SpringData开发步骤

使用 Spring Data JPA 进行持久层开发需要的四个步骤：

1.配置 Spring 整合 JPA

第一步：导入所需的jar包

第二步：创建一个Spring的applicationContext.xm文件来整合

在 Spring 配置文件中配置 Spring Data，让 Spring 为声明的接口创建代理对象。配置了 <jpa:repositories> 后，Spring 初始化容器时将会扫描 base-package  指定的包目录及其子目录，为继承 Repository 或其子接口的接口创建代理对象，并将代理对象注册为 Spring Bean，业务层便可以通过 Spring 自动封装的特性来直接使用该对象。

1）创建一个db.properties文件来防数据库的连接信息

db.driver=com.mysql.jdbc.Driver
db.url=jdbc:mysql://localhost:3306/mybatis
db.username=root
db.password=root

2）创建一个applicationContext.xml的文件

<?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:jpa="http://www.springframework.org/schema/data/jpa" xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">

    <!--pezhi-->
    <context:component-scan base-package="org.peter.service"/>
    <context:property-placeholder location="classpath:db.properties"/>
    <bean class="com.alibaba.druid.pool.DruidDataSource" id="dataSource">
        <property name="driverClassName" value="${db.driver}"/>
        <property name="url" value="${db.url}"/>
        <property name="username" value="${db.username}"/>
        <property name="password" value="${db.password}"/>
    </bean>
    <!--配置JPA,,替代之前JPA中的persistence.xml文件-->
    <bean class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean" id="entityManagerFactory">
        <property name="dataSource" ref="dataSource"/>
        <!--配置JPA的实现类的适配器-->
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"/>
        </property>
        <!--配置所有Model的位置-->
        <property name="packagesToScan" value="org.peter.model"></property>
        <property name="jpaProperties">
            <props>
                <prop key="hibernate.show_sql">true</prop>
                <prop key="hibernate.format_sql">true</prop>
                <prop key="hibernate.hbm2ddl.auto">update</prop>
            </props>
        </property>
    </bean>
    <!--配置Spring Data，base-package表示要扫描的包-->
    <jpa:repositories base-package="org.peter.dao" entity-manager-factory-ref="entityManagerFactory"></jpa:repositories>

    <bean class="org.springframework.orm.jpa.JpaTransactionManager" id="transactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory"/>
    </bean>
    <tx:annotation-driven transaction-manager="transactionManager"/>
</beans>

第三步：创建一个model层 user

package org.peter.model;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

/**
 * Created by Lenovo on 2017/7/28.
 */
@Entity(name = "t_user")
public class User {
    private Long id;
    private String username;
    private String password;
    private String address;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", address='" + address + '\'' +
                '}';
    }
}

这里创建的model其实就是JPA里创建model是一样的

第四步：创建dao层，并且创建UserDao

声明持久层的接口，该接口继承  Repository，Repository 是一个标记型接口，它不包含任何方法，如必要，Spring Data 可实现 Repository 其他子接口，其中定义了一些常用的增删改查，以及分页相关的方法。

package org.peter.dao;

import org.peter.model.User;
import org.springframework.data.repository.Repository;

/**
 * Created by Lenovo on 2017/7/28.
 */
public interface UserDao extends Repository<User,Long>{
    User findById(Long id);
}

第四步：创建service层 并创建UserService

package org.peter.service;

import org.peter.dao.UserDao;
import org.peter.model.User;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

/**
 * Created by Lenovo on 2017/7/28.
 */
@Service
@Transactional
public class UserService {
    @Resource
    UserDao userDao;
    public User findById(Long id){
        User user = userDao.findById(id);
        return user;
    }
}

第五步：创建一个main类做测试

package org.peter;

import org.junit.Test;
import org.peter.model.User;
import org.peter.service.UserService;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * Created by Lenovo on 2017/7/28.
 */
public class main {

    private ClassPathXmlApplicationContext ctx;
    private UserService userService;
    {
        ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        userService = ctx.getBean(UserService.class);
    }

    @Test
    public void findById(){
      User user = userService.findById(1l);
      System.out.println(user);
    }
}

代码资料：http://download.youkuaiyun.com/detail/strive_peter/9913801