Java持久层框架MyBatis简单实例

2011年6月iBatis 更名为 MyBatis，从 iBatis 到 MyBatis，不只是名称上的变化，MyBatis 提供了更为强大的功能，同时并没有损失其易用性，相反，在很多地方都借助于 JDK 的泛型和注解特性进行了简化。所以你懂的，开始学习就从MyBatis吧。

例子使用MyBatis+MySQL实现一个用户表的查询，如下：

1、数据库

在MySQL中，test数据库下，简历user表，字段：id，name，password，建表语句略。

2、需导入的包

只有两个： mybatis-3.0.3.jar mysql-connector-java-5.1.16-bin.jar（JDBC包）

3、目录结构

采用最简单的结构，com.mybatis包下有且仅有四个文件：configuration.xml、user.xml、User.java、Test.java 。

4、mybatis配置文件configuration.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>  
    <typeAliases>  
        <typeAlias alias="User" type="com.mybatis.User"></typeAlias>  
    </typeAliases>  
      
    <environments default="development">  
        <environment id="development">  
            <transactionManager type="JDBC"></transactionManager>  
            <dataSource type="POOLED">  
                <property name="driver" value="com.mysql.jdbc.Driver" />  
                <property name="url" value="jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8" />  
                <property name="username" value="root" />  
                <property name="password" value="123456" />  
            </dataSource>  
        </environment>  
    </environments>  
      
    <mappers>  
        <mapper resource="user.xml"/>  
    </mappers>  
  
</configuration> 

5、User表sql文件User.xml

<?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="User">  
    <select id="selectUser" parameterType="int" resultType="User">  
        SELECT * FROM user WHERE id = #{id}  
    </select>  
      
    <select id="selectUsers" resultType="User">  
        SELECT * FROM user  
    </select>  
</mapper>

6、表结构文件User.java

package com.mybatis; 
 
public class User {  
    private int id;  
    private String name;  
    private String password;  
      
    public User(){}  
    public User(int id, String name) {  
        this.id = id;  
        this.name = name;  
    }  
      
    public int getId() {  
        return this.id;  
    }  
      
    public void setId(int id) {  
        this.id = id;  
    }  
      
    public String getName() {  
        return this.name;  
    }  
      
    public void setName(String name) {  
        this.name = name;  
    }  
      
    public String getPassword() {  
        return this.password;  
    }  
      
    public void setPassword(String password) {  
        this.password = password;  
    }  
      
    @Override  
    public String toString() {  
        return "User [id=" + this.id + ", name=" + this.name + ", password=" + this.password + "]";  
    }  
      
}

7、测试用例Test.java

package com.mybatis;  
  
import java.io.IOException;  
import java.io.Reader;  
import java.util.List;  
  
import org.apache.ibatis.io.Resources;  
import org.apache.ibatis.session.SqlSession;  
import org.apache.ibatis.session.SqlSessionFactory;  
import org.apache.ibatis.session.SqlSessionFactoryBuilder;  
  
public class Test {  
    public static void main(String[] args) throws IOException {  
        String resource = "configuration.xml";  
        Reader reader = Resources.getResourceAsReader(resource);  
        SqlSessionFactory ssf = new SqlSessionFactoryBuilder().build(reader);  
        SqlSession session = ssf.openSession();  
        try{  
            User user = session.selectOne("selectUser", "1");  
            System.out.println(user.getName());  
            System.out.println(user);  
            System.out.println("--------------分隔线---------------");  
          
            List<User> users = session.selectList("selectUsers");  
            for(int i=0; i<users.size(); i++) {  
                System.out.println(users.get(i).getName());  
            }  
              
        } catch (Exception e) {  
            e.printStackTrace();  
        } finally {  
            session.close();  
        }  
    }  
}