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openJPA从数据库生成代码操作

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一、新建一个普通的Java项目（不是WTP项目）

二、转换为Maven项目

增加一些库依赖，pom.xml代码如下：

Xml代码

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>

<groupId>StrongOpenJPA</groupId>

<artifactId>StrongOpenJPA</artifactId>

<version>0.0.1-SNAPSHOT</version>

<dependencies>

<dependency>

<groupId>org.slf4j</groupId>

<artifactId>slf4j-api</artifactId>

<version>1.6.4</version>

</dependency>

<dependency>

<groupId>org.slf4j</groupId>

<artifactId>slf4j-log4j12</artifactId>

<version>1.6.4</version>

</dependency>

<dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-aop</artifactId>

<version>3.1.1.RELEASE</version>

</dependency>

<dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-context</artifactId>

<version>3.1.1.RELEASE</version>

</dependency>

<dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-test</artifactId>

<version>3.1.1.RELEASE</version>

</dependency>

<dependency>

<groupId>org.apache.openjpa</groupId>

<artifactId>openjpa</artifactId>

<version>2.1.1</version>

<scope>compile</scope>

</dependency>

</dependencies>

</project>

因为pom.xml中没有配置src的未知，所以默认转换为maven项目之后，build path中的source中会变为空，这个时候要吧src重新增加进去，最简单的方法就是直接加！

三、增加slf4j记录日志

在src中新建一个log4j.properties文件，修改内容如下：

Cpp代码

# This is the configuring for logging displayed in the Application Server

log4j.rootCategory=INFO, stdout

#stdout configure

log4j.appender.stdout=org.apache.log4j.ConsoleAppender

log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

log4j.appender.stdout.layout.ConversionPattern=[%-d{HH:mm:ss}-%p]%m%n

四、转换为JPA项目

首先在Data Source Explorer中增加对应的数据库，Drivers没有请自己设置

然后右键项目，将其转换为JPA的项目

因为Eclipse没有直接支持OpenJPA，所以这里直接选择Generic2.0

完成后，Eclipse会自动在src中新建META-INF目录，在META-INF中新建persistence.xml文件，自动生成的大多不能用，结合OpenJPA的配置方法修改内容如下：

Xml代码

<?xml version="1.0" encoding="UTF-8"?>

<persistence version="1.0" 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">
<persistence-unit name="StrongOpenJPAPU" transaction-type="RESOURCE_LOCAL">

<provider>org.apache.openjpa.persistence.PersistenceProviderImpl</provider>

<properties>

<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />

<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/strongjpa" />

<property name="javax.persistence.jdbc.user" value="root" />

<property name="javax.persistence.jdbc.password" value="root" />



<property name="openjpa.Log" value="DefaultLevel=WARN, Runtime=WARN, Tool=INFO, SQL=TRACE" />

<property name="openjpa.RemoteCommitProvider" value="sjvm" />



<property name="openjpa.DataCache" value="true(CacheSize=5000, SoftReferenceSize=100)" />



<property name="openjpa.QueryCache" value="true(CacheSize=5000, SoftReferenceSize=100)" />



<property name="openjpa.QueryCompilationCache" value="true" />



<property name="openjpa.ConnectionFactoryProperties" value="PrettyPrint=true, PrettyPrintLineLength=100" />



<property name="openjpa.FetchBatchSize" value="-1" />

</properties>

</persistence-unit>

</persistence>

这些配置的参数在OpenJPA的文档中都有，因为没有找到中文的文档，大家有需要的话直接去看官方文档吧。其中有一个地方需要解释的，javax.persistence.jdbc.driver等等这些参数是JPA标准，OpenJPA中也有类似的参数，一般情况下建议大家还是直接使用标准参数来配置

五、生成Entities From Tables

转换为JPA项目之后，Eclipse就能够使用JPA Tools进行JPA的管理，尤其是Entities From Tables非常好用（虽然我重来不用 ^_^）。

右键项目，选择JPA Tools进行操作，我们先把数据库中的t_xx表转换出来

剩下的操作，大家就按照步骤来吧，因为演示的t_xx没有任何外键，所以按照最简单的方式转出来就可以。有可能自动生成后这个class会报错，这个时因为Eclipse诶有把TXx定义到persistence.xml中，如果报错大家就手工添加进去，下载的源码包内我已经手工修改过。

但是自动化生成的东西并不非常合适，至少在以后的通过Entities生成Tables的时候就存在很多的问题，因此我一般都用自己的做的一个转换工具进行代码自动生成。

com.strong.module.txx.jpa.TXx

Java代码

package com.strong.module.txx.jpa;

import java.util.Date;

import javax.persistence.Column;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.GenerationType;

import javax.persistence.Id;

import javax.persistence.SequenceGenerator;

import javax.persistence.Table;

import javax.persistence.Temporal;

import javax.persistence.TemporalType;

/**

* TXx entity

*

* @author Simen 自动生成时间: 2011-10-02 08:31:29

*/

@Entity

@Table(name = "t_xx")

public class TXx implements java.io.Serializable {

/**

*

*/

private static final long serialVersionUID = 1L;

public static final String S_XXID = "xx_id"; // PRIMARY

public static final String S_XXBZ = "xx_bz"; // 选项备注

public static final String S_XXDM = "xx_dm"; // 选项代码

public static final String S_XXLX = "xx_lx"; // 选项类型

public static final String S_XXMC = "xx_mc"; // 选项名称

public static final String S_XXXH = "xx_xh"; // 选项序号在同一分类中的顺序号

public static final String S_XXBY1 = "xx_by1"; // 备用1

public static final String S_XXBY2 = "xx_by2"; // 备用2

public static final String S_XXBY3 = "xx_by3"; // 备用3

public static final String S_XXBY4 = "xx_by4"; // 备用4

public static final String S_XXBY5 = "xx_by5"; // 备用5

public static final String S_XXBY6 = "xx_by6"; // 备用6

public static final String S_XXBY7 = "xx_by7"; // 备用7

public static final String S_XXBY8 = "xx_by8"; // 备用8

// Fields

private Integer xxId; // PRIMARY

private String xxBz; // 选项备注

private String xxDm; // 选项代码

private String xxLx; // 选项类型

private String xxMc; // 选项名称

private Integer xxXh; // 选项序号在同一分类中的顺序号

private String xxBy1; // 备用1

private String xxBy2; // 备用2

private String xxBy3; // 备用3

private Integer xxBy4; // 备用4

private Integer xxBy5; // 备用5

private Date xxBy6; // 备用6

private Date xxBy7; // 备用7

private Float xxBy8; // 备用8

public TXx() {

}

// Constructors

@Id

@GeneratedValue(strategy = GenerationType.IDENTITY, generator = "AuthorSeqXX")

@SequenceGenerator(name = "AuthorSeqXX", allocationSize = 1)

@Column(name = "xx_id", unique = true, nullable = false, insertable = true, updatable = true)

public Integer getXxId() {

return xxId;

}

public void setXxId(Integer xxId) {

this.xxId = xxId;

}

@Column(name = "xx_bz", length = 255)

public String getXxBz() {

return xxBz;

}

public void setXxBz(String xxBz) {

this.xxBz = xxBz;

}

@Column(name = "xx_dm", length = 255)

public String getXxDm() {

return xxDm;

}

public void setXxDm(String xxDm) {

this.xxDm = xxDm;

}

@Column(name = "xx_lx", length = 255)

public String getXxLx() {

return xxLx;

}

public void setXxLx(String xxLx) {

this.xxLx = xxLx;

}

@Column(name = "xx_mc", length = 255)

public String getXxMc() {

return xxMc;

}

public void setXxMc(String xxMc) {

this.xxMc = xxMc;

}

@Column(name = "xx_xh", length = 10)

public Integer getXxXh() {

return xxXh;

}

public void setXxXh(Integer xxXh) {

this.xxXh = xxXh;

}

@Column(name = "xx_by1", length = 255)

public String getXxBy1() {

return xxBy1;

}

public void setXxBy1(String xxBy1) {

this.xxBy1 = xxBy1;

}

@Column(name = "xx_by2", length = 255)

public String getXxBy2() {

return xxBy2;

}

public void setXxBy2(String xxBy2) {

this.xxBy2 = xxBy2;

}

@Column(name = "xx_by3", length = 255)

public String getXxBy3() {

return xxBy3;

}

public void setXxBy3(String xxBy3) {

this.xxBy3 = xxBy3;

}

@Column(name = "xx_by4", length = 10)

public Integer getXxBy4() {

return xxBy4;

}

public void setXxBy4(Integer xxBy4) {

this.xxBy4 = xxBy4;

}

@Column(name = "xx_by5", length = 10)

public Integer getXxBy5() {

return xxBy5;

}

public void setXxBy5(Integer xxBy5) {

this.xxBy5 = xxBy5;

}

@Temporal(TemporalType.TIMESTAMP)

@Column(name = "xx_by6", length = 19)

public Date getXxBy6() {

return xxBy6;

}

public void setXxBy6(Date xxBy6) {

this.xxBy6 = xxBy6;

}

@Temporal(TemporalType.TIMESTAMP)

@Column(name = "xx_by7", length = 19)

public Date getXxBy7() {

return xxBy7;

}

public void setXxBy7(Date xxBy7) {

this.xxBy7 = xxBy7;

}

@Column(name = "xx_by8", length = 12)

public Float getXxBy8() {

return xxBy8;

}

public void setXxBy8(Float xxBy8) {

this.xxBy8 = xxBy8;

}

}

com.strong.module.txx.jpa.TXx_ 这个类比较奇特，是JPA规范中定义个一个特殊类，主要的作用是构造查询，这个以后再说

Java代码

package com.strong.module.txx.jpa;

import java.util.Date;

import javax.persistence.metamodel.SingularAttribute;

import javax.persistence.metamodel.StaticMetamodel;

/**

* TXx_ entity

*

* @author Simen 自动生成时间: 2011-10-02 08:31:29

*/

@StaticMetamodel(TXx.class)

public abstract class TXx_ {

public static volatile SingularAttribute<TXx, Integer> xxId;

public static volatile SingularAttribute<TXx, String> xxBz;

public static volatile SingularAttribute<TXx, String> xxDm;

public static volatile SingularAttribute<TXx, String> xxLx;

public static volatile SingularAttribute<TXx, String> xxMc;

public static volatile SingularAttribute<TXx, Integer> xxXh;

public static volatile SingularAttribute<TXx, String> xxBy1;

public static volatile SingularAttribute<TXx, String> xxBy2;

public static volatile SingularAttribute<TXx, String> xxBy3;

public static volatile SingularAttribute<TXx, Integer> xxBy4;

public static volatile SingularAttribute<TXx, Integer> xxBy5;

public static volatile SingularAttribute<TXx, Date> xxBy6;

public static volatile SingularAttribute<TXx, Date> xxBy7;

public static volatile SingularAttribute<TXx, Float> xxBy8;

}

六、配置Spring

在src下新建applicationContext.xml文件如下：

Xml代码

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"

xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd">


<context:component-scan base-package="com.strong" />



<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">

<property name="persistenceUnitName" value="StrongOpenJPAPU" />

<property name="loadTimeWeaver">

<bean class="org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver" />

</property>

</bean>



<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">

<property name="entityManagerFactory" ref="entityManagerFactory" />

</bean>



<tx:annotation-driven transaction-manager="transactionManager" />

</beans>

七、建立Junit测试单元

新建一个类：test.com.strong.StringOpenJPATest

Java代码

package test.com.strong;

import javax.persistence.EntityManager;

import javax.persistence.PersistenceContext;

import org.junit.Test;

import org.junit.runner.RunWith;

import org.springframework.test.context.ContextConfiguration;

import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)

@ContextConfiguration(locations = { "classpath:applicationContext.xml" })

public class StringOpenJPATest {

// 使用注解的方式注入，3.1以前版本使用JpaDaoSupport和JpaTemplate实现

@PersistenceContext

private EntityManager entityManager;

@Test

public void doTest() {

System.out.println("=====Hello OpenJPA " + entityManager + "=======");

}

}

这里和Spring3.1以前的版本有一些不同，具体内容请参见Spring3.1+ JpaDaoSupport被deprecated后的研究

执行测试获得结果如下：

Cpp代码

......

=====Hello OpenJPA Shared EntityManager proxy for target factory [org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean@6087e704]=======

.......

到这里，我们成功的运行起来Spring+OpenJPA，并获取了对应的EntityManager，下一步将在这个的基础之上其他的操作，因为我是按照最初始的步骤进行的，所以现在的配置文件正式运行可能定存在问题，下节将进行详细的介绍

本节资源下载

SQL文件：strongjpa.sql.tar.gz

项目文件：StrongOpenJPA.tar.gz

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