关于HttpStatus
在SpringBoot中关于状态码有一个枚举类型，如下。
public enum HttpStatus {CONTINUE(100, "Continue"),SWITCHING_PROTOCOLS(101, "Switching Protocols"),PROCESSING(102, "Processing"),CHECKPOINT(103, "Checkpoint"),OK(200, "OK"),...}
通过以下三种方法均可实现
1. 通过@ResponseStatus注解
eg：
@ResponseStatus(code=HttpStatus.INTERNAL_SERVER_ERROR,reason="server error")public class ServerException extends Exception {...}
在全局异常捕捉的类中定义，可以自定义特定的异常来返回特定的状态码。
2. 修改response的status属性
eg：
@RequestMapping(value = "/index", method = RequestMethod.GET)public void index(HttpServletResponse response) throws IOException{response.setStatus(500);response.getWriter().append("server error");}
需要多加response参数，但这样的控制器都必须为void，有诸多限制。
3.ResponseEntity
eg：
@RequestMapping(value = "/user", method = RequestMethod.GET)public ResponseEntity<Map<String,Object>> getUser() throws IOException{Map<String,Object> map = new HashMap<String,Object>();map.put("name", "user");return new ResponseEntity<Map<String,Object>>(map,HttpStatus.OK);}
这样返回类型就只能是ResponseEntity。
前后端分离开发一般都会自定义返回的数据格式。
都会包含msg,code,data三个属性。
可用上述思路实现以下工具类。实现自定义返回的状态码，需将返回格式设置为以下类的格式，将返回数据传入data。
JSONResult.java
public class JSONResult<T> extends ResponseEntity<Message> {public JSONResult(HttpStatus status) {super(status);}public JSONResult(String code, String msg, T data) {super(Message.custom(code, msg, data), Message.num2HttpStatus(code));}public JSONResult(String code, String msg) {super(Message.custom(code, msg), Message.num2HttpStatus(code));}public static <T> JSONResult<T> success(T data) {return new JSONResult("200", "成功", data);}public static <T> JSONResult<T> failed(T data) {return new JSONResult("422", "失败", data);}public static <T> JSONResult<T> failMsg(String msg) {return new JSONResult("422", msg);}public static <T> JSONResult<T> custom(String code, String msg, T data) {return new JSONResult(code, msg, data);}}class Message<T> {String status;//向前端返回的内容String message;T data;public Message() {}public Message(String status, String message) {this.status = status;this.message = message;}public Message(String status, String message, T data) {this.data = data;this.status = status;this.message = message;}public static <T> Message<T> custom(String status, String message, T data) {return new Message(status, message, data);}public static <T> Message<T> custom(String status, String message) {return new Message(status, message);}public static HttpStatus num2HttpStatus(String code) {HttpStatus status = HttpStatus.NOT_FOUND;for (HttpStatus httpStatus : HttpStatus.values()) {boolean b = Integer.parseInt(code) == httpStatus.value();if (b) {return httpStatus;}}return status;}public String getStatus() {return status;}public void setStatus(String status) {this.status = status;}public String getMessage() {return message;}public void setMessage(String message) {this.message = message;}public T getData() {return data;}public void setData(T data) {this.data = data;}}
通过继承ResponseEntity类来实现自定义返回类的自定义状态码返回。
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