RPC異常處理指是,當客戶端調用遠端的服務,若是服務執行過程當中發生異常,這個異常可否序列到客戶端?java
若是服務在執行過程當中可能發生異常,那麼在服務接口的聲明中,就該聲明該接口可能拋出的異常。web
在Hessian中,服務器端發生異常,能夠將異常信息從服務器端序列化到客戶端,由於Exception自己是實現了Serializable的,所以,咱們在自定義異常時,不須要顯式的讓自定義的服務器
異常實現Serializable接口app
繼續以【RPC框架Hessian二】中的代碼爲例,修改服務的save方法,刻意的讓服務器端的代碼拋出異常(拋出的是運行時異常,受檢異常與此相似)框架
package com.tom.hessian.server; import com.tom.hessian.common.ComplexModel; import com.tom.hessian.common.IComplexModelService; import java.util.HashMap; import java.util.Map; /** * Created by yuzhitao on 14-9-2. */ public class ComplexModelService implements IComplexModelService { private Map<Integer,ComplexModel> models = new HashMap<Integer, ComplexModel>(); @Override public void save(ComplexModel model) { if (model.getId() == null){ throw new IllegalArgumentException("id could not be null"); } if (model.getId() == 1) { //客戶端的model的id爲1,所以會發生unchecked exception throw new IllegalArgumentException("id could not be 1"); } models.put(model.getId(), model); } @Override public ComplexModel read(Integer modelId) { return models.get(modelId); } }
當客戶端的model的id爲1時,調用save方法,拋出webapp
if (model.getId() == 1) { //客戶端的model的id爲1,所以會發生unchecked exception throw new IllegalArgumentException("id could not be 1"); }
此時服務器端沒有拋出異常,而客戶端拋出異常:ide
Exception in thread "main" java.lang.IllegalArgumentException: id could not be 1 at com.tom.hessian.server.ComplexModelService.save(ComplexModelService.java:21) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at com.caucho.hessian.server.HessianSkeleton.invoke(HessianSkeleton.java:302) at com.caucho.hessian.server.HessianSkeleton.invoke(HessianSkeleton.java:198) at com.caucho.hessian.server.HessianServlet.invoke(HessianServlet.java:399) at com.caucho.hessian.server.HessianServlet.service(HessianServlet.java:379) at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487) at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:362) at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181) at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:726) at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405) at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:206) at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:139) at org.mortbay.jetty.Server.handle(Server.java:324) at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505) at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:842) at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:648) at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380) at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:395) at org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:450)
在Hessian的HessianSkeleton類的invoke方法中,經過反射調用服務代碼:this
try { result = method.invoke(service, values); //調用的服務端類、參數和方法 } catch (Exception e) { //捕獲異常 Throwable e1 = e; if (e1 instanceof InvocationTargetException) e1 = ((InvocationTargetException) e).getTargetException(); log.log(Level.FINE, this + " " + e1.toString(), e1); out.writeFault("ServiceException", escapeMessage(e1.getMessage()), e1);//將異常信息序列到客戶端 out.close(); return; }