Java学习之道：mybatis简单应用（基于配置文件）

雨点打透心脏的1/2处 2021-09-30 01:46 203阅读 0赞

1.创建数据库表（User表）

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CREATE TABLE `NewTable` (
    `userId`  bigint(20) NOT NULL AUTO_INCREMENT ,
    `userName`  varchar(30) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL ,
    `password`  varchar(80) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL ,
    `comment`  varchar(250) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL ,
    PRIMARY KEY (`userId`),
    UNIQUE INDEX `UQ_User_userName` (`userName`) USING BTREE
    )

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2.2. 创建实体类

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package com.mybatis.config;
    
    public class User {
         
        private int userId;
        private String userName;
        private String password;
        private String comment;
        public int getUserId() {
         
            return userId;
        }
        public void setUserId(int userId) {
         
            this.userId = userId;
        }
        public String getUserName() {
         
            return userName;
        }
        public void setUserName(String userName) {
         
            this.userName = userName;
        }
        public String getPassword() {
         
            return password;
        }
        public void setPassword(String password) {
         
            this.password = password;
        }
        public String getComment() {
         
            return comment;
        }
        public void setComment(String comment) {
         
            this.comment = comment;
        }
    }

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3. 定义数据访问接口

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package com.mybatis.config;
    
    import java.util.List;
    
    public interface UserDao {
         
        
        public int insert(User user);
        
        public int update(User user);
        
        public int delete(String userName);
        
        public List<User> selectAll();
        
        public int countAll();
        
        public User findByUserName(String userName);
    }

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4.创建MyBatis映射文件（UserDaoMapper.xml）

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<?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.mybatis.config.UserDao">
        <select id="countAll" resultType="int">
            select count(*) c from user;
        </select>
        
        <select id="selectAll" resultType="com.mybatis.config.User">
            select * from user order by userName asc
        </select>
        
        <insert id="insert" parameterType="com.mybatis.config.User">
            insert into user(userName,password,comment) values(#{userName},#{password},#{comment})
        </insert>
        
        <update id="update" parameterType="com.mybatis.config.User">
            update user set userName=#{userName},password=#{password},comment=#{comment} where userName=#{userName}
        </update>
        
        <delete id="delete" parameterType="int">
            delete from user where userName=#{userName}
        </delete>
        
        <select id="findByUserName" parameterType="String" resultType="com.mybatis.config.User">
            select * from user where userName=#{userName}
        </select>
    </mapper>

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5. 创建mybatis配置文件

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<?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.jdbc.Driver" />
                    <property name="url" value="jdbc:mysql://localhost:3306/hlp?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull" />
                    <property name="username" value="root" />
                    <property name="password" value="1234" />
                </dataSource>
            </environment>
        </environments>
        <mappers>
            <mapper resource="com/mybatis/config/UserDaoMapper.xml"/>
        </mappers>
    </configuration>

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6. 编写测试代码

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package com.mybatis.config;
    
    import java.io.Reader;
    import java.util.Iterator;
    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.Test;
    
    public class UserDaoTest {
         
        @Test
        public void userDaoTest() throws Exception
        {
         
            String resource = "MyBatis-Configuration.xml";
            Reader reader = Resources.getResourceAsReader(resource);
            SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
            SqlSessionFactory factory = builder.build(reader);
            
            SqlSession session = factory.openSession();
            UserDao userDao = session.getMapper(UserDao.class);
            
            User user = new User();
            user.setUserName("hongye");
            user.setPassword("123456");
            user.setComment("备注");
            
            userDao.insert(user);
            System.out.println("记录条数："+userDao.countAll());
            
            List<User> users = userDao.selectAll();
            Iterator<User> iter = users.iterator();
            while(iter.hasNext()){
         
                User u = iter.next();
                System.out.println("用户名："+u.getUserName()+"密码："+u.getPassword());
            }
            
            user.setComment("comment");
            userDao.update(user);
            User u = userDao.findByUserName("hongye");
            System.out.println(u.getComment());
            
            userDao.delete("hongye");
            System.out.println("记录条数："+userDao.countAll());
            
            session.commit();
            session.close();
        }
    }

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[copycode.gif]: /images/20210825/9162c74b07ec44bcaf9101fae82bd2e4.png