常用Servlet过滤器

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解决POST请求参数中文和输出中文的乱码过滤器

过滤器代码

package com.study.java.filter;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;/*** @Name: SetCharacterEncodingFilter* @Description: 过滤器应用案例一：解决POST请求参数中文和输出中文的乱码过滤器* @Author: XXX* @CreateDate: XXX* @Version: V1.0 */public class SetCharacterEncodingFilter implements Filter {    private FilterConfig filterConfig ;    public void init(FilterConfig filterConfig) throws ServletException {        this.filterConfig = filterConfig ;    }    public void doFilter(ServletRequest request, ServletResponse response,            FilterChain chain) throws IOException, ServletException {        //拦截客户端请求        //设置客户端请求参数内容编码，针对post请求        String encode = filterConfig.getInitParameter("encode") ;        if(encode == null || "".equals(encode.toString().trim())) {            encode = "UTF-8" ;        }        request.setCharacterEncoding(encode) ;         //设置服务端响应内容编码        response.setContentType("text/html;charset=" + encode) ;        //放行，让目标资源执行        chain.doFilter(request, response) ;     }    public void destroy() {    }}

web.xml配置

<!-- 解决POST请求参数中文和输出中文的乱码 --><filter>    <filter-name>SetCharacterEncodingFilter</filter-name>    <filter-class>com.study.java.filter.SetCharacterEncodingFilter</filter-class>    <!-- 设置客户端请求参数编码 -->    <init-param>        <param-name>encode</param-name>        <param-value>UTF-8</param-value>    </init-param></filter><!-- 过滤器执行顺序以此标签定义的顺序为准 --><filter-mapping>    <filter-name>SetCharacterEncodingFilter</filter-name>    <url-pattern>/*</url-pattern></filter-mapping>

控制动态资源不要在客户端缓存过滤器

过滤器代码

package com.study.java.filter;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;import javax.servlet.http.HttpServletResponse;/*** @Name: DynamicResourceNoCacheFilter* @Description: 过滤器应用案例二：控制动态资源不要在客户端缓存* @Author: XXX* @CreateDate: XXX* @Version: V1.0 */public class DynamicResourceNoCacheFilter implements Filter {    public void init(FilterConfig filterConfig) throws ServletException {    }    public void doFilter(ServletRequest req, ServletResponse res,            FilterChain chain) throws IOException, ServletException {        //拦截客户端请求        //对请求与响应对象进行类型转换，参考HttpServlet的service()方法实现        HttpServletRequest request;        HttpServletResponse response;        try {            request = (HttpServletRequest)req;            response = (HttpServletResponse)res;        } catch(ClassCastException e) {            throw new ServletException("non-HTTP request or response");        }        //设置http响应头信息：禁止浏览器缓存        response.setHeader("expires", "-1") ;        response.setHeader("cache-control", "no-cache") ;        response.setHeader("pragma", "no-cache") ;        //放行，让目标资源执行        chain.doFilter(request, response) ;    }    public void destroy() {    }}

web.xml配置

<!-- 控制动态资源不要在客户端缓存 --><filter>    <filter-name>DynamicResourceNoCacheFilter</filter-name>    <filter-class>com.study.java.filter.DynamicResourceNoCacheFilter</filter-class></filter><filter-mapping>    <filter-name>DynamicResourceNoCacheFilter</filter-name>    <url-pattern>*.jsp</url-pattern></filter-mapping><filter-mapping>    <filter-name>DynamicResourceNoCacheFilter</filter-name>    <url-pattern>/servlet/*</url-pattern></filter-mapping>

控制静态资源的缓存时间过滤器

过滤器代码

package com.study.java.filter;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;import javax.servlet.http.HttpServletResponse;/*** @Name: SetStaticResourceCacheTime* @Description: 过滤器应用案例三：控制静态资源的缓存时间* @Author: XXX* @CreateDate: XXX* @Version: V1.0 */public class SetStaticResourceCacheTime implements Filter {    private FilterConfig filterconfig ;    public void init(FilterConfig filterconfig) throws ServletException {        this.filterconfig = filterconfig ;    }    public void doFilter(ServletRequest req, ServletResponse res, FilterChain filterchain)            throws IOException, ServletException {        //拦截客户端请求        //对请求与响应对象进行类型转换，参考HttpServlet的service()方法实现        HttpServletRequest request;        HttpServletResponse response;        try {            request = (HttpServletRequest)req;            response = (HttpServletResponse)res;        } catch(ClassCastException e) {            throw new ServletException("non-HTTP request or response");        }        //缓存时间：毫秒为单位        long time = 0 ;        //获取用户的访问资源类型        String uri = request.getRequestURI() ;        //截取扩展名        String subname = uri.substring(uri.lastIndexOf(".") + 1) ;        //说明访问的是html资源        if("html".equals(subname)) {            String value = filterconfig.getInitParameter(subname) ;            time = Long.parseLong(value) * 60 * 60 * 1000 ;        }      //说明访问的是css资源        if("css".equals(subname)) {            String value = filterconfig.getInitParameter(subname) ;            time = Long.parseLong(value) * 60 * 60 * 1000 ;        }      //说明访问的是js资源        if("js".equals(subname)) {            String value = filterconfig.getInitParameter(subname) ;            time = Long.parseLong(value) * 60 * 60 * 1000 ;        }        //设置缓存过期时间        response.setDateHeader("Expires", System.currentTimeMillis() + time) ;        //放行，让目标资源执行        filterchain.doFilter(request, response) ;    }    public void destroy() {    }}

web.xml配置

<!-- 控制静态资源的缓存时间 --><filter>    <filter-name>SetStaticResourceCacheTime</filter-name>    <filter-class>com.study.java.filter.SetStaticResourceCacheTime</filter-class>    <init-param>        <param-name>html</param-name>        <!-- 单位：小时 -->        <param-value>1</param-value>    </init-param>    <init-param>        <param-name>js</param-name>        <!-- 单位：小时 -->        <param-value>2</param-value>    </init-param>    <init-param>        <param-name>css</param-name>        <!-- 单位：小时 -->        <param-value>3</param-value>    </init-param></filter><filter-mapping>    <filter-name>SetStaticResourceCacheTime</filter-name>    <url-pattern>*.html</url-pattern></filter-mapping><filter-mapping>    <filter-name>SetStaticResourceCacheTime</filter-name>    <url-pattern>*.css</url-pattern></filter-mapping><filter-mapping>    <filter-name>SetStaticResourceCacheTime</filter-name>    <url-pattern>*.js</url-pattern></filter-mapping>

控制用户资源访问权限过滤器

过滤器代码

package com.study.java.filter;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;import javax.servlet.http.HttpServletResponse;/*** @Name: ResourceAuthorityFilter* @Description: 过滤器应用案例四：控制用户资源访问权限* @Author: XXX* @CreateDate: XXX* @Version: V1.0 */public class ResourceAuthorityFilter implements Filter {    public void init(FilterConfig filterconfig) throws ServletException {    }    public void doFilter(ServletRequest req, ServletResponse res, FilterChain filterchain)            throws IOException, ServletException {        //拦截客户端请求        //对请求与响应对象进行类型转换，参考HttpServlet的service()方法实现        HttpServletRequest request;        HttpServletResponse response;        try {            request = (HttpServletRequest)req;            response = (HttpServletResponse)res;        }        catch(ClassCastException e) {            throw new ServletException("non-HTTP request or response");        }        //获取请求uri地址        String uri = request.getRequestURI() ; //应用名+资源访问路径        String resourcePath = uri.substring(request.getContextPath().length()) ; //资源访问路径        //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(request,response);                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 destroy() {    }}

web.xml配置

<!-- 控制用户资源访问权限过滤器 --><filter>    <filter-name>ResourceAuthorityFilter</filter-name>    <filter-class>com.study.java.filter.ResourceAuthorityFilter</filter-class></filter><filter-mapping>    <filter-name>ResourceAuthorityFilter</filter-name>    <url-pattern>/admin/*</url-pattern></filter-mapping><filter-mapping>    <filter-name>ResourceAuthorityFilter</filter-name>    <url-pattern>/manage/*</url-pattern></filter-mapping>