spring 如何从弹簧控制器返回未找到状态
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how to return not found status from spring controller
提问by Sergey
I have following spring controller code and want to return not found status if user is not found in database, how to do it?
我有以下 spring 控制器代码，如果在数据库中找不到用户，我想返回未找到状态，该怎么做？
@Controller
public class UserController {
@RequestMapping(value = "/user?${id}", method = RequestMethod.GET)
public @ResponseBody User getUser(@PathVariable Long id) {
....
}
}
回答by wypieprz
JDK8 approach:
JDK8 方法：
@RequestMapping(value = "/user/{id}", method = RequestMethod.GET)
public ResponseEntity<User> getUser(@PathVariable Long id) {
return Optional
.ofNullable( userRepository.findOne(id) )
.map( user -> ResponseEntity.ok().body(user) ) //200 OK
.orElseGet( () -> ResponseEntity.notFound().build() ); //404 Not found
}
回答by Sotirios Delimanolis
Change your handler method to have a return type of ResponseEntity. You can then return appropriately
将您的处理程序方法更改为具有ResponseEntity. 然后你可以适当地返回
@RequestMapping(value = "/user/{id}", method = RequestMethod.GET)
public ResponseEntity<User> getUser(@PathVariable Long id) {
User user = ...;
if (user != null) {
return new ResponseEntity<User>(user, HttpStatus.OK);
}
return new ResponseEntity<>(HttpStatus.NOT_FOUND);
}
Spring will use the same HttpMessageConverterobjects to convert the Userobject as it does with @ResponseBody, except now you have more control over the status code and headers you want to return in the response.
Spring 将使用与使用相同的HttpMessageConverter对象来转换User对象@ResponseBody，但现在您可以更好地控制要在响应中返回的状态代码和标头。
回答by cdesmetz
@GetMapping(value = "/user/{id}")
public ResponseEntity<User> getUser(@PathVariable final Long id) {
return ResponseEntity.of(userRepository.findOne(id)));
}
public Optional<User> findOne(final Long id) {
MapSqlParameterSource paramSource = new MapSqlParameterSource().addValue("id", id);
try {
return Optional.of(namedParameterJdbcTemplate.queryForObject(SELECT_USER_BY_ID, paramSource, new UserMapper()));
} catch (DataAccessException dae) {
return Optional.empty();
}
}
回答by Rohit Naik
With the latest update you can just use
使用最新的更新，您可以使用
return ResponseEntity.of(Optional<user>);
The rest is handled by below code
其余由以下代码处理
/**
* A shortcut for creating a {@code ResponseEntity} with the given body
* and the {@linkplain HttpStatus#OK OK} status, or an empty body and a
* {@linkplain HttpStatus#NOT_FOUND NOT FOUND} status in case of a
* {@linkplain Optional#empty()} parameter.
* @return the created {@code ResponseEntity}
* @since 5.1
*/
public static <T> ResponseEntity<T> of(Optional<T> body) {
Assert.notNull(body, "Body mus`enter code here`t not be null");
return body.map(ResponseEntity::ok).orElse(notFound().build());
}
回答by Olivier Boissé
it could be shorter using Method Reference operator ::
使用方法引用运算符可能会更短 ::
@RequestMapping(value = "/user/{id}", method = RequestMethod.GET)
public ResponseEntity<User> getUser(@PathVariable Long id) {
return Optional.ofNullable(userRepository.findOne(id))
.map(ResponseEntity::ok)
.orElse(ResponseEntity.notFound().build());
}
回答by Aliaksandr Shpak
Need use ResponseEntity or @ResponseStatus, or with "extends RuntimeException"
需要使用 ResponseEntity 或 @ResponseStatus，或使用“extends RuntimeException”
@DeleteMapping(value = "")
public ResponseEntity<Employee> deleteEmployeeById(@RequestBody Employee employee) {
Employee tmp = employeeService.deleteEmployeeById(employee);
return new ResponseEntity<>(tmp, Objects.nonNull(tmp) ? HttpStatus.OK : HttpStatus.NOT_FOUND);
}
or
或者
@ResponseStatus(value=HttpStatus.NOT_FOUND, reason="was Not Found")
