spring filter拦截器配置

Filter可以认为是Servlet的一种“加强版”，它主要用于对用户请求进行预处理，也可以对HttpServletResponse进行后处理，是个典型的处理链。Filter也可以对用户请求生成响应，这一点与Servlet相同，但实际上很少会使用Filter向用户请求生成响应。使用Filter完整的流程是：Filter对用户请求进行预处理，接着将请求交给Servlet进行预处理并生成响应，最后Filter再对服务器响应进行后处理。

  Filter有如下几个用处。

在HttpServletRequest到达Servlet之前，拦截客户的HttpServletRequest。
根据需要检查HttpServletRequest，也可以修改HttpServletRequest头和数据。
在HttpServletResponse到达客户端之前，拦截HttpServletResponse。
根据需要检查HttpServletResponse，也可以修改HttpServletResponse头和数据。
Filter有如下几个种类。

用户授权的Filter：Filter负责检查用户请求，根据请求过滤用户非法请求。
日志Filter：详细记录某些特殊的用户请求。
负责解码的Filter:包括对非标准编码的请求解码。
能改变XML内容的XSLT Filter等。
Filter可以负责拦截多个请求或响应；一个请求或响应也可以被多个Filter拦截。
创建一个Filter只需两个步骤：
1.创建File类：

package com.symapgis.filter;import java.io.IOException;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.Map;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;
import javax.servlet.http.HttpServletResponse;import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.methods.PostMethod;
import com.google.gson.Gson;/*** Servlet Filter implementation class TokenFilter*/
public class TokenFilter implements Filter {/*** Default constructor. */public TokenFilter() {// TODO Auto-generated constructor stub}/*** @see Filter#destroy()*/public void destroy() {// TODO Auto-generated method stub}/*** @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)*/public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain chain) throws IOException, ServletException {HttpServletRequest request = (HttpServletRequest)servletRequest;String token = request.getHeader("token");String url = request.getRequestURI();if(url.endsWith("login.do") || url.endsWith("getTitle.do")){chain.doFilter(servletRequest, servletResponse);			}else{if(token == null || token.isEmpty()){returnJson(servletResponse, "403");return;}else{//查询数据库判断Token是否存在try {if(tokenInDb(token)){chain.doFilter(servletRequest, servletResponse);}else{returnJson(servletResponse, "403");return;}} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}private boolean tokenInDb(String token) throws Exception{//判断token是否存在HttpClient client = new HttpClient();PostMethod method = null;// post 方式 get 方式 GetMethod gMethodString result = "";try {method = new PostMethod("http://localhost:8081/human_resource/admin/getToken.do");method.addRequestHeader("Content-Type", "application/x-www-form-urlencoded;charset=UTF-8");method.setParameter("token", token);// 设置参数client.executeMethod(method);if (method.getStatusCode() == HttpStatus.SC_OK) {// 响应成功result = method.getResponseBodyAsString();// 调用返回结果if(result.equals("cunzai")){return true;}else{return false;}} else {// 不成功组装结果Map<String, Object> map = new HashMap<String, Object>();Gson gson = new Gson();map.put("success", false);result = gson.toJson(map);}} catch (Exception e) {}return false;}private void returnJson(ServletResponse response,String result){PrintWriter writer=null;response.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=utf-8");try{writer=response.getWriter();writer.print(result);}catch(IOException e){}finally{if(writer!=null){writer.close();}}}/*** @see Filter#init(FilterConfig)*/public void init(FilterConfig fConfig) throws ServletException {// TODO Auto-generated method stub}}

2.配置web.xml

 <filter><filter-name>TokenFilter</filter-name>  //类名<filter-class>com.symapgis.filter.TokenFilter</filter-class>  //路径</filter><filter-mapping><filter-name>TokenFilter</filter-name><url-pattern>*.do</url-pattern></filter-mapping>