struts2拦截器

1. struts2拦截器简介

拦截器简介
Struts2拦截器是在访问某个Action或Action的某个方法，字段之前或之后实施拦截，并且Struts2拦截器是可插拔的，拦截器是AOP的一种实现。
优点：通用功能的封装，提供了可重用性；

新建项目HeadFirstStruts2Chap03

   
2. struts2预定义拦截器和拦截器栈

HelloAction.java

package com.andrew.action;
import com.opensymphony.xwork2.ActionSupport;
public class HelloAction extends ActionSupport {
    private String name;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @Override
    public String execute() throws Exception {
        System.out.println("执行了HelloAction的默认方法");
        return SUCCESS;
    }
}

MyInterceptor.java

package com.andrew.interceptor;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;
public class MyInterceptor implements Interceptor {
    public void init() {
        System.out.println("MyInterceptor初始化");
    }
    public String intercept(ActionInvocation invocation) throws Exception {
        System.out.println("在Action执行之前");
        String result = invocation.invoke();
        System.out.println("result:" + result);
        System.out.println("在Action执行之后");
        return result;
    }
    public void destroy() {
        System.out.println("MyInterceptor销毁");
    }
}

struts.xml

<package name="manage" namespace="/" extends="struts-default">
      <interceptors>
          <interceptor name="myInterceptor" class="com.andrew.interceptor.MyInterceptor"></interceptor>
      </interceptors>
      <action name="hello" class="com.andrew.action.HelloAction">
          <result name="success">success.jsp</result>
          <interceptor-ref name="myInterceptor"></interceptor-ref>
          <interceptor-ref name="defaultStack"></interceptor-ref>
      </action>
</package>

success.jsp

Name:${name }

MyInterceptor初始化
http://localhost:8080/HeadFirstStruts2Chap03/hello?name=struts2
运行结果：
Name:struts2 
控制台：
在Action执行之前
执行了HelloAction的默认方法
result:success
在Action执行之后

3. 自定义拦截器-登录验证拦截器

User.java

package com.andrew.model;
public class User {
    private String userName;
    private String password;
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
}

UserService.java

package com.andrew.service;
import com.andrew.model.User;
public class UserService {
    public boolean login(User user) {
        if ("andrew".equals(user.getUserName()) && "123456".equals(user.getPassword())) {
            return true;
        } else {
            return false;
        }
    }
}

UserAction.java

package com.andrew.action;
import java.util.Map;
import com.andrew.model.User;
import com.andrew.service.UserService;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;
public class UserAction extends ActionSupport {
    private UserService userService = new UserService();
    private User user;
    private String error;
    public User getUser() {
        return user;
    }
    public void setUser(User user) {
        this.user = user;
    }
    public String getError() {
        return error;
    }
    public void setError(String error) {
        this.error = error;
    }
    @Override
    public String execute() throws Exception {
        if (userService.login(user)) {
            ActionContext actionContext = ActionContext.getContext();
            Map<String, Object> session = actionContext.getSession();
            session.put("currentUser", user);
            return SUCCESS;
        } else {
            this.error = "用户名或密码错误";
            return "error";
        }
    }
}

GrilAction.java

package com.andrew.action;
import com.opensymphony.xwork2.ActionSupport;
public class GrilAction extends ActionSupport {
    @Override
    public String execute() throws Exception {
        System.out.println("GrilAction execute方法执行！");
        return SUCCESS;
    }
}

MyInterceptor.java

package com.andrew.interceptor;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;
public class LoginInterceptor implements Interceptor {
    public void init() {
        System.out.println("LoginInterceptor初始化");
    }
    public String intercept(ActionInvocation invocation) throws Exception {
        System.out.println("在Action执行之前");
        ActionContext actionContext = invocation.getInvocationContext();
        Map<String, Object> session = actionContext.getSession();
        Object currentUser = session.get("currentUser");
        String result = null;
        if (currentUser != null) {
            result = invocation.invoke();
        } else {
            HttpServletRequest request = (HttpServletRequest)invocation.getInvocationContext().get(ServletActionContext.HTTP_REQUEST);
            request.setAttribute("error", "请先登录！");
            result = "error";
        }
        System.out.println("result:" + result);
        System.out.println("在Action执行之后");
        return result;
    }
    public void destroy() {
        System.out.println("LoginInterceptor销毁");
    }
}

struts.xml

<package name="manage" namespace="/" extends="struts-default">
    <interceptors>
        <interceptor name="loginInterceptor" class="com.andrew.interceptor.LoginInterceptor"></interceptor>
        <interceptor-stack name="loginStack">
            <interceptor-ref name="loginInterceptor"></interceptor-ref>
            <interceptor-ref name="defaultStack"></interceptor-ref>
        </interceptor-stack>
    </interceptors>
    <default-interceptor-ref name="loginStack"></default-interceptor-ref>
    <global-results>
        <result name="error">error.jsp</result>
    </global-results>
    <action name="user" class="com.andrew.action.UserAction">
        <result name="success">success.jsp</result>
        <interceptor-ref name="defaultStack"></interceptor-ref>
    </action>
    <action name="gril" class="com.andrew.action.GrilAction">
        <result name="success">success.jsp</result>
    </action>
</package>

success.jsp

当前用户：${currentUser.userName }

login.jsp

<form action="user" method="post">
    用户名：<input type="text" name="user.userName"/>
    密码：<input type="password" name="user.password"/>
    <input type="submit" value="登录"/>
</form>

error.jsp

错误信息：${error }  <a href="login.jsp">登录</a>

LoginInterceptor初始化
http://localhost:8080/HeadFirstStruts2Chap03/login.jsp
123 123 submit
运行结果：
错误信息：用户名或密码错误 登录 
http://localhost:8080/HeadFirstStruts2Chap03/gril
运行结果：
错误信息：请先登录！ 登录 
控制台：
在Action执行之前
result:error
在Action执行之后

http://localhost:8080/HeadFirstStruts2Chap03/login.jsp
andrew 123456 submit
运行结果：
当前用户：andrew
http://localhost:8080/HeadFirstStruts2Chap03/gril
运行结果：
当前用户：andrew 
控制台：
在Action执行之前
GrilAction execute方法执行！
result:success
在Action执行之后