一、前言Spring Boot對(duì)異常的處理有一套默認(rèn)的機(jī)制當(dāng)應(yīng)用中產(chǎn)生異常時(shí)Spring Boot根據(jù)發(fā)送請(qǐng)求頭中的accept是否包含text/html來分別返回不同的響應(yīng)信息。當(dāng)從瀏覽器地址欄中訪問應(yīng)用接口時(shí)請(qǐng)求頭中的accept便會(huì)包含text/html信息產(chǎn)生異常時(shí)Spring Boot通過org.springframework.web.servlet.ModelAndView對(duì)象來裝載異常信息并以HTML的格式返回而當(dāng)從客戶端訪問應(yīng)用接口產(chǎn)生異常時(shí)客戶端訪問時(shí)請(qǐng)求頭中的accept不包含text/htmlSpring Boot則以JSON的格式返回異常信息。下面來驗(yàn)證一下。二、默認(rèn)異常處理機(jī)制假設(shè)應(yīng)用中有如下一個(gè)ControllerRestControllerRequestMapping(calculate)publicclassCalculateController{GetMapping(/{divisor:\\d}/{dividend:\\d})publicvoidcalculate(PathVariableLongdivisor,PathVariableLongdividend){thrownewRuntimeException(calculate is error);}}在代碼中我們主動(dòng)的拋出了一個(gè)RuntimeException使用瀏覽器訪問http://localhost:8080/calculate/1/0可看到頁面返回了一些異常描述并且請(qǐng)求頭的accpet包含了text/html片段。接著使用模擬發(fā)送REST請(qǐng)求,使用IDEA插件HTTP Client發(fā)送http://localhost:8080/calculate/1/0可以看到請(qǐng)求頭的accept值為*/*并且返回一段JSON格式的信息。查看Spring Boot的BasicErrorController類便可看到這一默認(rèn)機(jī)制的具體實(shí)現(xiàn)可看到errorHtml和error方法的請(qǐng)求地址和方法是一樣的唯一的區(qū)別就是errorHtml通過produces {“text/html”}判斷請(qǐng)求頭的accpet屬性中是否包含text/html如果包含便走該方法。三、自定義html異常頁面我們可以通過在src/main/resources/resources/error路徑下定義友好的異常頁面比如定義一個(gè)500.html頁面!DOCTYPEhtmlhtmllangenheadmetacharsetUTF-8title500/title/headbody系統(tǒng)內(nèi)部異常/body/html使用瀏覽器再次訪問http://localhost:8080/calculate/1/0同樣的我們也可以定義404.html等常見的HTTP狀態(tài)碼對(duì)應(yīng)的異常頁面。!DOCTYPEhtmlhtmllangenheadmetacharsetUTF-8title404/title/headbody鏈接走丟了/body/html使用瀏覽器訪問http://localhost:8080/calculater/1/0通過自定義html異常頁面并不會(huì)影響客戶端發(fā)送請(qǐng)求異常返回的結(jié)果。四、自定義異常處理除了可以通過自定義html異常頁面來改變?yōu)g覽器訪問接口時(shí)產(chǎn)生的異常信息我們也可以自定義異常處理來改表默認(rèn)的客戶端訪問接口產(chǎn)生的異常信息。我們手動(dòng)定義一個(gè)CalculateErrorException繼承RuntimeException。publicclassCalculateErrorExceptionextendsRuntimeException{privatestaticfinallongserialVersionUID-1L;privateStringid;publicCalculateErrorException(Stringid){super(calculate is error);this.idid;}publicStringgetId(){returnid;}publicvoidsetId(Stringid){this.idid;}}然后定義一個(gè)Controller異常處理類ControllerExceptionHandlerControllerAdvicepublicclassControllerExceptionHandler{ExceptionHandler(CalculateErrorException.class)ResponseBodyResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)publicMapString,ObjecthandleUserNotExistsException(CalculateErrorExceptione){MapString,ObjectmapnewHashMap();map.put(id,e.getId());map.put(message,e.getMessage());returnmap;}}其中注解ExceptionHandler指定了要處理的異常類型注解ResponseStatus指定異常處理方法返回的HTTP狀態(tài)碼為HttpStatus.INTERNAL_SERVER_ERROR即500。HttpStatus是一個(gè)spring自帶的枚舉類型封裝了常見的HTTP狀態(tài)碼及描述publicenumHttpStatus{CONTINUE(100,Continue),SWITCHING_PROTOCOLS(101,Switching Protocols),PROCESSING(102,Processing),CHECKPOINT(103,Checkpoint),OK(200,OK),CREATED(201,Created),ACCEPTED(202,Accepted),NON_AUTHORITATIVE_INFORMATION(203,Non-Authoritative Information),NO_CONTENT(204,No Content),RESET_CONTENT(205,Reset Content),PARTIAL_CONTENT(206,Partial Content),MULTI_STATUS(207,Multi-Status),ALREADY_REPORTED(208,Already Reported),IM_USED(226,IM Used),MULTIPLE_CHOICES(300,Multiple Choices),MOVED_PERMANENTLY(301,Moved Permanently),FOUND(302,Found),/** deprecated */DeprecatedMOVED_TEMPORARILY(302,Moved Temporarily),SEE_OTHER(303,See Other),NOT_MODIFIED(304,Not Modified),/** deprecated */DeprecatedUSE_PROXY(305,Use Proxy),TEMPORARY_REDIRECT(307,Temporary Redirect),PERMANENT_REDIRECT(308,Permanent Redirect),BAD_REQUEST(400,Bad Request),UNAUTHORIZED(401,Unauthorized),PAYMENT_REQUIRED(402,Payment Required),FORBIDDEN(403,Forbidden),NOT_FOUND(404,Not Found),METHOD_NOT_ALLOWED(405,Method Not Allowed),NOT_ACCEPTABLE(406,Not Acceptable),PROXY_AUTHENTICATION_REQUIRED(407,Proxy Authentication Required),REQUEST_TIMEOUT(408,Request Timeout),CONFLICT(409,Conflict),GONE(410,Gone),LENGTH_REQUIRED(411,Length Required),PRECONDITION_FAILED(412,Precondition Failed),PAYLOAD_TOO_LARGE(413,Payload Too Large),/** deprecated */DeprecatedREQUEST_ENTITY_TOO_LARGE(413,Request Entity Too Large),URI_TOO_LONG(414,URI Too Long),/** deprecated */DeprecatedREQUEST_URI_TOO_LONG(414,Request-URI Too Long),UNSUPPORTED_MEDIA_TYPE(415,Unsupported Media Type),REQUESTED_RANGE_NOT_SATISFIABLE(416,Requested range not satisfiable),EXPECTATION_FAILED(417,Expectation Failed),I_AM_A_TEAPOT(418,Im a teapot),/** deprecated */DeprecatedINSUFFICIENT_SPACE_ON_RESOURCE(419,Insufficient Space On Resource),/** deprecated */DeprecatedMETHOD_FAILURE(420,Method Failure),/** deprecated */DeprecatedDESTINATION_LOCKED(421,Destination Locked),UNPROCESSABLE_ENTITY(422,Unprocessable Entity),LOCKED(423,Locked),FAILED_DEPENDENCY(424,Failed Dependency),UPGRADE_REQUIRED(426,Upgrade Required),PRECONDITION_REQUIRED(428,Precondition Required),TOO_MANY_REQUESTS(429,Too Many Requests),REQUEST_HEADER_FIELDS_TOO_LARGE(431,Request Header Fields Too Large),UNAVAILABLE_FOR_LEGAL_REASONS(451,Unavailable For Legal Reasons),INTERNAL_SERVER_ERROR(500,Internal Server Error),NOT_IMPLEMENTED(501,Not Implemented),BAD_GATEWAY(502,Bad Gateway),SERVICE_UNAVAILABLE(503,Service Unavailable),GATEWAY_TIMEOUT(504,Gateway Timeout),HTTP_VERSION_NOT_SUPPORTED(505,HTTP Version not supported),VARIANT_ALSO_NEGOTIATES(506,Variant Also Negotiates),INSUFFICIENT_STORAGE(507,Insufficient Storage),LOOP_DETECTED(508,Loop Detected),BANDWIDTH_LIMIT_EXCEEDED(509,Bandwidth Limit Exceeded),NOT_EXTENDED(510,Not Extended),NETWORK_AUTHENTICATION_REQUIRED(511,Network Authentication Required);...}編寫完自定義異常處理邏輯后我們將CalculateController中的方法拋出的異常改為CalculateErrorExceptionGetMapping(/{divisor:\\d}/{dividend:\\d})publicvoidcalculate(PathVariableLongdivisor,PathVariableLongdividend){thrownewCalculateErrorException(500);}重啟項(xiàng)目再次訪問http://localhost:8080/calculater/1/0響應(yīng)如下