使用spring ResponseEntity来处理HTTP的返回请求

快来打我* 2022-01-13 04:57 349阅读 0赞

通常情况下，在前后端分离的大背景下，我们后台服务返回给前端的通常都是格式化的数据，比如Json，开始的时候，我们用json包生产一个json的字符串，配合http 协议的一些API 来自定义实现

spring发展到现在，已经都包装出来了通用的处理类:ResponseEntity ,此类继承自HttpEntity

>     public 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);
    }

并且做了扩展，用来处理http请求过程中的状态码 ，header，body 等数据。

ResponseEntity是一种泛型类型。因此，我们可以使用任何类型作为响应主体：

> @Controller  
> public class XXXController\{ [br/>@GetMapping("/hello")  
> public ResponseEntity<String> hello() \{  
> return new ResponseEntity<>("Hello !", HttpStatus.OK);  
> \} ][br_GetMapping_hello_ public ResponseEntity_String_ hello_ _ return new ResponseEntity_Hello _ HttpStatus.OK_ _]
> 
> 这里字符串"Hello World!"作为字符串返回给REST端。

我们可以设置HTTP标头：

> @GetMapping("/customHeader")  
> ResponseEntity<String> customHeader() \{  
> HttpHeaders headers = new HttpHeaders();  
> headers.add("Custom-Header", "foo");

return new ResponseEntity<>(  
"Custom header set", headers, HttpStatus.OK);  
\}

> 设置自定义标头：
> 
> @GetMapping("/customHeader")  
> ResponseEntity<String> customHeader() \{  
> return ResponseEntity.ok()  
> .header("Custom-Header", "foo")  
> .body("Custom header set")
> 
> 如果将一个对象放入：
> 
> @GetMapping("/hello")  
> public ResponseEntity<String> hello() \{  
> return new ResponseEntity<>(new User(‘jdon’), HttpStatus.OK);  
> \}
> 
> 返回是JSON字符串：

\[ \{ ‘name’: 'jdon'\}\]

下面是返回对象的JSON列表：

> public ResponseEntity<List<ProcessDef>> repositoryProcessDefinitionsGet() \{  
> return new ResponseEntity<>(processDefRepo.findAll(), HttpStatus.FOUND);  
> \}
> 
> 以上是通过ResponseEntity这个对象在代码中灵活操控响应，但是在一般情况下我们只是想返回一个带有数据的正常响应，那么只要使用@注解即可

@ResponseBody  
在类级别使用@Controller标注情况下， @ResponseBody注解告诉返回的对象将自动序列化为JSON，并通过回控制器的HttpResponse对象。

> @Controller  
> public class XXXController\{

@ResponseBody  
public User postResponseController(@RequestBody LoginForm loginForm) \{  
return new User("Thanks For Posting!!!");  
\}

> 将返回客户端JSON字符串：

\[ \{ ‘name’: Thanks For Posting!!!"\}\]

在@RestController注解了类的情况下，我们就不需要再使用@ResponseBody了，可以直接返回对象，并使用ResponseStatus返回状态码！

@ResponseStatus  
ResponseStatus虽然只是规定了返回的状态，但是只需要标注在方法上，简单，而且状态码与返回类型分离，比较清晰。我们将上面返回对象列表的代码使用ResponseStatus改写如下，注意类级别@RestController:

> @RestController  
> public class XXXController\{

@ResponseStatus(HttpStatus.FOUND)  
public User postResponseController() \{  
return new User("Thanks For Posting!!!");  
\}

> 这也会返回客户端JSON字符串：

\[ \{ ‘name’: Thanks For Posting!!!"\}\]

这样的代码更加专注于业务。

直接操控响应  
Spring还允许我们直接访问javax.servlet.http.HttpServletResponse对象; 我们只需要将它声明为方法参数：

> @GetMapping("/manual")  
> public void manual(HttpServletResponse response) throws IOException \{  
> response.setHeader("Custom-Header", "foo");  
> response.setStatus(200);  
> response.getWriter().println("Hello World!");  
> \}
> 
> 由于Spring在底层实现之上提供了抽象和附加功能，因此如果以这种方式直接操纵响应，会失去很多Spring提供方便功能。

实例代码：

> 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 = "获取问题概要标签列表", 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 = "项目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 = "获取问题概要标签值列表", 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 = "项目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 = "标签类型 app: 应用 device: 设备 server_name:服务名称 level:级别 logger:日志 os: 系统 user: 用户 url:URL transaction:事物", required = true) @PathVariable("tag_type") String tagType, @NotNull @Min(1) @ApiParam(value = "当前页数", required = true, defaultValue = "1") @RequestParam(value = "page_number", required = true, defaultValue = "1") Integer pageNumber, @NotNull @Min(1) @ApiParam(value = "每页显示条数", 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 = "项目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);
        }
    }

转载于:https://blog.51cto.com/chenhva/2393868

[br_GetMapping_hello_ public ResponseEntity_String_ hello_ _ return new ResponseEntity_Hello _ HttpStatus.OK_ _]: mailto:br/