Servlet过滤器大全

[u][/u]Java代码
 
一、字符编码的过滤器
Java代码
import javax.servlet.*;   
import java.io.IOException;   
 
/** *//** *//** *//**  
* 用于设置 HTTP 请求字符编码的过滤器，通过过滤器参数encoding指明使用何种字符编码,用于处理Html Form请求参数的中文问题  
*/   
public class CharacterEncodingFilter   
implements Filter   
{   
protected FilterConfig filterConfig = null;   
protected String encoding = "";   
 
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException   
{   
if(encoding != null)   
servletRequest.setCharacterEncoding(encoding);   
filterChain.doFilter(servletRequest, servletResponse);   
}   
 
public void destroy()   
{   
filterConfig = null;   
encoding = null;   
}   
 
public void init(FilterConfig filterConfig) throws ServletException   
{   
this.filterConfig = filterConfig;   
this.encoding = filterConfig.getInitParameter("encoding");   
 
}   
}  

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

/** *//** *//** *//**
* 用于设置 HTTP 请求字符编码的过滤器，通过过滤器参数encoding指明使用何种字符编码,用于处理Html Form请求参数的中文问题
*/
public class CharacterEncodingFilter
implements Filter
{
protected FilterConfig filterConfig = null;
protected String encoding = "";

public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException
{
if(encoding != null)
servletRequest.setCharacterEncoding(encoding);
filterChain.doFilter(servletRequest, servletResponse);
}

public void destroy()
{
filterConfig = null;
encoding = null;
}

public void init(FilterConfig filterConfig) throws ServletException
{
this.filterConfig = filterConfig;
this.encoding = filterConfig.getInitParameter("encoding");

}
}


二、使浏览器不缓存页面的过滤器

Java代码
import javax.servlet.*;   
import javax.servlet.http.HttpServletResponse;   
import java.io.IOException;   
 
/** *//** *//** *//**  
* 用于的使 Browser 不缓存页面的过滤器  
*/   
public class ForceNoCacheFilter implements Filter {   
 
public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException   
{   
((HttpServletResponse) response).setHeader("Cache-Control","no-cache");   
((HttpServletResponse) response).setHeader("Pragma","no-cache");   
((HttpServletResponse) response).setDateHeader ("Expires", -1);   
filterChain.doFilter(request, response);   
}   
 
public void destroy() {   
}   
 
public void init(FilterConfig filterConfig) throws ServletException {   
}   
}  

import javax.servlet.*;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/** *//** *//** *//**
* 用于的使 Browser 不缓存页面的过滤器
*/
public class ForceNoCacheFilter implements Filter {

public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException
{
((HttpServletResponse) response).setHeader("Cache-Control","no-cache");
((HttpServletResponse) response).setHeader("Pragma","no-cache");
((HttpServletResponse) response).setDateHeader ("Expires", -1);
filterChain.doFilter(request, response);
}

public void destroy() {
}

public void init(FilterConfig filterConfig) throws ServletException {
}
}

三、检测用户是否登陆的过滤器
Java代码
import javax.servlet.*;   
import javax.servlet.http.HttpServletRequest;   
import javax.servlet.http.HttpServletResponse;   
import javax.servlet.http.HttpSession;   
import java.util.List;   
import java.util.ArrayList;   
import java.util.StringTokenizer;   
import java.io.IOException;   
 
/** *//** *//** *//**  
* 用于检测用户是否登陆的过滤器，如果未登录，则重定向到指的登录页面  


* 配置参数  


* checkSessionKey 需检查的在 Session 中保存的关键字  

* redirectURL 如果用户未登录，则重定向到指定的页面，URL不包括 ContextPath  

* notCheckURLList 不做检查的URL列表，以分号分开，并且 URL 中不包括 ContextPath  

*/   
public class CheckLoginFilter   
implements Filter   
{   
protected FilterConfig filterConfig = null;   
private String redirectURL = null;   
private List notCheckURLList = new ArrayList();   
private String sessionKey = null;   
 
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException   
{   
HttpServletRequest request = (HttpServletRequest) servletRequest;   
HttpServletResponse response = (HttpServletResponse) servletResponse;   
 
HttpSession session = request.getSession();   
if(sessionKey == null)   
{   
filterChain.doFilter(request, response);   
return;   
}   
if((!checkRequestURIIntNotFilterList(request)) && session.getAttribute(sessionKey) == null)   
{   
response.sendRedirect(request.getContextPath() + redirectURL);   
return;   
}   
filterChain.doFilter(servletRequest, servletResponse);   
}   
 
public void destroy()   
{   
notCheckURLList.clear();   
}   
 
private boolean checkRequestURIIntNotFilterList(HttpServletRequest request)   
{   
String uri = request.getServletPath() + (request.getPathInfo() == null ? "" : request.getPathInfo());   
return notCheckURLList.contains(uri);   
}   
 
public void init(FilterConfig filterConfig) throws ServletException   
{   
this.filterConfig = filterConfig;   
redirectURL = filterConfig.getInitParameter("redirectURL");   
sessionKey = filterConfig.getInitParameter("checkSessionKey");   
 
String notCheckURLListStr = filterConfig.getInitParameter("notCheckURLList");   
 
if(notCheckURLListStr != null)   
{   
StringTokenizer st = new StringTokenizer(notCheckURLListStr, ";");   
notCheckURLList.clear();   
while(st.hasMoreTokens())   
{   
notCheckURLList.add(st.nextToken());   
}   
}   
}   
}  

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.util.List;
import java.util.ArrayList;
import java.util.StringTokenizer;
import java.io.IOException;

/** *//** *//** *//**
* 用于检测用户是否登陆的过滤器，如果未登录，则重定向到指的登录页面


* 配置参数


* checkSessionKey 需检查的在 Session 中保存的关键字

* redirectURL 如果用户未登录，则重定向到指定的页面，URL不包括 ContextPath

* notCheckURLList 不做检查的URL列表，以分号分开，并且 URL 中不包括 ContextPath

*/
public class CheckLoginFilter
implements Filter
{
protected FilterConfig filterConfig = null;
private String redirectURL = null;
private List notCheckURLList = new ArrayList();
private String sessionKey = null;

public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException
{
HttpServletRequest request = (HttpServletRequest) servletRequest;
HttpServletResponse response = (HttpServletResponse) servletResponse;

HttpSession session = request.getSession();
if(sessionKey == null)
{
filterChain.doFilter(request, response);
return;
}
if((!checkRequestURIIntNotFilterList(request)) && session.getAttribute(sessionKey) == null)
{
response.sendRedirect(request.getContextPath() + redirectURL);
return;
}
filterChain.doFilter(servletRequest, servletResponse);
}

public void destroy()
{
notCheckURLList.clear();
}

private boolean checkRequestURIIntNotFilterList(HttpServletRequest request)
{
String uri = request.getServletPath() + (request.getPathInfo() == null ? "" : request.getPathInfo());
return notCheckURLList.contains(uri);
}

public void init(FilterConfig filterConfig) throws ServletException
{
this.filterConfig = filterConfig;
redirectURL = filterConfig.getInitParameter("redirectURL");
sessionKey = filterConfig.getInitParameter("checkSessionKey");

String notCheckURLListStr = filterConfig.getInitParameter("notCheckURLList");

if(notCheckURLListStr != null)
{
StringTokenizer st = new StringTokenizer(notCheckURLListStr, ";");
notCheckURLList.clear();
while(st.hasMoreTokens())
{
notCheckURLList.add(st.nextToken());
}
}
}
}

四、资源保护过滤器

Java代码
package catalog.view.util;   
 
import javax.servlet.Filter;   
import javax.servlet.FilterConfig;   
import javax.servlet.ServletRequest;   
import javax.servlet.ServletResponse;   
import javax.servlet.FilterChain;   
import javax.servlet.ServletException;   
import javax.servlet.http.HttpServletRequest;   
import java.io.IOException;   
import java.util.Iterator;   
import java.util.Set;   
import java.util.HashSet;   
//   
import org.apache.commons.logging.Log;   
import org.apache.commons.logging.LogFactory;   
 
/** *//** *//** *//**  
* This Filter class handle the security of the application.  
*  
* It should be configured inside the web.xml.  
*  
* @author Derek Y. Shen  
*/   
public class SecurityFilter implements Filter {   
//the login page uri   
private static final String LOGIN_PAGE_URI = "login.jsf";   
 
//the logger object   
private Log logger = LogFactory.getLog(this.getClass());   
 
//a set of restricted resources   
private Set restrictedResources;   
 
/** *//** *//** *//**  
* Initializes the Filter.  
*/   
public void init(FilterConfig filterConfig) throws ServletException {   
this.restrictedResources = new HashSet();   
this.restrictedResources.add("/createProduct.jsf");   
this.restrictedResources.add("/editProduct.jsf");   
this.restrictedResources.add("/productList.jsf");   
}   
 
/** *//** *//** *//**  
* Standard doFilter object.  
*/   
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)   
throws IOException, ServletException {   
this.logger.debug("doFilter");   
 
String contextPath = ((HttpServletRequest)req).getContextPath();   
String requestUri = ((HttpServletRequest)req).getRequestURI();   
 
this.logger.debug("contextPath = " + contextPath);   
this.logger.debug("requestUri = " + requestUri);   
 
if (this.contains(requestUri, contextPath) && !this.authorize((HttpServletRequest)req)) {   
this.logger.debug("authorization failed");   
((HttpServletRequest)req).getRequestDispatcher(LOGIN_PAGE_URI).forward(req, res);   
}   
else {   
this.logger.debug("authorization succeeded");   
chain.doFilter(req, res);   
}   
}   
 
public void destroy() {}   
 
private boolean contains(String value, String contextPath) {   
Iterator ite = this.restrictedResources.iterator();   
 
while (ite.hasNext()) {   
String restrictedResource = (String)ite.next();   
 
if ((contextPath + restrictedResource).equalsIgnoreCase(value)) {   
return true;   
}   
}   
 
return false;   
}   
 
private boolean authorize(HttpServletRequest req) {   
 
//处理用户登录   
/** *//**//* UserBean user = (UserBean)req.getSession().getAttribute(BeanNames.USER_BEAN);  

if (user != null && user.getLoggedIn()) {  
//user logged in  
return true;  
}  
else {  
return false;  
}*/   
}   
}  

package catalog.view.util;

import javax.servlet.Filter;
import javax.servlet.FilterConfig;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.util.Iterator;
import java.util.Set;
import java.util.HashSet;
//
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/** *//** *//** *//**
* This Filter class handle the security of the application.
*
* It should be configured inside the web.xml.
*
* @author Derek Y. Shen
*/
public class SecurityFilter implements Filter {
//the login page uri
private static final String LOGIN_PAGE_URI = "login.jsf";

//the logger object
private Log logger = LogFactory.getLog(this.getClass());

//a set of restricted resources
private Set restrictedResources;

/** *//** *//** *//**
* Initializes the Filter.
*/
public void init(FilterConfig filterConfig) throws ServletException {
this.restrictedResources = new HashSet();
this.restrictedResources.add("/createProduct.jsf");
this.restrictedResources.add("/editProduct.jsf");
this.restrictedResources.add("/productList.jsf");
}

/** *//** *//** *//**
* Standard doFilter object.
*/
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
throws IOException, ServletException {
this.logger.debug("doFilter");

String contextPath = ((HttpServletRequest)req).getContextPath();
String requestUri = ((HttpServletRequest)req).getRequestURI();

this.logger.debug("contextPath = " + contextPath);
this.logger.debug("requestUri = " + requestUri);

if (this.contains(requestUri, contextPath) && !this.authorize((HttpServletRequest)req)) {
this.logger.debug("authorization failed");
((HttpServletRequest)req).getRequestDispatcher(LOGIN_PAGE_URI).forward(req, res);
}
else {
this.logger.debug("authorization succeeded");
chain.doFilter(req, res);
}
}

public void destroy() {}

private boolean contains(String value, String contextPath) {
Iterator ite = this.restrictedResources.iterator();

while (ite.hasNext()) {
String restrictedResource = (String)ite.next();

if ((contextPath + restrictedResource).equalsIgnoreCase(value)) {
return true;
}
}

return false;
}

private boolean authorize(HttpServletRequest req) {

//处理用户登录
/** *//**//* UserBean user = (UserBean)req.getSession().getAttribute(BeanNames.USER_BEAN);

if (user != null && user.getLoggedIn()) {
//user logged in
return true;
}
else {
return false;
}*/
}
}


五 利用Filter限制用户浏览权限
在一个系统中通常有多个权限的用户。不同权限用户的可以浏览不同的页面。使用Filter进行判断不仅省下了代码量，而且如果要更改的话只需要在Filter文件里动下就可以。
以下是Filter文件代码：
Java代码
import java.io.IOException;   
 
 
import javax.servlet.Filter;   
import javax.servlet.FilterChain;   
import javax.servlet.FilterConfig;   
import javax.servlet.ServletException;   
import javax.servlet.ServletRequest;   
import javax.servlet.ServletResponse;   
import javax.servlet.http.HttpServletRequest;   
 
public class RightFilter implements Filter {   
 
public void destroy() {   
 
}   
 
public void doFilter(ServletRequest sreq, ServletResponse sres, FilterChain arg2) throws IOException, ServletException {   
// 获取uri地址   
HttpServletRequest request=(HttpServletRequest)sreq;   
String uri = request.getRequestURI();   
String ctx=request.getContextPath();   
uri = uri.substring(ctx.length());   
//判断admin级别网页的浏览权限   
if(uri.startsWith("/admin")) {   
if(request.getSession().getAttribute("admin")==null) {   
request.setAttribute("message","您没有这个权限");   
request.getRequestDispatcher("/login.jsp").forward(sreq,sres);   
return;   
}   
}   
//判断manage级别网页的浏览权限   
if(uri.startsWith("/manage")) {   
//这里省去   
}   
}   
//下面还可以添加其他的用户权限，省去。   
 
}   
 
public void init(FilterConfig arg0) throws ServletException {   
 
}   
 
}   
 
<!-- 判断页面的访问权限 -->   
<filter>   
<filter-name>RightFilter</filter-name>   
<filter-class>cn.itkui.filter.RightFilter</filter-class>   
</filter>   
<filter-mapping>   
<filter-name>RightFilter</filter-name>   
<url-pattern>/admin/** *//**//*</url-pattern>   
</filter-mapping>   
<filter-mapping>   
<filter-name>RightFilter</filter-name>   
<url-pattern>/manage/*</url-pattern>   
</filter-mapping>   
 
在web.xml中加入Filter的配置，如下：   
<filter>   
 
<filter-name>EncodingAndCacheflush</filter-name>   
<filter-class>EncodingAndCacheflush</filter-class>   
<init-param>   
<param-name>encoding</param-name>   
<param-value>UTF-8</param-value>   
</init-param>   
</filter>   
<filter-mapping>   
<filter-name>EncodingAndCacheflush</filter-name>   
<url-pattern>/*</url-pattern>   
</filter-mapping>  

import java.io.IOException;


import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

public class RightFilter implements Filter {

public void destroy() {

}

public void doFilter(ServletRequest sreq, ServletResponse sres, FilterChain arg2) throws IOException, ServletException {
// 获取uri地址
HttpServletRequest request=(HttpServletRequest)sreq;
String uri = request.getRequestURI();
String ctx=request.getContextPath();
uri = uri.substring(ctx.length());
//判断admin级别网页的浏览权限
if(uri.startsWith("/admin")) {
if(request.getSession().getAttribute("admin")==null) {
request.setAttribute("message","您没有这个权限");
request.getRequestDispatcher("/login.jsp").forward(sreq,sres);
return;
}
}
//判断manage级别网页的浏览权限
if(uri.startsWith("/manage")) {
//这里省去
}
}
//下面还可以添加其他的用户权限，省去。

}

public void init(FilterConfig arg0) throws ServletException {

}

}

<!-- 判断页面的访问权限 -->
<filter>
<filter-name>RightFilter</filter-name>
<filter-class>cn.itkui.filter.RightFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>RightFilter</filter-name>
<url-pattern>/admin/** *//**//*</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>RightFilter</filter-name>
<url-pattern>/manage/*</url-pattern>
</filter-mapping>

在web.xml中加入Filter的配置，如下：
<filter>

<filter-name>EncodingAndCacheflush</filter-name>
<filter-class>EncodingAndCacheflush</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>EncodingAndCacheflush</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>

要传递参数的时候最好使用form进行传参，如果使用链接的话当中文字符的时候过滤器转码是不会起作用的，还有就是页面上

form的method也要设置为post，不然过滤器也起不了作用。