guide/components/recents.jd

page.title=Mn hnh Tng quan
page.tags="recents","overview"

@jd:body

<div id="qv-wrapper">
<div id="qv">

  <h2>Trong ti liu ny</h2>
  <ol>
    <li><a href="#adding">Thm Tc v vo Mn hnh Tng quan</a>
      <ol>
        <li><a href="#flag-new-doc">S dng c  nh  thm mt tc v</a></li>
        <li><a href="#attr-doclaunch">S dng thuc tnh Hot ng  thm mt tc v</a></li>
      </ol>
    </li>
    <li><a href="#removing">Loi b Tc v</a>
      <ol>
        <li><a href="#apptask-remove">S dng lp AppTask  loi b tc v</a></li>
        <li><a href="#retain-finished">Gi li tc v  hon thnh</a></li>
      </ol>
    </li>
  </ol>

  <h2>Lp kha</h2>
  <ol>
    <li>{@link android.app.ActivityManager.AppTask}</li>
    <li>{@link android.content.Intent}</li>
  </ol>

  <h2>M mu</h2>
  <ol>
    <li><a href="{@docRoot}samples/DocumentCentricApps/index.html">ng dng tp trung vo ti liu</a></li>
  </ol>

</div>
</div>

<p>Mn hnh tng quan (cn c gi l mn hnh gn y, danh sch tc v gn y, hay ng dng gn y)
l mt UI cp h thng lit k cc <a href="{@docRoot}guide/components/activities.html">
hot ng</a> v <a href="{@docRoot}guide/components/tasks-and-back-stack.html">tc v</a> mi c truy cp gn y. Ngi dng
c th iu hng qua danh sch ny v chn mt tc v  tip tc, hoc ngi dng c th loi b mt tc v khi
danh sch bng cch trt nhanh n i. Vi vic pht hnh Android 5.0 (API mc 21), nhiu thc th ca
hot ng tng t cha cc ti liu khc nhau c th xut hin di dng cc tc v trong mn hnh tng quan. V d,
Google Drive c th c mt tc v cho tng ti liu trong mt vi ti liu Google. Mi ti liu xut hin thnh mt
tc v trong mn hnh tng quan.</p>

<img src="{@docRoot}images/components/recents.png" alt="" width="284" />
<p class="img-caption"><strong>Hnh 1.</strong> Mn hnh tng quan hin th ba ti liu Google Drive
, mi ti liu c biu din nh mt tc v ring.</p>

<p>Thng th bn s cho php h thng nh ngha cch tc v v
hot ng ca mnh c biu din nh th no trong mn hnh tng quan, v bn khng cn sa i hnh vi ny.
Tuy nhin, ng dng ca bn c th xc nh cch thc v thi gian cc hot ng xut hin trong mn hnh tng quan. Lp
{@link android.app.ActivityManager.AppTask} cho php bn qun l tc v, v c hot ng ca
lp {@link android.content.Intent} cho php bn quy nh khi no th mt hot ng c thm hoc loi b khi
mn hnh tng quan. ng thi, thuc tnh <code><a href="{@docRoot}guide/topics/manifest/activity-element.html">
&lt;activity&gt;</a></code> cho php bn t hnh vi trong bn k khai.</p>

<h2 id="adding">Thm Tc v vo Mn hnh Tng quan</h2>

<p>S dng c ca lp {@link android.content.Intent}  thm mt tc v cho php kim sot nhiu hn
i vi thi im v cch thc mt ti liu c m hoc m li trong mn hnh tng quan. Khi s dng cc thuc tnh
<code><a href="{@docRoot}guide/topics/manifest/activity-element.html">&lt;activity&gt;</a></code>
, bn c th chn gia lun m ti liu trong mt tc v mi hoc s dng li mt
tc v hin c cho ti liu.</p>

<h3 id="flag-new-doc">S dng c  nh  thm mt tc v</h3>

<p>Khi to mt ti liu mi cho hot ng ca bn, bn gi phng php
{@link android.app.ActivityManager.AppTask#startActivity(android.content.Context, android.content.Intent, android.os.Bundle) startActivity()}
ca lp {@link android.app.ActivityManager.AppTask}, chuyn cho n  nh c
chc nng khi chy hot ng.  chn mt ngt l-gic sao cho h thng coi hot ng ca bn nh mt tc v
mi trong mn hnh tng quan, hy chuyn c {@link android.content.Intent#FLAG_ACTIVITY_NEW_DOCUMENT}
trong phng php {@link android.content.Intent#addFlags(int) addFlags()} ca {@link android.content.Intent}
c chc nng khi chy hot ng.</p>

<p class="note"><strong>Lu :</strong> C {@link android.content.Intent#FLAG_ACTIVITY_NEW_DOCUMENT}
thay th c {@link android.content.Intent#FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET},
c rt bt k t phin bn Android 5.0 (API mc 21).</p>

<p>Nu bn t c {@link android.content.Intent#FLAG_ACTIVITY_MULTIPLE_TASK} khi to
ti liu mi, h thng s lun to mt tc v mi ly hot ng mc tiu  lm gc.
Thit t ny cho php m cng ti liu trong nhiu hn mt tc v. on m sau th hin
cch m hot ng chnh thc hin iu ny:</p>

<p class="code-caption"><a href="{@docRoot}samples/DocumentCentricApps/index.html">
DocumentCentricActivity.java</a></p>
<pre>
public void createNewDocument(View view) {
      final Intent newDocumentIntent = newDocumentIntent();
      if (useMultipleTasks) {
          newDocumentIntent.addFlags(Intent.FLAG_ACTIVITY_MULTIPLE_TASK);
      }
      startActivity(newDocumentIntent);
  }

  private Intent newDocumentIntent() {
      boolean useMultipleTasks = mCheckbox.isChecked();
      final Intent newDocumentIntent = new Intent(this, NewDocumentActivity.class);
      newDocumentIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_DOCUMENT);
      newDocumentIntent.putExtra(KEY_EXTRA_NEW_DOCUMENT_COUNTER, incrementAndGet());
      return newDocumentIntent;
  }

  private static int incrementAndGet() {
      Log.d(TAG, "incrementAndGet(): " + mDocumentCounter);
      return mDocumentCounter++;
  }
}
</pre>

<p class="note"><strong>Lu :</strong> Cc hot ng c khi chy bng c {@code FLAG_ACTIVITY_NEW_DOCUMENT}
phi c gi tr thuc tnh {@code android:launchMode="standard"} (mc nh) c t trong
bn k khai.</p>

<p>Khi hot ng chnh khi chy mt hot ng mi, h thng s tm kim thng qua cc tc v hin ti
xem tc v no c  nh khp vi tn thnh phn  nh v d liu  nh cho hot ng . Nu tc v
khng c tm thy, hoc  nh cha c {@link android.content.Intent#FLAG_ACTIVITY_MULTIPLE_TASK}
th mt tc v mi s c to ly hot ng lm gc. Nu tm thy, n s mang tc v
ti pha trc v chuyn  nh mi ti {@link android.app.Activity#onNewIntent onNewIntent()}.
Hot ng mi s nhn  nh v to mt ti liu mi trong mn hnh tng quan, nh trong v d
sau:</p>

<p class="code-caption"><a href="{@docRoot}samples/DocumentCentricApps/index.html">
NewDocumentActivity.java</a></p>
<pre>
&#64;Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_new_document);
    mDocumentCount = getIntent()
            .getIntExtra(DocumentCentricActivity.KEY_EXTRA_NEW_DOCUMENT_COUNTER, 0);
    mDocumentCounterTextView = (TextView) findViewById(
            R.id.hello_new_document_text_view);
    setDocumentCounterText(R.string.hello_new_document_counter);
}

&#64;Override
protected void onNewIntent(Intent intent) {
    super.onNewIntent(intent);
    /* If FLAG_ACTIVITY_MULTIPLE_TASK has not been used, this activity
    is reused to create a new document.
     */
    setDocumentCounterText(R.string.reusing_document_counter);
}
</pre>


<h3 id="#attr-doclaunch">S dng thuc tnh hot ng  thm mt tc v</h3>

<p>Mt hot ng cng c th quy nh trong bn k khai ca n rng n lun khi chy vo mt tc v mi bng cch s dng
thuc tnh <code><a href="{@docRoot}guide/topics/manifest/activity-element.html">&lt;activity&gt;</a></code>
, <a href="{@docRoot}guide/topics/manifest/activity-element.html#dlmode">
{@code android:documentLaunchMode}</a>. Thuc tnh ny c bn gi tr to ra hiu ng
sau khi ngi dng m mt ti liu bng ng dng:</p>

<dl>
  <dt>"{@code intoExisting}"</dt>
  <dd>Hot ng s dng li mt tc v hin c cho ti liu. iu ny ging nh khi thit t c
  {@link android.content.Intent#FLAG_ACTIVITY_NEW_DOCUMENT} m <em>khng</em> thit t c
  {@link android.content.Intent#FLAG_ACTIVITY_MULTIPLE_TASK}, nh c m t trong phn
  <a href="#flag-new-doc">S dng c  nh  thm mt tc v</a> bn trn.</dd>

  <dt>"{@code always}"</dt>
  <dd>Hot ng to mt tc v mi cho ti liu, ngay c khi ti liu  c m. S dng
  gi tr ny ging nh thit t c c {@link android.content.Intent#FLAG_ACTIVITY_NEW_DOCUMENT}
  v {@link android.content.Intent#FLAG_ACTIVITY_MULTIPLE_TASK}.</dd>

  <dt>"{@code none}"</dt>
  <dd>Hot ng khng to mt tc v mi cho ti liu. Mn hnh tng quan x l hot ng
  nh theo mc nh: n hin th mt tc v n l cho ng dng, tc v ny
  tip tc t bt k hot ng no m ngi dng  gi ra cui cng.</dd>

  <dt>"{@code never}"</dt>
  <dd>Hot ng khng to mt tc v mi cho ti liu. Vic thit t gi tr ny s khng ch
  hnh vi ca {@link android.content.Intent#FLAG_ACTIVITY_NEW_DOCUMENT}
  v c {@link android.content.Intent#FLAG_ACTIVITY_MULTIPLE_TASK}, nu mt trong hai c t
  trong  nh, v mn hnh tng quan s hin th mt tc v n l cho ng dng, tc v ny tip tc t
  bt k hot ng no m ngi dng  gi ra cui cng.</dd>
</dl>

<p class="note"><strong>Lu :</strong> i vi nhng gi tr ngoi {@code none} v {@code never}
hot ng phi c nh ngha bng {@code launchMode="standard"}. Nu thuc tnh ny khng c quy nh th
{@code documentLaunchMode="none"} s c s dng.</p>

<h2 id="removing">Loi b Tc v</h2>

<p>Theo mc nh, mt tc v ti liu s t ng c loi b khi mn hnh tng quan khi hot ng ca n
hon thnh. Bn c th khng ch hnh vi ny bng lp {@link android.app.ActivityManager.AppTask},
bng mt c {@link android.content.Intent}, hoc bng mt thuc tnh<code><a href="{@docRoot}guide/topics/manifest/activity-element.html">
&lt;activity&gt;</a></code>.</p>

<p>Bn c th lun loi tr hon ton mt tc v khi mn hnh tng quan bng cch thit t thuc tnh
<code><a href="{@docRoot}guide/topics/manifest/activity-element.html">&lt;activity&gt;</a></code>
, <a href="{@docRoot}guide/topics/manifest/activity-element.html#exclude">
{@code android:excludeFromRecents}</a> thnh {@code true}.</p>

<p>Bn c th thit t s lng tc v ti a m ng dng ca bn c th bao gm trong mn hnh tng quan bng cch t thuc tnh
 <code><a href="{@docRoot}guide/topics/manifest/activity-element.html">&lt;activity&gt;</a></code>
 <a href="{@docRoot}guide/topics/manifest/activity-element.html#maxrecents">{@code android:maxRecents}
</a> thnh mt gi tr s nguyn. Mc nh l 16. Khi t c s tc v ti a,
tc v t s dng gn y nht s b loi b khi mn hnh tng quan. Gi tr ti a {@code android:maxRecents}
bng 50 (25 trn cc thit b c b nh thp); gi tr thp hn 1 khng hp l.</p>

<h3 id="#apptask-remove">S dng lp AppTask  loi b tc v</h3>

<p>Trong hot ng m to mt tc v mi trong mn hnh tng quan, bn c th
quy nh khi no th loi b tc v v hon thnh tt c cc hot ng gn lin vi n bng cch gi
phng php {@link android.app.ActivityManager.AppTask#finishAndRemoveTask() finishAndRemoveTask()}.</p>

<p class="code-caption"><a href="{@docRoot}samples/DocumentCentricApps/index.html">
NewDocumentActivity.java</a></p>
<pre>
public void onRemoveFromRecents(View view) {
    // The document is no longer needed; remove its task.
    finishAndRemoveTask();
}
</pre>

<p class="note"><strong>Lu :</strong> S dng phng php
{@link android.app.ActivityManager.AppTask#finishAndRemoveTask() finishAndRemoveTask()}
s khng ch vic s dng tag {@link android.content.Intent#FLAG_ACTIVITY_RETAIN_IN_RECENTS},
nh c trnh by  bn di.</p>

<h3 id="#retain-finished">Gi li tc v  hon thnh</h3>

<p>Nu bn mun gi li mt tc v trong mn hnh tng quan, ngay c khi hot ng ca n  hon thnh, hy chuyn
c {@link android.content.Intent#FLAG_ACTIVITY_RETAIN_IN_RECENTS} trong phng php
{@link android.content.Intent#addFlags(int) addFlags()} ca  nh m khi chy hot ng.</p>

<p class="code-caption"><a href="{@docRoot}samples/DocumentCentricApps/index.html">
DocumentCentricActivity.java</a></p>
<pre>
private Intent newDocumentIntent() {
    final Intent newDocumentIntent = new Intent(this, NewDocumentActivity.class);
    newDocumentIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_DOCUMENT |
      android.content.Intent.FLAG_ACTIVITY_RETAIN_IN_RECENTS);
    newDocumentIntent.putExtra(KEY_EXTRA_NEW_DOCUMENT_COUNTER, incrementAndGet());
    return newDocumentIntent;
}
</pre>

<p> t c cng kt qu nh vy, hy t thuc tnh
<code><a href="{@docRoot}guide/topics/manifest/activity-element.html">&lt;activity&gt;</a></code>
<a href="{@docRoot}guide/topics/manifest/activity-element.html#autoremrecents">
{@code android:autoRemoveFromRecents}</a> thnh {@code false}. Gi tr mc nh bng {@code true}
i vi cc hot ng ti liu, v {@code false} i vi cc hot ng thng thng. Vic s dng thuc tnh ny s khng ch
c {@link android.content.Intent#FLAG_ACTIVITY_RETAIN_IN_RECENTS}, nh  trnh by trc .</p>