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{ @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);
}
}
