Mybaits的使用方法

深碍√TFBOYSˉ_ 2022-08-14 00:48 163阅读 0赞

**一、定义一个User实体类**

package com.domain;
    public class User {
    	private Integer id;
    	private String username;
    	private Integer age;
    	public User()
    	{}
    	public User(String username, Integer age) {
    
    		this.username = username;
    		this.age = age;
    	}
    	public Integer getId() {
    		return id;
    	}
    	public void setId(Integer id) {
    		this.id = id;
    	}
    	public String getUsername() {
    		return username;
    	}
    	public void setUsername(String username) {
    		this.username = username;
    	}
    	public Integer getAge() {
    		return age;
    	}
    	public void setAge(Integer age) {
    		this.age = age;
    	}
        @Override
        public String toString() {
        	// TODO Auto-generated method stub
        	return "id:"+id +",username:"+username+",age:"+age;
        }
    }

**二、首先写一个接口类：**

package com.dao;
    import java.util.List;
    import com.domain.MyUser;
    import com.domain.User;
    public interface UserMapper {
    	/*根据id查找一个对象*/
    	public User findById(Integer id);
    	/*添加一个对象*/
    	public void addUser(User user);
    	/*根据id删除一个对象*/
    	public void deleteById(Integer id);
    	/*查找所有对象*/
    	public List<User> lists();
    	/*数据库记录条数*/
    	public int showCount();
    	/*批量查找对象*/
    	public List<User> findByIds(MyUser myUser);
    	/*ids批量删除对象*/
    	public void deleteByIds(MyUser myUser);
    }

**三、写一个与接口类UserMapper对应的UserMapper.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="com.dao.UserMapper">
    
     <select id="findById" parameterType="Integer" resultType="User">
    	select * from t_user where id=#{id}
    </select>
    
    <insert id="addUser" parameterType="User">
    	insert into t_user(username,age) values(#{username},#{age})
    </insert>
    
    <delete id="deleteById" parameterType="Integer">
    	delete from t_user where id=#{id}
    </delete>
    
    <select id="lists" resultType="User">
    	select * from t_user order by id desc
    </select>
    
    <select id="showCount" resultType="Integer">
    	select count(*) from t_user
    </select>
    
    <select id="findByIds" parameterType="MyUser" resultType="User">
        select * from t_user where id in
    <foreach item="item" index="index" collection="ids" open="(" separator="," close=")">
        #{item}
    </foreach>
    </select>
    
    <delete id="deleteByIds" parameterType="MyUser">
        delete from t_user where id in <foreach collection="ids" index="index" item="item" open="(" separator="," close=")">#{item}</foreach>
    </delete> 
    </mapper>

其中MyUser 表示一个构造参数的实体类用来封装一些参数，这里是用来封闭用户id集合：

package com.domain;
    import java.io.Serializable;
    public class MyUser implements Serializable {
    	private static final long serialVersionUID = 1L;
    	 private Integer[] ids;
    
    	public Integer[] getIds() {
    		return ids;
    	}
    	public void setIds(Integer[] ids) {
    		this.ids = ids;
    	}
    }

**四、为MyBabits增加一个配置数据库信息的配置文件：**

<?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>
    	<typeAliases>  
    	
    	 <typeAlias alias="MyUser" type="com.domain.MyUser"/> 
    	 <typeAlias alias="User" type="com.domain.User"/>
    	 
    	</typeAliases> 
    	<environments default="development">  
    	  <environment id="development"> 
    	     
    		 <transactionManager type="JDBC" /> 
    		 
    		 <dataSource type="POOLED">    
    		   <property name="driver" value="com.mysql.jdbc.Driver" />  
    		   <property name="url" value="jdbc:mysql://192.168.1.188:3306/mybatis"/>
    		   <property name="username" value="root" />   
    		   <property name="password" value="root" />  
    		 </dataSource>	 
    	  </environment> 	  
    	</environments>  
    	
        <mappers>      
           <mapper resource="com/dao/UserMapper.xml"/>  
       </mappers>   
    </configuration>

**五、使用已经写好的接口，这里使用Junit单元测试,这里只测试了查找对象，其它方法可以自己去测试：**

package com.test;
    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;
    import org.junit.*;
    import com.dao.UserMapper;
    import com.domain.MyUser;
    import com.domain.User;
    public class testMybatis {
    
    	static SqlSessionFactory ssf=null;
    	static SqlSession session=null;
            //加载配置文件，使用到SqlSessionFactoryBuilder工厂，并得到session
            @BeforeClass
    	public static void before() throws IOException
    	{
                    String resource="SqlMapConfig.xml";
    		Reader reader=Resources.getResourceAsReader(resource);
    		ssf=new SqlSessionFactoryBuilder().build(reader);
    		session=ssf.openSession();
    	}
    	/*查找一个对象 */
    	@Test
    	public void testGetById()
    	{
    	    try{
    	       UserMapper userMapper=session.getMapper(UserMapper.class);    	   
    	       User user=userMapper.findById(2);
        	   System.out.println(user);
               }catch(Exception e)
               {
        	      e.printStackTrace();
               }
    	}
            //最后关闭session
            @AfterClass
    	public static void afterClass()
    	{
    	   session.close();
    	}