mybatis學習筆記——01實現簡單的增刪查改

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idea剛剛進去，還有修改xml文件都會在下載，不要急。

下載的時候我們就寫好數據庫，以備下面的操作：

CREATE DATABASE `mybatis`;

USE `mybatis`;

CREATE TABLE `user`(
  `id` INT(20) NOT NULL PRIMARY KEY,
  `name` VARCHAR(30) DEFAULT NULL,
  `pwd` VARCHAR(30) DEFAULT NULL
)ENGINE=INNODB DEFAULT CHARSET=utf8;

INSERT INTO `user`(`id`,`name`,`pwd`) VALUES 
(1,'狂神','123456'),
(2,'張三','123456'),
(3,'李四','123890')

首先創建一個普通的maven項目。一直next就好了：

然後刪除src，創建新的module（還是maven）結構如下：

上圖的pom.xml代碼如下(這種配置文件最好不要全部複製，看看哪裏少就複製哪裏)：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <!---->
    <groupId>org.example</groupId>
    <artifactId>untitled2</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <modules>
        <module>mybatis-01</module>
        <module>mybatis-02</module>
        <module>mybatis-03-01</module>
        <module>mybatis-04</module>
        <module>mybatis-005</module>
        <module>mybatis-006</module>
        <module>mybatis-07</module>
        <module>mybatis-08</module>
        <module>mybatis-09</module>
    </modules>
    <!---->
    <dependencies>
        <!--mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.15</version><!--8.0.15-->
        </dependency>
        <!--mybatis-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>
        <!--junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>5.2.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.1.10.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.1.10.RELEASE</version>
        </dependency>
        <!---->
        <!---->
        <!---->
        <!---->
    </dependencies>
    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.3.2</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

接下來mybatis-01中的結構和各個代碼如下，ps：main在test下面：

UserMapper：

package com.kuang.dao;

import com.kuang.pojo.User;

import java.util.List;
import java.util.Map;

public interface UserMapper {
     List<User> getUserLike(String value);
     //獲取全部用戶
     List<User> getUserList();
     //根據id查詢用戶
     User getUserById(int id);
     //增加用戶
     int addUser(User user);

     int addUser2(Map<String,Object> map);
     //修改用戶
     int updateUser(User user);
     //刪除
     int deleteUser(int id);
}

UserMapper.xml

<?xml version="1.0" encoding="UTF8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.kuang.dao.UserMapper">
    <select id="getUserLike" resultType="com.kuang.pojo.User">
        select * from mybatis.user where name like #{value};
    </select>

    <select id="getUserList" resultType="com.kuang.pojo.User">
        select * from mybatis.user;
    </select>
    
    <select id="getUserById" resultType="com.kuang.pojo.User" parameterType="int">
        select * from mybatis.user where id=#{id}
    </select>
    
    <insert id="addUser" parameterType="com.kuang.pojo.User">
        insert into mybatis.user (id, name, pwd) values (#{id},#{name},#{pwd});
    </insert>
    
    <insert id="addUser2" parameterType="map">
        insert into mybatis.user (id,name,pwd) values (#{uid},#{username},#{password});
    </insert>

    <update id="updateUser" parameterType="com.kuang.pojo.User">
        update mybatis.user set name=#{name},pwd=#{pwd}  where id = #{id};
    </update>

    <delete id="deleteUser" parameterType="int">
        delete from mybatis.user where id=#{id};
    </delete>
</mapper>

User:

package com.kuang.pojo;

public class User {
    private int id;
    private String name;
    private String pwd;
    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getPwd() {
        return pwd;
    }

    public void setId(int id) {
        this.id = id;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", pwd='" + pwd + '\'' +
                '}';
    }

    public User(){

    }
    public User(int id,String name,String pwd)
    {
        this.id=id;
        this.name=name;
        this.pwd=pwd;
    }
}

MybatisUtils:

package com.kuang.utils;

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 java.io.IOException;
import java.io.InputStream;
//SqlSessionFactory->SqlSession
public class MybatisUtils {
    static SqlSessionFactory sqlSessionFactory;
    static{
        try{
            //使用mybatis獲取SqlSessionFactory對象
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        }
        catch(IOException e)
        {
            e.printStackTrace();
        }
    }

    public static SqlSession getSqlSession(){
        SqlSession sqlSession = sqlSessionFactory.openSession();
        return sqlSession;
    }
}

mybatis-config.xml(其中username，和password改成自己的，url中3306後面的mybatis是我的數據庫名字):

<?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"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?serverTimezone=UTC&amp;useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/kuang/dao/UserMapper.xml"/>
    </mappers>
</configuration>

UserMapperTest:

package com.kuang.dao;

import com.kuang.pojo.User;
import com.kuang.utils.MybatisUtils;

import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class UserMapperTest {
    @Test
    public void test()
    {
        //第一步獲得SqlSession對象
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        //方式一：getMApper

        //關閉sqlSession
        try{
            sqlSession = MybatisUtils.getSqlSession();
            UserMapper userMapper =sqlSession.getMapper(UserMapper.class);//.class可以獲取本項目中任意一個實體類
            List<User> userList = userMapper.getUserList();
            System.out.println(userList.size());
            System.out.println(123456789);
            for(User user:userList)
            {
                System.out.println(user);
            }
        }
        finally {
            sqlSession.close();
        }
    }
    @Test
    public void getUserById(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = mapper.getUserById(1);
        System.out.println(user);

        sqlSession.close();
    }
    @Test
    public void addUser(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);


        mapper.addUser(new User(4,"嘿嘿","654321"));
        sqlSession.commit();
        sqlSession.close();
    }
    @Test
    public void updateUser()
    {
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        mapper.updateUser(new User(3,"哈哈","123456"));

        sqlSession.commit();
        sqlSession.close();
    }
    @Test
    public void deleteUser()
    {
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        mapper.deleteUser(3);

        sqlSession.commit();
        sqlSession.close();
    }
    @Test
    public void addUser2(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        Map<String,Object> map = new HashMap<String,Object>();
        map.put("uid",5);
        map.put("username","嗚嗚");
        map.put("password","222222");
        mapper.addUser2(map);

        sqlSession.commit();
        sqlSession.close();
    }
    @Test
    public void getUserLike(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        List<User> userlist = mapper.getUserLike("%嗚%");
        for (User user : userlist) {
            System.out.println(user);
        }
        sqlSession.close();
    }
}

pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>untitled2</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>mybatis-01</artifactId>



    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
    </build>

</project>

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