Spring Data JPA教程，第一部分: Configuration（翻译）

trzxycx

　　Spring Data JPA项目旨在简化基于仓库的JPA的创建并减少与数据库交互的所需的代码量。本人在自己的工作和个人爱好项目中已经使用一段时间，它却是是事情如此简单和清洗，现在是时候与你分享我的知识。
　　本文是我的Spring Data JPA教程的第一部分，将向你描述的是，当你使用Hibernate作为你的jpa提供者时怎样配置Spring Data JPA，在我们开始之前，首先应该明白一件事情，本教程不是Hibernate, JPA 或 Spring的人们教程，如果你想理解在我的Spring Data JPA教程中描述的概念，你必须有关于这些技术方面的经验
　　本教程的依赖如下:

• BoneCP 0.7.1.RELEASE (同样你也可以采用其他的数据源实现)
  
• Hibernate 4.0.1.Final
  
• Spring Framework 3.1.0.RELEASE
  
• Spring Data JPA 1.0.2
  
• Servlet API 3.0
  

　　当然，既然本人使用Maven作为构建工具，如果你想运行我的example应用你必须安装它。

开始
　　现在开始了. 你可以通过如下步骤配置Spring Data JPA:

• 获取必须的依赖.
  
• 在Spring application context configuration里面配置必须的bean. Spring Data JPA需要的bean是: 数据源, 事务管理器 和 实体管理工厂.
  
• 配置Spring Data JPA.
  

　　这些步骤在下面详细解释:

获取必须的依赖
　　首先，你需要获取必须的依赖，你可以通过在你的pom.xml文件里面配置这些依赖，我的example的pom.xml如下：



<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/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>net.petrikainulainen.spring</groupId>
<artifactId>data-jpa-tutorial-part-one</artifactId>
<packaging>war</packaging>
<version>0.1</version>
<name>Spring Data JPA Tutorial Part One</name>
<description>Spring Data JPA Tutorial Part One</description>
<licenses>
<license>
<name>Apache License 2.0</name>
<url>http://www.apache.org/licenses/LICENSE-2.0</url>
</license>
</licenses>
<url>http://www.petrikainulainen.net</url>
<repositories>
<repository>
<id>repository.jboss.org-public</id>
<name>JBoss repository</name>
<url>https://repository.jboss.org/nexus/content/groups/public</url>
</repository>
</repositories>
<properties>
<hibernate.version>4.0.1.Final</hibernate.version>
<mysql.connector.version>5.1.18</mysql.connector.version>
<slf4j.version>1.6.1</slf4j.version>
<spring.version>3.1.0.RELEASE</spring.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<!-- Spring Framework -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-orm</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- Spring MVC -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>cglib</groupId>
<artifactId>cglib</artifactId>
<version>2.2.2</version>
</dependency>
<!-- Spring Data JPA -->
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-jpa</artifactId>
<version>1.0.2.RELEASE</version>
</dependency>
<!-- Hibernate -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>${hibernate.version}</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>${hibernate.version}</version>
</dependency>
<!-- H2 Database -->
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<version>1.3.160</version>
</dependency>
<!-- MySQL JDBC connector -->
<!-- If you want to use MySQL, uncomment this dependency declation. -->
<!--
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql.connector.version}</version>
</dependency>
-->
<!-- PostgreSQL JDBC 4 -->
<!-- If you don't want to use PostgreSQL, uncomment this dependency declaration. -->
<!--
<dependency>
<groupId>postgresql</groupId>
<artifactId>postgresql</artifactId>
<version>9.0-801.jdbc4</version>
</dependency>
-->
<!-- BoneCP -->
<dependency>
<groupId>com.jolbox</groupId>
<artifactId>bonecp</artifactId>
<version>0.7.1.RELEASE</version>
</dependency>
<!-- Servlet API 3.0 -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.0.1</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<!-- Logging dependencies -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.16</version>
</dependency>
<!-- Testing Dependencies -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.9</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<finalName>data-jpa-tutorial-part-one</finalName>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<source>1.6</source>
<target>1.6</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.1.1</version>
<configuration>
<failOnMissingWebXml>false</failOnMissingWebXml>
</configuration>
</plugin>
<plugin>
<groupId>org.mortbay.jetty</groupId>
<artifactId>jetty-maven-plugin</artifactId>
<version>8.1.0.RC2</version>
<configuration>
<scanIntervalSeconds>0</scanIntervalSeconds>
<webAppConfig>
<defaultsDescriptor>src/main/resources/webdefault.xml</defaultsDescriptor>
</webAppConfig>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-site-plugin</artifactId>
<version>3.0</version>
<configuration>
<reportPlugins>
<!-- Cobertura Plugin -->
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>cobertura-maven-plugin</artifactId>
<version>2.5.1</version>
</plugin>
</reportPlugins>
</configuration>
</plugin>
</plugins>
</build>
</project>
配置 Spring应用上下文
　　第二步，你必须配置Spring应用上下文，也许您还记得，你需要配置数据源，事务管理器和实体管理器工厂的bean。如果您正在使用Spring 3.1和Servlet 3.0，你可以这样做到，通过实现一个Java配置类，并在您的Web应用程序初始化的时候加载该配置类。我的应用程序上下文配置类的内容如下下：



import com.jolbox.bonecp.BoneCPDataSource;
import org.hibernate.ejb.HibernatePersistence;
import org.springframework.context.MessageSource;
import org.springframework.context.annotation.*;
import org.springframework.context.support.ResourceBundleMessageSource;
import org.springframework.core.env.Environment;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import org.springframework.web.servlet.view.JstlView;
import javax.annotation.Resource;
import javax.sql.DataSource;
/**
* An application context Java configuration class. The usage of Java configuration
* requires Spring Framework 3.0 or higher with following exceptions:
* <ul>
*     <li>@EnableWebMvc annotation requires Spring Framework 3.1</li>
* </ul>
* @author Petri Kainulainen
*/
@Configuration
@ComponentScan(basePackages = {"net.petrikainulainen.spring.datajpa.controller"})
@EnableWebMvc
@ImportResource("classpath:applicationContext.xml")
@PropertySource("classpath:application.properties")
public class ApplicationContext {
private static final String VIEW_RESOLVER_PREFIX = "/WEB-INF/jsp/";
private static final String VIEW_RESOLVER_SUFFIX = ".jsp";
private static final String PROPERTY_NAME_DATABASE_DRIVER = "db.driver";
private static final String PROPERTY_NAME_DATABASE_PASSWORD = "db.password";
private static final String PROPERTY_NAME_DATABASE_URL = "db.url";
private static final String PROPERTY_NAME_DATABASE_USERNAME = "db.username";
private static final String PROPERTY_NAME_HIBERNATE_DIALECT = "hibernate.dialect";
private static final String PROPERTY_NAME_HIBERNATE_FORMAT_SQL = "hibernate.format_sql";
private static final String PROPERTY_NAME_HIBERNATE_NAMING_STRATEGY = "hibernate.ejb.naming_strategy";
private static final String PROPERTY_NAME_HIBERNATE_SHOW_SQL = "hibernate.show_sql";
private static final String PROPERTY_NAME_ENTITYMANAGER_PACKAGES_TO_SCAN = "entitymanager.packages.to.scan";
private static final String PROPERTY_NAME_MESSAGESOURCE_BASENAME = "message.source.basename";
private static final String PROPERTY_NAME_MESSAGESOURCE_USE_CODE_AS_DEFAULT_MESSAGE = "message.source.use.code.as.default.message";
@Resource
private Environment environment;
@Bean
public DataSource dataSource() {
BoneCPDataSource dataSource = new BoneCPDataSource();
dataSource.setDriverClass(environment.getRequiredProperty(PROPERTY_NAME_DATABASE_DRIVER));
dataSource.setJdbcUrl(environment.getRequiredProperty(PROPERTY_NAME_DATABASE_URL));
dataSource.setUsername(environment.getRequiredProperty(PROPERTY_NAME_DATABASE_USERNAME));
dataSource.setPassword(environment.getRequiredProperty(PROPERTY_NAME_DATABASE_PASSWORD));
return dataSource;
}
@Bean
public JpaTransactionManager transactionManager() throws ClassNotFoundException {
JpaTransactionManager transactionManager = new JpaTransactionManager();
transactionManager.setEntityManagerFactory(entityManagerFactoryBean().getObject());
return transactionManager;
}
@Bean
public LocalContainerEntityManagerFactoryBean entityManagerFactoryBean() throws ClassNotFoundException {
LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
entityManagerFactoryBean.setDataSource(dataSource());
entityManagerFactoryBean.setPackagesToScan(environment.getRequiredProperty(PROPERTY_NAME_ENTITYMANAGER_PACKAGES_TO_SCAN));
entityManagerFactoryBean.setPersistenceProviderClass(HibernatePersistence.class);
Properties jpaProterties = new Properties();
jpaProterties.put(PROPERTY_NAME_HIBERNATE_DIALECT, environment.getRequiredProperty(PROPERTY_NAME_HIBERNATE_DIALECT));
jpaProterties.put(PROPERTY_NAME_HIBERNATE_FORMAT_SQL, environment.getRequiredProperty(PROPERTY_NAME_HIBERNATE_FORMAT_SQL));
jpaProterties.put(PROPERTY_NAME_HIBERNATE_NAMING_STRATEGY, environment.getRequiredProperty(PROPERTY_NAME_HIBERNATE_NAMING_STRATEGY));
jpaProterties.put(PROPERTY_NAME_HIBERNATE_SHOW_SQL, environment.getRequiredProperty(PROPERTY_NAME_HIBERNATE_SHOW_SQL));
entityManagerFactoryBean.setJpaProperties(jpaProterties);
return entityManagerFactoryBean;
}
@Bean
public MessageSource messageSource() {
ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
messageSource.setBasename(environment.getRequiredProperty(PROPERTY_NAME_MESSAGESOURCE_BASENAME));
messageSource.setUseCodeAsDefaultMessage(Boolean.parseBoolean(environment.getRequiredProperty(PROPERTY_NAME_MESSAGESOURCE_USE_CODE_AS_DEFAULT_MESSAGE)));
return messageSource;
}
@Bean
public ViewResolver viewResolver() {
InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
viewResolver.setViewClass(JstlView.class);
viewResolver.setPrefix(VIEW_RESOLVER_PREFIX);
viewResolver.setSuffix(VIEW_RESOLVER_SUFFIX);
return viewResolver;
}
}
　　我的web应用初始器如下：



import org.springframework.web.WebApplicationInitializer;
import org.springframework.web.context.ContextLoaderListener;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;
import javax.servlet.*;
/**
* Web application Java configuration class. The usage of web application
* initializer requires Spring Framework 3.1 and Servlet 3.0.
* @author Petri Kainulainen
*/
public class DataJPAExampleInitializer implements WebApplicationInitializer {
private static final String DISPATCHER_SERVLET_NAME = "dispatcher";
private static final String DISPATCHER_SERVLET_MAPPING = "/";
@Override
public void onStartup(ServletContext servletContext) throws ServletException {
AnnotationConfigWebApplicationContext rootContext = new AnnotationConfigWebApplicationContext();
rootContext.register(ApplicationContext.class);
ServletRegistration.Dynamic dispatcher = servletContext.addServlet(DISPATCHER_SERVLET_NAME, new DispatcherServlet(rootContext));
dispatcher.setLoadOnStartup(1);
dispatcher.addMapping(DISPATCHER_SERVLET_MAPPING);
servletContext.addListener(new ContextLoaderListener(rootContext));
}
}
　　你可能注意到，本人使用@PropertySource annotation来标识属性文件的位置，属性文件包含了使用的配置参数的值，myapplication.properties文件内容如下：



# The default database is H2 memory database but I have also
# added configuration needed to use either MySQL and PostgreSQL.
#Database Configuration
db.driver=org.h2.Driver
#db.driver=com.mysql.jdbc.Driver
#db.driver=org.postgresql.Driver
db.url=jdbc:h2:mem:datajpa
#db.url=jdbc:mysql://localhost:3306/datajpa
#db.url=jdbc:postgresql://localhost/datajpa
db.username=sa
db.password=
#Hibernate Configuration
hibernate.dialect=org.hibernate.dialect.H2Dialect
#hibernate.dialect=org.hibernate.dialect.MySQL5InnoDBDialect
#hibernate.dialect=org.hibernate.dialect.PostgreSQLDialect
hibernate.format_sql=true
hibernate.ejb.naming_strategy=org.hibernate.cfg.ImprovedNamingStrategy
hibernate.show_sql=true
#MessageSource
message.source.basename=i18n/messages
message.source.use.code.as.default.message=true
#EntityManager
#Declares the base package of the entity classes
entitymanager.packages.to.scan=net.petrikainulainen.spring.datajpa.model
配置Spring Data JPA
　　第三步，你必须配置Spring Data JPA,如果你留心，你可能已经注意到，本人在我的应用上下文配置类使用@ImportResource annotation 来从xml配置文件导入额外的配置. 当前Spring Data JPA不支持java配置，因此，唯一的方式是使用XML配置文件，我的applicationContext.xml文件如下：



<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:jpa="http://www.springframework.org/schema/data/jpa"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
http://www.springframework.org/schema/data/jpa
http://www.springframework.org/schema/data/jpa/spring-jpa-1.0.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-3.1.xsd">
<!--
Configures the location of static resources such as css files.
Requires Spring Framework 3.0 or higher.
-->
<mvc:resources mapping="/static/**" location="/static/"/>
<!--
Ensures that dispatcher servlet can be mapped to '/' and static resources
are still served by the containers default servlet. Requires Spring Framework
3.0 or higher.
-->
<mvc:default-servlet-handler/>
<!--
Configures Spring Data JPA and sets the base package of my DAOs.
-->
<jpa:repositories base-package="net.petrikainulainen.spring.datajpa.repository"/>
</beans>
You Are Done
　　本文介绍内容：我现在已经向你演示了如何配置Spring Data JPA。同时也创建了一个示例应用程序来演示配置的实际运行。你可以通过从Github获取我的示例应用程序来测试自己的配置，并通过使用Maven Jetty plugin来运行这个示例web应用（注：请记住，首先创建模型和仓库的package。既然不可能向Git暂存区域添加空目录，Github仓库也不具有它们）。
　　我的Spring Data JPA教程的第二部分介绍了如何通过使用Spring  Data JPA创建一个简单的CRUD Web应用程序。敬请关注。
　　---------------------------------------------------------------------------
　　本系列Spring Data JPA 教程翻译系本人原创
　　作者 博客园 刺猬的温驯
　　本文链接 http://www.cnblogs.com/chenying99/archive/2013/06/19/3143516.html
　　本文版权归作者所有，未经作者同意，严禁转载及用作商业传播，否则将追究法律责任。