实现DELETE方法删除用户资源 _JavaWeb服务

在本节中, 我们将实现一个delete方法来删除用户资源。
步骤1：打开UserDaoService.java文件。
步骤2：创建一种删除用户资源的方法。
UserDaoService.java

package com.srcmini.server.main.user; import java.util.ArrayList; import java.util.Date; import java.util.Iterator; import java.util.List; import org.springframework.stereotype.Component; @Componentpublic class UserDaoService {public static int usersCount=5; //creating an instance of ArrayListprivate static List< User> users=new ArrayList< > (); //static block static{//adding users to the listusers.add(new User(1, "John", new Date())); users.add(new User(2, "Robert", new Date())); users.add(new User(3, "Adam", new Date())); users.add(new User(4, "Andrew", new Date())); users.add(new User(5, "Jack", new Date())); }//method that retrieve all users from the listpublic List< User> findAll(){return users; }//method that adds a user in the list public User save(User user){if(user.getId()==null){user.setId(++usersCount); }users.add(user); return user; }//method that find a particular user from the listpublic User findOne(int id){for(User user:users){if(user.getId()==id)return user; }return null; }//method that delete a user resourcepublic User deleteById(int id){Iterator< User> iterator = users.iterator(); while(iterator.hasNext()){User user=iterator.next(); if(user.getId()==id){iterator.remove(); return user; //returns the deleted resource back}}return null; }}

步骤3：打开UserResource.java文件, 并创建一个删除映射以删除用户资源。
UserResource.java

package com.srcmini.server.main.user; import java.net.URI; import java.util.List; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.http.ResponseEntity; import org.springframework.web.bind.annotation.DeleteMapping; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.PostMapping; import org.springframework.web.bind.annotation.RequestBody; import org.springframework.web.bind.annotation.RestController; import org.springframework.web.servlet.support.ServletUriComponentsBuilder; @RestControllerpublic class UserResource {@Autowiredprivate UserDaoService service; @GetMapping("/users")public List< User> retriveAllUsers(){return service.findAll(); }//retrieves a specific user detail@GetMapping("/users/{id}")public User retriveUser(@PathVariable int id){User user= service.findOne(id); if(user==null)//runtime exceptionthrow new UserNotFoundException("id: "+ id); return user; }//method that delete a user resource//if the user deleted successfully it returns status 200 OK otherwise 404 Not Found@DeleteMapping("/users/{id}")public void deleteUser(@PathVariable int id){User user= service.deleteById(id); if(user==null)//runtime exceptionthrow new UserNotFoundException("id: "+ id); }//method that posts a new user detail and returns the status of the user resource@PostMapping("/users")public ResponseEntity< Object> createUser(@RequestBody User user) {User sevedUser=service.save(user); URI location=ServletUriComponentsBuilder.fromCurrentRequest().path("/{id}").buildAndExpand(sevedUser.getId()).toUri(); return ResponseEntity.created(location).build(); }}

步骤4：打开Postman, 选择DELETE request, 然后指定要删除的用户ID。现在单击发送按钮。