报错：HTTP Status 404 - There is no Action mapped for namespace [/] and action name [product-save] associated with context path [/20161101-struts2-2].

运行：index.jsp---->input.jsp----->details.jsp，但是在input.jsp到details.jsp的时候报错误。

异常如下：

严重: Could not find action or result
/
There is no Action mapped for namespace [/] and action name [] associated with c
ontext path []. - [unknown location]
at com.opensymphony.xwork2.DefaultActionProxy.prepare(DefaultActionProxy.java:1
85)
at org.apache.struts2.impl.StrutsActionProxy.prepare(StrutsActionProxy.java:63)
at org.apache.struts2.impl.StrutsActionProxyFactory.createActionProxy(StrutsAct
ionProxyFactory.java:39)
at com.opensymphony.xwork2.DefaultActionProxyFactory.createActionProxy(DefaultA
ctionProxyFactory.java:58)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:534)
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOper
ations.java:77)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilt
er(StrutsPrepareAndExecuteFilter.java:91)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler
.java:1419)
at com.bjhit.eranges.utils.SetCharacterEncodingFilter.doFilter(SetCharacterEnco
dingFilter.java:39)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler
.java:1419)
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:455)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:137
)
at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:557)
at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java
:231)
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java
:1075)
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:384)
at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:
193)
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:
1009)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135
)
at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHand
lerCollection.java:255)
at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.
java:154)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:1
16)
at org.eclipse.jetty.server.Server.handle(Server.java:368)
at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpCo
nnection.java:489)
at org.eclipse.jetty.server.AbstractHttpConnection.headerComplete(AbstractHttpC
onnection.java:942)
at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplet
e(AbstractHttpConnection.java:1004)
at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:640)
at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:235)
at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java
:82)
at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.
java:628)
at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.j
ava:52)
at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:
608)
at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:5
43)
at java.lang.Thread.run(Thread.java:662)

代码如下：

web.xml:

 <?xml version="1.0" encoding="UTF-8"?>

 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">

   <display-name>20161101-struts2-2</display-name>

      <!-- 配置struts2的Filter -->

      <filter>

         <filter-name>struts2</filter-name>

         <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>

     </filter>

     <filter-mapping>

         <filter-name>struts2</filter-name>

         <url-pattern>/*</url-pattern>

     </filter-mapping>

 </web-app>

struts.xml:

 <?xml version="1.0" encoding="UTF-8" ?>

 <!DOCTYPE struts PUBLIC

     "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"

     "http://struts.apache.org/dtds/struts-2.3.dtd">

 <struts>

    <!-- package:包，struts2使用package来组织模块

         name属性：必须，用于被其他包引用当前包

         extends:当前包继承哪个包，即可继承父包的所有配置，通常情况下继承struts-default

     -->

    <package name="helloworld" extends="struts-default">

          <!-- 配置一个action:一个struts2的请求就是一个action

               name:对应一个struts2的请求的名字(对应着servletPath,但去除/和扩展名)

               result:结果

           -->

          <action name="product-input">

               <result>/WEB-INF/pages/input.jsp</result>

          </action>

          <action name="product-save" class="com.tt.struts2.helloworld.Product"

                  method="save">

               <result name="details">/WEB-INF/pages/details.jsp</result>

          </action>   

    </package>

 </struts>

index.jsp:

 <%@ page language="java" contentType="text/html; charset=UTF-8"

     pageEncoding="UTF-8"%>

 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

 <html>

 <head>

 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

 <title>Insert title here</title>

 </head>

 <body>

         <!-- "product-input.action"就是servletPath -->

         <a href="product-input.action">Product Input</a>

 </body>

 </html>

input.jsp:

 <%@ page language="java" contentType="text/html; charset=UTF-8"

     pageEncoding="UTF-8"%>

 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

 <html>

 <head>

 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

 <title>Insert title here</title>

 </head>

 <body>

           <!-- "product-save.action"就是servletPath -->

           <form action="product-save.action">

                 ProductName:<input type="text" name="productName"/>

                 <br><br>

                 ProductDesc:<input type="text" name="productDesc"/>

                 <br><br>

                 ProductPrice:<input type="text" name="productPrice"/>

                 <br><br>

                 <input type="submit" value="Submit"/>

                 <br><br>

           </form>

 </body>

 </html>

details.jsp:

 <%@ page language="java" contentType="text/html; charset=UTF-8"

     pageEncoding="UTF-8"%>

 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

 <html>

 <head>

 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

 <title>Insert title here</title>

 </head>

 <body>

                 ProductId:${productId }

                 <br><br>

                 ProductName:${productName }

                 <br><br>

                 ProductDesc:${productDesc }

                 <br><br>

                 ProductPrice:${productPrice }

                 <br><br>

 </body>

 </html>

Product.java:

 package com.tt.struts2.helloworld;

 public class Product {

     private Integer productId;

     private String productName ;

     private String productDesc ;

     private double productPrice ;

     public String getProductName() {

         return productName;

     }

     public void setProductName(String productName) {

         this.productName = productName;

     }

     public String getProductDesc() {

         return productDesc;

     }

     public void setProductDesc(String productDesc) {

         this.productDesc = productDesc;

     }

     public double getProductPrice() {

         return productPrice;

     }

     public void setProductPrice(double productPrice) {

         this.productPrice = productPrice;

     }

     public Integer getProductId() {

         return productId;

     }

     public void setProductId(Integer productId) {

         this.productId = productId;

     }

     @Override

     public String toString() {

         return "Product [productId=" + productId + ", productName=" + productName + ", productDesc=" + productDesc

                 + ", productPrice=" + productPrice + "]";

     }

     public String save(){

         System.out.println("sava: "+this);

         return "details";

     }

 }

原因分析：

猜测应该是struts.xml的问题，但是第一个product-input的action都可以正常跳转(index.jsp---->input.jsp),为什么第二个product-save(input.jsp----->details.jsp)的action无法正常呢？

报错：HTTP Status 404 - There is no Action mapped for namespace [/] and action name [product-save] associated with context path [/20161101-struts2-2].

二者唯一的区别就是第二个action明确指定需要利用反射调用Product类里的save( )方法。但save方法没问题，最后怀疑表单提交上的问题。

仔细看input.jsp页面，发现input.jsp里的form表单的提交方式没有设置method(注意：html提交表单的方式默认为get)。

报错：HTTP Status 404 - There is no Action mapped for namespace [/] and action name [product-save] associated with context path [/20161101-struts2-2].

解决办法：将input.jsp里的form添加method="post"问题就解决了。

那么get请求和post请求有何区别呢？见http://www.cnblogs.com/TTTTT/p/6650117.html

在网上查找的这个报错的常见原因如下：

1.struts.xml文件错误。

这种错误又分为以下几种：

1)struts.xml里配置action的class时，全类名要写正确。

2)struts.xml文件名错误。一定要注意拼写问题；

3)struts.xml文件放置路径错误。一定要将此文件放置在src目录下。编译成功后，要确认是否编译到classes目录中；

4)struts.xml文件内容错误:启动页面一定要是自己工程里有的jsp文件。

<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>

如果你在Eclipse工程的WebContent文件夹下没有这个index.jsp文件，也会报同样的错误。
比如我自己定义了一个login.jsp文件，放在WebContent文件夹下，就写成
<welcome-file>login.jsp</welcome-file>
把login.jsp文件放在WEB-INF下自定义的jsp文件夹下，就写成
<welcome-file>/WEB-INF/jsp/login.jsp</welcome-file>

2.表单提交页面的错误

比如上面我的错误。