filter[过滤器]使用大全

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helloaini 2011-11-06 00:03:50 博主文章分类：servlet

文章标签 职场休闲 filter[过滤器]使用大全 文章分类 数字化转型

一．页面编码过滤器

1．开发EncodingFilter.java文件，继承自javax.servlet.Filter：
package bluemoon.crm.systemmanage.struts.Filter;

import java.io.*;
import javax.servlet.*;

public class EncodingFilter implements Filter
{
protected String encoding = null;
protected FilterConfig config;

public void init(FilterConfig filterConfig) throws ServletException
{
this.config = filterConfig;
//从web.xml配置文件中获取编码配置
this.encoding = filterConfig.getInitParameter("Encoding");
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException
{
if(request.getCharacterEncoding() == null)
{
String encode = getEncoding();
if(encode != null)
{
//设置request的编码方式
request.setCharacterEncoding(encode);
}
}
chain.doFilter(request,response);
}
public String getEncoding()
{
return encoding;
}
public void destroy()
{

}
}
2. 在web.xml文件中加入如下配置信息：

<filter>
<filter-name>encodingFilter</filter-name>
<filter-class>bluemoon.crm.systemmanage.struts.Filter.EncodingFilter</filter-class>
<init-param>
<param-name>Encoding</param-name>
<param-value>GB2312</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>encodingFilter</filter-name>

<url-pattern>/*</url-pattern>
</filter-mapping>

二．用户是否登陆过滤器：
1．首先增加一个Action、ActionForm & JSP:
login.jsp中为一个登陆表单：
UserActionForm.java为一个Struts的ActionForm。
UserAction.java将用户登陆信息添加到session中。
2．开发UserLoginedFilter.java：
package bluemoon.crm.systemmanage.struts.Filter;

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.*;

import bluemoon.crm.systemmanage.struts.forms.UserActionForm;

public class UserLoginedFilter extends HttpServlet implements Filter
{
protected FilterConfig config;

public void init(FilterConfig filterConfig) throws ServletException
{
this.config = filterConfig;
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException
{
RequestDispatcher dispatcher = request.getRequestDispatcher("userLogin.jsp");
HttpServletRequest userRequest = (HttpServletRequest)request;
UserActionForm userActionForm = (UserActionForm)userRequest.getSession().getAttribute("userActionForm");
if(userActionForm == null || userActionForm.getUser_name() == null || userActionForm.getUser_name().trim().length()<1)
{
System.out.println("用户未登录!");
dispatcher.forward(request,response);
return;
}
System.out.println("用户已登录!");
chain.doFilter(request,response);
}
public void destroy()
{

}
}
3．在web.xml文件中添加如下配置信息：
<!—用户是否登陆过滤器配置注意只过虑jsp页面，不过虑.do -->
<filter>
<filter-name>userLoginedFilter</filter-name>
<filter-class>bluemoon.crm.systemmanage.struts.Filter.UserLoginedFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>userLoginedFilter</filter-name>
<url-pattern>*.jsp</url-pattern>
</filter-mapping>
<!—用户是否登陆过滤器配置结束 -->

1.首先写一个权限过滤filter类,实现Filter接口

public class RightFilter implements Filter {
     public void init(FilterConfig filterConfig) throws ServletException { }
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {

HttpServletRequest req = (HttpServletRequest) request;
HttpServletResponse res = (HttpServletResponse) response;
HttpSession session = req.getSession(true);
String path = req.getRequestURI();

// 从session里取的用户名信息
String userid= (String) session.getAttribute("userid");
for (int i = 0; i < Constants.NoFilter_Pages.length; i++) {
if (path.indexOf(Constants.NoFilter_Pages[i]) > -1) {
   chain.doFilter(req, res);
   return;
}
}
if (username == null || "".equals(username)) {
// 跳转到登陆页面
res.sendRedirect("http://"+req.getHeader("Host")+"/task/login.jsp");;
} else {
// 已经登陆,继续此次请求
chain.doFilter(request, response);
}
}

public void destroy() { }
}

public class Constants {
public Constants() {
}

public static String[] NoFilter_Pages = {
    "/index.jsp",
    "/login.jsp",

};
}

2.然后在web.xml里配置需要登陆权限验证的JSP文件:

a.如果是某个具体的JSP文件(如a.jsp)需要登陆验证

<web-app>

...

<filter>
<filter-name>right</filter-name>
    <filter-class>com.dayou.util.RightFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>right</filter-name>
    <url-pattern>/a.jsp</url-pattern>
</filter-mapping>
...

</web-app>

b.如果是某一个目录(如pages/目录)整个目录下的文件都需要登陆验证:

<web-app>

...

<filter>
      <filter-name>right</filter-name>
<filter-class>com.dayou.util.RightFilter</filter-class>
      </filter>

<filter-mapping>
<filter-name>right</filter-name>
      <url-pattern>/pages/*</url-pattern>
</filter-mapping>
     ...
</web-app>

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