struts 2.2.1 中ActionChainResult的修改[CSDN迁移文章]

如果你因struts2暴露的安全漏洞 而希望升级到struts 2.2.1，那么你需要仔细测试你的程序是否能在2.2.1的环境下顺利运行。因为struts 2.2.1版本升级了OGNL、freemarker，以及对我们代码影响很大的xwork。

其中xwork的一个bug编号为"WW-2869 "的修订，对我们熟悉的chain result type做了重要的修改。这个bug的出发点是在一个Action a执行后，跳转到执行result。假设这个result是一张jsp页面，而这张jsp页面中调用了<s:action name="bar"/>标签。假设在执行a Action时，执行了类似代码"addActionError("an error from FooAction");"，那么会停止对Action bar的正确调用，而执行Action bar的input。

这个问题的归结原因是在ChainingInterceptor中，在调用Action bar前，会将上一个Action(面假设中的Action a)的一些属性值拷贝到bar中。以下是在strtus 2.2.1前的xwork中的ChainingInterceptor代码

    @Override
    public String intercept(ActionInvocation invocation) throws Exception {
        ValueStack stack = invocation.getStack();
        CompoundRoot root = stack.getRoot();
        if (root.size() > 1) {
            List<CompoundRoot> list = new ArrayList<CompoundRoot>(root);
            list.remove(0);
            Collections.reverse(list);
            Map<String, Object> ctxMap = invocation.getInvocationContext().getContextMap();
            Iterator<CompoundRoot> iterator = list.iterator();
            int index = 1; // starts with 1, 0 has been removed
            while (iterator.hasNext()) {
            	index = index + 1;
                Object o = iterator.next();
                if (o != null) {
                	if (!(o instanceof Unchainable)) {
						//拷贝属性值到将要执行的Action中
                		reflectionProvider.copy(o, invocation.getAction(), ctxMap, excludes, includes);
                	}
                }
                else {
                	LOG.warn("compound root element at index "+index+" is null");
                }
            }
        }

 

    @Override
    public String intercept(ActionInvocation invocation) throws Exception {
        ValueStack stack = invocation.getStack();
        CompoundRoot root = stack.getRoot();
        if (root.size() > 1) {
            List<CompoundRoot> list = new ArrayList<CompoundRoot>(root);
            list.remove(0);
            Collections.reverse(list);
            Map<String, Object> ctxMap = invocation.getInvocationContext().getContextMap();
            Iterator<CompoundRoot> iterator = list.iterator();
            int index = 1; // starts with 1, 0 has been removed
            while (iterator.hasNext()) {
            	index = index + 1;
                Object o = iterator.next();
                if (o != null) {
                	if (!(o instanceof Unchainable)) {
						//拷贝属性值到将要执行的Action中
                		reflectionProvider.copy(o, invocation.getAction(), ctxMap, excludes, includes);
                	}
                }
                else {
                	LOG.warn("compound root element at index "+index+" is null");
                }
            }
        }

对于这种方式的好处，我们或许已经默默的在使用了。还是前面提到的Action a和Action bar，若Action a和Action bar都有一个共同的属性叫common，并且都有get、set方法。那么在Action a中的一些处理后，属性common有了值，经过chain resultType时，Action bar的common会自动被赋值。如果你在升级到struts2.2.1后，发现一些请求返回了NullPointerException，那么很有可 能是struts2.2.1对ChainingInterceptor的修改导致了这个问题。

以下是struts 2.2.1中的ChainingInterceptor源代码

    public String intercept(ActionInvocation invocation) throws Exception {
        ValueStack stack = invocation.getStack();
        CompoundRoot root = stack.getRoot();
        if (root.size() > 1 && isChainResult(invocation)) {
            List<CompoundRoot> list = new ArrayList<CompoundRoot>(root);
            list.remove(0);
            Collections.reverse(list);
            Map<String, Object> ctxMap = invocation.getInvocationContext().getContextMap();
            Iterator<CompoundRoot> iterator = list.iterator();
            int index = 1; // starts with 1, 0 has been removed
            while (iterator.hasNext()) {
                index = index + 1;
                Object o = iterator.next();
                if (o != null) {
                    if (!(o instanceof Unchainable)) {
                        reflectionProvider.copy(o, invocation.getAction(), ctxMap, excludes, includes);
                    }
                } else {
                    LOG.warn("compound root element at index " + index + " is null");
                }
            }
        }
        return invocation.invoke();
    }

 

    public String intercept(ActionInvocation invocation) throws Exception {
        ValueStack stack = invocation.getStack();
        CompoundRoot root = stack.getRoot();
        if (root.size() > 1 && isChainResult(invocation)) {
            List<CompoundRoot> list = new ArrayList<CompoundRoot>(root);
            list.remove(0);
            Collections.reverse(list);
            Map<String, Object> ctxMap = invocation.getInvocationContext().getContextMap();
            Iterator<CompoundRoot> iterator = list.iterator();
            int index = 1; // starts with 1, 0 has been removed
            while (iterator.hasNext()) {
                index = index + 1;
                Object o = iterator.next();
                if (o != null) {
                    if (!(o instanceof Unchainable)) {
                        reflectionProvider.copy(o, invocation.getAction(), ctxMap, excludes, includes);
                    }
                } else {
                    LOG.warn("compound root element at index " + index + " is null");
                }
            }
        }
        return invocation.invoke();
    }

和前面的相比，if (root.size() > 1) 中对了一个判断isChainResult(invocation)。这个判断让我有些纳闷，因为根据我的一些跟踪，在ActionInvocation 调用invoke()方法前，ActionInvocation中的result属性是null，所以这个if总是false。难道有什么其他设置能恢复 原来类似功能吗？希望有高人解答。正是因为这个问题，若你还希望使用原来chain的拷贝功能，你需要删除 isChainResult(invocation)这个判断。

以下是一个很有趣的实验，首先我们看核心的struts.xml配置信息：

    <package name="default" namespace="/" extends="struts-default">
        <!-- <default-action-ref name="index" /> -->
        <action name="index">
            <result>index.jsp</result>
        </action>
        
        <action name="chainSrc" class="ChainSrcAction">
        	<result type="chain">chainDest</result>
        </action>
         <action name="chainDest" class="ChainDestAction">
        	<result>chainDest.jsp</result>
        </action>
        
    </package>

 

    <package name="default" namespace="/" extends="struts-default">
        <!-- <default-action-ref name="index" /> -->
        <action name="index">
            <result>index.jsp</result>
        </action>
        
        <action name="chainSrc" class="ChainSrcAction">
        	<result type="chain">chainDest</result>
        </action>
         <action name="chainDest" class="ChainDestAction">
        	<result>chainDest.jsp</result>
        </action>
        
    </package>

ChainSrcAction的源代码：

import com.opensymphony.xwork2.ActionSupport;
public class ChainSrcAction extends ActionSupport {
	
	private String p1;
	private String p2 = "chain";
	@Override
	public String execute() throws Exception {
		System.out.println(ChainSrcAction.class+"p1="+p1);
		System.out.println(ChainSrcAction.class+"p2="+p2);
		return SUCCESS;
	}
	
	public String getP1() {
		return p1;
	}
	public void setP1(String p1) {
		this.p1 = p1;
	}
	public String getP2() {
		return p2;
	}
}

 

import com.opensymphony.xwork2.ActionSupport;
public class ChainSrcAction extends ActionSupport {
	
	private String p1;
	private String p2 = "chain";
	@Override
	public String execute() throws Exception {
		System.out.println(ChainSrcAction.class+"p1="+p1);
		System.out.println(ChainSrcAction.class+"p2="+p2);
		return SUCCESS;
	}
	
	public String getP1() {
		return p1;
	}
	public void setP1(String p1) {
		this.p1 = p1;
	}
	public String getP2() {
		return p2;
	}
}

ChainDestAction的源代码：

import com.opensymphony.xwork2.ActionSupport;
public class ChainDestAction extends ActionSupport {
	
	private String p1;
	private String p2 ;
	@Override
	public String execute() throws Exception {
		System.out.println(ChainDestAction.class+"p1="+p1);
		System.out.println(ChainDestAction.class+"p2="+p2);
		return SUCCESS;
	}
	
	public String getP1() {
		return p1;
	}
	public void setP1(String p1) {
		this.p1 = p1;
	}
	public String getP2() {
		return p2;
	}
	public void setP2(String p2) {
		this.p2 = p2;
	}
}

 

import com.opensymphony.xwork2.ActionSupport;
public class ChainDestAction extends ActionSupport {
	
	private String p1;
	private String p2 ;
	@Override
	public String execute() throws Exception {
		System.out.println(ChainDestAction.class+"p1="+p1);
		System.out.println(ChainDestAction.class+"p2="+p2);
		return SUCCESS;
	}
	
	public String getP1() {
		return p1;
	}
	public void setP1(String p1) {
		this.p1 = p1;
	}
	public String getP2() {
		return p2;
	}
	public void setP2(String p2) {
		this.p2 = p2;
	}
}

在struts 2.2.1的环境下，在地址栏上输入"http://127.0.0.1/s221/chainSrc.action?p1=struts2.2.1"你将会得到以下答案：

class ChainSrcActionp1=struts2.2.1
class ChainSrcActionp2=chain
class ChainDestActionp1=struts2.2.1
class ChainDestActionp2=null

在struts 2.1.8的环境下，相同的访问你会得到答案：

class ChainSrcActionp1=struts2.2.1
class ChainSrcActionp2=chain
class ChainDestActionp1=struts2.2.1
class ChainDestActionp2=chain

如果你将ChainingInterceptor中的if (root.size() > 1 && isChainResult(invocation))改为if (root.size() > 1 )，你也可以得到struts 2.1.8的结果。对于熟悉p1，它始终都得到了赋值是因为还有ParametersInterceptor对它赋值。