MyBatis入门范例

MyBatis入门实例
关于MyBatis，不作太多介绍，在google一搜索，有很多资料，我也是参考别人的例子，MyBatis入门非常容易，希望我现在发的代码对大家有用。

实体类：

package bean;public class User {private String name;private Integer age;public User() {}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;}}

映射器，这是一个接口，这个接口不需要实现类

package mapper;import org.apache.ibatis.annotations.Select;import bean.User;/** * 映射器 * */public interface UserMapper {public void insertUser(User user); //可以使用Java注解来替换XML@Select("select * from user where name=#{name}")    public User getUser(String name); }

SQL映射的XML文件

<?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 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 user where name=#{name} --><!--    </select> -->    </mapper>

XML映射配置文件

<?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元素体中包含对事务管理和连接池的环境配置 -->   <!-- 你可以配置多种环境，但你只能为每个SqlSessionFactory实例选择一个。 -->       <environment id="development">            <transactionManager type="jdbc"/>            <dataSource type="POOLED">               <property name="driver" value="com.mysql.jdbc.Driver"/>               <property name="url" value="jdbc:mysql://localhost:3306/test"/>               <property name="username" value="root"/>               <property name="password" value="123"/>            </dataSource>        </environment>     </environments>     <mappers>         <mapper resource="resource/UserMapper.xml" />     </mappers> </configuration>

创建SqlSessionFactory的工具类

package utils;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 {//每一个MyBatis的应用程序都以一个SqlSessionFactory对象的实例为核心//使用SqlSessionFactory的最佳实践是在应用运行期间不要重复创建多次,最佳范围是应用范围 private  final static SqlSessionFactory sqlSessionFactory;     static {        String resource = "resource/configuration.xml";        Reader reader = null;        try {            reader = Resources.getResourceAsReader(resource);        } catch (IOException e) {            System.out.println(e.getMessage());         }        //SqlSessionFactory对象的实例可以通过SqlSessionFactoryBuilder对象来获得       //SqlSessionFactoryBuilder实例的最佳范围是方法范围（也就是本地方法变量）。       sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);     }      public static SqlSessionFactory getSqlSessionFactory() {        return sqlSessionFactory;     } }

测试类

package testMapper;import mapper.UserMapper;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.junit.Test;import utils.MyBatisUtil;import bean.User;public class TestMapper {static SqlSessionFactory sqlSessionFactory = null;     static {        sqlSessionFactory = MyBatisUtil.getSqlSessionFactory();     }      @Test     public void addUser() {     //获得SqlSession的实例    //每个线程都应该有它自己的SqlSession实例。SqlSession的实例不能被共享，也是线程不安全的。因此最佳的范围是请求或方法范围。       SqlSession sqlSession = sqlSessionFactory.openSession();        try {        //映射器实例的最佳范围是方法范围。           UserMapper userMapper = sqlSession.getMapper(UserMapper.class);            User user = new User("neng",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 {        //确保SqlSession关闭           sqlSession.close();        }     }      @Test     public void getUser() {        SqlSession sqlSession = sqlSessionFactory.openSession();        try {            UserMapper userMapper = sqlSession.getMapper(UserMapper.class);            User user = userMapper.getUser("neng");            System.out.println("name: "+user.getName()+"|age: "+user.getAge());        } finally {            sqlSession.close();        }     } }

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