编写用户表接口

1、前置知识

controller：控制层
service：业务层
repository：数据控制访问层

2、编写接口步骤

3、编写三层结构代码

• 控制层（SysUserController）

package edu.friday.controller;
import edu.friday.common.base.BaseController;
import edu.friday.common.result.RestResult;
import edu.friday.service.SysUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
/**
 * 用户表 控制层
 * */
@RestController
@RequestMapping("/system/user")
public class SysUserController extends BaseController {
    @Autowired
    SysUserService sysUserService;
    /**
     * 显示所有用户
     * */
    @GetMapping("/list")
    public RestResult list(){
        return RestResult.success("操作成功！",sysUserService.selectUserList());
    }
}

• 业务层
  业务层分为业务层接口（SysUserService）和业务层实现（SysUserServiceImpl）

package edu.friday.service;
import edu.friday.model.SysUser;
import java.util.List;
/**
 * 用户表 业务层接口
 * */
public interface SysUserService {
    List<SysUser> selectUserList();
}

package edu.friday.service.impl;
import edu.friday.model.SysUser;
import edu.friday.repository.SysUserRepository;
import edu.friday.service.SysUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
/**
 * 用户表 业务层
 * */
@Service
public class SysUserServiceImpl implements SysUserService {
    @Autowired
    SysUserRepository sysUserRepository;
    /**
     * 显示所有用户列表
     * */
    @Override
    public List<SysUser> selectUserList() {
        return sysUserRepository.findAll();
    }
}

• 数据控制访问层（SysUserRepository）

package edu.friday.repository;
import edu.friday.model.SysUser;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
/**
 * 用户表 数据层
 * */
@Repository
public interface SysUserRepository extends JpaRepository<SysUser,Long> {
}

• 调试工具运行结果