MybatisMyBatis对表执行CRUD操作

Posted 2021-02-03 H__D

　　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）

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 3 <!-- 
 4 namespace：名称空间
 5 id：唯一标识
 6 resultType：返回值类型
 7 #{id}：从传过来的参数中取出id值
 8  -->
 9 <mapper namespace="com.hd.test.mapper.EmployeeMapper">
10     <select id="getEmployeeById"
11         resultType="com.hd.test.pojo.Employee">
12         select id, last_name lastName, gender, email from employee where id =
13         #{id}
14     </select>
15     
16     <!-- public Long insertEmployee(Employee employee); -->
17     <!-- parameterType 可写可不写 -->
18     <insert id="insertEmployee" parameterType="com.hd.test.pojo.Employee" >
19         insert into employee(last_name, email, gender) values(#{lastName}, #{email}, #{gender})
20     </insert>    
21     
22     <!-- public boolean updateEmployee(Employee employee); -->
23     <update id="updateEmployee">
24         update employee 
25             set last_name = #{lastName}, email = #{email}, gender = #{gender}
26         where 
27             id = #{id}
28     </update>    
29     
30     <!-- public Integer deleteEmployeeById(Integer id); -->
31     <delete id="deleteEmployeeById">
32         delete from employee where id = #{id}
33     </delete>    
34     
35 </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

 1 package com.hd.test.mapper;
 2 
 3 import com.hd.test.pojo.Employee;
 4 
 5 public interface EmployeeMapper {
 6     
 7     public Employee getEmployeeById(Integer id);
 8     
 9     // 新增
10     public Long insertEmployee(Employee employee);
11     
12     // 修改
13     public boolean updateEmployee(Employee employee);
14     
15     // 删除
16     public Integer deleteEmployeeById(Integer id);
17     
18 }

　　4、编写mybatis单元测试类（TestMybatis.java）

  1 package com.hd.test.mybatis;
  2 
  3 import java.io.IOException;
  4 import java.io.InputStream;
  5 
  6 import javax.sound.midi.Soundbank;
  7 
  8 import org.apache.ibatis.io.Resources;
  9 import org.apache.ibatis.session.SqlSession;
 10 import org.apache.ibatis.session.SqlSessionFactory;
 11 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
 12 import org.junit.Test;
 13 
 14 import com.hd.test.mapper.EmployeeMapper;
 15 import com.hd.test.pojo.Employee;
 16 
 17 import sun.print.resources.serviceui;
 18 
 19 
 20 
 21 /**
 22  * 1、SqlSession代表和数据库的一次会话，用完必须关闭
 23     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
 24     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
 25     （将接口和xml进行绑定）
 26     EmployeeMapper empMapper = sqlSession.getMapper(EmployeeMapper.class)
 27     4、连个重要的配置文件：
 28     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
 29     sql映射文件：保存了每一个sql语句的映射信息：
 30         将sql抽取出来。
 31  *
 32  */
 33 public class TestMybatis {
 34     
 35     /**
 36      * 测试增删改
 37      * 1、mybatis允许增删改直接定义一下类型返回值
 38      *         Ingteger、Long、Boolean
 39      * 2、需要手动提交数据
 40      *         SqlSession session = sqlSessionFactory.openSession(); ==> 手动提交
 41      *         SqlSession session = sqlSessionFactory.openSession(true); ==> 自动提交
 42      * @throws IOException
 43      */
 44     
 45     
 46     // 插入
 47     @Test
 48     public void test1() throws IOException {
 49         
 50         // 获取SqlSessionFactory
 51         InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
 52         SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
 53         // 获取的sqlsession不会自动提交数据
 54         SqlSession session = sqlSessionFactory.openSession();
 55         
 56         try {
 57             EmployeeMapper mapper = session.getMapper(EmployeeMapper.class);
 58             
 59             // 1、插入数据
 60             Employee employee = new Employee("小红", "1", "[e-mail]");
 61             Long returnValue = mapper.insertEmployee(employee);
 62             System.out.println("插入返回值：" + returnValue);
 63             
 64             // 手动提交数据
 65             session.commit();
 66         
 67         } finally {
 68             session.close();
 69         }
 70     }
 71     
 72     // 修改
 73     @Test
 74     public void test2() throws IOException {
 75         
 76         // 获取SqlSessionFactory
 77         InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
 78         SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
 79         
 80         // 获取的sqlsession 自动提交数据
 81         SqlSession session = sqlSessionFactory.openSession(true);
 82         try {
 83             EmployeeMapper mapper = session.getMapper(EmployeeMapper.class);
 84             
 85             // 2、更新数据
 86             Employee employee = new Employee(1, "小红", "0", "[e-mail]");
 87             boolean returnValue = mapper.updateEmployee(employee);
 88             System.out.println("更新返回值：" + returnValue);
 89         
 90         } finally {
 91             session.close();
 92         }
 93     }
 94     
 95     // 删除
 96     @Test
 97     public void test3() throws IOException {
 98         
 99         // 获取SqlSessionFactory
100         InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
101         SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
102         
103         // 获取的sqlsession 自动提交数据
104         SqlSession session = sqlSessionFactory.openSession(true);
105         try {
106             EmployeeMapper mapper = session.getMapper(EmployeeMapper.class);
107             
108             // 3、删除数据
109             Integer returnValue = mapper.deleteEmployeeById(8);
110             System.out.println("删除返回值：" + returnValue);
111         
112         } finally {
113             session.close();
114         }
115     }
116     
117     
118     
119     /**
120      * 查询
121      * @throws IOException
122      */
123     @Test
124     public void test() throws IOException {
125         // 1、根据mybatis全局配置文件，获取SqlSessionFactory
126         String resource = "mybatis-config.xml";
127         // 使用MyBatis提供的Resources类加载mybatis的配置文件，获取输入流
128         InputStream inputStream = Resources.getResourceAsStream(resource);
129         // 构建sqlSession的工厂
130         SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
131 
132         // 2、从SqlSession工厂中，获取sqlsession，用来执行sql
133         SqlSession session = sqlSessionFactory.openSession();
134         try {
135             // 查询selectOne
136             // @param statement Unique identifier matching the statement to use.      一个唯一标识
137             // @param parameter A parameter object to pass to the statement.        参数
138             EmployeeMapper mapper = session.getMapper(EmployeeMapper.class);
139             Employee employee = mapper.getEmployeeById(1);
140             // 输出信息
141             System.out.println("查询返回值：" + employee);
142         } finally {
143             // 关闭session
144             session.close();
145         }
146     }
147     
148     
149 }

 　　5、运行单元测试类，结果如下：