filter的request增强

BufferedReader的增强

package cn.lcp.damo;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.Reader;

/*
1.实现与被增强对象相同的接口  BufferedReader
2、定义一个变量记住被增强对象
3、定义一个构造器，接收被增强对象
4、覆盖需要增强的方法
5、对于不想增强的方法，直接调用被增强对象（目标对象）的方法
 */

public class BufferedReaderWrapper extends BufferedReader {

    private BufferedReader br;
    private int linenum = 1;
    public BufferedReaderWrapper(BufferedReader in) {
        super(in);
        this.br = in;
    }
    @Override
    public String readLine() throws IOException {

        String line = br.readLine();
        if(line==null){
            return line;
        }
        return linenum++ + ":" + line;
    }
}
package cn.lcp.damo;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class TestBufferedReaderWrapper {

    /**
     * @param args
     * @throws IOException
     */
    public static void main(String[] args) throws IOException {

        BufferedReader br = new BufferedReader(new FileReader("src/cn/lcp/demo/BufferedReaderWrapper.java"));
        BufferedReaderWrapper wrapper = new BufferedReaderWrapper(br);

        FileWriter fw = new FileWriter("c:\\1.java");

        String line = null;
        while((line=wrapper.readLine())!=null){
            fw.write(line + "\r\n");
        }

        fw.close();
        wrapper.close();
        br.close();
    }

}

为解决全站乱码

package cn.lcp.web.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.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;

//为解决全站乱码
public class CharacterEncodingFilter implements Filter {

    public void destroy() {
        // TODO Auto-generated method stub

    }

    public void doFilter(ServletRequest req, ServletResponse resp,
            FilterChain chain) throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) resp;

        // 对get提交的数据还是没有办法对其改变编码，所以要对request的getParameter方法缺少功能了。
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");

        //放行的是自己的包装类
        MyCharacterEncodingRequest requestWrapper = new MyCharacterEncodingRequest(
                request);
        chain.doFilter(requestWrapper, response);

    }

    public void init(FilterConfig filterConfig) throws ServletException {
        // TODO Auto-generated method stub

    }
}

/*
 * 1.实现与被增强对象相同的接口 2、定义一个变量记住被增强对象 3、定义一个构造器，接收被增强对象 4、覆盖需要增强的方法
 * 5、对于不想增强的方法，直接调用被增强对象（目标对象）的方法
 */
// 包装类。
class MyCharacterEncodingRequest extends HttpServletRequestWrapper {

    private HttpServletRequest request;

    // 接受被增强对象
    public MyCharacterEncodingRequest(HttpServletRequest request) {
        super(request);
        this.request = request;
    }

    @Override
    public String getParameter(String name) {

        try {
            // 客户机提交的值
            String value = this.request.getParameter(name);
            if (value == null) {
                return null;
            }
            // 判断客户机的提交方式是不是get。这里忽略了get和GET方式
            if (!this.request.getMethod().equalsIgnoreCase("get")) {
                return value;
            }

            //客户机的原始码表
            value = new String(value.getBytes("ISO8859-1"),
                    this.request.getCharacterEncoding()); //获取上面的request设定的编码
            return value;

        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
}
package cn.lcp.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ServletDemo1 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        System.out.println(request.getParameter("username"));

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        doGet(request, response);
    }

}
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>day18_4</display-name>

    <filter>
        <filter-name>CharacterEncodingFilter</filter-name>
        <filter-class>cn.lcp.web.filter.CharacterEncodingFilter</filter-class>
    </filter>

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

    <servlet>
        <description>This is the description of my J2EE component
        </description>
        <display-name>This is the display name of my J2EE component
        </display-name>
        <servlet-name>ServletDemo1</servlet-name>
        <servlet-class>cn.lcp.servlet.ServletDemo1</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>ServletDemo1</servlet-name>
        <url-pattern>/servlet/ServletDemo1</url-pattern>
    </servlet-mapping>

    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>

</web-app>
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>My JSP ‘test.jsp‘ starting page</title>
  </head>

  <body>

       <c:url value="/servlet/ServletDemo1" scope="page" var="servletDemo1">
           <c:param name="username" value="吊死扶伤"></c:param>
       </c:url>

       <a href="${servletDemo1 }">点点</a>

       <form action="${pageContext.request.contextPath }/servlet/ServletDemo1" method="post">
           用户名：<input type="text" name="username">
           <input type="submit">
       </form>
  <%
        String param = request.getParameter("param");
    %>
  <a href="URLCharset.jsp?param=‘中文‘">请点击这个链接</a><br>
        你提交的参数为：<%=param%>  

  </body>
</html>

脏话过滤器

package cn.lcp.web.filter;

import java.io.IOException;
import java.util.Arrays;
import java.util.List;

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.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;

//脏话过滤器
public class DirtyFilter implements Filter {

    public void doFilter(ServletRequest req, ServletResponse resp,
            FilterChain chain) throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) resp;
        DirtyRequest dirtyrequest = new DirtyRequest(request);

        chain.doFilter(dirtyrequest, response);
    }

    public void init(FilterConfig filterConfig) throws ServletException {
    }

    public void destroy() {
    }
}

//记住所有的脏话
class DirtyRequest extends HttpServletRequestWrapper{

    private List<String> dirtyWords = Arrays.asList("傻B","操蛋","畜生");
    private HttpServletRequest request;

    public DirtyRequest(HttpServletRequest request) {
        super(request);
        this.request = request;
    }

    @Override
    public String getParameter(String name) {
        //获取数据
        String value = this.request.getParameter(name);
        if(value==null){
            return null;
        }
        //检测是否有脏话
        for(String dirtyWord : dirtyWords){
            if(value.contains(dirtyWord)){
                value = value.replace(dirtyWord, "****");
            }
        }
        return value;
    }
}
package cn.lcp.web.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.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;

//为解决全站乱码
public class CharacterEncodingFilter implements Filter {

    public void destroy() {
        // TODO Auto-generated method stub

    }

    public void doFilter(ServletRequest req, ServletResponse resp,
            FilterChain chain) throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) resp;

        // 对get提交的数据还是没有办法对其改变编码，所以要对request的getParameter方法缺少功能了。
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");

        //放行的是自己的包装类
        MyCharacterEncodingRequest requestWrapper = new MyCharacterEncodingRequest(
                request);
        chain.doFilter(requestWrapper, response);

    }

    public void init(FilterConfig filterConfig) throws ServletException {
        // TODO Auto-generated method stub

    }
}

/*
 * 1.实现与被增强对象相同的接口 2、定义一个变量记住被增强对象 3、定义一个构造器，接收被增强对象 4、覆盖需要增强的方法
 * 5、对于不想增强的方法，直接调用被增强对象（目标对象）的方法
 */
// 包装类。
class MyCharacterEncodingRequest extends HttpServletRequestWrapper {

    private HttpServletRequest request;

    // 接受被增强对象
    public MyCharacterEncodingRequest(HttpServletRequest request) {
        super(request);
        this.request = request;
    }

    @Override
    public String getParameter(String name) {

        try {
            // 客户机提交的值
            String value = this.request.getParameter(name);
            if (value == null) {
                return null;
            }
            // 判断客户机的提交方式是不是get。这里忽略了get和GET方式
            if (!this.request.getMethod().equalsIgnoreCase("get")) {
                return value;
            }

            //客户机的原始码表
            value = new String(value.getBytes("ISO8859-1"),
                    this.request.getCharacterEncoding()); //获取上面的request设定的编码
            return value;

        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
}
package cn.lcp.web.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ServletDemo2 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        String message = request.getParameter("message");   //<script>
        response.getWriter().write("您上次的留言是：<br/>" + message);

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        doGet(request, response);
    }

}
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    id="WebApp_ID" version="3.0">
    <display-name>day18_5</display-name>

    <filter>
        <filter-name>DirtyFilter</filter-name>
        <filter-class>cn.lcp.web.filter.DirtyFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>DirtyFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <servlet>
        <description>This is the description of my J2EE component
        </description>
        <display-name>This is the display name of my J2EE component</display-name>
        <servlet-name>ServletDemo2</servlet-name>
        <servlet-class>cn.lcp.web.servlet.ServletDemo2</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>ServletDemo2</servlet-name>
        <url-pattern>/servlet/ServletDemo2</url-pattern>
    </servlet-mapping>

    <filter>
        <filter-name>CharacterEncodingFilter</filter-name>
        <filter-class>cn.lcp.web.filter.CharacterEncodingFilter</filter-class>
    </filter>

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

    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>
</web-app>
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>My JSP ‘test2.jsp‘ starting page</title>
  </head>

  <body>

       <form action="${pageContext.request.contextPath }/servlet/ServletDemo2" method="post">
       留言:
       <textarea rows="8" cols="60" name="message"></textarea>
       <input type="submit" value="发表">

       </form>

  </body>
</html>

html转义过滤器

public class HtmlFilter implements Filter {

    public void doFilter(ServletRequest req, ServletResponse resp,
            FilterChain chain) throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) resp;

        MyHtmlRequest myrequest = new MyHtmlRequest(request);
        chain.doFilter(myrequest, response);

    }

    public void destroy() {
        // TODO Auto-generated method stub

    }

    public void init(FilterConfig filterConfig) throws ServletException {
        // TODO Auto-generated method stub

    }
}

class MyHtmlRequest extends HttpServletRequestWrapper{

    private HttpServletRequest request;

    public MyHtmlRequest(HttpServletRequest request) {
        super(request);
        this.request = request;
    }

    @Override
    public String getParameter(String name) {
        //tomcat帮获取值。
        String value = this.request.getParameter(name);
        if(value==null){
            return null;  //检查值是否存在
        }
        return filter(value);
    }

     public String filter(String message) {

            if (message == null)
                return (null);

            char content[] = new char[message.length()];
            message.getChars(0, message.length(), content, 0);
            StringBuffer result = new StringBuffer(content.length + 50);
            for (int i = 0; i < content.length; i++) {
                switch (content[i]) {
                case ‘<‘:
                    result.append("&lt;");
                    break;
                case ‘>‘:
                    result.append("&gt;");
                    break;
                case ‘&‘:
                    result.append("&amp;");
                    break;
                case ‘"‘:
                    result.append("&quot;");
                    break;
                default:
                    result.append(content[i]);
                }
            }
            return (result.toString());

        }
}
时间： 2024-07-30 07:27:36

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