MyBatis入门示例
说明：1，本文采用的Mybatis框架版本为： mybatis-3.0.4.jar
2， 以持久化一个简单的User bean为例
User实体类的代码如下：
[*]package bean;
[*]
[*]public class User {
[*] private String name;
[*] private Integer age;
[*]
[*] public String getName() {
[*] return name;
[*] }
[*] public void setName(String name) {
[*] this.name = name;
[*] }
[*] public Integer getAge() {
[*] return age;
[*] }
[*] public void setAge(Integer age) {
[*] this.age = age;
[*] }
[*] public User(String name, Integer age) {
[*] super();
[*] this.name = name;
[*] this.age = age;
[*] }
[*]
[*] public User() {
[*] super();
[*] } //必须要有这个无参构造方法，不然根据UserMapper.xml中的配置，在查询数据库时，将不能反射构造出User实例
[*]}
User实体的映射器取名为UserMapper(接口)，其代码如下
[*]package Mapper;
[*]import bean.User;
[*]
[*]public interface UserMapper {
[*] public void insertUser(User user);
[*] public User getUser(String name);
[*]}
注意，该接口类似于Hibernate中的DAO层接口，唯一不同的是，MyBatis中，只声明该接口就可以，不需要去实现.
UserMapper映射器对应的配置文件如下(相当于Hibernate中的User.hbm.xml,当然这里面不是属性映射字段，而是直接是映射器中各种方法对应的sql语句)：
[*]<?xml version="1.0" encoding="UTF-8" ?>
[*]<!DOCTYPE mapper
[*] PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
[*] "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
[*]<mapper namespace="Mapper.UserMapper">
[*]<!-- 这里namespace必须是UserMapper接口的路径，不然要运行的时候要报错 “is not known to the MapperRegistry”-->
[*] <insert id="insertUser" parameterType="User">
[*] insert into vincent_user(name,age) values(#{name},#{age})
[*] <!-- 这里sql结尾不能加分号，否则报“ORA-00911”的错误 -->
[*] </insert>
[*]
[*] <!-- 这里的id必须和UserMapper接口中的接口方法名相同，不然运行的时候也要报错 -->
[*] <select id="getUser" resultType="User" parameterType="java.lang.String">
[*] select * from vincent_user where name=#{name}
[*] </select>
[*]</mapper>
MyBatis的配置文件这里取名为mybatis-config.xml其配置代码如下(相当与Hibernate的hibernate.cfg.xml):
[*]<?xml version="1.0" encoding="UTF-8"?>
[*]<!DOCTYPE configuration
[*] PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
[*] "http://mybatis.org/dtd/mybatis-3-config.dtd">
[*]
[*]<configuration>
[*] <settings>
[*] <!-- changes from the defaults for testing -->
[*] <setting name="cacheEnabled" value="false" />
[*] <setting name="useGeneratedKeys" value="true" />
[*] <setting name="defaultExecutorType" value="REUSE" />
[*] </settings>
[*] <typeAliases>
[*] <typeAlias alias="User" type="bean.User"/>
[*] </typeAliases>
[*] <environments default="development">
[*] <environment id="development">
[*] <transactionManager type="jdbc"/>
[*] <dataSource type="POOLED">
[*] <property name="driver" value="oracle.jdbc.driver.OracleDriver"/>
[*] <property name="url" value="jdbc:oracle:thin:@192.168.56.201:1521:system"/>
[*] <property name="username" value="vincent"/>
[*] <property name="password" value="1234"/>
[*] </dataSource>
[*] </environment>
[*] </environments>
[*] <mappers>
[*] <mapper resource="resource/UserMapper.xml" />
[*] </mappers>
[*]</configuration>
加载配置文件得到sqlSessionFactory的工具类
[*]package Util;
[*]
[*]import java.io.IOException;
[*]import java.io.Reader;
[*]
[*]import org.apache.ibatis.io.Resources;
[*]import org.apache.ibatis.session.SqlSessionFactory;
[*]import org.apache.ibatis.session.SqlSessionFactoryBuilder;
[*]
[*]public class MyBatisUtil {
[*] private final static SqlSessionFactory sqlSessionFactory;
[*] static {
[*] String resource = "resource/mybatis-config.xml";
[*] Reader reader = null;
[*] try {
[*] reader = Resources.getResourceAsReader(resource);
[*] } catch (IOException e) {
[*] System.out.println(e.getMessage());
[*]
[*] }
[*] sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
[*] }
[*]
[*] public static SqlSessionFactory getSqlSessionFactory() {
[*] return sqlSessionFactory;
[*] }
[*]}
测试代码如下：
[*]package TestMapper;
[*]import org.apache.ibatis.session.SqlSession;
[*]import org.apache.ibatis.session.SqlSessionFactory;
[*]import org.junit.Test;
[*]
[*]public class TestMapper {
[*] static SqlSessionFactory sqlSessionFactory = null;
[*] static {
[*] sqlSessionFactory = MyBatisUtil.getSqlSessionFactory();
[*] }
[*]
[*] @Test
[*] public void testAdd() {
[*] SqlSession sqlSession = sqlSessionFactory.openSession();
[*] try {
[*] UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
[*] User user = new User("tom",new Integer(5));
[*] userMapper.insertUser(user);
[*] sqlSession.commit();//这里一定要提交，不然数据进不去数据库中
[*] } finally {
[*] sqlSession.close();
[*] }
[*] }
[*]
[*] @Test
[*] public void getUser() {
[*] SqlSession sqlSession = sqlSessionFactory.openSession();
[*] try {
[*] UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
[*] User user = userMapper.getUser("jun");
[*] System.out.println("name: "+user.getName()+"|age: "+user.getAge());
[*] } finally {
[*] sqlSession.close();
[*] }
[*] }
[*]
[*]}
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