后端Springboot框架搭建APi接口开发第三章末

盒子里的加菲猫

2024-05-06 帮助1人

前两章节讲述了如何通过APi接口实现对数据库的查询操作

这章主要讲述，Stringboot对数据库数据的查询、新增、修改、删除操作

第一节：数据库查询

首先编写UserMapper.xml。定义SQl语句

文件结构：demo\src\main\java\com\example\demo\mapper\usermapper.xml

<?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.example.demo.mapper.UserMapper">
    <select id="UserList" resultType="com.example.demo.entity.User">
        Select *
        from user;
    </select>
</mapper>

编写UserMapper.java。编写interface接口

文件结构：demo\src\main\java\com\example\demo\mapper\usermapper.java

package com.example.demo.mapper;

import com.example.demo.entity.User;

import java.util.List;

public interface UserMapper {
    List<User> UserList();
}

编写UserApi.java，定义接口并编写逻辑处理

文件结构：demo\src\main\java\com\example\demo\controller\UserApi.java

package com.example.demo.controller;

import com.example.demo.entity.User;
import com.example.demo.mapper.UserMapper;
import com.example.demo.util.APIResultUtil;
import com.example.demo.util.MybatisUtl;
import org.apache.ibatis.session.SqlSession;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;


@RestController
@RequestMapping("/api")
public class UserAPi {
    //    查询全部用户数据 测试成功
    @RequestMapping("/setUserList")
    public Object setUserList() {
        try {
            SqlSession sqlSession = MybatisUtl.sqlSession();
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            List<User> users = mapper.UserList();
//            这里判断是否有数据（注意是倒过来的）
            if (users.isEmpty()) {
//                没有数据
                return APIResultUtil.APIResultUtil(false, null, "无用户数据");
            } else {
//                有数据
                return APIResultUtil.APIResultUtil(true, users, "读取成功");

            }
        } catch (Exception e) {
            System.out.println("程序错误！错误原因："   e);
            return APIResultUtil.APIResultUtil(false, null, "程序错误");
        }
    }
}

最后启动主类

文件结构：demo\src\main\java\com\example\demo\DemoApplication.java

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第二节：数据库新增

首先编写UserMapper.xml。定义SQl语句

文件结构：demo\src\main\java\com\example\demo\mapper\usermapper.xml

<?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.example.demo.mapper.UserMapper">
    <insert id="addUser" parameterType="com.example.demo.entity.User">
        insert into user(UserEmail, UserName, UserPwd)
        values (#{UserEmail}, #{UserName}, #{UserPwd});
    </insert>
</mapper>

编写UserMapper.java。编写interface接口

文件结构：demo\src\main\java\com\example\demo\mapper\usermapper.java

package com.example.demo.mapper;

import org.apache.ibatis.annotations.Param;

public interface UserMapper {
    int addUser(@Param("UserEmail") String UserEmail, @Param("UserName") String UserName, @Param("UserPwd") String UserPwd);
}

编写UserApi.java，定义接口并编写逻辑处理

文件结构：demo\src\main\java\com\example\demo\controller\UserApi.java

package com.example.demo.controller;

import com.example.demo.mapper.UserMapper;
import com.example.demo.util.APIResultUtil;
import com.example.demo.util.SqlSessionUtil;
import org.apache.ibatis.session.SqlSession;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/api")
public class UserApi {
    @RequestMapping("addUser")
    public Object GetUserList(@RequestParam(value = "UserEmail") String UserEmail, @RequestParam(value = "UserName") String UserName, @RequestParam(value = "UserPwd") String UserPwd) {
        try {
            SqlSession sqlSession = SqlSessionUtil.sqlSession();
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            int i = mapper.addUser(UserEmail, UserName, UserPwd);
            sqlSession.commit();
            if (i == 1) {
                return APIResultUtil.apiResult(true, null, "添加成功");
            } else {
                return APIResultUtil.apiResult(false, null, "添加失败");
            }
        } catch (Exception e) {
            return APIResultUtil.apiResult(false, null, "程序错误，错误原因："   e.getCause());
        }
    }
}

最后启动主类

文件结构：demo\src\main\java\com\example\demo\DemoApplication.java

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第三节：数据库修改

首先编写UserMapper.xml。定义SQl语句

文件结构：demo\src\main\java\com\example\demo\mapper\usermapper.xml

<?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.example.demo.mapper.UserMapper">
    <update id="updateUser" parameterType="com.example.demo.entity.User">
        update user set UserName = #{UserName} where UserEmail = #{UserEmail};
    </update>
</mapper>

编写UserMapper.java。编写interface接口

文件结构：demo\src\main\java\com\example\demo\mapper\usermapper.java

package com.example.demo.mapper;

import org.apache.ibatis.annotations.Param;

public interface UserMapper {
    int updateUser(@Param("UserName") String UserName, @Param("UserEmail") String UserEmail);
}

编写UserApi.java，定义接口并编写逻辑处理

文件结构：demo\src\main\java\com\example\demo\controller\UserApi.java

package com.example.demo.controller;

import com.example.demo.mapper.UserMapper;
import com.example.demo.util.APIResultUtil;
import com.example.demo.util.SqlSessionUtil;
import org.apache.ibatis.session.SqlSession;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/api")
public class UserApi {
    @RequestMapping("updateUser")
    public Object updateUser(@RequestParam(value = "UserName") String UserName, @RequestParam(value = "UserEmail") String UserEmail) {
        try {
            SqlSession sqlSession = SqlSessionUtil.sqlSession();
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            int i = mapper.updateUser(UserName, UserEmail);
            sqlSession.commit();
            if (i == 1) {
                return APIResultUtil.apiResult(true, null, "修改成功");
            } else {
                return APIResultUtil.apiResult(false, null, "修改失败");
            }
        } catch (Exception e) {
            return APIResultUtil.apiResult(false, null, "程序错误，错误原因："   e.getCause());
        }
    }
}

最后启动主类

文件结构：demo\src\main\java\com\example\demo\DemoApplication.java

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第四节：数据库删除

首先编写UserMapper.xml。定义SQl语句

文件结构：demo\src\main\java\com\example\demo\mapper\usermapper.xml

<?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.example.demo.mapper.UserMapper">
    <delete id="DelUser" parameterType="com.example.demo.entity.User">
        delete from user where UserEmail= #{UserEmail};
    </delete>
</mapper>

编写UserMapper.java。编写interface接口

文件结构：demo\src\main\java\com\example\demo\mapper\usermapper.java

package com.example.demo.mapper;

import org.apache.ibatis.annotations.Param;

public interface UserMapper {
    int DelUser(@Param("UserEmail") String UserEmail);
}

编写UserApi.java，定义接口并编写逻辑处理

文件结构：demo\src\main\java\com\example\demo\controller\UserApi.java

package com.example.demo.controller;

import com.example.demo.mapper.UserMapper;
import com.example.demo.util.APIResultUtil;
import com.example.demo.util.SqlSessionUtil;
import org.apache.ibatis.session.SqlSession;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/api")
public class UserApi {
    @RequestMapping("DelUser")
    public Object DelUser(@RequestParam(value = "UserEmail") String UserEmail) {
        try {
            SqlSession sqlSession = SqlSessionUtil.sqlSession();
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            int i = mapper.DelUser(UserEmail);
            sqlSession.commit();
            if (i == 1) {
                return APIResultUtil.apiResult(true, null, "删除成功");
            } else {
                return APIResultUtil.apiResult(false, null, "删除失败");
            }
        } catch (Exception e) {
            return APIResultUtil.apiResult(false, null, "删除失败，错误原因："   e.getCause());
        }
    }
}

最后启动主类

文件结构：demo\src\main\java\com\example\demo\DemoApplication.java

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这篇好文章是转载于：学新通技术网

后端Springboot框架搭建APi接口开发第三章末

第一节：数据库查询

第二节：数据库新增

第三节：数据库修改

第四节：数据库删除

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