初学struts1，遇到的问题................

Question

我在input.jsp中填好信息，按submit按钮，然后就报错了
myeclipse报错：警告: Unhandled exception
java.lang.NullPointerException
at org.apache.struts.config.FormBeanConfig.createActionForm(FormBeanConfig.java:289)
at org.apache.struts.config.FormBeanConfig.createActionForm(FormBeanConfig.java:357)
at org.apache.struts.chain.commands.CreateActionForm.execute(CreateActionForm.java:92)
at org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
at org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:305)
at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
at org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:449)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)
at java.lang.Thread.run(Thread.java:619)
2010-7-13 9:24:58 org.apache.struts.chain.commands.ExceptionCatcher postprocess
警告: Exception from exceptionCommand 'servlet-exception'
java.lang.NullPointerException
at org.apache.struts.config.FormBeanConfig.createActionForm(FormBeanConfig.java:289)
at org.apache.struts.config.FormBeanConfig.createActionForm(FormBeanConfig.java:357)
at org.apache.struts.chain.commands.CreateActionForm.execute(CreateActionForm.java:92)
at org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
at org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:305)
at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
at org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:449)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)
at java.lang.Thread.run(Thread.java:619)
2010-7-13 9:24:58 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet action threw exception
java.lang.NullPointerException
at org.apache.struts.config.FormBeanConfig.createActionForm(FormBeanConfig.java:289)
at org.apache.struts.config.FormBeanConfig.createActionForm(FormBeanConfig.java:357)
at org.apache.struts.chain.commands.CreateActionForm.execute(CreateActionForm.java:92)
at org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
at org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:305)
at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)
at org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:449)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)
at java.lang.Thread.run(Thread.java:619)web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
xmlns="http://java.sun.com/xml/ns/javaee" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
   <servlet-name>action</servlet-name>
   <servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
    <init-param>
     <param-name>config</param-name>
     <param-value>/WEB-INF/struts-config.xml</param-value>
    </init-param>
  </servlet>
  <servlet-mapping>
   <servlet-name>action</servlet-name>
   <url-pattern>*.do</url-pattern>
  </servlet-mapping></web-app>struts-config.xml
<?xml version="1.0" encoding="ISO-8859-1" ?><!DOCTYPE struts-config PUBLIC
          "-//Apache Software Foundation//DTD Struts Configuration 1.3//EN"
          "http://struts.apache.org/dtds/struts-config_1_3.dtd">
<struts-config>
  <form-beans>
     <form-bean name="testForm" type="com.demo.struts.forms.TestForm">
     </form-bean>
  </form-beans>
  <action-mappings>
    <action path="/test" name="testForm" scope="request" type="com.demo.struts.actions.TestAction" input="/input.jsp">
     <forward name="sucess" path="/success.jsp"/>
     <forward name="failure" path="/error.jsp"/>
    </action>
  </action-mappings>
 
</struts-config>package com.demo.struts.forms.TestForm;
import org.apache.struts.action.ActionForm;;
public class TestForm extends ActionForm{
protected String str1 = null;
protected String str2 = null;
public String getStr1(){
return str1;
}
public String getStr2() {
return str2;
}
public void setStr2(String str2) {
this.str2 = str2;
}
public void setStr1(String str1) {
this.str1 = str1;
}
}
package com.demo.struts.actions;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.actions.DispatchAction;import com.demo.struts.forms.TestForm.TestForm;public class TestAction extends DispatchAction{ @SuppressWarnings("deprecation")
public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws Exception { ActionErrors errors = new ActionErrors();
ActionForward forward = new ActionForward();
TestForm testForm = (TestForm) form; try {
// 取得表单参数
String str1 = testForm.getStr1();
String str2 = testForm.getStr2();

//调用JavaBean执行处理逻辑
request.setAttribute("str1", str1);
request.setAttribute("str2", str2);
} catch (Exception e) {
}

//根据处理逻辑返回成功或失败的页面
if (!errors.isEmpty()) {
saveErrors(request, errors);
forward = mapping.findForward("failure");
} else {
forward = mapping.findForward("success");
}
return forward;
}
}

Answer 1

input.jsp[code=HTML]
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!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=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<form action="test.do" methord="post" >
<input type="text" name="str1"/>
<input type="text" name="str2"/>
<input type="submit"/>
</form>
</body>
</html>[/code]

Answer 2

protected String str1 = null;
protected String str2 = null;
改成
protected String str1；
protected String str2；另外，你表单里面的文本框的name属性要写成str1和str2

Answer 3

其实楼主...我们一般做strut1.x的时候.都不使用formBean的...太麻烦了.
直接用request.getParameter("XXXXXXX");方便多了..

Answer 4

public class TestForm extends ActionForm{
    private String str1;
    private String str2;
    public String getStr1(){
        return str1;
    }
    public String getStr2() {
        return str2;
    }
    public void setStr2(String str2) {
        this.str2 = str2;
    }
    public void setStr1(String str1) {
        this.str1 = str1;
    }
}

Answer 5

把str1 str2 后的null去掉还是报错
表单里面的文本框的name属性不就是str1和str2么

Answer 6

你表单的值并没有取到，更没有复给formbean，肯定要报错啊。

Answer 7

你get的只不过是formbean里面的值，因为你给他的是null，所以报空指针异常了嘛

Answer 8

private String str1;
private String str2;
表单组件中name的名字要起str1与str2才行。

Answer 9

给你几点建议错误自己找吧第一：  我刚看了你报的异常。提示 是 actionform 但是 你接着往下看。。会发现是 diapatchaction。我建议你 修改一下。。execute 方法
因为你继承了 dispatch  你的 strut.xml
 中。。 你不加parameter="method"行么？？？第二。。：记好了。。、以后 formbean中。。建议用private  生成setter getter 方法。。
不建议使用 protected。。就这么多了看看吧。提醒一点： form 提交的时候 。。注意你的method 方法加上。也就是 你struts-config.xml配置的。。

Answer 10

form表单的名字你定义了么
<form action="test.do" methord="post" name="testForm">
这样看看。
既然你都用struts尽量多用用他的标签。什么都不用就用个action 那你还费那么大劲干什么，还不如直接用servlet得了。

Answer 11

<form action="/test.do" methord="post" >

Answer 12

++++首先要看看你的form提交到Action里面没有。加个“/”

Answer 13

看了看你的 异常显示， 是 空指针异常啊！我没有看你的代码 想的话，估计就是你的 jsp页面上的 要传递的 属性 和formbean 里面的属性不一样 或者是 根本就没有！
在struts 里面 要弄清楚 什么时候填充 Formbean 怎么填充formbean .这些原理搞清楚了 就好了！我也是干刚学习 的 说的不对 请见谅！

Answer 14

把TestAction类继承Action 看看对不！

Answer 15

<?xml version="1.0" encoding="ISO-8859-1" ?><!DOCTYPE struts-config PUBLIC
          "-//Apache Software Foundation//DTD Struts Configuration 1.3//EN"
          "http://struts.apache.org/dtds/struts-config_1_3.dtd">
<struts-config>
  <form-beans>
        <form-bean name="testForm" type="com.demo.struts.forms.TestForm">
        </form-bean>
  </form-beans>
  <action-mappings>
       <action path="/test" name="testForm" scope="request" type="com.demo.struts.actions.TestAction" input="/input.jsp">
        <forward name="sucess" path="/success.jsp"/>
        <forward name="failure" path="/error.jsp"/>
    </action>
  </action-mappings>
 
</struts-config>
你没有发现你的action和form没有映射在一起么？？？、
<action-mappings>
       <action attribute="testForm"path="/test" name="testForm" scope="request" type="com.demo.struts.actions.TestAction" input="/input.jsp">
       
        <forward name="sucess" path="/success.jsp"/>
        <forward name="failure" path="/error.jsp"/>
    </action>
  </action-mappings>
认真一点下次...

Answer 16

attribute="testForm"
楼上加个这个干嘛呢，我看人家例子里面没有这个也行呢

Answer 17

java.lang.NullPointerException如果lz通过debug下，发现指的是哪个对象的话，应该很容易解决的吧？