第詳解java封裝返回結(jié)果與RestControllerAdvice注解目錄1.為什么要把結(jié)果封裝成統(tǒng)一格式？2.統(tǒng)一異常接收

1.為什么要把結(jié)果封裝成統(tǒng)一格式？

異常和正常情況無法區(qū)分：異常情況返回?cái)?shù)據(jù)為null，正常情況下查詢結(jié)果也為null，返回給前端無法區(qū)分

顯示拋出異常信息：前端需要顯示拋出的異常信息

@AllArgsConstructor

publicenumResultCode{

CODE_200(200,"success"),

CODE_1000(1000,"fail");

@Getter

privateIntegercode;

@Getter

privateStringmsg;

@Data

publicclassResultT{

privateStringmsg;

privateIntegercode;

privateTdata;

privateResult(Stringmsg,Integercode){

this.msg=msg;

this.code=code;

privateResult(ResultCoderesultCode,Stringmsg){

this(msg,resultCode.getCode());

privateResult(ResultCoderesultCode){

this(resultCode.getMsg(),resultCode.getCode());

publicstaticTResultTresult(ResultCoderesultCode,Tdata){

Resultresult=newResult(resultCode);

result.setData(data);

returnresult;

publicstaticTResultTfail(ResultCoderesultCode,Stringmessage){

Resultresult=newResult(resultCode,message);

result.setData(null);

returnresult;

publicstaticTResultTfail(Tdata){

Resultresult=newResult(ResultCode.CODE_1000);

result.setData(data);

returnresult;

publicstaticTResultTsuccess(Tdata){

Resultresult=newResult(ResultCode.CODE_200);

result.setData(data);

returnresult;

不封裝：

封裝：

2.統(tǒng)一異常接收

為什么要用統(tǒng)一異常接收？

通常在service層拋異常，涉及到事務(wù)時(shí)不會(huì)進(jìn)行try-catch，需要在controller里處理異常。即使能夠進(jìn)行try-catch的地方也需要統(tǒng)一返回格式，造成重復(fù)代碼很多，可讀性比較差。

如何實(shí)現(xiàn)統(tǒng)一的異常接收？

@Slf4j

@RestControllerAdvice

publicclassGlobalException{

@ExceptionHandler(Exception.class)

publicResulthandlerException(Exceptionexception){

("Exception異常信息："+exception.getMessage());

returnResult.fail(ResultCode.CODE_1000,exception.getMessage());

@ExceptionHandler(value={MyException.class})

publicResulthandlerMyException(Exceptionexception){

("MyException異常信息："+exception.getMessage());

returnResult.fail(ResultCode.CODE_1000,exception.getMessage());

拋出異常后，會(huì)進(jìn)入到@RestControllerAdvice注解的方法，過濾出和拋出異常相同的class的方法，執(zhí)行相應(yīng)的方法。

protectedModelAndViewdoResolveHandlerMethodException(HttpServletRequestrequest,HttpServletResponseresponse,@NullableHandlerMethodhandlerMethod,Exceptionexception){

//根據(jù)異常類型過濾方法

ServletInvocableHandlerMethodexceptionHandlerMethod=this.getExceptionHandlerMethod(handlerMethod,exception);

if(exceptionHandlerMethod==null){

returnnull;

}else{

if(this.argumentResolvers!=null){

exceptionHandlerMethod.setHandlerMethodArgumentResolvers(this.argumentResolvers);

if(this.returnValueHandlers!=null){

exceptionHandlerMethod.setHandlerMethodReturnValueHandlers(this.returnValueHandlers);

ServletWebRequestwebRequest=newServletWebRequest(request,response);

ModelAndViewContainermavContainer=newModelAndViewContainer();

ArrayListThrowableexceptions=newArrayList();

try{

if(this.logger.isDebugEnabled()){

this.logger.debug("Using@ExceptionHandler"+exceptionHandlerMethod);

Throwablecause;

for(ThrowableexToExpose=exception;exToExpose!=null;exToExpose=cause!=exToExposecause:null){

exceptions.add(exToExpose);

cause=((Throwable)exToExpose).getCause();

Object[]arguments=newObject[exceptions.size()+1];

exceptions.toArray(arguments);

arguments[arguments.length-1]=handlerMethod;

//執(zhí)行方法

exceptionHandlerMethod.invokeAndHandle(webRequest,mavContainer,arguments);

}catch(Throwablevar13){

if(!exceptions.contains(var13)this.logger.isWarnEnabled()){

this.logger.warn("Failurein@ExceptionHandler"+exceptionHandlerMethod,var13);

returnnull;

if(mavContainer.isRequestHandled()){

returnnewModelAndView();

}else{

ModelMapmodel=mavContainer.getModel();

HttpStatusstatus=mavContainer.getStatus();

ModelAndViewmav=newModelAndView(mavContainer.getViewName(),model,status);

mav.setViewName(mavContainer.getViewName());

if(!mavContainer.isViewReference()){

mav.setView((View)mavContainer.getView());

if(modelinstanceofRedirectAttributes){

MapString,flashAttributes=((RedirectAttributes)model).getFlashAttributes();

RequestContextUtils.getOutputFlashMap(request).putAll(flashAttributes);

returnmav;

protectedServletInvocableHandlerMethodgetExceptionHandlerMethod(@NullableHandlerMethodhandlerMethod,Exceptionexception){

ClasshandlerType=null;

if(handlerMethod!=null){

handlerType=handlerMethod.getBeanType();

ExceptionHandlerMethodResolverresolver=(ExceptionHandlerMethodResolver)this.exceptionHandlerCache.get(handlerType);

if(resolver==null){

resolver=newExceptionHandlerMethodResolver(handlerType);

this.exceptionHandlerCache.put(handlerType,resolver);

Methodmethod=resolver.resolveMethod(exception);

if(method!=null){

returnnewServletInvocableHandlerMethod(handlerMethod.getBean(),method,this.applicationContext);

if(Proxy.isProxyClass(handlerType)){

handlerType=AopUtils.getTargetClass(handlerMethod.getBean());

//初始化的時(shí)候已經(jīng)將beanType作為key，標(biāo)注@ExceptionHandler的方法包裝成resolve作為value放到exceptionHandlerAdviceCache中

Iteratorvar9=this.exceptionHandlerAdviceCache.entrySet().iterator();

while(var9.hasNext()){

Map.EntryControllerAdviceBean,ExceptionHandlerMethodResolverentry=(Map.Entry)var9.next();

ControllerAdviceBeanadvice=(ControllerAdviceBean)entry.getKey();

if(advice.isApplicableToBeanType(handlerType)){

ExceptionHandlerMethodResolverresolver=(ExceptionHandlerMethodResolver)entry