java——mybatis随笔

迷南。 2024-02-25 01:31 67阅读 0赞

教程：https://www.cnblogs.com/xiaobaibailongma/p/17019484.html

本地示例：https://www.cnblogs.com/xiaobaibailongma/p/17019676.html

=========================================================================

gitee：示例

spring\_boot/pom.xml

配置文件：https://gitee.com/xiaobailongbailongma/springboot/blob/master/spring\_boot/pom.xml

spring\_boot/src/main/resources/application.properties

配置文件：https://gitee.com/xiaobailongbailongma/springboot/blob/master/spring\_boot/src/main/resources/application.properties

spring\_boot/src/main/resources/mappers/MyUserMapper.xml

配置文件：https://gitee.com/xiaobailongbailongma/springboot/blob/master/spring\_boot/src/main/resources/mappers/MyUserMapper.xml

spring\_boot/src/main/java/org/example/mapper/UserMapper.java

配置文件：https://gitee.com/xiaobailongbailongma/springboot/blob/master/spring\_boot/src/main/java/org/example/mapper/UserMapper.java

spring\_boot/src/main/java/org/example/service/UserService.java

配置文件：https://gitee.com/xiaobailongbailongma/springboot/blob/master/spring\_boot/src/main/java/org/example/service/UserService.java

spring\_boot/src/main/java/org/example/service/Impl/UserServiceImpl.java

配置文件：https://gitee.com/xiaobailongbailongma/springboot/blob/master/spring\_boot/src/main/java/org/example/service/Impl/UserServiceImpl.java

spring\_boot/src/main/java/org/example/controller/mybatis/MyUserController.java

配置文件：https://gitee.com/xiaobailongbailongma/springboot/blob/master/spring\_boot/src/main/java/org/example/controller/mybatis/MyUserController.java

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总体步骤按照如下：

![b9c662ee03f6c130d9523a231ca75394.png][]

第二步——修改pom文件：

![复制代码][de765b934d6f0bcdcd403663a32a32a6.gif]

<?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>spring_boot</artifactId>
        <version>1.0-SNAPSHOT</version>
    
        <properties>
            <maven.compiler.source>8</maven.compiler.source>
            <maven.compiler.target>8</maven.compiler.target>
        </properties>
    
    
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.4.5</version>
            <relativePath/> 
        </parent>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
                <version>2.1.1</version>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-jdbc</artifactId>
            </dependency>
    
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <scope>runtime</scope>
            </dependency>
    
        </dependencies>
    
    
    </project>

![复制代码][e953fb0f6309a84ead6d9ef4c2570a7f.gif]

![43f75daed213077cf2954f3cf2efc70b.png][]

![95fe2038b85508c51184862f4b92a52b.png][]

也可以按照教程上面的写，格式如下：

![复制代码][e22ae6733a89e29034b9a6a0e100e3b2.gif]

<?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>spring_boot</artifactId>
        <version>1.0-SNAPSHOT</version>
    
        <properties>
            <maven.compiler.source>8</maven.compiler.source>
            <maven.compiler.target>8</maven.compiler.target>
        </properties>
    
    
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.4.5</version>
            <relativePath/> 
        </parent>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
                <version>2.1.1</version>
            </dependency>
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <scope>runtime</scope>
            </dependency>
    
        </dependencies>
    
    
    </project>

![复制代码][9f4ac1438e2f110c9482ce37f137e2a0.gif]

![3b45bb749ea769ef118f3785c9d98c22.png][]

![a94bd85f58a1524015832f6db97139af.png][]

第二步——配置数据源：

application.properties：

![复制代码][fe6293afe1bbbcc4ccdc9c5c3805bbe0.gif]

spring.main.banner-mode = off
    test.environment = read config by environment
    obj.sname=chenheng
    obj.sage=88
    
    #设定日志的默认级别为info
    logging.level.root=info
    
    ##设定org包下的日志级别为warn
    #logging.level.org=warn
    
    ##设定com.ch.ch4_1包下的日志级别为debug
    #logging.level.com.ch.ch4_1=debug
    
    logging.file=c:/log/my.log
    logging.pattern.console=%level %date{yyyy-MM-dd HH:mm:ss:SSS} %logger{50}.%M %L :%m%n
    logging.pattern.file=%level %date{ISO8601} %logger{50}.%M %L :%m%n
    
    
    ###
    ##数据源信息配置
    ###
    #数据库地址
    spring.datasource.url=jdbc:mysql://localhost:3306/mysql8?characterEncoding=utf8
    
    #数据库用户名
    spring.datasource.username=root
    
    #数据库密码
    spring.datasource.password=123456
    
    #数据库驱动  spring.datasource.driver-class-name=com.mysql.jdbc.Driver
    spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
    
    #告诉系统在哪里去找mapper.xml文件(映射文件)
    mybatis.mapperLocations=classpath:mappers/*.xml

![复制代码][1eb290d72e198d844df59cbe358e7604.gif]

![601a3665b084e2b0a1c668252389bd33.png][]

第四步——创建实体类：

![复制代码][ab6ed726148401bb8d1ee0cdd24b76d5.gif]

package org.example.entity;
    
    public class MyUser
    {
        private int id;
        private String name;
        private int age;
    
        
        public int getId() {
            return id;
        }
    
        public void setId(int id) {
            this.id = id;
        }
    
        
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
        
        
    
        public int getAge() {
            return age;
        }
    
        public void setAge(int age) {
            this.age = age;
        }
    }

![复制代码][95adb858a24af670d8509a20748644ec.gif]

![8cc3185f102267dc94112104cd0f9014.png][]

第五步——创建数据库访问接口：

![复制代码][3dace49446fa9dcabce091af0509fef8.gif]

package org.example.mapper;
    
    import org.example.entity.MyUser;
    import org.apache.ibatis.annotations.Mapper;
    
    import java.util.List;
    
    @Mapper
    public interface UserMapper
    {
    
        public List<MyUser> findAll();
    
    }

![复制代码][d348f53172364809ab8d7ad6fff3d83f.gif]

![9b2d78fb77beb7da1fadd9437a182b7a.png][]

第六步——创建mapper映射文件：

![复制代码][f804883582232841eed6699416ad9640.gif]

<?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="org.example.mapper.UserMapper">
        <select id="findAll" resultType="org.example.entity.MyUser">
            select * from users
        </select>
    </mapper>

![复制代码][8f4f5354a7d0a790ca5d3999944b42d7.gif]

![109141794db7ec34ecd0e6fa4e7e939d.png][]

第七步——创建业务层：

![复制代码][949566e3c69d7b7014b383c1c55c85d3.gif]

package org.example.service;
    
    
    import org.example.entity.MyUser;
    
    import java.util.List;
    
    public interface UserService
    {
        List<MyUser> findAll();
        
        
    }

![复制代码][c9f3f9887ee77f9f0af76e3c23296a0d.gif]

![a3923844783ff4e669a700e830802ae8.png][]

![复制代码][5aab4bc96831a364effcd9d3a38594ed.gif]

package org.example.service.Impl;
    
    
    import org.example.entity.MyUser;
    import org.example.mapper.UserMapper;
    import org.example.service.UserService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    
    import java.util.List;
    
    @Service
    public class UserServiceImpl implements UserService
    {
        @Autowired
        UserMapper userMapper;
    
        @Override
        public List<MyUser> findAll()
        {
    
            return userMapper.findAll();
        }
    
    }

![复制代码][390f0b58b0c94e297130d97e8307db1f.gif]

![5c3473cdf25f580cfefbe8dc093a4040.png][]

第八步——创建控制器类：

![复制代码][d4accc50d144ecbde1ac36bc3c75fe69.gif]

package org.example.controller;
    
    import java.util.List;
    import org.example.entity.MyUser;
    import org.example.service.UserService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    @RestController
    public class MyUserController
    {
    
        @Autowired
        private UserService userService;
    
        @GetMapping(value = "/1")
        public List<MyUser> home1()
        {
            // 查询所有网站
            List<MyUser> users = userService.findAll();
    
            for (MyUser user : users)
            {
                System.out.println(user.getId()+"  "+user.getName()+"  "+user.getName());
            }
            
            
    
            return users;
        }
        
        
    }

![复制代码][19c9ce93254392ec321adc3f18d45900.gif]

![cc634e03635207a4fdc1e1ca1374815c.png][]

第九步——运行主类：

![复制代码][f3a93ef5fa11f76281f4e6b97dfc4670.gif]

package org.example;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    
    
    @SpringBootApplication
    public class helloWorldApplication
    {
    
        public static void main(String[] args)
        {
    
            SpringApplication.run(helloWorldApplication.class, args);
    
        }
    }

![复制代码][711d79d9989146af4a78fd5ea944d803.gif]

![fac173603260a6784dca27e55facdef9.png][]

第十步——访问：

![d79d71b57a82ad5c6511372644423963.png][]

![a1af8f06225aa8bcc0239cf8fda25065.png][]

![fe68ecb82f85b77355ab44243f9afc46.png][]

数据库表信息：

![复制代码][f66f3c95500ce8edd6e4421f7c03bae8.gif]

CREATE TABLE `users` (
    
      `id` int NOT NULL,
      `name` varchar(255) DEFAULT NULL,
      `age` int DEFAULT NULL,
      PRIMARY KEY (`id`)
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb3;

![复制代码][2a7b614afd00b39d5fb6e6086d302a8c.gif]

![33e3b58e195b8d22fb0f787fe73a885a.png][]

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