使用spring ResponseEntity來處理HTTP的返回請求
spring發展到現在，已經都包裝出來了通用的處理類:ResponseEntity ,此類繼承自HttpEntitypublic class ResponseEntity<T> extends HttpEntity<T> {
private final Object status; /** * Create a new {@code ResponseEntity} with the given status code, and no body nor headers. * @param status the status code */ public ResponseEntity(HttpStatus status) { this(null, null, status); } /** * Create a new {@code ResponseEntity} with the given body and status code, and no headers. * @param body the entity body * @param status the status code */ public ResponseEntity(@Nullable T body, HttpStatus status) { this(body, null, status); }
並且做了擴展，用來處理http請求過程中的狀態碼 ，header，body 等數據。ResponseEntity是一種泛型類型。因此，我們可以使用任何類型作為響應主體：
@Controller
public class XXXController{br/>@GetMapping("/hello")
return new ResponseEntity<>("Hello !", HttpStatus.OK);
}這裏字符串"Hello World!"作為字符串返回給REST端。
我們可以設置HTTP標頭：
@GetMapping("/customHeader")
ResponseEntity<String> customHeader() {
HttpHeaders headers = new HttpHeaders();
headers.add("Custom-Header", "foo");
return new ResponseEntity<>(
"Custom header set", headers, HttpStatus.OK);
}
設置自定義標頭：
@GetMapping("/customHeader")
ResponseEntity<String> customHeader() {
return ResponseEntity.ok()
.header("Custom-Header", "foo")
.body("Custom header set")如果將一個對象放入：
@GetMapping("/hello")
public ResponseEntity<String> hello() {
return new ResponseEntity<>(new User(‘jdon’), HttpStatus.OK);
}返回是JSON字符串：
[ { ‘name’: ‘jdon‘}]
下面是返回對象的JSON列表：
public ResponseEntity<List<ProcessDef>> repositoryProcessDefinitionsGet() {
return new ResponseEntity<>(processDefRepo.findAll(), HttpStatus.FOUND);
}以上是通過ResponseEntity這個對象在代碼中靈活操控響應，但是在一般情況下我們只是想返回一個帶有數據的正常響應，那麽只要使用@註解即可
@ResponseBody
在類級別使用@Controller標註情況下， @ResponseBody註解告訴返回的對象將自動序列化為JSON，並通過回控制器的HttpResponse對象。
@Controller
public class XXXController{
@ResponseBody
public User postResponseController(@RequestBody LoginForm loginForm) {
return new User("Thanks For Posting!!!");
}
將返回客戶端JSON字符串：
[ { ‘name’: Thanks For Posting!!!"}]
在@RestController註解了類的情況下，我們就不需要再使用@ResponseBody了，可以直接返回對象，並使用ResponseStatus返回狀態碼！
@ResponseStatus
ResponseStatus雖然只是規定了返回的狀態，但是只需要標註在方法上，簡單，而且狀態碼與返回類型分離，比較清晰。我們將上面返回對象列表的代碼使用ResponseStatus改寫如下，註意類級別@RestController:
@RestController
public class XXXController{
@ResponseStatus(HttpStatus.FOUND)
public User postResponseController() {
return new User("Thanks For Posting!!!");
}
這也會返回客戶端JSON字符串：
[ { ‘name’: Thanks For Posting!!!"}]
這樣的代碼更加專註於業務。
直接操控響應
Spring還允許我們直接訪問javax.servlet.http.HttpServletResponse對象; 我們只需要將它聲明為方法參數：
@GetMapping("/manual")
public void manual(HttpServletResponse response) throws IOException {
response.setHeader("Custom-Header", "foo");
response.setStatus(200);
response.getWriter().println("Hello World!");
}由於Spring在底層實現之上提供了抽象和附加功能，因此如果以這種方式直接操縱響應，會失去很多Spring提供方便功能。
實例代碼：
import io.swagger.annotations.*;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import javax.validation.constraints.*;
@javax.annotation.Generated(value = "io.swagger.codegen.languages.SpringCodegen", date = "2019-03-09T21:32:18.308+08:00")
@Api(value = "tag", tags={ "tag", }, description = "the tag API")
public interface TagApi {
@ApiOperation(value = "獲取問題概要標簽列表", notes = "get_issue_summary_tags", response = OperateResult.class, tags={ "tag", })
@ApiResponses(value = {
@ApiResponse(code = 200, message = "OK", response = OperateResult.class),
@ApiResponse(code = 500, message = "system error", response = Void.class) })
@RequestMapping(value = "/tag/{issue_summary_key}/tags",
produces = { "application/json" },
method = RequestMethod.GET)
default ResponseEntity<OperateResult> getIssueSummaryTags(@NotNull @ApiParam(value = "項目key", required = true) @RequestParam(value = "project_key", required = true) String projectKey, @ApiParam(value = "issue_summary_key", required = true) @PathVariable("issue_summary_key") String issueSummaryKey) {
// do some magic!
return new ResponseEntity<OperateResult>(HttpStatus.OK);
}
@ApiOperation(value = "獲取問題概要標簽值列表", notes = "get_tag_values", response = OperateResult.class, tags={ "tag", })
@ApiResponses(value = {
@ApiResponse(code = 200, message = "OK", response = OperateResult.class),
@ApiResponse(code = 500, message = "system error", response = Void.class) })
@RequestMapping(value = "/tag/{issue_summary_key}/tag_value/{tag_type}",
produces = { "application/json" },
method = RequestMethod.GET)
default ResponseEntity<OperateResult> getTagValues(@NotNull @ApiParam(value = "項目key", required = true) @RequestParam(value = "project_key", required = true) String projectKey, @ApiParam(value = "issue_summary_key", required = true) @PathVariable("issue_summary_key") String issueSummaryKey, @ApiParam(value = "標簽類型 app: 應用 device: 設備 server_name:服務名稱 level:級別 logger:日誌 os: 系統 user: 用戶 url:URL transaction:事物", required = true) @PathVariable("tag_type") String tagType, @NotNull @Min(1) @ApiParam(value = "當前頁數", required = true, defaultValue = "1") @RequestParam(value = "page_number", required = true, defaultValue = "1") Integer pageNumber, @NotNull @Min(1) @ApiParam(value = "每頁顯示條數", required = true, defaultValue = "10") @RequestParam(value = "page_size", required = true, defaultValue = "10") Integer pageSize) {
// do some magic!
return new ResponseEntity<OperateResult>(HttpStatus.OK);
}}
@Controller
public class TagApiController implements TagApi {
private final static Logger logger = LoggerFactory.getLogger(TagApiController.class);
@Autowired
private TagService tagService;
@Override
public ResponseEntity<OperateResult> getIssueSummaryTags(@NotNull @ApiParam(value = "項目key", required = true) @RequestParam(value = "project_key", required = true) String projectKey, @ApiParam(value = "issue_summary_key", required = true) @PathVariable("issue_summary_key") String issueSummaryKey) {
OperateResult operateResult = new OperateResult();
try {
Preconditions.checkArgument(StringUtils.isNotBlank(projectKey));
Preconditions.checkArgument(StringUtils.isNotBlank(issueSummaryKey));
List<TagDetail> tagValueArrayList = tagService.getIssueSummaryTagList(projectKey, issueSummaryKey);
operateResult = OperateResult.success(tagValueArrayList);
return new ResponseEntity<OperateResult>(operateResult,HttpStatus.OK);
} catch (Exception e) {
logger.error("api getIssueSummaryTags error.{}", e);
operateResult = OperateResult.exception(OperateCode.SYSTEM_ERROR,e);
return new ResponseEntity<OperateResult>(operateResult, HttpStatus.INTERNAL_SERVER_ERROR);
}
}使用spring ResponseEntity來處理HTTP的返回請求