Struts2拦截器和监听器

第一种方法： 
直接implements实现com.opensymphony.xwork2.interceptor.Interceptor 

public class MyInterceptor implements Interceptor {

    public void destroy() {
        System.out.println("destroy()");
    }

    public void init() {
        System.out.println("init()");
    }

    public String intercept(ActionInvocation invocation) throws Exception {
        System.out.println("Interceptor");
        String result = invocation.invoke();
        return result;
    }

}

第二种方法 
直接extends com.opensymphony.xwork2.interceptor.AbstractInterceptor 
这种方法是少了destroy,init方法 

public class MyInterceptor2 extends AbstractInterceptor {

    @Override
    public String intercept(ActionInvocation invocation) throws Exception {
        System.out.println("MyInterceptor2222");
        String result = invocation.invoke();
        return result;
    }

}

第三种方法 
直接extends com.opensymphony.xwork2.interceptor.MethodFilterInterceptor 
这种方法能对Action里面的方法级进行控制，是否执行这个方法 

public class MyInterceptor3 extends MethodFilterInterceptor {

    @Override
    protected String doIntercept(ActionInvocation invocation) throws Exception {
        System.out.println("use MethodFilterInterceptor");
        String result = invocation.invoke();
        return result;
    }

}

然就是配置 

<interceptors>
            <interceptor name="myInterceptor" class="com.langhua.interceptor.MyInterceptor">
            </interceptor>

            <interceptor name="myInterceptor2" class="com.langhua.interceptor.MyInterceptor2">
            </interceptor>

            <interceptor name="myInterceptor3" class="com.langhua.interceptor.MyInterceptor3">
                <param name="excludeMethods">execute</param>
                <param name="includeMethods">addmessage</param>
            </interceptor>

            <interceptor-stack name="myInterceptorStack">
                <interceptor-ref name="myInterceptor3"></interceptor-ref>
                <interceptor-ref name="defaultStack"></interceptor-ref>
            </interceptor-stack>
        </interceptors>

里面分interceptor和interceptor-stack 
stack也能引用stack 

default-interceptor-ref表示Action如果不指定interceptor就用这个default的 

extends="struts-default"表示这个XML文件是extends 另一个xml的，名字叫struts-default 

在这个XML中，配置了一个常用的interceptor可以去Core包中找到这个XML 

interceptor配置很灵活的。如果要写自己的interceptor就要把<interceptor-ref name="defaultStack"></interceptor-ref>默认的给加上，当然也可以自己配置。 

interceptor的参数 

<interceptor-stack name="myInterceptorStack">
                <interceptor-ref name="myInterceptor3"></interceptor-ref>
                <interceptor-ref name="defaultStack"></interceptor-ref>
            </interceptor-stack>

这个是因为MethodFilterInterceptor 里有这两个成员变量，如果你自己的interceptor要带参数的话就要相应的Action里面写到成员变量，并加上get,set方法 

public abstract class MethodFilterInterceptor extends AbstractInterceptor {
    protected transient Logger log = LoggerFactory.getLogger(getClass());

    protected Set<String> excludeMethods = Collections.emptySet();
    protected Set<String> includeMethods = Collections.emptySet();

监听器 
首先要实现com.opensymphony.xwork2.interceptor.PreResultListener类 
并重写里面的方法beforeResult 

public class MyListener implements PreResultListener {

    public void beforeResult(ActionInvocation invocation, String resultCode) {
        System.out.println(resultCode);
    }

}

然后再在拦截器里面调用 

invocation.addPreResultListener(new MyListener());

监听器是在这个拦截器完成别的拦截器之后调用的 


struts2 Action获得HttpSession,HttpServletRequest,HttpSevletResponse的方法 
非IOC方式 
这种方式主要是利用了com.opensymphony.xwork2.ActionContext类以及org.apache.struts2.ServletActionContext类 

ActionContext ctx = ActionContext.getContext();

  HttpServletRequest request = (HttpServletRequest)ctx.get(ServletActionContext.HTTP_REQUEST);

  HttpServletResponse response = (HttpServletResponse)ctx.get(ServletActionContext.HTTP_RESPONSE);

  //ServletActionContext.APPLICATION;
  //ServletActionContext.SESSION;
  //ServletActionContext.PAGE_CONTEXT;
//或者
HttpServletRequest request = ServletActionContext.getRequest ();

主要是这两个类com.opensymphony.xwork2.ActionContext和org.apache.struts2.ServletActionContext都对request等进行了大量的封装,直接调用方法就可以获和 

更好一点的IOC方式 
action类实现ServletRequestAware接口，并新建一个HttpServletRequest request 

public class UserLoginAction extends ActionSupport implements ServletRequestAware{
   public void setServletRequest(HttpServletRequest request) {
     this.request=request;
  }
 然后可以生成的request得到对象，如request.getRemoteAddr()
action类实现SessionAware接口，并创建一个MAP对象session
public class UserLoginAction extends ActionSupport implements ServletRequestAware,SessionAware{
   public void setServletRequest(HttpServletRequest request) {
     this.request=request;
  }
public void setSession(Map session) {
  this.session=session;

} 

这些获得HttpServletRequest等对象需要implments的接口都在 
org.apache.struts2.interceptor下面 
如Apllication的是ApplicationAware 
如HttpSession的是SessionAware(struts2的Session都被封装成Map了) 
如HttpServletRequest的是ServletRequestAware 
如HttpServletResponse的是ServletResponseAware