JPOX:免费的JDO实现(1.2版本开始支持JPA1)

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官方主页：http://www.jpox.org/

下载：http://www.jpox.org/docs/download.html

另外还需要JDO，可以使用sun的实现，也可以使用apache的实现(http://db.apache.org/jdo/downloads.html)。

测试步骤如下：

MySQL中新建数据库jpox备用。

工程布局如下图：

jpox.properties：

javax.jdo.PersistenceManagerFactoryClass=org.jpox.jdo.JDOPersistenceManagerFactory
javax.jdo.option.ConnectionDriverName=com.mysql.jdbc.Driver
javax.jdo.option.ConnectionURL=jdbc:mysql://localhost:3306/jpox
javax.jdo.option.ConnectionUserName=root
javax.jdo.option.ConnectionPassword=root
org.jpox.autoCreateSchema=true
org.jpox.validateTables=false
org.jpox.validateConstraints=false

log4j.properties

# LOG4J Configuration
# ===================
# Basic logging goes to "jpox.log"
log4j.appender.A1=org.apache.log4j.FileAppender
log4j.appender.A1.File=jpox.log
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern=%d{HH:mm:ss,SSS} (%t) %-5p [%c] - %m%n
#log4j.appender.A1.Threshold=INFO
# Categories
# Each category can be set to a "level", and to direct to an appender
# Default to DEBUG level for all JPOX categories
log4j.logger.JPOX = DEBUG, A1
#log4j.category.JPOX.JDO=DEBUG, A1
#log4j.category.JPOX.JPA=DEBUG, A1
#log4j.category.JPOX.Persistence=DEBUG, A1
#log4j.category.JPOX.Lifecycle=DEBUG, A1
#log4j.category.JPOX.Query=DEBUG, A1
#log4j.category.JPOX.Cache=DEBUG, A1
#log4j.category.JPOX.Reachability=DEBUG, A1
#log4j.category.JPOX.MetaData=DEBUG, A1
#log4j.category.JPOX.General=DEBUG, A1
#log4j.category.JPOX.Utility=DEBUG, A1
#log4j.category.JPOX.Transaction=DEBUG, A1
#log4j.category.JPOX.Store.Poid=DEBUG, A1
#log4j.category.JPOX.Naming=DEBUG, A1
#log4j.category.JPOX.Management=DEBUG, A1
#log4j.category.JPOX.Datastore=DEBUG, A1
#log4j.category.JPOX.Connection=DEBUG, A1
#log4j.category.JPOX.ClassLoading=DEBUG, A1
#log4j.category.JPOX.Plugin=DEBUG, A1
#log4j.category.JPOX.Enhancer=DEBUG, A1
#log4j.category.JPOX.SchemaTool=DEBUG, A1
#log4j.category.JPOX.TEST=DEBUG, A1
#
# C3P0 logging
#
#log4j.category.com.mchange.v2.c3p0=INFO, A1
#log4j.category.com.mchange.v2.resourcepool=INFO, A1
#
# Proxool logging
#
#log4j.category.org.logicalcobwebs.proxool=INFO,A1

Author.java

package examples.jdo2.model;
public class Author {
    
    private int books;
    private String name;
    public Author(String name, int books) {
        this.name = name;
        this.books = books;
    }
    protected Author() {
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getBooks() {
        return books;
    }
    public void setBooks(int books) {
        this.books = books;
    }
}

Author.jdo

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE jdo PUBLIC
    "-//Sun Microsystems, Inc.//DTD Java Data Objects Metadata 2.0//EN"
    "http://java.sun.com/dtd/jdo_2_0.dtd">
<jdo>
   <package name="examples.jdo2.model">
       <class name="Author" identity-type="datastore">
           <field name="books" persistence-modifier="persistent"></field>
           <field name="name" persistence-modifier="persistent">
                <column length="50" jdbc-type="VARCHAR"/>
           </field>
       </class>
   </package>
</jdo>

MakePersistent.java

package examples.jdo2;
import javax.jdo.JDOHelper;
import javax.jdo.PersistenceManager;
import javax.jdo.PersistenceManagerFactory;
import javax.jdo.Transaction;
import examples.jdo2.model.Author;
public class MakePersistent {
    
    public static void main(String[] args) {
        
        PersistenceManagerFactory pmf = JDOHelper.getPersistenceManagerFactory("jpox.properties");
        PersistenceManager pm = pmf.getPersistenceManager();
        Transaction tx = pm.currentTransaction();
        tx.begin();
        Author au = new Author("Chen Yan", 5);
        System.out.println("Author: " + au.getName() + "/t" + au.getBooks() + " Books");
        pm.makePersistent(au);
        tx.commit();
        // tx.rollback(); 
        // Can not read fields outside of transactions. Or set: 
        // pmf.setNontransactionalRead(true); 
        // System.out.println("Author: " + au.getName() + "/t" + au.getBooks() + " Books"); 
        tx.begin();
        String name = au.getName();
        System.out.println("Author: " + name);
        tx.commit();
        pm.close();
        pmf.close();
    }
}

ReadExtent.java

package examples.jdo2;
import java.util.Iterator;
import javax.jdo.Extent;
import javax.jdo.JDOHelper;
import javax.jdo.PersistenceManager;
import javax.jdo.PersistenceManagerFactory;
import javax.jdo.Transaction;
import examples.jdo2.model.Author;
public class ReadExtent {
    public static void main(String[] args) {
        
        PersistenceManagerFactory pmf = JDOHelper.getPersistenceManagerFactory("jpox.properties");
        PersistenceManager pm = pmf.getPersistenceManager();
        Transaction tx = pm.currentTransaction();
        tx.begin();
        Extent extent = pm.getExtent(Author.class, false);
        Iterator itor = extent.iterator();
        Author au;
        while (itor.hasNext()) {
            au = (Author) itor.next();
            System.out.println("Author: " + au.getName() + " |/t"
            + au.getBooks());
        }
        extent.close(itor);
        tx.commit();
        pm.close();
        pmf.close();
    }
}

ReadQuery.java

package examples.jdo2;
import java.util.Collection;
import java.util.Iterator;
import javax.jdo.JDOHelper;
import javax.jdo.PersistenceManager;
import javax.jdo.PersistenceManagerFactory;
import javax.jdo.Query;
import javax.jdo.Transaction;
import examples.jdo2.model.Author;
public class ReadQuery {
    public static void main(String[] args) {
        PersistenceManagerFactory pmf = JDOHelper.getPersistenceManagerFactory("jpox.properties");
        PersistenceManager pm = pmf.getPersistenceManager();
        Transaction tx = pm.currentTransaction();
        tx.begin();
        Query query = pm.newQuery(Author.class, "books == 7");
        Collection result = (Collection) query.execute();
        Iterator itor = result.iterator();
        Author au;
        while (itor.hasNext()) {
            au = (Author) itor.next();
            System.out.println("Author: " + au.getName() + " |/t" + au.getBooks());
        }
        query.close(result);
        tx.commit();
        pm.close();
        pmf.close();
    }
}

因为在JDO需要Enhance以得到的PO，而且只能静态编译，不能运行期编译。这里使用ant脚本。

build.xml

<!--
===================================================================
tutorial build
===================================================================
-->
<project name="jdo2jpox" default="compile">
<property environment="env"/>
<property file="jpox.properties"/>
<property name="project.location" location="."/>
<property name="project.build.debug" value="on"/>
<property name="Name" value="tutorial"/>
<property name="name" value="${Name}"/>
<property name="version" value="1.2"/>
<property name="java.dir" value="src"/>
<property name="lib.dir" value="."/>
<property name="classes.dir" value="bin"/>
<!--
===================================================================
Classpath properties
===================================================================
-->
<path id="lib.classpath">
<fileset dir="${lib.dir}">
<include name="**/*.jar"/>
</fileset>
<pathelement location="${classes.dir}"/>
<pathelement location="${basedir}"/>
</path>
<path id="compile.classpath">
<pathelement location="${classes.dir}"/>
<path refid="lib.classpath"/>
</path>
<!--
===================================================================
TARGET : clean
===================================================================
-->
<target name="clean">
<delete includeEmptyDirs="true" quiet="true">
<fileset dir="${classes.dir}" includes="**/*.class,**/*.properties,**/*.*"/>
</delete>
</target>
<!--
===================================================================
TARGET : prepare
===================================================================
-->
<target name="prepare">
<mkdir dir="${classes.dir}"/>
</target>
<!--
===================================================================
TARGET : compile.java
===================================================================
-->
<target name="compile" depends="clean,prepare">
<echo message="==================================================================="/>
<echo message="Compile configuration:"/>
<echo message="java.dir = ${java.dir}"/>
<echo message="classes.dir = ${classes.dir}"/>
<echo message="basedir = ${basedir}"/>
<echo message="==================================================================="/>
<javac srcdir="${java.dir}" destdir="${classes.dir}" debug="${project.build.debug}" classpathref="compile.classpath">
<include name="**/*.java"/>
</javac>
</target>
<!--
===================================================================
TARGET : copy jdo metadata files
===================================================================
-->
<target name="copy.metadata">
<copy todir="${classes.dir}">
<fileset dir="${java.dir}" includes="**/*.jdo"/>
</copy>
</target>
<!--
===================================================================
TARGET : enhance
===================================================================
-->
<target name="enhance" depends="compile,copy.metadata">
<taskdef name="enhancer" classname="org.jpox.enhancer.tools.EnhancerTask">
<classpath refid="compile.classpath"/>
</taskdef>
<enhancer classpathref="compile.classpath"
dir="${classes.dir}"
verbose="true">
<sysproperty key="log4j.configuration" value="file:log4j.properties"/>
</enhancer>
</target>
<target name="createschema">
<taskdef name="schematool" classname="org.jpox.SchemaToolTask">
<classpath refid="compile.classpath"/>
</taskdef>
<schematool classpathref="compile.classpath"
failonerror="true" verbose="true" mode="create" props="jpox.properties">
<fileset dir="${basedir}/bin">
<include name="**/*.jdo"/>
</fileset>
<sysproperty key="log4j.configuration" value="${basedir}/log4j.properties"/>
</schematool>
</target>
<target name="deleteschema">
<taskdef name="schematool" classname="org.jpox.SchemaToolTask">
<classpath refid="compile.classpath"/>
</taskdef>
<schematool classpathref="compile.classpath"
failonerror="true" fork="true" verbose="true" mode="delete" props="jpox.properties">
<fileset dir="${basedir}/bin">
<include name="**/*.jdo"/>
</fileset>
<sysproperty key="log4j.configuration" value="log4j.properties"/>
</schematool>
</target>
<target name="schemainfo">
<taskdef name="schematool" classname="org.jpox.SchemaToolTask">
<classpath refid="compile.classpath"/>
</taskdef>
<schematool classpathref="compile.classpath"
failonerror="true" fork="true" verbose="true" mode="dbinfo" props="jpox.properties">
<fileset dir="${basedir}/bin">
<include name="**/*.jdo"/>
</fileset>
<sysproperty key="log4j.configuration" value="log4j.properties"/>
</schematool>
</target>
<target name="runtutorial" description="Run the application">
<java classname="examples.jdo2.MakePersistent" classpathref="lib.classpath" fork="true"/>
<java classname="examples.jdo2.ReadExtent" classpathref="lib.classpath" fork="true"/>
<java classname="examples.jdo2.ReadQuery" classpathref="lib.classpath" fork="true"/>
</target>
</project>

先进行enhance后再进行runtutorial操作即可。

这时数据库中将直接生成数据库并进行数据操作。

注意：JDO在运行时会自动生成jpox_tables和sequence_table这2张表。

当然我们还可以使用persistence.xml文件配置数据库连接：

<?xml version="1.0" encoding="UTF-8" ?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence 
        http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" version="1.0">
    <persistence-unit name="JPoxStore">
        <provider>org.jpox.jpa.PersistenceProviderImpl</provider>
        <class>examples.jdo2.model.Author</class>
        <properties>
            <property name="javax.jdo.option.ConnectionDriverName" value="com.mysql.jdbc.Driver"/>
            <property name="javax.jdo.option.ConnectionURL" value="jdbc:mysql://localhost:3306/jpox"/>
            <property name="javax.jdo.option.ConnectionUserName" value="root"/>
            <property name="javax.jdo.option.ConnectionPassword" value="root"/>
        </properties>
    </persistence-unit>
</persistence>

调用的方法是：

  Properties props = new Properties();
  props.put("javax.jdo.option.PersistenceUnitName", "JPoxStore");
  PersistenceManagerFactory pmf = JDOHelper.getPersistenceManagerFactory(props);

参考：http://www.jpox.org/docs/1_2/persistence_unit.html

本例参考自：http://blog.csdn.net/e_ville/archive/2006/12/27/1464180.aspx

关于Hibernate和JDO的比较：http://www.bitscn.com/mysql/JSPMySQL/200701/93732.html

其他资料：http://blog.csdn.net/liumm1983/archive/2007/03/19/1533726.aspx