目录

1.概念

2.解决办法

3.覆盖Http请求方法

XSS:Cross Site Script ，为了区分css改写成xss，通过注入“HTML注入”，篡改了网页，插入了恶意脚本。

等到用户加载的时候就会自动执行恶意脚本，如果在浏览器上执行javacript就可以盗取Cookie或者Token

2.解决办法

1).设置过滤器

编写过滤器，拦截请求，把请求里面的数据进行转义

2).覆盖Http请求方法

在请求里面获取数据的时候，调用HttpServletRequest类中getParameter()方法和getParameterValues()方法，如果我们把这两个方法覆盖，返回数据的时候进行转译再返回

但是HttpServletRequest是接口,采用包装类的方式增加请求功能HttpServletRequestWrapper

3).HttpServletRequestWrapper

HttpServletRequestWrapper使用了装饰器模式

使用了装饰器模式，装饰器封装了厂家的Request的实现类，只要覆盖wrapper类的方法，就能做到覆盖厂商请求对象的方法 

步骤;创建过滤器，把Request对象传入Wrapper对象

3.覆盖Http请求方法

导入依赖

        
            cn.hutool
            hutool-all
            5.4.0
        

编写配置类

主要编写连个配置类

XssHttpServletRequestWrapper

import cn.hutool.core.util.StrUtil;
import cn.hutool.http.HtmlUtil;
import cn.hutool.json.JSONUtil;

import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.*;
import java.nio.charset.Charset;
import java.util.LinkedHashMap;
import java.util.Map;

public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {

    public XssHttpServletRequestWrapper(HttpServletRequest request) {
        super(request);
    }
//进行转义
    @Override
    public String getParameter(String name) {
//        从请求中获取原始数据
        String value = super.getParameter(name);
        if(!StrUtil.hasEmpty(value)){
//            把标签变成文本
            value= HtmlUtil.filter(value);
        }
        return value;
    }

    @Override
    public String[] getParameterValues(String name) {
        String[] values = super.getParameterValues(name);
        if(values!=null){
            for (int i = 0; i < values.length; i++) {
                String value=values[i];
                if(!StrUtil.hasEmpty(value)){
                    value= HtmlUtil.filter(value);
                }
                values[i]=value;
            }
        }
        return values;
    }

    @Override
    public Map getParameterMap() {
        Map paramters = super.getParameterMap();
//        使用hashMap插入的是乱序的，使用LinkdHasMap
        LinkedHashMap map=new LinkedHashMap();
        if(paramters!=null){
            for (String key:paramters.keySet()){
                String[] values=paramters.get(key);
                for (int i = 0; i < values.length; i++) {
                    String value=values[i];
                    if(!StrUtil.hasEmpty(value)){
                        value= HtmlUtil.filter(value);
                    }
                    values[i]=value;
                }
                map.put(key,values);
            }
        }
        return map;
    }

    @Override
    public String getHeader(String name) {
        String value = super.getHeader(name);
        if(!StrUtil.hasEmpty(value)){
            value = HtmlUtil.filter(value);
        }
        return value;
    }

    @Override
    public ServletInputStream getInputStream() throws IOException {
        InputStream in = super.getInputStream();
        InputStreamReader reader=new InputStreamReader(in, Charset.forName("UTF-8"));
        BufferedReader buffer = new BufferedReader(reader);
        StringBuffer body = new StringBuffer();
        String line=buffer.readLine();
        while (line!=null){
            body.append(line);
            line=buffer.readLine();
        }
        buffer.close();
        reader.close();
        in.close();
//        把json格式转换成字符串
        Map map=JSONUtil.parseObj(body.toString());
        Map result=new LinkedHashMap<>();
        for (String key : map.keySet()) {
            Object val=map.get(key);
            if(val instanceof String){
                if(!StrUtil.hasEmpty( val.toString())){
                    result.put(key,HtmlUtil.filter(val.toString()));
                }
            }else {
                result.put(key,val);
            }
        }
        String json = JSONUtil.toJsonStr(result);
        ByteArrayInputStream bain = new ByteArrayInputStream(json.getBytes());
        return new ServletInputStream() {
            @Override
            public boolean isFinished() {
                return false;
            }

            @Override
            public boolean isReady() {
                return false;
            }

            @Override
            public void setReadListener(ReadListener readListener) {
            }
//            方法用来读数据
            @Override
            public int read() throws IOException {
                return bain.read();
            }
        };
    }
}

 XssFilter类

补充：Filter能再request到达servlet的服务方法前拦截HttpServletRequest对象，而在方法转移后又能拦截HttpServletResponse对象

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.util.logging.LogRecord;

@WebFilter(urlPatterns = "/*")
public class XssFilter implements Filter {


    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        Filter.super.init(filterConfig);
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request=(HttpServletRequest)servletRequest;
        XssHttpServletRequestWrapper wrapper=new XssHttpServletRequestWrapper(request);
        filterChain.doFilter(wrapper,servletResponse);
    }

    @Override
    public void destroy() {
        Filter.super.destroy();
    }
}

ps:在著启动类上要加@ServletComponentScan