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

　　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

　　　　JavaWeb_(Mybatis框架)关联查询_六传送门　　　　　　　　　　　　　　　　　　传送门

　　　　JavaWeb_(Mybatis框架)动态sql_七传送门　　　　　　　　　　　　　　　　　　　传送门

　　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);

    }

}

HelloMyBatis.java

　　　　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);

        }

    }

}

HelloMyBatis2.java

　　　　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();

    }

}

HelloMyBatis3.java

　　　　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();

    }

}

HelloMyBatis4.java

　　　　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();

    }

}

HelloMyBatis5.java

<?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>

UserMapper.xml

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

log4j.properties

　　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);

    }

}

HelloMyBatis.java

　　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>

UserMapper.xml

　　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);

    }

}

HelloMyBatis.java

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>

UserMapper.xml

　　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);

        }

    }

}

HelloMyBatis2.java

　　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);

        }

    }

}

HelloMyBatis2.java

<?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>

UserMapper.xml

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>

UserMapper.xml

　　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();

    }

}

HelloMyBatis3.java

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>

UserMapper.xml

　　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();

    }

}

HelloMybatis4.java

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>

UserMapper.xml

　　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>

HelloMyBatis5.java

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);

}

UserDao.java

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);

    }

}

UserDaoImpl.java

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);

    }

}

UserDaoTest.java

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