【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：