1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2 <!--NewPage--> 3 <HTML> 4 <HEAD> 5 <!-- Generated by javadoc (build 1.5.0_16) on Mon Oct 12 16:11:19 PDT 2009 --> 6 <TITLE> 7 Scope 8 </TITLE> 9 10 <META NAME="keywords" CONTENT="javax.inject.Scope class"> 11 12 <LINK REL ="stylesheet" TYPE="text/css" HREF="../../stylesheet.css" TITLE="Style"> 13 14 <SCRIPT type="text/javascript"> 15 function windowTitle() 16 { 17 parent.document.title="Scope"; 18 } 19 </SCRIPT> 20 <NOSCRIPT> 21 </NOSCRIPT> 22 23 </HEAD> 24 25 <BODY BGCOLOR="white" onload="windowTitle();"> 26 27 28 <!-- ========= START OF TOP NAVBAR ======= --> 29 <A NAME="navbar_top"><!-- --></A> 30 <A HREF="#skip-navbar_top" title="Skip navigation links"></A> 31 <TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY=""> 32 <TR> 33 <TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> 34 <A NAME="navbar_top_firstrow"><!-- --></A> 35 <TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY=""> 36 <TR ALIGN="center" VALIGN="top"> 37 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../javax/inject/package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A> </TD> 38 <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT> </TD> 39 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A> </TD> 40 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A> </TD> 41 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A> </TD> 42 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A> </TD> 43 </TR> 44 </TABLE> 45 </TD> 46 <TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM> 47 </EM> 48 </TD> 49 </TR> 50 51 <TR> 52 <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> 53 <A HREF="../../javax/inject/Qualifier.html" title="annotation in javax.inject"><B>PREV CLASS</B></A> 54 <A HREF="../../javax/inject/Singleton.html" title="annotation in javax.inject"><B>NEXT CLASS</B></A></FONT></TD> 55 <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> 56 <A HREF="../../index.html?javax/inject/Scope.html" target="_top"><B>FRAMES</B></A> 57 <A HREF="Scope.html" target="_top"><B>NO FRAMES</B></A> 58 <SCRIPT type="text/javascript"> 59 <!-- 60 if(window==top) { 61 document.writeln('<A HREF="../../allclasses-noframe.html"><B>All Classes</B></A>'); 62 } 63 //--> 64 </SCRIPT> 65 <NOSCRIPT> 66 <A HREF="../../allclasses-noframe.html"><B>All Classes</B></A> 67 </NOSCRIPT> 68 69 70 </FONT></TD> 71 </TR> 72 <TR> 73 <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> 74 SUMMARY: REQUIRED | OPTIONAL</FONT></TD> 75 <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> 76 DETAIL: ELEMENT</FONT></TD> 77 </TR> 78 </TABLE> 79 <A NAME="skip-navbar_top"></A> 80 <!-- ========= END OF TOP NAVBAR ========= --> 81 82 <HR> 83 <!-- ======== START OF CLASS DATA ======== --> 84 <H2> 85 <FONT SIZE="-1"> 86 javax.inject</FONT> 87 <BR> 88 Annotation Type Scope</H2> 89 <HR> 90 <DL> 91 <DT><PRE><FONT SIZE="-1">@Target(value=ANNOTATION_TYPE) 92 @Retention(value=RUNTIME) 93 @Documented 94 </FONT>public @interface <B>Scope</B></DL> 95 </PRE> 96 97 <P> 98 Identifies scope annotations. A scope annotation applies to a class 99 containing an injectable constructor and governs how the injector reuses 100 instances of the type. By default, if no scope annotation is present, the 101 injector creates an instance (by injecting the type's constructor), uses 102 the instance for one injection, and then forgets it. If a scope annotation 103 is present, the injector may retain the instance for possible reuse in a 104 later injection. If multiple threads can access a scoped instance, its 105 implementation should be thread safe. The implementation of the scope 106 itself is left up to the injector. 107 108 <p>In the following example, the scope annotation <code>@Singleton</code> ensures 109 that we only have one Log instance: 110 111 <pre> 112 @Singleton 113 class Log { 114 void log(String message) { ... } 115 }</pre> 116 117 <p>The injector generates an error if it encounters more than one scope 118 annotation on the same class or a scope annotation it doesn't support. 119 120 <p>A scope annotation: 121 <ul> 122 <li>is annotated with <code>@Scope</code>, <code>@Retention(RUNTIME)</code>, 123 and typically <code>@Documented</code>.</li> 124 <li>should not have attributes.</li> 125 <li>is typically not <code>@Inherited</code>, so scoping is orthogonal to 126 implementation inheritance.</li> 127 <li>may have restricted usage if annotated with <code>@Target</code>. While 128 this specification covers applying scopes to classes only, some 129 injector configurations might use scope annotations 130 in other places (on factory method results for example).</li> 131 </ul> 132 133 <p>For example: 134 135 <pre> 136 @java.lang.annotation.Documented 137 @java.lang.annotation.Retention(RUNTIME) 138 @javax.inject.Scope 139 public @interface RequestScoped {}</pre> 140 141 <p>Annotating scope annotations with <code>@Scope</code> helps the injector 142 detect the case where a programmer used the scope annotation on a class but 143 forgot to configure the scope in the injector. A conservative injector 144 would generate an error rather than not apply a scope. 145 <P> 146 147 <P> 148 <DL> 149 <DT><B>See Also:</B><DD><A HREF="../../javax/inject/Singleton.html" title="annotation in javax.inject"><CODE>@Singleton</CODE></A></DL> 150 151 <P> 152 153 <P> 154 <!-- ========= END OF CLASS DATA ========= --> 155 <HR> 156 157 158 <!-- ======= START OF BOTTOM NAVBAR ====== --> 159 <A NAME="navbar_bottom"><!-- --></A> 160 <A HREF="#skip-navbar_bottom" title="Skip navigation links"></A> 161 <TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY=""> 162 <TR> 163 <TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> 164 <A NAME="navbar_bottom_firstrow"><!-- --></A> 165 <TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY=""> 166 <TR ALIGN="center" VALIGN="top"> 167 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../javax/inject/package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A> </TD> 168 <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT> </TD> 169 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A> </TD> 170 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A> </TD> 171 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A> </TD> 172 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A> </TD> 173 </TR> 174 </TABLE> 175 </TD> 176 <TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM> 177 </EM> 178 </TD> 179 </TR> 180 181 <TR> 182 <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> 183 <A HREF="../../javax/inject/Qualifier.html" title="annotation in javax.inject"><B>PREV CLASS</B></A> 184 <A HREF="../../javax/inject/Singleton.html" title="annotation in javax.inject"><B>NEXT CLASS</B></A></FONT></TD> 185 <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> 186 <A HREF="../../index.html?javax/inject/Scope.html" target="_top"><B>FRAMES</B></A> 187 <A HREF="Scope.html" target="_top"><B>NO FRAMES</B></A> 188 <SCRIPT type="text/javascript"> 189 <!-- 190 if(window==top) { 191 document.writeln('<A HREF="../../allclasses-noframe.html"><B>All Classes</B></A>'); 192 } 193 //--> 194 </SCRIPT> 195 <NOSCRIPT> 196 <A HREF="../../allclasses-noframe.html"><B>All Classes</B></A> 197 </NOSCRIPT> 198 199 200 </FONT></TD> 201 </TR> 202 <TR> 203 <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> 204 SUMMARY: REQUIRED | OPTIONAL</FONT></TD> 205 <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> 206 DETAIL: ELEMENT</FONT></TD> 207 </TR> 208 </TABLE> 209 <A NAME="skip-navbar_bottom"></A> 210 <!-- ======== END OF BOTTOM NAVBAR ======= --> 211 212 <HR> 213 <font size='-1'>Copyright (C) 2009 <a href='http://code.google.com/p/atinject/'>The JSR-330 Expert Group</a>. 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