后台项目开发流程

最新推荐文章于 2025-03-11 19:09:28 发布

原创最新推荐文章于 2025-03-11 19:09:28 发布 · 679 阅读

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文章标签：

#java #spring #开发语言

本文详细介绍了使用Java Spring进行后台项目开发的流程，包括实体层的User和Pager类定义，创建UserMapper.xml文件，建立实体与数据库表的映射，UserMapper中的查询方法，IUserService接口及UserServiceImpl的实现，最后在UserController中进行测试。

一、实体层

User.java

package demo.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data  //生成Get和Set方法
@AllArgsConstructor //生成有参构造
@NoArgsConstructor  //生成无参构造
public class User {
    private Long id;
    private String userName;
    private String passwd;
    private String createDate;
}

Pager.java

package demo.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Pager {
    private Object data; //用于响应的数据
    private int pageTotal; //总条数
}

二、创建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="demo.dao.UserMapper">

</mapper>

三、通过ResultMap建立User实体和t_user表的映射关系

<!--    建立映射,将数据库中t_user表和Java实体User建立关联-->
<!--          userResult 此处为变量名-->
    <resultMap id="userResult" type="User">
        <result column="id" property="id"/>
        <result column="user_name" property="userName"/>
        <result column="passwd" property="passwd"/>
        <result column="create_date" property="createDate"/>
    </resultMap>

四、在UserMapper中添加查询所有用户的方法

UserMapper.java

public interface UserMapper {

    public List<User> selectAll(int pageIndex, int pageSize);
}

UserMapper.xml

   <sql id="sqlUser">
        select id,user_name,passwd,create_date from t_user
    </sql>
    
    <select id="selectAll" resultMap="userResult">
        <include refid="sqlUser"></include> limit #{pageIndex},#{pageSize}
    </select>

五、在IUserService中添加业务方法

IUserService接口

public interface IUserService {
    public Pager queryUserList(int pageIndex, int pageSize);

UserServiceImpl实现类

package demo.service.impl;

import demo.dao.UserMapper;
import demo.entity.Pager;
import demo.entity.User;
import demo.service.IUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class UserServiceImpl implements IUserService {

    @Autowired(required = false)
    private UserMapper userMapper;

    @Override
    public Pager queryUserList(int pageIndex, int pageSize) {
        List<User> list = userMapper.selectAll((pageIndex-1)*pageSize, pageSize);
        int count = userMapper.selectCount();
        return new Pager(list, count);
    }
}

六、在UserController中测试

package demo.controller;

import demo.dao.UserMapper;
import demo.entity.Pager;
import demo.entity.User;
import demo.service.IUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
@RequestMapping("/user")
public class UserController {

    @Autowired
   private IUserService userService;

    @RequestMapping("/list")
    @CrossOrigin(origins = "*") //允许所有跨源请求
    public Pager findUserList(int pageIndex, int pageSize){
        
        return userService.queryUserList(pageIndex,pageSize);
    }
}