详解SpringCloud Finchley Gateway 统一异常处理

package pro.chenggang.example.spring.cloud.gateway.support;

import org.slf4j.logger;

import org.slf4j.loggerfactory;

import org.springframework.boot.web.reactive.error.errorwebexceptionhandler;

import org.springframework.cloud.gateway.support.notfoundexception;

import org.springframework.http.httpstatus;

import org.springframework.http.mediatype;

import org.springframework.http.codec.httpmessagereader;

import org.springframework.http.codec.httpmessagewriter;

import org.springframework.http.server.reactive.serverhttprequest;

import org.springframework.util. assert ;

import org.springframework.web.reactive.function.bodyinserters;

import org.springframework.web.reactive.function.server.requestpredicates;

import org.springframework.web.reactive.function.server.routerfunctions;

import org.springframework.web.reactive.function.server.serverrequest;

import org.springframework.web.reactive.function.server.serverresponse;

import org.springframework.web.reactive.result.view.viewresolver;

import org.springframework.web.server.responsestatusexception;

import org.springframework.web.server.serverwebexchange;

import reactor.core.publisher.mono;

import java.util.collections;

import java.util.hashmap;

import java.util.list;

import java.util.map;

/**

  * @classdesc: 统一异常处理,参考{@link org.springframework.web.server.abstracterrorwebexceptionhandler}修改

  * @author: chenggang

  * @createtime: 2018/10/30

  */

public class jsonexceptionhandler implements errorwebexceptionhandler {

  private static final logger log = loggerfactory.getlogger(jsonexceptionhandler. class );

  /**

   * messagereader

   */

  private list<httpmessagereader<?>> messagereaders = collections.emptylist();

  /**

   * messagewriter

   */

  private list<httpmessagewriter<?>> messagewriters = collections.emptylist();

  /**

   * viewresolvers

   */

  private list<viewresolver> viewresolvers = collections.emptylist();

  /**

   * 存储处理异常后的信息

   */

  private threadlocal<map<string,object>> exceptionhandlerresult = new threadlocal<>();

  /**

   * 参考abstracterrorwebexceptionhandler

   * @param messagereaders

   */

  public void setmessagereaders(list<httpmessagereader<?>> messagereaders) {

   assert .notnull(messagereaders, "'messagereaders' must not be null" );

   this .messagereaders = messagereaders;

  }

  /**

   * 参考abstracterrorwebexceptionhandler

   * @param viewresolvers

   */

  public void setviewresolvers(list<viewresolver> viewresolvers) {

   this .viewresolvers = viewresolvers;

  }

  /**

   * 参考abstracterrorwebexceptionhandler

   * @param messagewriters

   */

  public void setmessagewriters(list<httpmessagewriter<?>> messagewriters) {

   assert .notnull(messagewriters, "'messagewriters' must not be null" );

   this .messagewriters = messagewriters;

  }

  @override

  public mono< void > handle(serverwebexchange exchange, throwable ex) {

   /**

    * 按照异常类型进行处理

    */

   httpstatus httpstatus;

   string body;

   if (ex instanceof notfoundexception) {

    httpstatus = httpstatus.not_found;

    body = "service not found" ;

   } else if (ex instanceof responsestatusexception) {

    responsestatusexception responsestatusexception = (responsestatusexception) ex;

    httpstatus = responsestatusexception.getstatus();

    body = responsestatusexception.getmessage();

   } else {

    httpstatus = httpstatus.internal_server_error;

    body = "internal server error" ;

   }

   /**

    * 封装响应体,此body可修改为自己的jsonbody

    */

   map<string,object> result = new hashmap<>( 2 , 1 );

   result.put( "httpstatus" ,httpstatus);

   result.put( "body" ,body);

   /**

    * 错误记录

    */

   serverhttprequest request = exchange.getrequest();

   log.error( "[全局异常处理]异常请求路径:{},记录异常信息:{}" ,request.getpath(),ex.getmessage());

   /**

    * 参考abstracterrorwebexceptionhandler

    */

   if (exchange.getresponse().iscommitted()) {

    return mono.error(ex);

   }

   exceptionhandlerresult.set(result);

   serverrequest newrequest = serverrequest.create(exchange, this .messagereaders);

   return routerfunctions.route(requestpredicates.all(), this ::rendererrorresponse).route(newrequest)

     .switchifempty(mono.error(ex))

     .flatmap((handler) -> handler.handle(newrequest))

     .flatmap((response) -> write(exchange, response));

  }

  /**

   * 参考defaulterrorwebexceptionhandler

   * @param request

   * @return

   */

  protected mono<serverresponse> rendererrorresponse(serverrequest request) {

   map<string,object> result = exceptionhandlerresult.get();

   return serverresponse.status((httpstatus) result.get( "httpstatus" ))

     .contenttype(mediatype.application_json_utf8)

     .body(bodyinserters.fromobject(result.get( "body" )));

  }

  /**

   * 参考abstracterrorwebexceptionhandler

   * @param exchange

   * @param response

   * @return

   */

  private mono<? extends void > write(serverwebexchange exchange,

           serverresponse response) {

   exchange.getresponse().getheaders()

     .setcontenttype(response.headers().getcontenttype());

   return response.writeto(exchange, new responsecontext());

  }

  /**

   * 参考abstracterrorwebexceptionhandler

   */

  private class responsecontext implements serverresponse.context {

   @override

   public list<httpmessagewriter<?>> messagewriters() {

    return jsonexceptionhandler. this .messagewriters;

   }

   @override

   public list<viewresolver> viewresolvers() {

    return jsonexceptionhandler. this .viewresolvers;

   }

  }

}

/**

  * 自定义异常处理[@@]注册bean时依赖的bean，会从容器中直接获取，所以直接注入即可

  * @param viewresolversprovider

  * @param servercodecconfigurer

  * @return

  */

@primary

@bean

@order (ordered.highest_precedence)

public errorwebexceptionhandler errorwebexceptionhandler(objectprovider<list<viewresolver>> viewresolversprovider,

                servercodecconfigurer servercodecconfigurer) {

  jsonexceptionhandler jsonexceptionhandler = new jsonexceptionhandler();

  jsonexceptionhandler.setviewresolvers(viewresolversprovider.getifavailable(collections::emptylist));

  jsonexceptionhandler.setmessagewriters(servercodecconfigurer.getwriters());

  jsonexceptionhandler.setmessagereaders(servercodecconfigurer.getreaders());

  log.debug( "init json exception handler instead default errorwebexceptionhandler success" );

  return jsonexceptionhandler;

}