代理模式,数组,迭代器|一点小细节

要点以及遇到的问题:
1.代理模式增强功能
2.request.getParameterMap,底层源码给map加锁.map得值不可修改
3.解决:值放置到数组中时,遍历数组可修改.
注意:不能随便使用迭代器遍历修改.
引用数组修改的是内存地址中的实际参数,而for循环里面的局部变量为实际参数的副本,
修改其值不会修改实际的值

//过滤器
package com.fzq.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.*;

@WebFilter("/*")
public class SensitiveWordsFilter implements Filter {
    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {

        //代理过滤
        ServletRequest proxyObj = (ServletRequest) Proxy.newProxyInstance(req.getClass().getClassLoader(), req.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(req, args);
                    if (value != null) {
                        for (String s : list) {
                            if (value.contains(s)) {
                                value = value.replaceAll(s, "***");
                            }
                        }
                    }
                    return value;
                } else if (method.getName().equals("getParameterValues")) {
                    String[] value = (String[]) method.invoke(req, args);
                    for (int i = 0; i < value.length; i++) {
                        if (value[i] != null) {
                            for (String s : list) {
                                if (value[i].contains(s)) {
                                    value[i] = value[i].replaceAll(s, "***");
                                }
                            }
                        }

                    }
                    return value;

                } else if(method.getName().equals("getParameterMap")){
                    Map<String,String[]> map = (Map<String, String[]>) method.invoke(req, args);

                    if (map!=null){
                        for (Map.Entry<String, String[]> entry : map.entrySet()) {

                            /**
                             * 不能直接map.put使用修改覆盖的方法,map加锁无法修改
                             */
                            String[] values = entry.getValue();
                            /**
                             * emmmm呢
                             * 不能使用迭代器!!
                             * 迭代器新创建一个局部变量修改了值便销毁了
                             * 修改value数组,引用传递,修改的是内存地址里面的值
                             */
                            for (int i = 0; i < values.length; i++) {
                                for (String sensitiveWord : list) {
                                    if (values[i].contains(sensitiveWord)){
                                        values[i] = values[i].replaceAll(sensitiveWord,"小可爱");
                                    }
                                }
                            }

                        }
                    }

                    /************************************************************
                     * o98k
                     Set<String> set = map.keySet();
                    //获取key
                    if(map!=null){
                        for (String key : set) {
                            //value
                            String[] value = map.get(key);
                            //敏感词判断
                            for (int i = 0; i < value.length; i++) {
                                for (String sensitiveWords : list) {
                                    if (value[i].contains(sensitiveWords)){
                                        value[i] = value[i].replaceAll(sensitiveWords,"小可爱");
                                    }
                                }
                            }
                        }
                    }
                     ***************************************************/
/*
foolish  2.0
                   Iterator<Map.Entry<String, String[]>> it = map.entrySet().iterator();

                    while(it.hasNext()){
                        String[] value = it.next().getValue();
                        for (int i = 0; i < value.length; i++) {
                            for (String s : list) {
                                if (value[i].contains(s)){
                                    value[i] = value[i].replaceAll(s,"小可爱");
                                }
                            }
                        }
*/
/*
//foolish 1.0
                        if(value[0]!=null){
                            for (String s : list) {
                                if(value[0].contains(s)){
                                    value[0]=value[0].replaceAll(s,"***");
                                }
                            }
                        }*/


                        return map;
                    }

                return method.invoke(req, args);
            }
        });


        //放行
        chain.doFilter(proxyObj,resp);
    }

    private List<String> list = new ArrayList<String>();

    public void init(FilterConfig config) throws ServletException {
        //获取文件真实路径

        //读取文件
        try {
            ServletContext servletContext = config.getServletContext();
            String realPath = servletContext.getRealPath("/WEB-INF/classes/敏感词汇.txt");
            BufferedReader br = new BufferedReader(new FileReader(realPath));
            String line = null;
            while ((line = br.readLine()) != null) {
                list.add(line);
            }

            br.close();
            System.out.println(list);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void destroy() {

    }


}

//test

package com.fzq.web.servlet;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Map;

@WebServlet("/testServlet")
public class TestServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

       /* String name = request.getParameter("name");
        String msg = request.getParameter("msg");
        System.out.println(name+":"+msg);*/

       //map
        Map<String, String[]> map = request.getParameterMap();
        for (Map.Entry<String, String[]> entry : map.entrySet()) {
            String name = entry.getKey();
            String[] msg = entry.getValue();
            System.out.println(name+":"+msg[0]);
        }


/*

        String name = request.getParameterValues("name")[0];
        String msg = request.getParameterValues("msg")[0];
        System.out.println(name+":"+msg);
*/



    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }
}