JavaWeb_(Mybatis框架)使用Mybatis对表进行增、删、改、查操作_二

 

 

　　系列博文：　　

　　　　JavaWeb_(Mybatis框架)JDBC操作数据库和Mybatis框架操作数据库区别_一　　　　传送门

　　　　JavaWeb_(Mybatis框架)使用Mybatis对表进行增、删、改、查操作_二　　　　　　  传送门

　　　　JavaWeb_(Mybatis框架)Mapper动态代理开发_三 　　　　　　　　　　　　　　　 传送门

　　　　JavaWeb_(Mybatis框架)主配置文件介绍_四　　　　　　　　　　　　　　　 　　   传送门

　　　　JavaWeb_(Mybatis框架)输入和输出参数_五　　　　　　　　　　　　　　　　　　 传送门

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　　原有基础上，创建HelloMyBatis.java、HelloMyBatis2.java、HelloMyBatis3.java、HelloMyBatis4.java、HelloMyBatis5.java分别为

　　　　a)通过ID去查询一个用户

package com.Gary.test;

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

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.jupiter.api.Test;

import com.Gary.bean.User;

public class HelloMyBatis {

    @Test
    //入门程序，通过ID，查询用户
    public void Test1() throws IOException {
        //读取配置文件
        String resource = "sqlMapConfig.xml";
        
        InputStream in = Resources.getResourceAsStream(resource);
        
        //需要sqlSessionFactoryBuilder
        SqlSessionFactoryBuilder ssfb = new SqlSessionFactoryBuilder();
        
        //创建sqlSessionFactory
        SqlSessionFactory ssf = ssfb.build(in);
        
        //生产一个sqlSession
        SqlSession session = ssf.openSession();
        
        //操作数据库
        //参数1：要操作的sql语句   参数2：sql语句的参数
        User user = session.selectOne("UserMapper.selectUserById", 1);
        System.err.println(user);
        
        
    }
    
}

 

　　　　b)通过用户名模糊查找匹配的用户列表

package com.Gary.test;

import java.io.IOException;
import java.io.InputStream;
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.jupiter.api.Test;

import com.Gary.bean.User;

public class HelloMyBatis2 {

    @Test
    //入门程序，通过ID，查询用户
    public void Test1() throws IOException {
        //读取配置文件
        String resource = "sqlMapConfig.xml";
        
        InputStream in = Resources.getResourceAsStream(resource);
        
        //需要sqlSessionFactoryBuilder
        SqlSessionFactoryBuilder ssfb = new SqlSessionFactoryBuilder();
        
        //创建sqlSessionFactory
        SqlSessionFactory ssf = ssfb.build(in);
        
        //生产一个sqlSession
        SqlSession session = ssf.openSession();
        
        //操作数据库
        //参数1：要操作的sql语句   参数2：sql语句的参数
        List<User> list = session.selectList("UserMapper.selectUserByName", "王");
    
        for(User u : list) {
            System.out.println(u);
        }
        
        
    }
    
}

 

　　　　c)完成添加用户

package com.Gary.test;

import java.io.IOException;
import java.io.InputStream;
import java.util.Date;
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.jupiter.api.Test;

import com.Gary.bean.User;

public class HelloMyBatis3 {

    @Test
    //入门程序，通过ID，查询用户
    public void Test1() throws IOException {
        //读取配置文件
        String resource = "sqlMapConfig.xml";
        
        InputStream in = Resources.getResourceAsStream(resource);
        
        //需要sqlSessionFactoryBuilder
        SqlSessionFactoryBuilder ssfb = new SqlSessionFactoryBuilder();
        
        //创建sqlSessionFactory
        SqlSessionFactory ssf = ssfb.build(in);
        
        //生产一个sqlSession
        SqlSession session = ssf.openSession();
        
        //操作数据库
        //参数1：要操作的sql语句   参数2：sql语句的参数
        User user = new User();
        
        user.setU_username("Gary");
        user.setU_password("494949");
        user.setU_sex("1");
        user.setU_createTime(new Date());
        user.setU_cid(1);
        
        session.insert("UserMapper.insertUser", user);
        //提交事务
        session.commit();
    
        
        
    }
    
}

 

　　　　d)修改用户

package com.Gary.test;

import java.io.IOException;
import java.io.InputStream;
import java.util.Date;
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.jupiter.api.Test;

import com.Gary.bean.User;

public class HelloMyBatis4 {

    @Test
    //入门程序，通过ID，查询用户
    public void Test1() throws IOException {
        //读取配置文件
        String resource = "sqlMapConfig.xml";
        
        InputStream in = Resources.getResourceAsStream(resource);
        
        //需要sqlSessionFactoryBuilder
        SqlSessionFactoryBuilder ssfb = new SqlSessionFactoryBuilder();
        
        //创建sqlSessionFactory
        SqlSessionFactory ssf = ssfb.build(in);
        
        //生产一个sqlSession
        SqlSession session = ssf.openSession();
        
        //操作数据库
        //参数1：要操作的sql语句   参数2：sql语句的参数
        User user = new User();
        user.setU_id(13);
        user.setU_username("修改后Gary");

        session.insert("UserMapper.updateUser", user);
        //提交事务
        session.commit();
    
        
        
    }
    
}

 

　　　　e)根据id删除用户

package com.Gary.test;

import java.io.IOException;
import java.io.InputStream;
import java.util.Date;
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.jupiter.api.Test;

import com.Gary.bean.User;

public class HelloMyBatis5 {

    @Test
    //入门程序，通过ID，查询用户
    public void Test1() throws IOException {
        //读取配置文件
        String resource = "sqlMapConfig.xml";
        
        InputStream in = Resources.getResourceAsStream(resource);
        
        //需要sqlSessionFactoryBuilder
        SqlSessionFactoryBuilder ssfb = new SqlSessionFactoryBuilder();
        
        //创建sqlSessionFactory
        SqlSessionFactory ssf = ssfb.build(in);
        
        //生产一个sqlSession
        SqlSession session = ssf.openSession();
        
        //操作数据库
        //参数1：要操作的sql语句   参数2：sql语句的参数

        session.delete("UserMapper.deleteUserById", 13);
        //提交事务
        session.commit();
    
        
        
    }
    
}

 

<?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="UserMapper">
 
     <select id="selectUserById" parameterType="Integer" resultType="com.Gary.bean.User">
         select * from user where u_id = #{id}
     </select>
     
     <!-- #{}占位符 尽量使用#{}来解决问题 -->
     <!-- ${}字符串拼接   容易sql注入 (or 1 = 1) -->
     
     <!-- ${value}中间的字符串一定需要使用value -->
     <select id="selectUserByName" parameterType="String" resultType="com.Gary.bean.User">
         <!-- select * from user where u_username like '%${value}%' -->
              select * from user where u_username like "%"#{name}"%"
     </select>
     
     <!-- 添加用户 参数为全包名 -->
     <insert id="insertUser" parameterType="com.Gary.bean.User">
         insert into user values(null,#{u_username},#{u_password},#{u_sex},#{u_createTime},#{u_cid})
     </insert>
     
    <!-- 根据id修改username字段的语句 -->
     <update id="updateUser" parameterType="com.Gary.bean.User">
         update user set u_username = #{u_username} where u_id = #{u_id}
     </update>
     
     <!-- 根据id删除用户 -->
     <delete id="deleteUserById" parameterType="Integer">
         delete from user where u_id = #{id}
     </delete>
     
</mapper>


 
 

 

　　

 

实现过程

　　添加log4j.properties用于测试时打印执行数据库的语句

# Global logging configuration
log4j.rootLogger=DEBUG, stdout
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

 

　　获取sqlSession

package com.Gary.test;

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

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.jupiter.api.Test;

public class HelloMyBatis {

    @Test
    //入门程序，通过ID，查询用户
    public void Test1() throws IOException {
        //读取配置文件
        String resource = "sqlMapConfig.xml";
        
        InputStream in = Resources.getResourceAsStream(resource);
        
        //需要sqlSessionFactoryBuilder
        SqlSessionFactoryBuilder ssfb = new SqlSessionFactoryBuilder();
        
        //创建sqlSessionFactory
        SqlSessionFactory ssf = ssfb.build(in);
        
        //生产一个sqlSession
        SqlSession session = ssf.openSession();
        
        //操作数据库
        //参数1：要操作的sql语句   参数2：sql语句的参数
        //session.select(statement, parameter);
        
        
        
    }
    
}

 

　　接下来的操作在UserMapper中书写sql语句并完成查询

 

一、通过ID去查找一个用户

 <mapper namespace="UserMapper">
     <select id="selectUserById" parameterType="Integer" resultType="com.Gary.bean.User">
         select * from user where u_id = #{id}
     </select>
 </mapper>

 

<?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="UserMapper">
     <select id="selectUserById" parameterType="Integer" resultType="com.Gary.bean.User">
         select * from user where u_id = #{id}
     </select>
 </mapper>

 

　　

 

　　通过ID去查询一个用户

　　//参数1：要操作的sql语句   参数2：sql语句的参数
　　User user = session.selectOne("UserMapper.selectUserById", 1);

 

　　

package com.Gary.test;

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

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.jupiter.api.Test;

import com.Gary.bean.User;

public class HelloMyBatis {

    @Test
    //入门程序，通过ID，查询用户
    public void Test1() throws IOException {
        //读取配置文件
        String resource = "sqlMapConfig.xml";
        
        InputStream in = Resources.getResourceAsStream(resource);
        
        //需要sqlSessionFactoryBuilder
        SqlSessionFactoryBuilder ssfb = new SqlSessionFactoryBuilder();
        
        //创建sqlSessionFactory
        SqlSessionFactory ssf = ssfb.build(in);
        
        //生产一个sqlSession
        SqlSession session = ssf.openSession();
        
        //操作数据库
        //参数1：要操作的sql语句   参数2：sql语句的参数
        User user = session.selectOne("UserMapper.selectUserById", 1);
        System.err.println(user);
        
        
    }
    
}

 

 

二、通过用户名模糊查询用户列表

　　查找数据库中名字带有王字的数据

     <!-- ${value}中间的字符串一定需要使用value -->
     <select id="selectUserByName" parameterType="String" resultType="com.Gary.bean.User">
         select * from user where u_username like '%${value}%'
     </select>

 

<?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="UserMapper">
 
     <select id="selectUserById" parameterType="Integer" resultType="com.Gary.bean.User">
         select * from user where u_id = #{id}
     </select>
     
     <!-- ${value}中间的字符串一定需要使用value -->
     <select id="selectUserByName" parameterType="String" resultType="com.Gary.bean.User">
         select * from user where u_username like '%${value}%'
     </select>

 </mapper>

 
 

 

　　

  

　　通过字符串去进行模糊查询

　　//操作数据库
　　//参数1：要操作的sql语句   参数2：sql语句的参数
　　List<User> list = session.selectList("UserMapper.selectUserByName", "王");

 

　　

 

package com.Gary.test;

import java.io.IOException;
import java.io.InputStream;
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.jupiter.api.Test;

import com.Gary.bean.User;

public class HelloMyBatis2 {

    @Test
    //入门程序，通过ID，查询用户
    public void Test1() throws IOException {
        //读取配置文件
        String resource = "sqlMapConfig.xml";
        
        InputStream in = Resources.getResourceAsStream(resource);
        
        //需要sqlSessionFactoryBuilder
        SqlSessionFactoryBuilder ssfb = new SqlSessionFactoryBuilder();
        
        //创建sqlSessionFactory
        SqlSessionFactory ssf = ssfb.build(in);
        
        //生产一个sqlSession
        SqlSession session = ssf.openSession();
        
        //操作数据库
        //参数1：要操作的sql语句   参数2：sql语句的参数
        List<User> list = session.selectList("UserMapper.selectUserByName", "王");
    
        for(User u : list) {
            System.out.println(u);
        }
        
        
    }
    
}

 

　　注意：

　　　　#{}占位符 尽量使用#{}来解决问题　　使用占位符#{}中间的字符串一定要为value

　　　　${}字符串拼接   容易sql注入 (or 1 = 1)　　

     <!-- ${value}中间的字符串一定需要使用value -->
     <select id="selectUserByName" parameterType="String" resultType="com.Gary.bean.User">
         <!-- select * from user where u_username like '%${value}%' -->
              select * from user where u_username like "%"#{name}"%"
     </select>

 

　　

package com.Gary.test;

import java.io.IOException;
import java.io.InputStream;
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.jupiter.api.Test;

import com.Gary.bean.User;

public class HelloMyBatis2 {

    @Test
    //入门程序，通过ID，查询用户
    public void Test1() throws IOException {
        //读取配置文件
        String resource = "sqlMapConfig.xml";
        
        InputStream in = Resources.getResourceAsStream(resource);
        
        //需要sqlSessionFactoryBuilder
        SqlSessionFactoryBuilder ssfb = new SqlSessionFactoryBuilder();
        
        //创建sqlSessionFactory
        SqlSessionFactory ssf = ssfb.build(in);
        
        //生产一个sqlSession
        SqlSession session = ssf.openSession();
        
        //操作数据库
        //参数1：要操作的sql语句   参数2：sql语句的参数
        List<User> list = session.selectList("UserMapper.selectUserByName", "王");
    
        for(User u : list) {
            System.out.println(u);
        }
        
        
    }
    
}

 

<?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="UserMapper">
 
     <select id="selectUserById" parameterType="Integer" resultType="com.Gary.bean.User">
         select * from user where u_id = #{id}
     </select>
     
     <!-- #{}占位符 尽量使用#{}来解决问题 -->
     <!-- ${}字符串拼接   容易sql注入 (or 1 = 1) -->
     
     <!-- ${value}中间的字符串一定需要使用value -->
     <select id="selectUserByName" parameterType="String" resultType="com.Gary.bean.User">
         <!-- select * from user where u_username like '%${value}%' -->
              select * from user where u_username like "%"#{name}"%"
     </select>

 </mapper>

 
 

 

 

三、添加用户

 　　在UserMapper.xml中编写插入User对象

　　<!-- 添加用户 参数为全包名 -->
　　<insert id="insertUser" parameterType="com.Gary.bean.User">
　　　　insert into user values(null,#{u_username},#{u_password},#{u_sex},#{u_createTime},#{u_cid})
　　</insert>

 

<?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="UserMapper">
 
     <select id="selectUserById" parameterType="Integer" resultType="com.Gary.bean.User">
         select * from user where u_id = #{id}
     </select>
     
     <!-- #{}占位符 尽量使用#{}来解决问题 -->
     <!-- ${}字符串拼接   容易sql注入 (or 1 = 1) -->
     
     <!-- ${value}中间的字符串一定需要使用value -->
     <select id="selectUserByName" parameterType="String" resultType="com.Gary.bean.User">
         <!-- select * from user where u_username like '%${value}%' -->
              select * from user where u_username like "%"#{name}"%"
     </select>
     
     <!-- 添加用户 参数为全包名 -->
     <insert id="insertUser" parameterType="com.Gary.bean.User">
         insert into user values(null,#{u_username},#{u_password},#{u_sex},#{u_createTime},#{u_cid})
     </insert>

     
</mapper>


 
 

 

　　使用了session.insert()后别忘记提交事务！

 　　

package com.Gary.test;

import java.io.IOException;
import java.io.InputStream;
import java.util.Date;
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.jupiter.api.Test;

import com.Gary.bean.User;

public class HelloMyBatis3 {

    @Test
    //入门程序，通过ID，查询用户
    public void Test1() throws IOException {
        //读取配置文件
        String resource = "sqlMapConfig.xml";
        
        InputStream in = Resources.getResourceAsStream(resource);
        
        //需要sqlSessionFactoryBuilder
        SqlSessionFactoryBuilder ssfb = new SqlSessionFactoryBuilder();
        
        //创建sqlSessionFactory
        SqlSessionFactory ssf = ssfb.build(in);
        
        //生产一个sqlSession
        SqlSession session = ssf.openSession();
        
        //操作数据库
        //参数1：要操作的sql语句   参数2：sql语句的参数
        User user = new User();
        
        user.setU_username("Gary");
        user.setU_password("494949");
        user.setU_sex("1");
        user.setU_createTime(new Date());
        user.setU_cid(1);
        
        session.insert("UserMapper.insertUser", user);
        //提交事务
        session.commit();
    
        
        
    }
    
}

 

　　

 

 

四、修改用户

　　修改id为13的Gary的username字段

　　在UserMapper.xml中编写修改User对象字段username

　　<!-- 根据id修改username字段的语句 -->
　　<update id="updateUser" parameterType="com.Gary.bean.User">
　　　　update user set u_username = #{u_username} where u_id = #{u_id}
　　</update>

 

<?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="UserMapper">
 
     <select id="selectUserById" parameterType="Integer" resultType="com.Gary.bean.User">
         select * from user where u_id = #{id}
     </select>
     
     <!-- #{}占位符 尽量使用#{}来解决问题 -->
     <!-- ${}字符串拼接   容易sql注入 (or 1 = 1) -->
     
     <!-- ${value}中间的字符串一定需要使用value -->
     <select id="selectUserByName" parameterType="String" resultType="com.Gary.bean.User">
         <!-- select * from user where u_username like '%${value}%' -->
              select * from user where u_username like "%"#{name}"%"
     </select>
     
     <!-- 添加用户 参数为全包名 -->
     <insert id="insertUser" parameterType="com.Gary.bean.User">
         insert into user values(null,#{u_username},#{u_password},#{u_sex},#{u_createTime},#{u_cid})
     </insert>
     
    <!-- 根据id修改username字段的语句 -->
     <update id="updateUser" parameterType="com.Gary.bean.User">
         update user set u_username = #{u_username} where u_id = #{u_id}
     </update>
     
</mapper>


 
 

 

　　将id为13的用户，名字修改成"修改后Gary"

　　

 

package com.Gary.test;

import java.io.IOException;
import java.io.InputStream;
import java.util.Date;
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.jupiter.api.Test;

import com.Gary.bean.User;

public class HelloMyBatis4 {

    @Test
    //入门程序，通过ID，查询用户
    public void Test1() throws IOException {
        //读取配置文件
        String resource = "sqlMapConfig.xml";
        
        InputStream in = Resources.getResourceAsStream(resource);
        
        //需要sqlSessionFactoryBuilder
        SqlSessionFactoryBuilder ssfb = new SqlSessionFactoryBuilder();
        
        //创建sqlSessionFactory
        SqlSessionFactory ssf = ssfb.build(in);
        
        //生产一个sqlSession
        SqlSession session = ssf.openSession();
        
        //操作数据库
        //参数1：要操作的sql语句   参数2：sql语句的参数
        User user = new User();
        user.setU_id(13);
        user.setU_username("修改后Gary");

        session.insert("UserMapper.updateUser", user);
        //提交事务
        session.commit();
    
        
        
    }
    
}

 

　　

 

 

五、根据id删除用户

　　删除id为13的Gary用户

　　在UserMapper.xml中编写根据id删除用户

     <!-- 根据id删除用户 -->
     <delete id="deleteUserById" parameterType="Integer">
         delete from user where u_id = #{id}
     </delete>

 

<?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="UserMapper">
 
     <select id="selectUserById" parameterType="Integer" resultType="com.Gary.bean.User">
         select * from user where u_id = #{id}
     </select>
     
     <!-- #{}占位符 尽量使用#{}来解决问题 -->
     <!-- ${}字符串拼接   容易sql注入 (or 1 = 1) -->
     
     <!-- ${value}中间的字符串一定需要使用value -->
     <select id="selectUserByName" parameterType="String" resultType="com.Gary.bean.User">
         <!-- select * from user where u_username like '%${value}%' -->
              select * from user where u_username like "%"#{name}"%"
     </select>
     
     <!-- 添加用户 参数为全包名 -->
     <insert id="insertUser" parameterType="com.Gary.bean.User">
         insert into user values(null,#{u_username},#{u_password},#{u_sex},#{u_createTime},#{u_cid})
     </insert>
     
    <!-- 根据id修改username字段的语句 -->
     <update id="updateUser" parameterType="com.Gary.bean.User">
         update user set u_username = #{u_username} where u_id = #{u_id}
     </update>
     
     <!-- 根据id删除用户 -->
     <delete id="deleteUserById" parameterType="Integer">
         delete from user where u_id = #{id}
     </delete>
     
</mapper>


 
 

 

　　删除id为13的user对象

 　　

 

<?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="UserMapper">
 
     <select id="selectUserById" parameterType="Integer" resultType="com.Gary.bean.User">
         select * from user where u_id = #{id}
     </select>
     
     <!-- #{}占位符 尽量使用#{}来解决问题 -->
     <!-- ${}字符串拼接   容易sql注入 (or 1 = 1) -->
     
     <!-- ${value}中间的字符串一定需要使用value -->
     <select id="selectUserByName" parameterType="String" resultType="com.Gary.bean.User">
         <!-- select * from user where u_username like '%${value}%' -->
              select * from user where u_username like "%"#{name}"%"
     </select>
     
     <!-- 添加用户 参数为全包名 -->
     <insert id="insertUser" parameterType="com.Gary.bean.User">
         insert into user values(null,#{u_username},#{u_password},#{u_sex},#{u_createTime},#{u_cid})
     </insert>
     
    <!-- 根据id修改username字段的语句 -->
     <update id="updateUser" parameterType="com.Gary.bean.User">
         update user set u_username = #{u_username} where u_id = #{u_id}
     </update>
     
     <!-- 根据id删除用户 -->
     <delete id="deleteUserById" parameterType="Integer">
         delete from user where u_id = #{id}
     </delete>
     
</mapper>


 
 

 

　　

 

 

 六、使用MyBatis开发简易Dao层

 　　实现根据用户id查询用户测试方法

 　　

 

　　

package com.Gary.dao;

import com.Gary.bean.User;

public interface UserDao {

    //根据id查询用户
    public User getUserById(Integer id);
    
}

 

package com.Gary.dao;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;

import com.Gary.bean.User;

public class UserDaoImpl implements UserDao{

    //sqlSession工厂
    private SqlSessionFactory ssf;
    
    //通过构造器给ssf赋值
    public UserDaoImpl(SqlSessionFactory ssf) {
        super();
        this.ssf = ssf;
    }

    @Override
    public User getUserById(Integer id) {
        //生产一个sqlSession
        SqlSession session = ssf.openSession();
                
        //操作数据库
        //参数1：要操作的sql语句   参数2：sql语句的参数
        return session.selectOne("UserMapper.selectUserById", id);
    
    }
}

 

package com.Gary.dao;

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

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

import com.Gary.bean.User;

//取代Service层
public class UserDaoTest {

    //sqlSession工厂
    private static SqlSessionFactory ssf;

    //利用静态代码块获取sqlSessionFactory
    static {
        //读取配置文件
        String resource = "sqlMapConfig.xml";
        InputStream in;
        try {
            in = Resources.getResourceAsStream(resource);
            //需要sqlSessionFactoryBuilder
            SqlSessionFactoryBuilder ssfb = new SqlSessionFactoryBuilder();
            //创建sqlSessionFactory
            ssf = ssfb.build(in);
            in.close();
        } catch (IOException e) {
            
            e.printStackTrace();
        }

    }
    
    @Test
    public void DaoTest() {
        UserDao dao = new UserDaoImpl(ssf);
        //查询id为1的兑对象
        User user = dao.getUserById(1);
        System.out.println(user);
    }
    
}