java用户登录拦截判断

用maven生成了appfuse的webssh项目里面东西比较多调查了下做个记录。

web应用中，我们经常使用filter机制来确定外部请求的用户是否登录，角色是否合法等。spring提供了
一个DelegatingFilterProxy机制来完成filter的部分功能。通过例子做一个简单对比。   二者看起来
没有什么太大的区别，在spring中，filter被纳入了bean 管理机制。

1.servlet filter
* LoginFilter .Java 

[java] view plain copy

1. package servlet.filter;  
2. import javax.servlet.*;  
3. import javax.servlet.http.*;  
4. import java.io.*;  
5. public class LoginFilter implements Filter {  
6. protected FilterConfig filterConfig;  
7. public void init(FilterConfig filterConfig) throws ServletException {  
8. this.filterConfig = filterConfig;  
9. }  
10. public void destroy() {  
11. this.filterConfig = null;  
12. }  
13. public void doFilter(ServletRequest request, ServletResponse response,  
14. FilterChain chain) throws java.io.IOException, ServletException {  
15. HttpServletRequest req = (HttpServletRequest) request;  
16. HttpServletResponse res = (HttpServletResponse) response;  
17. String username = req.getParameter("j_username");  
18. System.out.println("this is in servlet filter");  
19. chain.doFilter(request, response);  
20. }  
21. }  

*web.xml

[html] view plain copy

1. <filter>  
2. <filter-name>simplelogin</filter-name>  
3. <filter-class>servlet.filter.LoginFilter</filter-class>  
4. <init-param>  
5. <param-name>hello</param-name>  
6. <param-value>hello filter</param-value>  
7. </init-param>  
8. </filter>  
9. <filter-mapping>  
10. <filter-name>simplelogin</filter-name>  
11. <url-pattern>/*</url-pattern>  
12. </filter-mapping>  

2. Spring filter 
*LoginFilter.java

[java] view plain copy

1. package filter;  
2. import java.io.IOException;  
3. import java.security.Principal;  
4. import javax.servlet.*;  
5. import javax.servlet.http.*;  
6. import org.apache.commons.logging.*;  
7. public class LoginFilter implements Filter {  
8. private FilterConfig filterConfig = null;  
9. Log log = LogFactory.getLog(LoginFilter.class);  
10. public void doFilter(ServletRequest req, ServletResponse res,FilterChain chain) throws IOException, ServletException {  
11. HttpServletRequest request = (HttpServletRequest) req;  
12. Principal principal=request.getUserPrincipal();  
13. HttpServletResponse response=(HttpServletResponse)res;   
14. log.info("filter user name:"+request.getParameter("j_username")+":"+principal.toString());  
15. log.info("filter password :"+request.getParameter("j_password"));  
16. chain.doFilter(req,res);  
17. }  
18. public void init(FilterConfig config) throws ServletException {  
19. this.filterConfig = config;  
20. }  
21. public void destroy() {  
22. filterConfig = null;  
23. }  
24. }  

*
web.xml

[html] view plain copy

1. <filter>  
2. <description>LoginFilter</description>  
3. <display-name> LoginFilter</display-name>  
4. <filter-name>LoginFilter</filter-name>  
5. <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>  
6. <init-param>  
7. <description>  
8. </description>  
9. <param-name>targetBeanName</param-name>  
10. <param-value>loginFilter</param-value>  
11. </init-param>  
12. </filter>  
13. <filter-mapping>  
14. <filter-name>LoginFilter</filter-name>  
15. <url-pattern>/*</url-pattern>  
16. </filter-mapping>  

*spring context config

[html] view plain copy

1. <bean id="loginFilter" class="filter.LoginFilter" />  

3.struts2 的拦截器

[html] view plain copy

1. <interceptors>  
2.     <!-- 登录验证拦截器 -->  
3.     <interceptor name="authority"  
4.         class="com.bolo.examples.common.interceptor.AuthorityInterceptor" />  
5.     <!-- 自定义拦截器栈 -->  
6.     <interceptor-stack name="boloStack">  
7.         <!-- 将登录验证拦截器加入默认的拦截器栈中 -->  
8.         <interceptor-ref name="authority">  
9.             <param name="excludeMethods">welcome,login</param>  
10.         </interceptor-ref>  
11.         <interceptor-ref name="defaultStack"></interceptor-ref>  
12.     </interceptor-stack>  
13. </interceptors>  
14. <!-- 将自定义拦截器栈设置默认的全局拦截器 -->  
15. <default-interceptor-ref name="boloStack" />  
16. <!-- 全局跳转页面 -->  
17. <global-results>  
18.     <result name="login">/jump.jsp</result>  
19. </global-results>  

Interceptor类

[java] view plain copy

1. /** 
2.  * 登录验证拦截器 
3.  * @author 菠萝大象 
4.  */  
5. public class AuthorityInterceptor extends MethodFilterInterceptor{  
6.   
7.     @Override  
8.     protected String doIntercept(ActionInvocation actioninvocation) throws Exception {  
9.         Object user = ServletActionContext.getRequest().getSession().getAttribute("user");  
10.         if(user != null){  
11.             return actioninvocation.invoke(); //递归调用拦截器  
12.         }else{  
13.             return Action.LOGIN; //返回到登录页面  
14.         }  
15.     }  
16. }