Filter-案例-过滤敏感词汇-分析Filter案例-过滤敏感词汇-代码实现

Filter-案例-过滤敏感词汇-分析

需求：

　　1.对day17_case案例录入的数据进行敏感词汇过滤

　　2.敏感词汇参考《敏感词汇.txt》

　　3.如果是敏感词汇，替换为 * *

 分析：

　　1.对request对象进行增强。增强获取参数相关方法

　　2.放行。传递代理对象

Filter-案例-过滤敏感词汇-代码实现

 敏感词汇.txt

SensitiWordsFilter类

package com.jstl.web.filter;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.ArrayList;
import java.util.List;

@WebFilter("/*")
public class SensitiveWordsFilter implements Filter {

    // 敏感词汇集合
    private List<String> list = new ArrayList<String>();

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        try {
            // 获取文件真实路径
            ServletContext servletContext = filterConfig.getServletContext();
            String realPath = servletContext.getRealPath("/WEB-INF/敏感词汇.txt");

            // 读取文件
            BufferedReader bufferedReader = new BufferedReader(new FileReader(realPath));

            // 将文件的每一行数据添加到list中
            String line = null;
            while ((line = bufferedReader.readLine()) != null) {
                list.add(line);
            }
            bufferedReader.close();
            System.out.println(list);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        // 创建代理对象,增强getParameter方法
        ServletRequest proxy_req = (ServletRequest)Proxy.newProxyInstance(
                        servletRequest.getClass().getClassLoader(),
                        servletRequest.getClass().getInterfaces(),
                        new InvocationHandler() {
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

                // 增强getParameter方法
                // 判断是否是getParameter方法
                if (method.getName().equals("getParameter")) {
                    // 增强返回值
                    // 获取返回值
                    String value = (String) method.invoke(servletRequest,servletResponse);
                    if (value != null) {
                        for (String str : list) {
                            if (value.contains(str)) {
                                value = value.replaceAll(str,"***");
                            }
                        }
                    }
                    return value;
                }
                return method.invoke(servletRequest,args);
            }
        });
        // 放行
        filterChain.doFilter(proxy_req,servletResponse);
    }

    @Override
    public void destroy() {

    }
}

TextServlet类

package com.jstl.web.servlet;

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

@WebServlet("/textServlet")
public class TextServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doGet(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String name = req.getParameter("name");
        String msg = req.getParameter("msg");

        System.out.println(name+":"+msg);
    }
}