| <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> |
| <!--NewPage--> |
| <HTML> |
| <HEAD> |
| <!-- Generated by javadoc (build 1.5.0_16) on Mon Oct 12 16:11:19 PDT 2009 --> |
| <TITLE> |
| Inject |
| </TITLE> |
| |
| <META NAME="keywords" CONTENT="javax.inject.Inject class"> |
| |
| <LINK REL ="stylesheet" TYPE="text/css" HREF="../../stylesheet.css" TITLE="Style"> |
| |
| <SCRIPT type="text/javascript"> |
| function windowTitle() |
| { |
| parent.document.title="Inject"; |
| } |
| </SCRIPT> |
| <NOSCRIPT> |
| </NOSCRIPT> |
| |
| </HEAD> |
| |
| <BODY BGCOLOR="white" onload="windowTitle();"> |
| |
| |
| <!-- ========= START OF TOP NAVBAR ======= --> |
| <A NAME="navbar_top"><!-- --></A> |
| <A HREF="#skip-navbar_top" title="Skip navigation links"></A> |
| <TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY=""> |
| <TR> |
| <TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> |
| <A NAME="navbar_top_firstrow"><!-- --></A> |
| <TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY=""> |
| <TR ALIGN="center" VALIGN="top"> |
| <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../javax/inject/package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A> </TD> |
| <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT> </TD> |
| <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A> </TD> |
| <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A> </TD> |
| <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A> </TD> |
| <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A> </TD> |
| </TR> |
| </TABLE> |
| </TD> |
| <TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM> |
| </EM> |
| </TD> |
| </TR> |
| |
| <TR> |
| <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> |
| PREV CLASS |
| <A HREF="../../javax/inject/Named.html" title="annotation in javax.inject"><B>NEXT CLASS</B></A></FONT></TD> |
| <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> |
| <A HREF="../../index.html?javax/inject/Inject.html" target="_top"><B>FRAMES</B></A> |
| <A HREF="Inject.html" target="_top"><B>NO FRAMES</B></A> |
| <SCRIPT type="text/javascript"> |
| <!-- |
| if(window==top) { |
| document.writeln('<A HREF="../../allclasses-noframe.html"><B>All Classes</B></A>'); |
| } |
| //--> |
| </SCRIPT> |
| <NOSCRIPT> |
| <A HREF="../../allclasses-noframe.html"><B>All Classes</B></A> |
| </NOSCRIPT> |
| |
| |
| </FONT></TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> |
| SUMMARY: REQUIRED | OPTIONAL</FONT></TD> |
| <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> |
| DETAIL: ELEMENT</FONT></TD> |
| </TR> |
| </TABLE> |
| <A NAME="skip-navbar_top"></A> |
| <!-- ========= END OF TOP NAVBAR ========= --> |
| |
| <HR> |
| <!-- ======== START OF CLASS DATA ======== --> |
| <H2> |
| <FONT SIZE="-1"> |
| javax.inject</FONT> |
| <BR> |
| Annotation Type Inject</H2> |
| <HR> |
| <DL> |
| <DT><PRE><FONT SIZE="-1">@Target(value={METHOD,CONSTRUCTOR,FIELD}) |
| @Retention(value=RUNTIME) |
| @Documented |
| </FONT>public @interface <B>Inject</B></DL> |
| </PRE> |
| |
| <P> |
| Identifies injectable constructors, methods, and fields. May apply to static |
| as well as instance members. An injectable member may have any access |
| modifier (private, package-private, protected, public). Constructors are |
| injected first, followed by fields, and then methods. Fields and methods |
| in superclasses are injected before those in subclasses. Ordering of |
| injection among fields and among methods in the same class is not specified. |
| |
| <p>Injectable constructors are annotated with <code>@Inject</code> and accept |
| zero or more dependencies as arguments. <code>@Inject</code> can apply to at most |
| one constructor per class. |
| |
| <p><tt><blockquote style="padding-left: 2em; text-indent: -2em;">@Inject |
| <i>ConstructorModifiers<sub>opt</sub></i> |
| <i>SimpleTypeName</i>(<i>FormalParameterList<sub>opt</sub></i>) |
| <i>Throws<sub>opt</sub></i> |
| <i>ConstructorBody</i></blockquote></tt> |
| |
| <p><code>@Inject</code> is optional for public, no-argument constructors when no |
| other constructors are present. This enables injectors to invoke default |
| constructors. |
| |
| <p><tt><blockquote style="padding-left: 2em; text-indent: -2em;"> |
| @Inject<sub><i>opt</i></sub> |
| <i>Annotations<sub>opt</sub></i> |
| public |
| <i>SimpleTypeName</i>() |
| <i>Throws<sub>opt</sub></i> |
| <i>ConstructorBody</i></blockquote></tt> |
| |
| <p>Injectable fields: |
| <ul> |
| <li>are annotated with <code>@Inject</code>. |
| <li>are not final. |
| <li>may have any otherwise valid name.</li></ul> |
| |
| <p><tt><blockquote style="padding-left: 2em; text-indent: -2em;">@Inject |
| <i>FieldModifiers<sub>opt</sub></i> |
| <i>Type</i> |
| <i>VariableDeclarators</i>;</blockquote></tt> |
| |
| <p>Injectable methods: |
| <ul> |
| <li>are annotated with <code>@Inject</code>.</li> |
| <li>are not abstract.</li> |
| <li>do not declare type parameters of their own.</li> |
| <li>may return a result</li> |
| <li>may have any otherwise valid name.</li> |
| <li>accept zero or more dependencies as arguments.</li></ul> |
| |
| <p><tt><blockquote style="padding-left: 2em; text-indent: -2em;">@Inject |
| <i>MethodModifiers<sub>opt</sub></i> |
| <i>ResultType</i> |
| <i>Identifier</i>(<i>FormalParameterList<sub>opt</sub></i>) |
| <i>Throws<sub>opt</sub></i> |
| <i>MethodBody</i></blockquote></tt> |
| |
| <p>The injector ignores the result of an injected method, but |
| non-<code>void</code> return types are allowed to support use of the method in |
| other contexts (builder-style method chaining, for example). |
| |
| <p>Examples: |
| |
| <pre> |
| public class Car { |
| // Injectable constructor |
| @Inject public Car(Engine engine) { ... } |
| |
| // Injectable field |
| @Inject private Provider<Seat> seatProvider; |
| |
| // Injectable package-private method |
| @Inject void install(Windshield windshield, Trunk trunk) { ... } |
| }</pre> |
| |
| <p>A method annotated with <code>@Inject</code> that overrides another method |
| annotated with <code>@Inject</code> will only be injected once per injection |
| request per instance. A method with <i>no</i> <code>@Inject</code> annotation |
| that overrides a method annotated with <code>@Inject</code> will not be |
| injected. |
| |
| <p>Injection of members annotated with <code>@Inject</code> is required. While an |
| injectable member may use any accessibility modifier (including |
| <tt>private</tt>), platform or injector limitations (like security |
| restrictions or lack of reflection support) might preclude injection |
| of non-public members. |
| |
| <h3>Qualifiers</h3> |
| |
| <p>A <A HREF="../../javax/inject/Qualifier.html" title="annotation in javax.inject">qualifier</A> may annotate an injectable field |
| or parameter and, combined with the type, identify the implementation to |
| inject. Qualifiers are optional, and when used with <code>@Inject</code> in |
| injector-independent classes, no more than one qualifier should annotate a |
| single field or parameter. The qualifiers are bold in the following example: |
| |
| <pre> |
| public class Car { |
| @Inject private <b>@Leather</b> Provider<Seat> seatProvider; |
| |
| @Inject void install(<b>@Tinted</b> Windshield windshield, |
| <b>@Big</b> Trunk trunk) { ... } |
| }</pre> |
| |
| <p>If one injectable method overrides another, the overriding method's |
| parameters do not automatically inherit qualifiers from the overridden |
| method's parameters. |
| |
| <h3>Injectable Values</h3> |
| |
| <p>For a given type T and optional qualifier, an injector must be able to |
| inject a user-specified class that: |
| |
| <ol type="a"> |
| <li>is assignment compatible with T and</li> |
| <li>has an injectable constructor.</li> |
| </ol> |
| |
| <p>For example, the user might use external configuration to pick an |
| implementation of T. Beyond that, which values are injected depend upon the |
| injector implementation and its configuration. |
| |
| <h3>Circular Dependencies</h3> |
| |
| <p>Detecting and resolving circular dependencies is left as an exercise for |
| the injector implementation. Circular dependencies between two constructors |
| is an obvious problem, but you can also have a circular dependency between |
| injectable fields or methods: |
| |
| <pre> |
| class A { |
| @Inject B b; |
| } |
| class B { |
| @Inject A a; |
| }</pre> |
| |
| <p>When constructing an instance of <code>A</code>, a naive injector |
| implementation might go into an infinite loop constructing an instance of |
| <code>B</code> to set on <code>A</code>, a second instance of <code>A</code> to set on |
| <code>B</code>, a second instance of <code>B</code> to set on the second instance of |
| <code>A</code>, and so on. |
| |
| <p>A conservative injector might detect the circular dependency at build |
| time and generate an error, at which point the programmer could break the |
| circular dependency by injecting <A HREF="../../javax/inject/Provider.html" title="interface in javax.inject"><CODE>Provider<A></CODE></A> or <code>Provider<B></code> instead of <code>A</code> or <code>B</code> respectively. Calling <A HREF="../../javax/inject/Provider.html#get()"><CODE>get()</CODE></A> on the provider directly from the constructor or |
| method it was injected into defeats the provider's ability to break up |
| circular dependencies. In the case of method or field injection, scoping |
| one of the dependencies (using <A HREF="../../javax/inject/Singleton.html" title="annotation in javax.inject">singleton scope</A>, for |
| example) may also enable a valid circular relationship. |
| <P> |
| |
| <P> |
| <DL> |
| <DT><B>See Also:</B><DD><A HREF="../../javax/inject/Qualifier.html" title="annotation in javax.inject"><CODE>@Qualifier</CODE></A>, |
| <A HREF="../../javax/inject/Provider.html" title="interface in javax.inject"><CODE>Provider</CODE></A></DL> |
| |
| <P> |
| |
| <P> |
| <!-- ========= END OF CLASS DATA ========= --> |
| <HR> |
| |
| |
| <!-- ======= START OF BOTTOM NAVBAR ====== --> |
| <A NAME="navbar_bottom"><!-- --></A> |
| <A HREF="#skip-navbar_bottom" title="Skip navigation links"></A> |
| <TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY=""> |
| <TR> |
| <TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> |
| <A NAME="navbar_bottom_firstrow"><!-- --></A> |
| <TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY=""> |
| <TR ALIGN="center" VALIGN="top"> |
| <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../javax/inject/package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A> </TD> |
| <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT> </TD> |
| <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A> </TD> |
| <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A> </TD> |
| <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A> </TD> |
| <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A> </TD> |
| </TR> |
| </TABLE> |
| </TD> |
| <TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM> |
| </EM> |
| </TD> |
| </TR> |
| |
| <TR> |
| <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> |
| PREV CLASS |
| <A HREF="../../javax/inject/Named.html" title="annotation in javax.inject"><B>NEXT CLASS</B></A></FONT></TD> |
| <TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> |
| <A HREF="../../index.html?javax/inject/Inject.html" target="_top"><B>FRAMES</B></A> |
| <A HREF="Inject.html" target="_top"><B>NO FRAMES</B></A> |
| <SCRIPT type="text/javascript"> |
| <!-- |
| if(window==top) { |
| document.writeln('<A HREF="../../allclasses-noframe.html"><B>All Classes</B></A>'); |
| } |
| //--> |
| </SCRIPT> |
| <NOSCRIPT> |
| <A HREF="../../allclasses-noframe.html"><B>All Classes</B></A> |
| </NOSCRIPT> |
| |
| |
| </FONT></TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> |
| SUMMARY: REQUIRED | OPTIONAL</FONT></TD> |
| <TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> |
| DETAIL: ELEMENT</FONT></TD> |
| </TR> |
| </TABLE> |
| <A NAME="skip-navbar_bottom"></A> |
| <!-- ======== END OF BOTTOM NAVBAR ======= --> |
| |
| <HR> |
| <font size='-1'>Copyright (C) 2009 <a href='http://code.google.com/p/atinject/'>The JSR-330 Expert Group</a>. Licensed under the <a href='http://www.apache.org/licenses/LICENSE-2.0'>Apache License</a>, Version 2.0.</font> |
| </BODY> |
| </HTML> |