni dung trnh by d liu cho cc ng dng bn ngoi di dng mt hoc nhiu bng tng t
    nh cc bng c tm thy trong mt c s d liu quan h. Mi hng th hin mt thc th ca mt s kiu d liu
    m trnh cung cp thu thp, v mi ct trong hng th hin mt phn ring bit ca d liu c thu thp
    i vi mt thc th.
</p>
<p>
    V d, mt trong cc trnh cung cp tch hp trong nn tng Android  l t in ngi dng, n
    lu gi chnh t ca nhng t phi tiu chun m ngi dng mun gi li. Bng 1 minh ha
    cch m d liu c th c trnh by trong bng ca trnh cung cp ny:
</p>
<p class="table-caption">
    <strong>Bng 1:</strong> Bng t in ngi dng mu.
</p>
<table id="table1" style="width: 50%;">
    <tr>
        <th style="width:20%" align="center" scope="col">t</th>
        <th style="width:20%" align="center" scope="col">id ng dng</th>
        <th style="width:20%" align="center" scope="col">tn sut</th>
        <th style="width:20%" align="center" scope="col">bn a</th>
        <th style="width:20%" align="center" scope="col">_ID</th>
    </tr>
    <tr>
        <td align="center" scope="row">mapreduce</td>
        <td align="center">user1</td>
        <td align="center">100</td>
        <td align="center">en_US</td>
        <td align="center">1</td>
    </tr>
    <tr>
        <td align="center" scope="row">precompiler</td>
        <td align="center">user14</td>
        <td align="center">200</td>
        <td align="center">fr_FR</td>
        <td align="center">2</td>
    </tr>
    <tr>
        <td align="center" scope="row">applet</td>
        <td align="center">user2</td>
        <td align="center">225</td>
        <td align="center">fr_CA</td>
        <td align="center">3</td>
    </tr>
    <tr>
        <td align="center" scope="row">const</td>
        <td align="center">user1</td>
        <td align="center">255</td>
        <td align="center">pt_BR</td>
        <td align="center">4</td>
    </tr>
    <tr>
        <td align="center" scope="row">int</td>
        <td align="center">user5</td>
        <td align="center">100</td>
        <td align="center">en_UK</td>
        <td align="center">5</td>
    </tr>
</table>
<p>
    Trong bng 1, mi hng th hin mt thc th ca mt t m c th khng thy c
    trong t in chun. Mi ct th hin mt s d liu cho t , chng hn nh
    t bn a c dng ln u cho t . Tiu  ct l cc tn ct c lu gi trong
    trnh cung cp.  tham kho ti bn a ca mt hng, bn tham kho ti ct <code>locale</code> ca hng . i vi
    trnh cung cp ny, ct <code>_ID</code> ng vai tr l ct "kha chnh" m
    trnh cung cp t ng duy tr.
</p>
<p class="note">
    <strong>Lu :</strong> Trnh cung cp khng bt buc phi c mt kha chnh, v khng bt buc phi
    s dng <code>_ID</code> lm tn ct ca mt kha chnh nu c kha. Tuy nhin,
    nu bn mun gn kt d liu t mt trnh cung cp vi mt {@link android.widget.ListView}, mt trong cc
    tn ct s phi l <code>_ID</code>. Yu cu ny c gii thch chi tit hn trong
    phn <a href="#DisplayResults">Hin th cc kt qu truy vn</a>.
</p>
<h3 id="ClientProvider">Truy cp mt trnh cung cp</h3>
<p>
    Mt ng dng truy cp d liu t mt trnh cung cp ni dung bng
    mt i tng my khch {@link android.content.ContentResolver}. i tng ny c cc phng php  gi
    nhng phng php c tn ging nhau trong i tng trnh cung cp, mt thc th ca mt trong nhng lp con
    c th ca {@link android.content.ContentProvider}. Cc phng php
    {@link android.content.ContentResolver} cung cp cc chc nng
    "CRUD" (to, truy xut, cp nht, v xa) c bn ca thit b lu tr lin tc.
</p>
<p>
    i tng {@link android.content.ContentResolver} trong tin trnh
    ca ng dng my khch v i tng {@link android.content.ContentProvider} trong ng dng m s hu
    trnh cung cp s t ng x l truyn thng lin tin trnh.
    {@link android.content.ContentProvider} cng ng vai tr nh mt lp rt gn gia kho d liu
    ca n v biu din bn ngoi ca d liu di dng bng.
</p>
<p class="note">
    <strong>Lu :</strong>  truy cp mt trnh cung cp, ng dng ca bn thng phi yu cu cc quyn
    c th trong tp bn k khai ca mnh. iu ny c m t chi tit hn trong phn
    <a href="#Permissions">Quyn ca Trnh cung cp Ni dung</a>
</p>
<p>
    V d,  c mt danh sch cc t v ni dung bn a ca chng t Trnh cung cp T in Ngi dng,
    bn hy gi {@link android.content.ContentResolver#query ContentResolver.query()}.
    Phng php {@link android.content.ContentResolver#query query()} s gi phng php
    {@link android.content.ContentProvider#query ContentProvider.query()} c nh ngha bi
    Trnh cung cp T in Ngi dng. Cc dng m sau th hin mt lnh gi
    {@link android.content.ContentResolver#query ContentResolver.query()}:
<p>
<pre>
// Queries the user dictionary and returns results
mCursor = getContentResolver().query(
    UserDictionary.Words.CONTENT_URI,   // The content URI of the words table
    mProjection,                        // The columns to return for each row
    mSelectionClause                    // Selection criteria
    mSelectionArgs,                     // Selection criteria
    mSortOrder);                        // The sort order for the returned rows
</pre>
<p>
    Bng 2 cho bit cc tham i ti
    {@link android.content.ContentResolver#query
    query(Uri,projection,selection,selectionArgs,sortOrder)} khp vi mt cu lnh SQL SELECT nh th no:
</p>
<p class="table-caption">
    <strong>Bng 2:</strong> Query() so vi truy vn SQL.
</p>
<table id="table2" style="width: 75%;">
    <tr>
        <th style="width:25%" align="center" scope="col">tham i query()</th>
        <th style="width:25%" align="center" scope="col">T kha/tham s SELECT</th>
        <th style="width:50%" align="center" scope="col">Lu </th>
    </tr>
    <tr>
        <td align="center"><code>Uri</code></td>
        <td align="center"><code>FROM <em>table_name</em></code></td>
        <td><code>Uri</code> nh x ti bng trong trnh cung cp c tn <em>table_name</em>.</td>
    </tr>
    <tr>
        <td align="center"><code>projection</code></td>
        <td align="center"><code><em>col,col,col,...</em></code></td>
        <td>
            <code>projection</code> l mt mng gm cc ct nn c a vo i vi mi hng
            c truy xut.
        </td>
    </tr>
    <tr>
        <td align="center"><code>selection</code></td>
        <td align="center"><code>WHERE <em>col</em> = <em>value</em></code></td>
        <td><code>selection</code> quy nh cc tiu ch  la chn hng.</td>
    </tr>
    <tr>
        <td align="center"><code>selectionArgs</code></td>
        <td align="center">
            (Khng c s tng ng chnh xc. Cc tham i la chn s thay th cc ch dnh sn <code>?</code> trong
            mnh  la chn.)
        </td>
    </tr>
    <tr>
        <td align="center"><code>sortOrder</code></td>
        <td align="center"><code>ORDER BY <em>col,col,...</em></code></td>
        <td>
            <code>sortOrder</code> quy nh th t cc hng xut hin trong
            {@link android.database.Cursor} c tr v.
        </td>
    </tr>
</table>
<h3 id="ContentURIs">URI Ni dung</h3>
<p>
    <strong>URI ni dung</strong> l mt URI xc nh d liu trong mt trnh cung cp. URI ni dung
    bao gm tn biu tng ca ton b trnh cung cp (<strong>quyn</strong> ca n) v mt
    tn tr n mt bng (<strong>ng dn</strong>). Khi bn gi
    mt phng php my khch  truy cp mt bng trong mt trnh cung cp, URI ni dung cho bng l mt trong cc
    tham i.
</p>
<p>
    Trong cc dng m trc, hng s
    {@link android.provider.UserDictionary.Words#CONTENT_URI} cha URI ni dung ca
    bng "t" ca t in ngi dng. i tng {@link android.content.ContentResolver}
    s phn tch quyn ca URI, v s dng n  "gii quyt" trnh cung cp bng cch
    so snh quyn vi mt bng h thng ca cc trnh cung cp  bit. Khi ,
    {@link android.content.ContentResolver} c th phn phi cc tham i truy vn ti ng
    trnh cung cp.
</p>
<p>
    {@link android.content.ContentProvider} s dng phn ng dn ca URI ni dung nhm chn
    bng  truy cp. Trnh cung cp thng c mt <strong>ng dn</strong> cho mi bng m n hin ra.
</p>
<p>
    Trong cc dng m trc, URI y  cho bng "t" l:
</p>
<pre>
content://user_dictionary/words
</pre>
<p>
    trong  xu <code>user_dictionary</code> l quyn ca trnh cung cp, v
xu    <code>words</code> l ng dn ca bng. Xu
    <code>content://</code> (<strong>lc </strong>) s lun c mt,
   v xc nh y l mt URI ni dung.
</p>
<p>
    Nhiu trnh cung cp cho php bn truy cp mt hng n l trong mt bng bng cch ni mt gi tr ID
    vi ui ca URI. V d,  truy xut mt hng c <code>_ID</code> l
    <code>4</code> t mt t in ngi dng, bn c th s dng URI ni dung ny:
</p>
<pre>
Uri singleUri = ContentUris.withAppendedId(UserDictionary.Words.CONTENT_URI,4);
</pre>
<p>
    Bn thng s dng cc gi tr id khi bn  truy xut mt tp hp cc hng, sau  mun cp nht hoc xa
    mt trong s chng.
</p>
<p class="note">
    <strong>Lu :</strong> Cc lp {@link android.net.Uri} v {@link android.net.Uri.Builder}
    cha cc phng php thun tin  xy dng i tng URI nh dng tt t cc xu.
    {@link android.content.ContentUris} cha cc phng php thun tin  ni cc gi tr id vi
    mt URI. on m HTML trc s dng {@link android.content.ContentUris#withAppendedId
withAppendedId()}  ni mt id vi URI ni dung T in Ngi dng.
</p>


    <!-- Retrieving Data from the Provider -->
<h2 id="SimpleQuery">Truy xut D liu t Trnh cung cp</h2>
<p>
    Phn ny m t cch truy xut d liu t mt trnh cung cp bng cch s dng Trnh cung cp T in Ngi dng
    lm v d.
</p>
<p class="note">
     gii thch r, on m HTML trong phn ny gi
    {@link android.content.ContentResolver#query ContentResolver.query()} trn "lung UI"". Tuy nhin, trong
    m thc s, bn nn thc hin cc truy vn khng ng b trn mt lung ring. Mt cch  lm
    iu ny  l s dng lp {@link android.content.CursorLoader}, n c m t chi tit hn
    trong hng dn <a href="{@docRoot}guide/components/loaders.html">
    Trnh ti</a>. Bnh cnh , cc dng m ch l on m HTML; chng khng th hin mt ng dng
    hon chnh.
</p>
<p>
     truy xut d liu t mt trnh cung cp, hy lm theo cc bc c bn sau:
</p>
<ol>
   <li>
        Yu cu quyn truy cp c cho trnh cung cp.
   </li>
   <li>
        nh ngha m  gi mt truy vn ti trnh cung cp.
   </li>
</ol>
<h3 id="RequestPermissions">Yu cu quyn truy cp c</h3>
<p>
     truy xut d liu t mt trnh cung cp, ng dng ca bn cn "quyn truy cp c" cho
    trnh cung cp. Bn khng th yu cu quyn ny trong thi gian chy; thay vo , bn phi ch nh rng
    bn cn quyn ny trong bn k khai ca mnh bng cch s dng phn t
<code><a href="{@docRoot}guide/topics/manifest/uses-permission-element.html">&lt;uses-permission&gt;</a></code>
    v tn quyn chnh xc c nh ngha bi
    trnh cung cp. Khi bn ch nh phn t ny trong bn k khai ca mnh, bn ang thc t ha "yu cu" quyn
    ny cho ng dng ca mnh. Khi ngi dng ci t ng dng ca bn, h ngm hiu cp
    yu cu ny.
</p>
<p>
     tm tn chnh xc ca quyn truy cp c cho trnh cung cp bn ang s dng, cng nh
    tn cho cc quyn truy cp khc c s dng bi trnh truy cp, hy xem trong ti liu
    ca trnh cung cp.
</p>
<p>
    Vai tr ca quyn trong vic truy cp cc trnh cung cp c m t chi tit hn trong phn
    <a href="#Permissions">Quyn ca Trnh cung cp Ni dung</a>.
</p>
<p>
    Trnh cung cp T in Ngi dng s nh ngha quyn
    <code>android.permission.READ_USER_DICTIONARY</code> trong tp bn k khai ca n, v vy mt
    ng dng mun c t trnh cung cp s phi yu cu quyn ny.
</p>
<!-- Constructing the query -->
<h3 id="Query">Xy dng truy vn</h3>
<p>
    Bc tip theo trong vic truy xut d liu t mt trnh cung cp  l xy dng mt truy vn. on m HTML u tin
    ny nh ngha mt s bin cho vic truy cp Trnh cung cp T in Ngi dng:
</p>
<pre class="prettyprint">

// A "projection" defines the columns that will be returned for each row
String[] mProjection =
{
    UserDictionary.Words._ID,    // Contract class constant for the _ID column name
    UserDictionary.Words.WORD,   // Contract class constant for the word column name
    UserDictionary.Words.LOCALE  // Contract class constant for the locale column name
};

// Defines a string to contain the selection clause
String mSelectionClause = null;

// Initializes an array to contain selection arguments
String[] mSelectionArgs = {""};

</pre>
<p>
    on m HTML tip theo cho bit cch s dng
    {@link android.content.ContentResolver#query ContentResolver.query()}, bng cch s dng Trnh cung cp T in
    Ngi dng nh mt v d. Truy vn my khch trnh cung cp tng t nh mt truy vn SQL, v n cha mt
    tp hp cc ct  tr v, mt tp hp cc tiu ch la chn, v mt th t sp xp.
</p>
<p>
    Tp hp cc ct m truy vn cn tr v c gi l <strong>d tho</strong>
    (bin <code>mProjection</code>).
</p>
<p>
    Biu thc  ch nh cc hng cn truy xut s c chia thnh mt mnh  la chn v
    tham i la chn. Mnh  la chn l s kt hp gia cc biu thc l-gic v biu thc Boolean,
    tn ct, v gi tr (bin <code>mSelectionClause</code>). Nu bn ch nh
    tham s thay th c <code>?</code> thay v mt gi tr, phng php truy vn s truy xut gi tr
    t mng tham i la chn (bin <code>mSelectionArgs</code>).
</p>
<p>
    Trong on m HTML tip theo, nu ngi dng khng in t th mnh  la chn c t thnh
    <code>null</code>, v truy vn tr v tt c cc t trong trnh cung cp. Nu ngi dng nhp
    mt t, mnh  la chn c t thnh <code>UserDictionary.Words.WORD + " = ?"</code> v
    phn t u tin ca mng tham i la chn c t thnh t m ngi dng  nhp.
</p>
<pre class="prettyprint">
/*
 * This defines a one-element String array to contain the selection argument.
 */
String[] mSelectionArgs = {""};

// Gets a word from the UI
mSearchString = mSearchWord.getText().toString();

// Remember to insert code here to check for invalid or malicious input.

// If the word is the empty string, gets everything
if (TextUtils.isEmpty(mSearchString)) {
    // Setting the selection clause to null will return all words
    mSelectionClause = null;
    mSelectionArgs[0] = "";

} else {
    // Constructs a selection clause that matches the word that the user entered.
    mSelectionClause = UserDictionary.Words.WORD + " = ?";

    // Moves the user's input string to the selection arguments.
    mSelectionArgs[0] = mSearchString;

}

// Does a query against the table and returns a Cursor object
mCursor = getContentResolver().query(
    UserDictionary.Words.CONTENT_URI,  // The content URI of the words table
    mProjection,                       // The columns to return for each row
    mSelectionClause                   // Either null, or the word the user entered
    mSelectionArgs,                    // Either empty, or the string the user entered
    mSortOrder);                       // The sort order for the returned rows

// Some providers return null if an error occurs, others throw an exception
if (null == mCursor) {
    /*
     * Insert code here to handle the error. Be sure not to use the cursor! You may want to
     * call android.util.Log.e() to log this error.
     *
     */
// If the Cursor is empty, the provider found no matches
} else if (mCursor.getCount() &lt; 1) {

    /*
     * Insert code here to notify the user that the search was unsuccessful. This isn't necessarily
     * an error. You may want to offer the user the option to insert a new row, or re-type the
     * search term.
     */

} else {
    // Insert code here to do something with the results

}
</pre>
<p>
    Truy vn ny tng t nh cu lnh SQL:
</p>
<pre>
SELECT _ID, word, locale FROM words WHERE word = &lt;userinput&gt; ORDER BY word ASC;
</pre>
<p>
    Trong cu lnh SQL ny, tn ct thc t c s dng thay v cc hng s lp hp ng.
</p>
<h4 id="Injection">Bo v trc mc nhp c hi</h4>
<p>
    Nu d liu c qun l bi trnh cung cp ni dung nm trong mt c s d liu SQL, vic in d liu khng c tin cy t bn ngoi
    vo cc cu lnh SQL th c th dn n tim li SQL.
</p>
<p>
    Hy xt mnh  la chn sau:
</p>
<pre>
// Constructs a selection clause by concatenating the user's input to the column name
String mSelectionClause =  "var = " + mUserInput;
</pre>
<p>
    Nu bn lm vy, bn ang cho php ngi dng ghp ni SQL c hi ln cu lnh SQL ca mnh.
    V d, ngi dng c th in "nothing; DROP TABLE *;" cho <code>mUserInput</code>, lm vy
    s dn n mnh  la chn <code>var = nothing; DROP TABLE *;</code>. Do
    mnh  la chn c coi nh mt cu lnh SQL, iu ny c th khin trnh cung cp xa tt c
    bng trong c s d liu SQLite c bn (tr khi trnh cung cp c thit lp  bt nhng ln th
    <a href="http://en.wikipedia.org/wiki/SQL_injection">tim li SQL</a>).
</p>
<p>
     trnh vn  ny, hy s dng mt mnh  la chn m s dng <code>?</code> lm tham s
    thay th c v mt mng cc tham i la chn ring. Khi bn lm nh vy, mc nhp ca ngi dng
    c gn kt trc tip vi truy vn thay v c gii ngha nh mt phn ca cu lnh SQL.
    V n khng c coi nh SQL, mc nhp ca ngi dng khng th tim li SQL c hi. Thay v s dng
    ghp ni  in mc nhp ca ngi dng, hy s dng mnh  la chn ny:
</p>
<pre>
// Constructs a selection clause with a replaceable parameter
String mSelectionClause =  "var = ?";
</pre>
<p>
    Thit lp mng cc tham i la chn nh sau:
</p>
<pre>
// Defines an array to contain the selection arguments
String[] selectionArgs = {""};
</pre>
<p>
    t mt gi tr trong mng cc tham i la chn nh sau:
</p>
<pre>
// Sets the selection argument to the user's input
selectionArgs[0] = mUserInput;
</pre>
<p>
    Mnh  la chn m s dng <code>?</code> nh mt tham s thay th c v mt mng
    cc tham i la chn l cch c u tin  ch nh mt la chn, ngay c khi trnh cung cp khng
    c da trn c s d liu SQL.
</p>
<!-- Displaying the results -->
<h3 id="DisplayResults">Hin th cc kt qu truy vn</h3>
<p>
    Phng php my khch {@link android.content.ContentResolver#query ContentResolver.query()} lun tr v
    mt {@link android.database.Cursor} cha cc ct c ch nh bi d tho ca
    truy vn cho cc hng khp vi cc tiu ch la chn ca truy vn. Mt i tng
    {@link android.database.Cursor} cung cp truy cp c ngu nhin vo cc hng v ct m n
    cha. Bng cch s dng phng php {@link android.database.Cursor}, bn c th lp li cc hng trong
    kt qu, xc nh kiu d liu ca tng ct, ly d liu ra khi ct, v kim tra cc tnh cht khc
    ca kt qu. Mt s trin khai {@link android.database.Cursor} s t ng
    cp nht i tng khi d liu ca trnh cung cp thay i, hoc kch khi cc phng php trong mt i tng quan st
    khi {@link android.database.Cursor} thay i, hoc c hai.
</p>
<p class="note">
    <strong>Lu :</strong> Mt trnh cung cp c th hn ch truy cp vo cc ct da trn tnh cht ca
    i tng thc hin truy vn. V d, Trnh cung cp Danh b hn ch truy cp i vi mt s ct cho
    cc trnh iu hp ng b, v th n s khng tr chng v mt hot ng hay dch v.
</p>
<p>
    Nu khng hng no khp vi cc tiu ch la chn, trnh cung cp
    s tr v mt i tng {@link android.database.Cursor} m trong 
    {@link android.database.Cursor#getCount Cursor.getCount()} bng 0 (con chy trng).
</p>
<p>
    Nu xy ra mt li ni b, cc kt qu ca truy vn s ph thuc vo trnh cung cp c th. N c th
    chn tr v <code>null</code>, hoc n c th a ra mt li {@link java.lang.Exception}.
</p>
<p>
    Do {@link android.database.Cursor} l mt "danh sch" hng, mt cch hay  hin th
    ni dung ca mt {@link android.database.Cursor}  l lin kt n vi mt {@link android.widget.ListView}
    thng qua mt {@link android.widget.SimpleCursorAdapter}.
</p>
<p>
    on m HTML sau tip tc t on m HTML trc. N to mt i tng
    {@link android.widget.SimpleCursorAdapter} cha {@link android.database.Cursor}
    c truy xut bi truy vn, v t i tng ny thnh trnh iu hp cho mt
    {@link android.widget.ListView}:
</p>
<pre class="prettyprint">
// Defines a list of columns to retrieve from the Cursor and load into an output row
String[] mWordListColumns =
{
    UserDictionary.Words.WORD,   // Contract class constant containing the word column name
    UserDictionary.Words.LOCALE  // Contract class constant containing the locale column name
};

// Defines a list of View IDs that will receive the Cursor columns for each row
int[] mWordListItems = { R.id.dictWord, R.id.locale};

// Creates a new SimpleCursorAdapter
mCursorAdapter = new SimpleCursorAdapter(
    getApplicationContext(),               // The application's Context object
    R.layout.wordlistrow,                  // A layout in XML for one row in the ListView
    mCursor,                               // The result from the query
    mWordListColumns,                      // A string array of column names in the cursor
    mWordListItems,                        // An integer array of view IDs in the row layout
    0);                                    // Flags (usually none are needed)

// Sets the adapter for the ListView
mWordList.setAdapter(mCursorAdapter);
</pre>
<p class="note">
    <strong>Lu :</strong>  li {@link android.widget.ListView} bng mt
    {@link android.database.Cursor}, con chy phi cha mt ct c tn <code>_ID</code>.
    V iu ny, truy vn c hin lc trc truy xut ct <code>_ID</code> cho
    bng "t" mc d {@link android.widget.ListView} khng hin th n.
    Hn ch ny cng gii thch l do ti sao phn ln trnh cung cp u c mt ct <code>_ID</code> cho mi
    bng ca n.
</p>

        <!-- Getting data from query results -->
<h3 id="GettingResults">Ly d liu t cc kt qu truy vn</h3>
<p>
    Thay v ch hin th cc kt qu truy vn, bn c th s dng chng cho cc tc v khc. V
    d, bn c th truy xut chnh t t mt t in ngi dng, ri sau  tm kim t  trong
    cc trnh cung cp khc.  lm iu ny, bn lp li cc hng trong {@link android.database.Cursor}:
</p>
<pre class="prettyprint">

// Determine the column index of the column named "word"
int index = mCursor.getColumnIndex(UserDictionary.Words.WORD);

/*
 * Only executes if the cursor is valid. The User Dictionary Provider returns null if
 * an internal error occurs. Other providers may throw an Exception instead of returning null.
 */

if (mCursor != null) {
    /*
     * Moves to the next row in the cursor. Before the first movement in the cursor, the
     * "row pointer" is -1, and if you try to retrieve data at that position you will get an
     * exception.
     */
    while (mCursor.moveToNext()) {

        // Gets the value from the column.
        newWord = mCursor.getString(index);

        // Insert code here to process the retrieved word.

        ...

        // end of while loop
    }
} else {

    // Insert code here to report an error if the cursor is null or the provider threw an exception.
}
</pre>
<p>
    Trin khai {@link android.database.Cursor} s cha mt vi phng php get" 
    truy xut cc kiu d liu khc nhau t i tng. V d, on m HTML trc
    s dng {@link android.database.Cursor#getString getString()}. Chng cng c mt phng php
    {@link android.database.Cursor#getType getType()}  tr v mt gi tr cho bit
    kiu d liu ca ct.
</p>


    <!-- Requesting permissions -->
<h2 id="Permissions">Quyn ca Trnh cung cp Ni dung</h2>
<p>
    ng dng ca mt trnh cung cp c th ch nh cc quyn m ng dng khc c th c 
    truy cp d liu ca trnh cung cp . Nhng quyn ny m bo rng ngi dng bit mt ng dng
    s c gng truy cp d liu no. Da trn cc yu cu ca trnh cung cp, cc ng dng khc
    yu cu quyn m chng cn  truy cp trnh d liu. Ngi dng cui thy cc quyn
    c yu cu khi h ci t ng dng.
</p>
<p>
    Nu ng dng ca mt trnh cung cp khng ch nh bt k quyn no, khi  cc ng dng khc khng c
    quyn truy cp d liu ca trnh cung cp. Tuy nhin, cc thnh phn trong ng dng ca trnh cung cp lun c
    y  quyn truy nhp c v ghi, khng ph thuc vo cc quyn c ch nh.
</p>
<p>
    Nh  lu , Trnh cung cp T in Ngi dng s yu cu
    quyn <code>android.permission.READ_USER_DICTIONARY</code>  truy xut d liu t n.
    Trnh cung cp c quyn <code>android.permission.WRITE_USER_DICTIONARY</code>
    ring  chn, cp nht, hoc xa d liu.
</p>
<p>
     nhn cc quyn cn  truy cp mt trnh cung cp, ng dng yu cu chng bng mt phn t
<code><a href="{@docRoot}guide/topics/manifest/uses-permission-element.html">&lt;uses-permission&gt;</a></code>
    trong tp bn k khai ca n. Khi Trnh qun l Gi Android ci t cc ng dng, ngi dng
    phi ph chun tt c quyn m ng dng yu cu. Nu ngi dng ph chun tt c quyn, khi 
    Trnh qun l Gi s tip tc ci t; nu ngi dng khng ph chun chng, Trnh qun l Gi s
    hy b vic ci t.
</p>
<p>
    Phn t
<code><a href="{@docRoot}guide/topics/manifest/uses-permission-element.html">&lt;uses-permission&gt;</a></code>
    sau yu cu quyn truy cp c vo Trnh cung cp T in Ngi dng:
</p>
<pre>
    &lt;uses-permission android:name="android.permission.READ_USER_DICTIONARY"&gt;
</pre>
<p>
    Tc ng ca cc quyn ti vic truy cp trnh cung cp c gii thch chi tit hn trong
    hng dn <a href="{@docRoot}guide/topics/security/security.html">Bo mt v Quyn</a>.
</p>


<!-- Inserting, Updating, and Deleting Data -->
<h2 id="Modifications">Chn, Cp nht, v Xa D liu</h2>
<p>
    Ging nh cch bn truy xut d liu t mt trnh cung cp, bn cng c th s dng tng tc gia
    mt my khch cung cp v {@link android.content.ContentProvider} ca trnh cung cp  sa i d liu.
    Bn gi mt phng php {@link android.content.ContentResolver} vi cc tham i c chuyn sang
    phng php {@link android.content.ContentProvider} tng ng. Trnh cung cp v
    my khch cung cp s t ng x l bo mt v truyn thng lin tin trnh.
</p>
<h3 id="Inserting">Chn d liu</h3>
<p>
     chn d liu vo mt trnh cung cp, bn gi phng php
    {@link android.content.ContentResolver#insert ContentResolver.insert()}
. Phng php ny chn mt hng mi vo trnh cung cp v tr v mt URI ni dung cho hng .
    on m HTML ny cho bit cch chn mt t mi vo Trnh cung cp T in Ngi dng:
</p>
<pre class="prettyprint">
// Defines a new Uri object that receives the result of the insertion
Uri mNewUri;

...

// Defines an object to contain the new values to insert
ContentValues mNewValues = new ContentValues();

/*
 * Sets the values of each column and inserts the word. The arguments to the "put"
 * method are "column name" and "value"
 */
mNewValues.put(UserDictionary.Words.APP_ID, "example.user");
mNewValues.put(UserDictionary.Words.LOCALE, "en_US");
mNewValues.put(UserDictionary.Words.WORD, "insert");
mNewValues.put(UserDictionary.Words.FREQUENCY, "100");

mNewUri = getContentResolver().insert(
    UserDictionary.Word.CONTENT_URI,   // the user dictionary content URI
    mNewValues                          // the values to insert
);
</pre>
<p>
    D liu cho hng mi i vo trong mt i tng {@link android.content.ContentValues} n l, i tng ny
    c dng tng t nh con chy mt hng. Cc ct trong i tng ny khng cn c
    cng kiu d liu, v nu hon ton khng mun ch nh mt gi tr, bn c th t mt ct
    thnh <code>null</code> bng cch s dng {@link android.content.ContentValues#putNull ContentValues.putNull()}.
</p>
<p>
    on m HTML khng thm ct <code>_ID</code> v ct ny c t ng
    duy tr. Trnh cung cp s gn mt gi tr duy nht <code>_ID</code> cho mi hng c
    thm. Cc trnh cung cp thng s dng gi tr ny lm kha chnh ca bng.
</p>
<p>
    URI ni dung c tr v trong <code>newUri</code> s xc nh hng mi thm, c
    nh dng nh sau:
</p>
<pre>
content://user_dictionary/words/&lt;id_value&gt;
</pre>
<p>
    <code>&lt;id_value&gt;</code> l ni dung ca <code>_ID</code> cho hng mi.
    Hu ht cc trnh cung cp u c th t ng pht hin dng URI ni dung ny ri thc hin thao tc c yu cu
    trn hng c th .
</p>
<p>
     nhn gi tr <code>_ID</code> t {@link android.net.Uri} c tr v, hy gi
    {@link android.content.ContentUris#parseId ContentUris.parseId()}.
</p>
<h3 id="Updating">Cp nht d liu</h3>
<p>
     cp nht mt hng, bn s dng mt i tng {@link android.content.ContentValues} vi cc gi tr
    c cp nht ging nh cch bn lm vi vic chn, v cc tiu ch la chn ging nh cch bn lm vi truy vn.
    Phng php my khch m bn s dng l
    {@link android.content.ContentResolver#update ContentResolver.update()}. Bn ch cn thm
    cc gi tr vo i tng {@link android.content.ContentValues} cho cc ct m bn ang cp nht. Nu bn
    mun xa cc ni dung ca mt ct, hy t gi tr thnh <code>null</code>.
</p>
<p>
    on m HTML sau thay i tt c hng vi ct bn a c ngn ng "en" thnh ct
    c bn a l <code>null</code>. Gi tr tr v l s hng  c cp nht:
</p>
<pre>
// Defines an object to contain the updated values
ContentValues mUpdateValues = new ContentValues();

// Defines selection criteria for the rows you want to update
String mSelectionClause = UserDictionary.Words.LOCALE +  "LIKE ?";
String[] mSelectionArgs = {"en_%"};

// Defines a variable to contain the number of updated rows
int mRowsUpdated = 0;

...

/*
 * Sets the updated value and updates the selected words.
 */
mUpdateValues.putNull(UserDictionary.Words.LOCALE);

mRowsUpdated = getContentResolver().update(
    UserDictionary.Words.CONTENT_URI,   // the user dictionary content URI
    mUpdateValues                       // the columns to update
    mSelectionClause                    // the column to select on
    mSelectionArgs                      // the value to compare to
);
</pre>
<p>
    Bn cng nn thanh lc thng tin u vo ca ngi dng khi gi
    {@link android.content.ContentResolver#update ContentResolver.update()}.  tm hiu thm v
    iu ny, hy c phn <a href="#Injection">Bo v trc mc nhp c hi</a>.
</p>
<h3 id="Deleting">Xa d liu</h3>
<p>
    Xa hng tng t nh truy xut d liu hng: bn ch nh cc tiu ch la chn cho hng
    m bn mun xa v phng php my khch tr v s hng c xa.
    on m HTML sau xa cc hng c appid khp vi "user". Phng php s tr v
    s hng c xa.
</p>
<pre>

// Defines selection criteria for the rows you want to delete
String mSelectionClause = UserDictionary.Words.APP_ID + " LIKE ?";
String[] mSelectionArgs = {"user"};

// Defines a variable to contain the number of rows deleted
int mRowsDeleted = 0;

...

// Deletes the words that match the selection criteria
mRowsDeleted = getContentResolver().delete(
    UserDictionary.Words.CONTENT_URI,   // the user dictionary content URI
    mSelectionClause                    // the column to select on
    mSelectionArgs                      // the value to compare to
);
</pre>
<p>
    Bn cng nn thanh lc thng tin u vo ca ngi dng khi gi
    {@link android.content.ContentResolver#delete ContentResolver.delete()}.  tm hiu thm v
    iu ny, hy c phn <a href="#Injection">Bo v trc mc nhp c hi</a>.
</p>
<!-- Provider Data Types -->
<h2 id="DataTypes">Cc Kiu D liu ca Trnh cung cp</h2>
<p>
    Trnh cung cp ni dung c th cung cp nhiu kiu d liu khc nhau. Trnh cung cp T in Ngi dng ch cung cp
    vn bn, nhng trnh cung cp cng c th cung cp cc nh dng sau:
</p>
    <ul>
        <li>
            integer
        </li>
        <li>
            long integer (long)
        </li>
        <li>
            floating point
        </li>
        <li>
            long floating point (double)
        </li>
    </ul>
<p>
    Mt kiu d liu khc m cc trnh cung cp thng s dng  l Binary Large OBject (BLOB) c trin khai nh mt
    mng 64KB byte. Bn c th xem cc kiu d liu c sn bng cch xem cc phng php "get" lp
    {@link android.database.Cursor}.
</p>
<p>
    Kiu d liu i vi mi ct trong mt trnh cung cp thng c lit k trong ti liu ca trnh cung cp .
    Cc kiu d liu dnh cho Trnh cung cp T in Ngi dng c lit k trong ti liu tham kho
    cho lp hp ng {@link android.provider.UserDictionary.Words} ca n (lp hp ng c
    m t trong phn <a href="#ContractClasses">Cc Lp Hp ng</a>).
    Bn cng c th xc nh kiu d liu bng cch gi {@link android.database.Cursor#getType
    Cursor.getType()}.
</p>
<p>
    Trnh cung cp cng duy tr thng tin v kiu d liu MIME cho mi URI ni dung m chng nh ngha. Bn c th
    s dng thng tin v kiu MIME  tm hiu xem ng dng ca mnh c th x l d liu m
    trnh cung cp a ra hay khng, hoc  chn mt kiu x l da trn kiu MIME. Bn thng cn kiu
    MIME khi ang lm vic vi mt trnh cung cp cha cc cu trc hoc tp
    d liu phc tp. V d, bng {@link android.provider.ContactsContract.Data}
    trong Trnh cung cp Danh b s dng cc kiu MIME  dn nhn kiu d liu lin lc c lu tr trong tng
    hng.  nhn c kiu MIME tng ng vi mt URI ni dung, hy gi
    {@link android.content.ContentResolver#getType ContentResolver.getType()}.
</p>
<p>
    Phn <a href="#MIMETypeReference">Tham kho Kiu MIME</a> m t
    c php ca c kiu MIME tiu chun ln ty chnh.
</p>


<!-- Alternative Forms of Provider Access -->
<h2 id="AltForms">Cc Hnh thc Truy cp Trnh cung cp Thay th</h2>
<p>
    C ba hnh thc truy cp trnh cung cp thay th quan trng trong pht trin ng dng:
</p>
<ul>
    <li>
        <a href="#Batch">Truy cp hng lot</a>: Bn c th to mt lot lnh gi truy cp bng cc phng php trong
        lp {@link android.content.ContentProviderOperation}, ri sau  p dng chng vi
        {@link android.content.ContentResolver#applyBatch ContentResolver.applyBatch()}.
    </li>
    <li>
        Truy vn khng ng b: Bn nn thc hin cc truy vn trong mt lung ring. Mt cch  lm iu ny  l
        s dng mt i tng {@link android.content.CursorLoader}. Cc v d trong
        hng dn <a href="{@docRoot}guide/components/loaders.html">Trnh ti</a> s minh ha
        cch lm iu ny.
    </li>
    <li>
        <a href="#Intents">Truy cp d liu thng qua  nh</a>: Mc d khng th gi mt  nh
        trc tip ti mt trnh cung cp, bn c th gi mt  nh ti ng dng ca trnh cung cp ,
        y thng l cch tt nht  sa i d liu ca trnh cung cp.
    </li>
</ul>
<p>
    Truy cp hng lot v sa i thng qua  nh c m t trong cc phn sau.
</p>
<h3 id="Batch">Truy cp hng lot</h3>
<p>
    Truy cp hng lot vo mt trnh cung cp l cch hu ch  chn nhiu hng, hoc  chn
    cc hng vo nhiu bng trong cng lnh gi phng php, hoc nhn chung  thc hin mt tp hp
    thao tc qua cc ranh gii tin trnh nh mt giao tc (thao tc nguyn t).
</p>
<p>
     truy cp mt trnh cung cp trong "ch  hng lot",
    bn to mt mng i tng {@link android.content.ContentProviderOperation} ri
    phn phi chng ti mt trnh cung cp ni dung bng
    {@link android.content.ContentResolver#applyBatch ContentResolver.applyBatch()}. Bn chuyn
    <em>quyn</em> ca trnh cung cp ni dung cho phng php ny thay v mt URI ni dung c th.
iu ny cho php i tng {@link android.content.ContentProviderOperation} trong mng c tc dng
    i vi mt bng khc. Mt lnh gi ti {@link android.content.ContentResolver#applyBatch
    ContentResolver.applyBatch()} tr v mt mng kt qu.
</p>
<p>
    M t lp hp ng {@link android.provider.ContactsContract.RawContacts}
    bao gm mt on m HTML th hin vic chn hng lot. ng dng mu
    <a href="{@docRoot}resources/samples/ContactManager/index.html">Trnh qun l Danh b</a>
    c mt v d v truy cp hng lot trong tp ngun <code>ContactAdder.java</code>
    ca n.
</p>
<div class="sidebox-wrapper">
<div class="sidebox">
<h2>Hin th d liu bng cch s dng mt ng dng trnh tr gip.</h2>
<p>
    Nu ng dng ca bn <em>c</em> quyn truy cp, bn vn c th cn s dng mt
     nh  hin th d liu trong mt ng dng khc. V d, ng dng Lch chp nhn mt
     nh {@link android.content.Intent#ACTION_VIEW}, nhm hin th mt ngy hoc s kin c th.
    iu ny cho php bn hin th thng tin lch m khng phi to UI ca chnh mnh.
     tm hiu thm v tnh nng ny, hy xem
    hng dn <a href="{@docRoot}guide/topics/providers/calendar-provider.html">Trnh cung cp Lch</a>.
</p>
<p>
    ng dng m bn gi  nh n khng nht thit phi l ng dng
    c lin kt vi trnh cung cp. V d, bn c th truy xut mt lin lc t
    Trnh cung cp Danh b, ri gi mt  nh {@link android.content.Intent#ACTION_VIEW}
    cha URI ni dung cho hnh nh lin lc ti mt trnh xem nh.
</p>
</div>
</div>
<h3 id="Intents">Truy cp d liu thng qua  nh</h3>
<p>
     nh c th cho php truy cp gin tip vo mt trnh cung cp ni dung. Bn cho php ngi dng truy cp
    d liu trong mt trnh cung cp ngay c khi ng dng ca bn khng c quyn truy cp, hoc bng cch
    nhn li mt  nh kt qu t mt ng dng c quyn, hoc bng cch kch hot mt
    ng dng c php v cho php ngi dng c lm vic trong n.
</p>
<h4>c truy cp vi cc quyn tm thi</h4>
<p>
    Bn c th truy cp d liu trong mt trnh cung cp ni dung, ngay c khi bn khng c quyn
    truy nhp ph hp, bng cch gi mt  nh ti mt ng dng c quyn v
    nhn li mt  nh kt qu cha quyn "URI".
    y l nhng quyn cho mt URI ni dung c th ko di ti khi hot ng nhn chng
    c hon thnh. ng dng c quyn lu di s cp quyn tm thi
    bng cch t mt c trong  nh kt qu:
</p>
<ul>
    <li>
        <strong>Quyn c:</strong>
        {@link android.content.Intent#FLAG_GRANT_READ_URI_PERMISSION}
    </li>
    <li>
        <strong>Quyn ghi:</strong>
        {@link android.content.Intent#FLAG_GRANT_WRITE_URI_PERMISSION}
    </li>
</ul>
<p class="note">
    <strong>Lu :</strong> Nhng c ny khng cp quyn truy cp c v ghi ni chung cho trnh cung cp
    m c quyn c cha trong URI ni dung. Quyn truy cp ny ch p dng cho chnh URI .
</p>
<p>
    Trnh cung cp s nh ngha quyn URI cho cc URI ni dung trong bn k khai ca n, bng cch s dng thuc tnh
<code><a href="{@docRoot}guide/topics/manifest/provider-element.html#gprmsn">android:grantUriPermission</a></code>
    ca phn t
<code><a href="{@docRoot}guide/topics/manifest/provider-element.html">&lt;provider&gt;</a></code>
    cng nh phn t con
<code><a href="{@docRoot}guide/topics/manifest/grant-uri-permission-element.html">&lt;grant-uri-permission&gt;</a></code>
    ca phn t
<code><a href="{@docRoot}guide/topics/manifest/provider-element.html">&lt;provider&gt;</a></code>
    . C ch cp quyn URI ny c gii thch chi tit hn trong
    hng dn <a href="{@docRoot}guide/topics/security/security.html">Bo mt v Quyn</a>,
    trong phn "Quyn URI".
</p>
<p>
    V d, bn c th truy xut d liu cho mt lin lc trong Trnh cung cp Danh b, ngay c khi bn khng
    c quyn {@link android.Manifest.permission#READ_CONTACTS}. Bn c th mun thc hin iu ny
    trong mt ng dng gi thip mng in t ti mt lin lc vo ngy sinh nht ca ngi . Thay v
    yu cu {@link android.Manifest.permission#READ_CONTACTS}, l ni cp cho bn quyn truy cp tt c lin lc
    ca ngi dng v tt c thng tin ca h, bn nn cho php ngi dng kim sot nhng lin lc
    no c s dng bi ng dng ca bn.  lm iu ny, bn s dng tin trnh sau:
</p>
<ol>
    <li>
        ng dng ca bn gi mt  nh cha hnh ng
        {@link android.content.Intent#ACTION_PICK} v kiu MIME "danh b"
{@link android.provider.ContactsContract.RawContacts#CONTENT_ITEM_TYPE}, bng cch s dng
        phng php {@link android.app.Activity#startActivityForResult
        startActivityForResult()}.
    </li>
    <li>
        V  nh ny khp vi b lc  nh cho hot ng
        "la chn" ca ng dng Danh b, hot ng s i n tin cnh.
    </li>
    <li>
        Trong hot ng la chn, ngi dng chn mt
        lin lc  cp nht. Khi iu ny xy ra, hot ng la chn s gi
        {@link android.app.Activity#setResult setResult(resultcode, intent)}
         thit lp mt  nh nhm gi li ng dng ca bn.  nh cha URI ni dung
        ca lin lc m ngi dng  chn, v cc c "ph thm"
        {@link android.content.Intent#FLAG_GRANT_READ_URI_PERMISSION}. Nhng c ny cp quyn URI
        cho ng dng ca bn  c d liu cho lin lc c tr n bi
        URI ni dung. Sau , hot ng la chn gi {@link android.app.Activity#finish()} 
        tr kim sot v ng dng ca bn.
    </li>
    <li>
        Hot ng ca bn tr v tin cnh, v h thng s gi phng php
        {@link android.app.Activity#onActivityResult onActivityResult()}
        ca hot ng ca bn. Phng php ny nhn c  nh kt qu do hot ng la chn to trong
        ng dng Danh b.
    </li>
    <li>
        Vi URI ni dung t  nh kt qu, bn c th c d liu ca lin lc
        t Trnh cung cp Danh b, ngay c khi bn khng yu cu quyn truy cp c lu di
        vo trnh cung cp trong bn k khai ca mnh. Sau , bn c th nhn thng tin ngy sinh ca lin lc
        hoc a ch e-mail ca ngi  ri gi thip mng in t.
    </li>
</ol>
<h4>S dng mt ng dng khc</h4>
<p>
    Mt cch n gin  cho php ngi dng sa i d liu m bn khng c quyn truy cp  l
    kch hot mt ng dng c quyn v cho php ngi dng lm vic  .
</p>
<p>
    V d, ng dng Lch chp nhn mt
     nh {@link android.content.Intent#ACTION_INSERT}, n cho php bn kch hot UI chn
    ca ng dng. Bn c th chuyn d liu "ph thm" trong  nh ny m c ng dng s dng
     in trc vo UI. V cc s kin nh k c c php phc tp, cch
    u tin  chn s kin vo Trnh cung cp Lch  l kch hot ng dng Lch vi mt
    {@link android.content.Intent#ACTION_INSERT} ri  ngi dng chn s kin ti .
</p>
<!-- Contract Classes -->
<h2 id="ContractClasses">Cc Lp Hp ng</h2>
<p>
    Lp hp ng nh ngha cc hng s s gip ng dng hot ng vi cc URI ni dung, tn
    ct, hnh ng  nh, v cc tnh nng khc ca mt trnh cung cp ni dung. Cc lp hp ng khng
    c t ng a vo cng mt trnh cung cp; nh pht trin ca trnh cung cp phi nh ngha chng ri
    cung cp chng cho cc nh pht trin khc. Nhiu trnh cung cp c bao gm cng vi nn tng
    Android c cc lp hp ng tng ng trong gi {@link android.provider}.
</p>
<p>
    V d, Trnh cung cp T in Ngi dng c mt lp hp ng
    {@link android.provider.UserDictionary} cha cc hng s URI ni dung v tn ct. URI ni dung
    i vi bng "t" c nh ngha trong hng s
    {@link android.provider.UserDictionary.Words#CONTENT_URI UserDictionary.Words.CONTENT_URI}.
    Lp {@link android.provider.UserDictionary.Words} cng cha cc hng s tn ct,
    chng c s dng trong on m HTML mu trong hng dn ny. V d, mt d tho truy vn c th c
    nh ngha l:
</p>
<pre>
String[] mProjection =
{
    UserDictionary.Words._ID,
    UserDictionary.Words.WORD,
    UserDictionary.Words.LOCALE
};
</pre>
<p>
    Mt lp hp ng khc l {@link android.provider.ContactsContract} dnh cho Trnh cung cp Danh b.
    Ti liu tham kho cho lp ny bao gm cc on m HTML mu. Mt trong s cc
    lp con ca n, {@link android.provider.ContactsContract.Intents.Insert}, l mt lp hp ng
    cha cc hng s cho  nh v d liu  nh.
</p>


<!-- MIME Type Reference -->
<h2 id="MIMETypeReference">Tham kho Kiu MIME</h2>
<p>
    Trnh cung cp ni dung c th tr v cc kiu phng tin MIME tiu chun, hoc xu kiu MIME ty chnh, hoc c hai.
</p>
<p>
    Cc kiu MIME c nh dng
</p>
<pre>
<em>type</em>/<em>subtype</em>
</pre>
<p>
    V d, kiu MIME thng dng <code>text/html</code> c kiu <code>text</code> v
    kiu con <code>html</code>. Nu trnh cung cp tr v loi ny cho mt URI, iu  c ngha rng mt
    truy vn ang s dng URI  s tr v vn bn cha th HTML.
</p>
<p>
    Cc xu kiu MIME ty chnh, cn gi l kiu MIME "theo nh cung cp", c cc gi tr
    <em>kiu</em> v <em>kiu con</em> phc tp hn. Gi tr <em>kiu</em> lun lun
</p>
<pre>
vnd.android.cursor.<strong>dir</strong>
</pre>
<p>
    p dng cho nhiu hng, hoc
</p>
<pre>
vnd.android.cursor.<strong>item</strong>
</pre>
<p>
    p dng cho mt hng.
</p>
<p>
    Gi tr <em>kiu con</em> p dng theo trnh cung cp. Cc trnh cung cp c tch hp trong Android thng c mt kiu con
    n gin. V d, khi ng dng Danh b to mt hng cho mt s in thoi,
    n t kiu MIME sau trong hng:
</p>
<pre>
vnd.android.cursor.item/phone_v2
</pre>
<p>
      rng gi tr kiu con n gin l <code>phone_v2</code>.
</p>
<p>
    Cc nh pht trin trnh cung cp khc c th to mu hnh kiu con ca ring mnh da trn quyn
    v tn bng ca trnh cung cp. V d, xt mt trnh cung cp cha cc biu thi gian lch tu.
    Quyn ca trnh cung cp l <code>com.example.trains</code>, v n cha cc bng
    Line1, Line2, v Line3.  phn hi li URI ni dung
</p>
<p>
<pre>
content://com.example.trains/Line1
</pre>
<p>
    i vi bng Line1, trnh cung cp tr v kiu MIME
</p>
<pre>
vnd.android.cursor.<strong>dir</strong>/vnd.example.line1
</pre>
<p>
      phn hi li URI ni dung
</p>
<pre>
content://com.example.trains/Line2/5
</pre>
<p>
    i vi hng 5 trong bng Line2, trnh cung cp tr v kiu MIME
</p>
<pre>
vnd.android.cursor.<strong>item</strong>/vnd.example.line2
</pre>
<p>
    Hu ht cc trnh cung cp ni dung u nh ngha hng s lp hp ng cho cc kiu MIME m chng s dng. V d nh lp hp ng
    ca Trnh cung cp Danh b {@link android.provider.ContactsContract.RawContacts},
    s nh ngha hng s
    {@link android.provider.ContactsContract.RawContacts#CONTENT_ITEM_TYPE} cho kiu MIME ca
    mt hng lin lc th duy nht.
</p>
<p>
    Cc URI ni dung i vi hng duy nht c m t trong phn
    <a href="#ContentURIs">URI ni dung</a>.
</p>