Maven+SpringBoot+JPA单表增删改查实例

package com.example.controller; import com.example.entity.User; import com.example.service.UserService; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.data.domain.Page; import org.springframework.data.domain.PageRequest; import org.springframework.data.domain.Pageable; import org.springframework.data.domain.Sort; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.bind.annotation.RequestParam; import org.springframework.web.bind.annotation.ResponseBody; import java.util.ArrayList; import java.util.Iterator; import java.util.List; /**http://localhost:8009/MavenDemo1/MavenDemo1Controller/hello * @author HYZX * 控制层 * @ResponseBody是作用在方法上的，@ResponseBody 表示该方法的返回结果直接写入 HTTP response body 中， * 一般在异步获取数据时使用【也就是AJAX】，在使用 @RequestMapping后，返回值通常解析为跳转路径， * 但是加上 @ResponseBody 后返回结果不会被解析为跳转路径，而是直接写入 HTTP response body 中。 * 比如异步获取 json 数据，加上 @ResponseBody 后，会直接返回 json 数据。@RequestBody 将 HTTP 请求正文插入方法中， * 使用适合的 HttpMessageConverter 将请求体写入某个对象。 */ @Controller @RequestMapping("/MavenDemo1Controller") public class UserController { @Autowired private UserService userService ; @RequestMapping(value = "/index") @ResponseBody public String index(){ return "index"; } @RequestMapping(value ="/hello") @ResponseBody public String hello(){ return "hello"; } /** 根据用户名查找 @param username http://localhost:8009/MavenDemo1/MavenDemo1Controller/showByName?name=wl */ @RequestMapping(value = "/showByName",method = RequestMethod.GET) @ResponseBody public String showByName(@RequestParam(value = "name") String username){ User user = null ; user = userService.findUserByName(username) ; return user.toString() ; } /** 根据id查找 @param userid http://localhost:8009/MavenDemo1/MavenDemo1Controller/showByUserId?userid=14 */ @RequestMapping(value = "/showByUserId",method = RequestMethod.GET) @ResponseBody public String showByUserId(@RequestParam("userid") Long userid){ User user = null ; user = userService.findByUserId(userid) ; return user.toString() ; } /** * 根据用户名删除 * @param username * http://localhost:8009/MavenDemo1/MavenDemo1Controller/deleteByUsername?username=wl88 */ @RequestMapping(value = "/deleteByUsername",method = RequestMethod.GET) @ResponseBody public String deleteByUsername(@RequestParam("username") String username){ User user = null; String msg = ""; String remsg = ""; try { msg = userService.deleteUserByName(username); if(msg.equals("0")){ remsg = "你要删除的用户名不存在！"; }else { remsg = "删除成功！"; } } catch (Exception e) { e.printStackTrace(); } return remsg; } /** * 查询所有 * @return List<User> * http://localhost:8009/MavenDemo1/MavenDemo1Controller/showAll */ @RequestMapping(value = "/showAll",method = RequestMethod.GET) @ResponseBody public String showAll(){ List<User> list = null ; try { list = userService.findAllUser() ; return list.toString() ; } catch (Exception e) { return e.getMessage() ; } } /** * 添加 * @param user * @return user * 正常：http://localhost:8009/MavenDemo1/MavenDemo1Controller/save?userid=107&username=wl7&age=97&password=wl7 * 正常：localhost:8009/MavenDemo1/MavenDemo1Controller/save?username=wl8&age=98&password=wl8 */ @RequestMapping(value = "/save",method = RequestMethod.GET) @ResponseBody public String save(User user) { User user1 = null; User user2 = null; user1 = userService.findUserByName(user.getUsername()); if (user == null||user.getUsername().equals("")) { return "controller层:用户名为空，添加失败！"; } else if(user1!=null){ return "controller层:用户名已占用，请重新输入！"; }else{ user2 = userService.save(user); return "用户 【"+user2.toString()+"】添加成功！"; } } /** * 修改 * @param * /localhost:8009/MavenDemo1/MavenDemo1Controller/updateUser?userid=15&username=wanglan8&age=999&password=wanglan8 * localhost:8009/MavenDemo1/MavenDemo1Controller/updateUser?userid=12&username=wanglan9&age=999&password=wanglan9 */ @RequestMapping(value = "/updateUser",method = RequestMethod.GET) @ResponseBody public String updateUser(String username,int age,String password,Long userid){ try { //先找到待修改的user User user1 = userService.findByUserId(userid) ; //进行修改 User user2 = userService.update(username,age,password,userid); user2 = new User(userid,username,age,password); if(user2==null){ return "controller层:该用户不存在，无法进行修改操作！"; }else { // user2 = userService.findByUserId(user2.getUserid()); return "▷修改前：" + " 【" + user1.toString() + "" + " 】;\n" + " ▷修改后：【" + user2.toString() + "】 修改成功！"; } } catch (Exception e) { return e.getMessage() ; } } /** * localhost:8009/MavenDemo1/MavenDemo1Controller/findAllToPage * 以3条记录为一页，查找第三页的三条数据，按ID降序排列。page=0是第一页 * localhost:8009/MavenDemo1/MavenDemo1Controller/findAllToPage?page=1&size=11 */ @RequestMapping(value = "/findAllToPage",method = RequestMethod.GET) @ResponseBody public String findAllToPage(@RequestParam(value = "page",defaultValue = "0")Integer page, @RequestParam(value = "size",defaultValue = "15")Integer size){ Sort sort = new Sort(Sort.Direction.DESC,"userid"); Pageable pageable = new PageRequest(page,size,sort); Page<User> pageAll = userService.findAllToPage(pageable); Iterator<User> iterator = pageAll.iterator() ; List<User> list = new ArrayList<User>(); while (iterator.hasNext()){ list.add((User) iterator.next()) ; } return list.toString()+pageable.toString(); } }