struts2学习4--拦截器

一、最简单的拦截器

1）自定义

拦截器类：

public class LoggerInterceptor  extends AbstractInterceptor{
    @Override
    public String intercept(ActionInvocation invocation) throws Exception {
        // TODO Auto-generated method stub
        System.out.println("记录日志............");
        return invocation.invoke();
    }
}

2）配置：

    <package name="User" namespace="/user" extends="struts-default">
        <!-- 包要用的拦截器 -->
         <interceptors>
         <interceptor name="logger"    class="com.meetcomet.LoggerInterceptor"/>
         <interceptor name="authority" class="com.meetcomet.AuthorityInterceptor"/>
         </interceptors>
        <action name="User*" class="com.meetcomet.action.UserAction" method="{1}" >
            <result name="success">/welcome.jsp</result>
            <interceptor-ref name="logger"/>
         </action>
    </package>

二、拦截器栈

1）拦截器类（同一）

2）配置

    <package name="User" namespace="/user" extends="struts-default">
        <!-- 包要用的拦截器 -->
         <interceptors>
            <interceptor name="logger"    class="com.meetcomet.LoggerInterceptor"/>
            <interceptor name="authority" class="com.meetcomet.AuthorityInterceptor"/>
            <interceptor-stack name="mystack" >
               <interceptor-ref name="authority"/>
               <interceptor-ref name="logger"/>
            </interceptor-stack>
         </interceptors>
        <action name="User*" class="com.meetcomet.action.UserAction" method="{1}" >
            <result name="success">/welcome.jsp</result>
            <interceptor-ref name="mystack"/>
         </action>
    </package>

按栈顺次运行。

三、拦截器的例子

1)用接口方法实现（可用类可用接口）的时间类，（其实可以直接用timer拦截器，见后）

public class MyLoggingInterceptor implements Interceptor{
 
    private static final long serialVersionUID = 1L;
 
    public String intercept(ActionInvocation invocation) throws Exception {
 
        String className = invocation.getAction().getClass().getName();
        long startTime = System.currentTimeMillis();
        System.out.println("Before calling action: " + className);
 
        String result = invocation.invoke();
 
        long endTime = System.currentTimeMillis();
        System.out.println("After calling action: " + className
                + " Time taken: " + (endTime - startTime) + " ms");
 
        return result;
    }
 
    public void destroy() {
        System.out.println("Destroying MyLoggingInterceptor...");
    }
    public void init() {
        System.out.println("Initializing MyLoggingInterceptor...");
    }
}

 2）权限管理（用AbstractInterceptor实现)

public class AuthorityInterceptor extends AbstractInterceptor {
    @Override
    public String intercept(ActionInvocation invocation) throws Exception {
        // TODO Auto-generated method stub
        ActionContext ctx = invocation.getInvocationContext();
        Map mySession = ctx.getSession();
        String role=(String)mySession.get("ROLE");
        if (null!=role && role.equals("admin"))
        {
            System.out.println("调用授权........");
            return invocation.invoke();
                                    
        }
        ctx.put("tip", "你还没有登录");
        return Action.LOGIN;
    }
}

 四、系统拦截器

系统提供了很多拦截器。比如 timer，会把action的运行时间打印在后台

        <action name="User*" class="com.meetcomet.action.UserAction" method="{1}" >
            <result name="success">/welcome.jsp</result>
            <interceptor-ref name="mystack"/>
            <interceptor-ref name="timer"/>
         </action>

五、拦截方法

1)拦截类 继承MethodFilterInterceptor类

public class MethodInterceptor extends MethodFilterInterceptor {
    @Override
    protected String doIntercept(ActionInvocation invocation) throws Exception {
        // TODO Auto-generated method stub
        System.out.println("拦截方法 ------");
        return invocation.invoke();
    }
}

2）配置：
add，del方法不用拦截。也可用includeMethod参数

        <action name="User*" class="com.meetcomet.action.UserAction" method="{1}" >
            <result name="success">/welcome.jsp</result>
            <interceptor-ref name="mystack"/>
            <interceptor-ref name="timer"/>
            <interceptor-ref name="method">
                <param name="excludeMethods">add,del</param>
            </interceptor-ref>
         </action>