j2ee ssh 整合项目时，出现了一下异常，最后发现，原来问题是这样是这样引起的。

先看异常：

--------------------------------------------------------------------------------------

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

Unable to instantiate Action, senlypan.action.UserAction,  defined for 'user' in namespace '/'Failed to convert property value of type 'senlypan.action.UserAction' to required type 'senlypan.model.User' for property 'user'; nested exception is java.lang.IllegalStateException: Cannot convert value of type [senlypan.action.UserAction] to required type [senlypan.model.User] for property 'user': no matching editors or conversion strategy found
        com.opensymphony.xwork2.DefaultActionInvocation.createAction(DefaultActionInvocation.java:306)
        com.opensymphony.xwork2.DefaultActionInvocation.init(DefaultActionInvocation.java:387)
        com.opensymphony.xwork2.DefaultActionProxy.prepare(DefaultActionProxy.java:186)
        org.apache.struts2.impl.StrutsActionProxy.prepare(StrutsActionProxy.java:61)
        org.apache.struts2.impl.StrutsActionProxyFactory.createActionProxy(StrutsActionProxyFactory.java:39)
        com.opensymphony.xwork2.DefaultActionProxyFactory.createActionProxy(DefaultActionProxyFactory.java:47)
        org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:458)
        org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
        org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:76)

root cause

org.springframework.beans.ConversionNotSupportedException: Failed to convert property value of type 'senlypan.action.UserAction' to required type 'senlypan.model.User' for property 'user'; nested exception is java.lang.IllegalStateException: Cannot convert value of type [senlypan.action.UserAction] to required type [senlypan.model.User] for property 'user': no matching editors or conversion strategy found
        org.springframework.beans.BeanWrapperImpl.convertIfNecessary(BeanWrapperImpl.java:485)
        org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:516)
        org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:510)
        org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.convertForProperty(AbstractAutowireCapableBeanFactory.java:1406)
        org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1365)
        org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1118)
        org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireBeanProperties(AbstractAutowireCapableBeanFactory.java:374)
        com.opensymphony.xwork2.spring.SpringObjectFactory.autoWireBean(SpringObjectFactory.java:176)
        com.opensymphony.xwork2.spring.SpringObjectFactory.buildBean(SpringObjectFactory.java:158)
        com.opensymphony.xwork2.spring.SpringObjectFactory.buildBean(SpringObjectFactory.java:129)
        com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:139)
        com.opensymphony.xwork2.ObjectFactory.buildAction(ObjectFactory.java:109)
        com.opensymphony.xwork2.DefaultActionInvocation.createAction(DefaultActionInvocation.java:287)
        com.opensymphony.xwork2.DefaultActionInvocation.init(DefaultActionInvocation.java:387)
        com.opensymphony.xwork2.DefaultActionProxy.prepare(DefaultActionProxy.java:186)
        org.apache.struts2.impl.StrutsActionProxy.prepare(StrutsActionProxy.java:61)
        org.apache.struts2.impl.StrutsActionProxyFactory.createActionProxy(StrutsActionProxyFactory.java:39)
        com.opensymphony.xwork2.DefaultActionProxyFactory.createActionProxy(DefaultActionProxyFactory.java:47)
        org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:458)
        org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
        org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:76)

root cause

java.lang.IllegalStateException: Cannot convert value of type [senlypan.action.UserAction] to required type [senlypan.model.User] for property 'user': no matching editors or conversion strategy found
        org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:241)
        org.springframework.beans.BeanWrapperImpl.convertIfNecessary(BeanWrapperImpl.java:470)
        org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:516)
        org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:510)
        org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.convertForProperty(AbstractAutowireCapableBeanFactory.java:1406)
        org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1365)
        org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1118)
        org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireBeanProperties(AbstractAutowireCapableBeanFactory.java:374)
        com.opensymphony.xwork2.spring.SpringObjectFactory.autoWireBean(SpringObjectFactory.java:176)
        com.opensymphony.xwork2.spring.SpringObjectFactory.buildBean(SpringObjectFactory.java:158)
        com.opensymphony.xwork2.spring.SpringObjectFactory.buildBean(SpringObjectFactory.java:129)
        com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:139)
        com.opensymphony.xwork2.ObjectFactory.buildAction(ObjectFactory.java:109)
        com.opensymphony.xwork2.DefaultActionInvocation.createAction(DefaultActionInvocation.java:287)
        com.opensymphony.xwork2.DefaultActionInvocation.init(DefaultActionInvocation.java:387)
        com.opensymphony.xwork2.DefaultActionProxy.prepare(DefaultActionProxy.java:186)
        org.apache.struts2.impl.StrutsActionProxy.prepare(StrutsActionProxy.java:61)
        org.apache.struts2.impl.StrutsActionProxyFactory.createActionProxy(StrutsActionProxyFactory.java:39)
        com.opensymphony.xwork2.DefaultActionProxyFactory.createActionProxy(DefaultActionProxyFactory.java:47)
        org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:458)
        org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
        org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:76)

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.35 logs.

异常解释： 大家请看上面红色的句子，如下

 Failed to convert property value of type 'senlypan.action.UserAction' to required type 'senlypan.model.User' for property 'user'

很明显， type 'senlypan.action.UserAction'  cant convert to   'senlypan.model.User'

看的出来一个是action类，一个是model类，那么他们之间为什么出现这种异常呢？

原因是，在ssh整合项目中，由于struts框架使用spring-plugin ，当struts初始化时，struts 会自动装载 Action 类中属性（即  setXxx() 方法），会把他们初始化到容器里面，所以由于我在UserAction类中使用了注解 @Component("user") ,以下即是action类的完整代码：

package senlypan.action;

import java.util.List;

import javax.annotation.Resource;

import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;

import senlypan.model.User;
import senlypan.service.UserManager;
import senlypan.vo.UserRegisterInfo;

import com.opensymphony.xwork2.ActionSupport;
import com.opensymphony.xwork2.ModelDriven;

@Component("user")
@Scope("prototype")
public class UserAction extends ActionSupport implements ModelDriven {

 private UserRegisterInfo userInfo = new UserRegisterInfo(); // 是ModelDriven必须new
                // 个

 private UserManager userManager;

 private List users;

 private User user;

 public User getUser() {
  return user;
 }

 public void setUser(User user) {
  this.user = user;
 }

 public List getUsers() {
  return users;
 }

 public void setUsers(List users) {
  this.users = users;
 }

 public UserManager getUserManager() {
  return userManager;
 }

 @Resource(name = "userManager")
 public void setUserManager(UserManager userManager) {
  this.userManager = userManager;
 }

 public UserRegisterInfo getUserInfo() {
  return userInfo;
 }

 public void setUserInfo(UserRegisterInfo userInfo) {
  this.userInfo = userInfo;
 }

 @Override
 public String execute() throws Exception {

  User user = new User();
  user.setUsername(userInfo.getUsername());
  user.setPassword(userInfo.getPassword());

  if (userManager.exists(user)) {
   System.out.println("already exists");
   return "fail";
  }
  System.err.println(" add success ...");
  userManager.add(user);
  return SUCCESS;
 }

 @Override
 public Object getModel() {
  return userInfo;
 }

 // 动态方法调用 user!list.action?
 public String list() {
  this.users = this.userManager.getUsers();
  return "list";
 }
 
 // 动态方法调用 user!load.action?id=1
 public String load() {
  this.user = this.userManager.loadById(userInfo.getId());
  return "load";
 }
}

从以上红色代码发现，UserAction 被初始化（被装载到初始化容器）时使用的名字为 user ，而UserAction的属性也有一个user (此为model包下的User类)，所以当 struts 初始化时，由于使用了spring-plugin ，所以struts试图把UserAction类中的属性装载进初始化容器，则此时属性 user （model下的User）装载时，容器会首先寻找user，发现已经存在user(此时的user正是被装载到初始化容器UserAction)，这是就出现了转换异常，即：

 Failed to convert property value of type 'senlypan.action.UserAction' to required type 'senlypan.model.User' for property 'user'

其实，这个归根到底，应该算是ssh的一个bug的，查看以下struts文档，在spring-plugin.html页面有一个设置，属性值为 struts.objectFactory.spring.autowire ，这个的描述即是，The autowire strategy , 他的默认值为 auto注入而且是 byName，所以当使用这个Spring-plugin时，action类中的属性（含setXxx()）会被自动装载，这个我个人觉得有点不好，本来应该让开发人员自动注入属性的，所以这个是我个人觉得不好的地方，当然，觉得的方法就是把UserAction名字改为 @Component("u")UserAction或者@Component("userAction")或者其他，记得也要在struts.xml配置里面修改action包的名字和页面提交时调用的action名字！

文章仅为个人愚见，有高见者，请策之明见！