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<!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_14) on Mon Jan 28 05:47:04 PST 2008 --><TITLE>EntityManager (Java EE 5)</TITLE><META NAME="keywords" CONTENT="javax.persistence.EntityManager interface"><LINK REL ="stylesheet" TYPE="text/css" HREF="../../stylesheet.css" TITLE="Style"><SCRIPT type="text/javascript">function windowTitle(){ parent.document.title="EntityManager (Java EE 5)";}</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="../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="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"> <A HREF="../../javax/persistence/EntityListeners.html" title="annotation in javax.persistence"><B>PREV CLASS</B></A> <A HREF="../../javax/persistence/EntityManagerFactory.html" title="interface in javax.persistence"><B>NEXT CLASS</B></A></FONT></TD><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../index.html?javax/persistence/EntityManager.html" target="_top"><B>FRAMES</B></A> <A HREF="EntityManager.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: NESTED | FIELD | CONSTR | <A HREF="#method_summary">METHOD</A></FONT></TD><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">DETAIL: FIELD | CONSTR | <A HREF="#method_detail">METHOD</A></FONT></TD></TR></TABLE><A NAME="skip-navbar_top"></A><!-- ========= END OF TOP NAVBAR ========= --><HR><!-- ======== START OF CLASS DATA ======== --><H2><FONT SIZE="-1">javax.persistence</FONT><BR>Interface EntityManager</H2><HR><DL><DT><PRE>public interface <B>EntityManager</B></DL></PRE><P>Interface used to interact with the persistence context. <p> An <code>EntityManager</code> instance is associated with a persistence context. A persistence context is a set of entity instances in which for any persistent entity identity there is a unique entity instance. Within the persistence context, the entity instances and their lifecycle are managed. This interface defines the methods that are used to interact with the persistence context. The <code>EntityManager</code> API is used to create and remove persistent entity instances, to find entities by their primary key, and to query over entities. <p> The set of entities that can be managed by a given <code>EntityManager</code> instance is defined by a persistence unit. A persistence unit defines the set of all classes that are related or grouped by the application, and which must be colocated in their mapping to a single database.<P><P><DL><DT><B>Since:</B></DT> <DD>Java Persistence 1.0</DD></DL><HR><P><!-- ========== METHOD SUMMARY =========== --><A NAME="method_summary"><!-- --></A><TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""><TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"><TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2"><B>Method Summary</B></FONT></TH></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> void</CODE></FONT></TD><TD><CODE><B><A HREF="../../javax/persistence/EntityManager.html#clear()">clear</A></B>()</CODE><BR> Clear the persistence context, causing all managed entities to become detached.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> void</CODE></FONT></TD><TD><CODE><B><A HREF="../../javax/persistence/EntityManager.html#close()">close</A></B>()</CODE><BR> Close an application-managed EntityManager.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> boolean</CODE></FONT></TD><TD><CODE><B><A HREF="../../javax/persistence/EntityManager.html#contains(java.lang.Object)">contains</A></B>(<A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/Object.html" title="class or interface in java.lang">Object</A> entity)</CODE><BR> Check if the instance belongs to the current persistence context.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../javax/persistence/Query.html" title="interface in javax.persistence">Query</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../javax/persistence/EntityManager.html#createNamedQuery(java.lang.String)">createNamedQuery</A></B>(<A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A> name)</CODE><BR> Create an instance of Query for executing a named query (in the Java Persistence query language or in native SQL).</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../javax/persistence/Query.html" title="interface in javax.persistence">Query</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../javax/persistence/EntityManager.html#createNativeQuery(java.lang.String)">createNativeQuery</A></B>(<A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A> sqlString)</CODE><BR> Create an instance of Query for executing a native SQL statement, e.g., for update or delete.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../javax/persistence/Query.html" title="interface in javax.persistence">Query</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../javax/persistence/EntityManager.html#createNativeQuery(java.lang.String, java.lang.Class)">createNativeQuery</A></B>(<A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A> sqlString, <A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/Class.html" title="class or interface in java.lang">Class</A> resultClass)</CODE><BR> Create an instance of Query for executing a native SQL query.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../javax/persistence/Query.html" title="interface in javax.persistence">Query</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../javax/persistence/EntityManager.html#createNativeQuery(java.lang.String, java.lang.String)">createNativeQuery</A></B>(<A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A> sqlString, <A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A> resultSetMapping)</CODE><BR> Create an instance of Query for executing a native SQL query.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../javax/persistence/Query.html" title="interface in javax.persistence">Query</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../javax/persistence/EntityManager.html#createQuery(java.lang.String)">createQuery</A></B>(<A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A> qlString)</CODE><BR> Create an instance of Query for executing a Java Persistence query language statement.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE><TABLE BORDER="0" CELLPADDING="0" CELLSPACING="0" SUMMARY=""><TR ALIGN="right" VALIGN=""><TD NOWRAP><FONT SIZE="-1"><CODE><T> T</CODE></FONT></TD></TR></TABLE></CODE></FONT></TD><TD><CODE><B><A HREF="../../javax/persistence/EntityManager.html#find(java.lang.Class, java.lang.Object)">find</A></B>(<A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/Class.html" title="class or interface in java.lang">Class</A><T> entityClass, <A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/Object.html" title="class or interface in java.lang">Object</A> primaryKey)</CODE><BR> Find by primary key.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> void</CODE></FONT></TD><TD><CODE><B><A HREF="../../javax/persistence/EntityManager.html#flush()">flush</A></B>()</CODE><BR> Synchronize the persistence context to the underlying database.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/Object.html" title="class or interface in java.lang">Object</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../javax/persistence/EntityManager.html#getDelegate()">getDelegate</A></B>()</CODE><BR> Return the underlying provider object for the EntityManager, if available.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../javax/persistence/FlushModeType.html" title="enum in javax.persistence">FlushModeType</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../javax/persistence/EntityManager.html#getFlushMode()">getFlushMode</A></B>()</CODE><BR> Get the flush mode that applies to all objects contained in the persistence context.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE><TABLE BORDER="0" CELLPADDING="0" CELLSPACING="0" SUMMARY=""><TR ALIGN="right" VALIGN=""><TD NOWRAP><FONT SIZE="-1"><CODE><T> T</CODE></FONT></TD></TR></TABLE></CODE></FONT></TD><TD><CODE><B><A HREF="../../javax/persistence/EntityManager.html#getReference(java.lang.Class, java.lang.Object)">getReference</A></B>(<A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/Class.html" title="class or interface in java.lang">Class</A><T> entityClass, <A HREF="http://java.sun.com/j2se/1.5/docs/api/java/lang/Object.html" title="class or interface in java.lang">Object</A> primaryKey)</CODE><BR> Get an instance, whose state may be lazily fetched.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../javax/persistence/EntityTransaction.html" title="interface in javax.persistence">EntityTransaction</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../javax/persistence/EntityManager.html#getTransaction()">getTransaction</A></B>()</CODE><BR> Returns the resource-level transaction object.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> boolean</CODE></FONT></TD><TD><CODE><B><A HREF="../../javax/persistence/EntityManager.html#isOpen()">isOpen</A></B>()</CODE><BR> Determine whether the EntityManager is open.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> void</CODE></FONT></TD><TD><CODE><B><A HREF="../../javax/persistence/EntityManager.html#joinTransaction()">joinTransaction</A></B>()</CODE><BR> Indicate to the EntityManager that a JTA transaction is active.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor">⌨️ 快捷键说明
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