【Mybatis】MyBatis对表执行CRUD操作（三）

　　本例在【Mybatis】MyBatis配置文件的使用（二）基础上继续学习对表执行CRUD操作

使用MyBatis对表执行CRUD操作

　　1、定义sql映射xml文件（EmployeeMapper.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">
<!-- 
namespace：名称空间
id：唯一标识
resultType：返回值类型
#{id}：从传过来的参数中取出id值
 -->
<mapper namespace="com.hd.test.mapper.EmployeeMapper">
    <select id="getEmployeeById"
        resultType="com.hd.test.pojo.Employee">
        select id, last_name lastName, gender, email from employee where id =
        #{id}
    </select>
    
    <!-- public Long insertEmployee(Employee employee); -->
    <!-- parameterType 可写可不写 -->
    <insert id="insertEmployee" parameterType="com.hd.test.pojo.Employee" >
        insert into employee(last_name, email, gender) values(#{lastName}, #{email}, #{gender})
    </insert>    
    
    <!-- public boolean updateEmployee(Employee employee); -->
    <update id="updateEmployee">
        update employee 
            set last_name = #{lastName}, email = #{email}, gender = #{gender}
        where 
            id = #{id}
    </update>    
    
    <!-- public Integer deleteEmployeeById(Integer id); -->
    <delete id="deleteEmployeeById">
        delete from employee where id = #{id}
    </delete>    
    
</mapper>

　　2、在mybatis-config.xml文件中注册这个映射文件EmployeeMapper.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>
    
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <!-- 配置数据库连接信息 -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url" value="jdbc:mysql://localhost:3306/test_mybatis?allowPublicKeyRetrieval=true" />
                <property name="username" value="admin" />
                <property name="password" value="123456" />
            </dataSource>
        </environment>
    </environments>
    
    

    <mappers>
        <!-- 添加sql射文件到Mybatis的全局配置文件中 -->
        <mapper resource="mapper/EmployeeMapper.xml" />

    </mappers>

</configuration>

　　3、编写一个EmployeeMapper接口

package com.hd.test.mapper;

import com.hd.test.pojo.Employee;

public interface EmployeeMapper {
    
    public Employee getEmployeeById(Integer id);
    
    // 新增
    public Long insertEmployee(Employee employee);
    
    // 修改
    public boolean updateEmployee(Employee employee);
    
    // 删除
    public Integer deleteEmployeeById(Integer id);
    
}

　　4、编写mybatis单元测试类（TestMybatis.java）

package com.hd.test.mybatis;

import java.io.IOException;
import java.io.InputStream;

import javax.sound.midi.Soundbank;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;

import com.hd.test.mapper.EmployeeMapper;
import com.hd.test.pojo.Employee;

import sun.print.resources.serviceui;



/**
 * 1、SqlSession代表和数据库的一次会话，用完必须关闭
    2、SqlSession和connection一样都是非线程安装的，每次使用都应该去获取新对象
    3、mapper接口没有实现累，但是mybatis会为这个接口生成一个代理对象
    （将接口和xml进行绑定）
    EmployeeMapper empMapper = sqlSession.getMapper(EmployeeMapper.class)
    4、连个重要的配置文件：
    mybatis的全局配置文件：包含数据库连接信息，事物管理等系统环境信息
    sql映射文件：保存了每一个sql语句的映射信息：
        将sql抽取出来。
 *
 */
public class TestMybatis {
    
    /**
     * 测试增删改
     * 1、mybatis允许增删改直接定义一下类型返回值
     *         Ingteger、Long、Boolean
     * 2、需要手动提交数据
     *         SqlSession session = sqlSessionFactory.openSession(); ==> 手动提交
     *         SqlSession session = sqlSessionFactory.openSession(true); ==> 自动提交
     * @throws IOException
     */
    
    
    // 插入
    @Test
    public void test1() throws IOException {
        
        // 获取SqlSessionFactory
        InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        // 获取的sqlsession不会自动提交数据
        SqlSession session = sqlSessionFactory.openSession();
        
        try {
            EmployeeMapper mapper = session.getMapper(EmployeeMapper.class);
            
            // 1、插入数据
            Employee employee = new Employee("小红", "1", "xiaohong@163.com");
            Long returnValue = mapper.insertEmployee(employee);
            System.out.println("插入返回值：" + returnValue);
            
            // 手动提交数据
            session.commit();
        
        } finally {
            session.close();
        }
    }
    
    // 修改
    @Test
    public void test2() throws IOException {
        
        // 获取SqlSessionFactory
        InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        
        // 获取的sqlsession 自动提交数据
        SqlSession session = sqlSessionFactory.openSession(true);
        try {
            EmployeeMapper mapper = session.getMapper(EmployeeMapper.class);
            
            // 2、更新数据
            Employee employee = new Employee(1, "小红", "0", "xiaohong@163.com");
            boolean returnValue = mapper.updateEmployee(employee);
            System.out.println("更新返回值：" + returnValue);
        
        } finally {
            session.close();
        }
    }
    
    // 删除
    @Test
    public void test3() throws IOException {
        
        // 获取SqlSessionFactory
        InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        
        // 获取的sqlsession 自动提交数据
        SqlSession session = sqlSessionFactory.openSession(true);
        try {
            EmployeeMapper mapper = session.getMapper(EmployeeMapper.class);
            
            // 3、删除数据
            Integer returnValue = mapper.deleteEmployeeById(8);
            System.out.println("删除返回值：" + returnValue);
        
        } finally {
            session.close();
        }
    }
    
    
    
    /**
     * 查询
     * @throws IOException
     */
    @Test
    public void test() throws IOException {
        // 1、根据mybatis全局配置文件，获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        // 使用MyBatis提供的Resources类加载mybatis的配置文件，获取输入流
        InputStream inputStream = Resources.getResourceAsStream(resource);
        // 构建sqlSession的工厂
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        // 2、从SqlSession工厂中，获取sqlsession，用来执行sql
        SqlSession session = sqlSessionFactory.openSession();
        try {
            // 查询selectOne
            // @param statement Unique identifier matching the statement to use.      一个唯一标识
            // @param parameter A parameter object to pass to the statement.        参数
            EmployeeMapper mapper = session.getMapper(EmployeeMapper.class);
            Employee employee = mapper.getEmployeeById(1);
            // 输出信息
            System.out.println("查询返回值：" + employee);
        } finally {
            // 关闭session
            session.close();
        }
    }
    
    
}

 　　5、运行单元测试类，结果如下：