package com.hopetesting.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;
/**
 * @author newcityman
 * @date 2019/9/13 - 19:41
 */
@WebFilter("/*")
public class SensitiveWordsFilter implements Filter {
  public void destroy() {
  }
  public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
    //1、創建代理對象，增強getParameter方法
    ServletRequest proxy_req = (ServletRequest) Proxy.newProxyInstance(req.getClass().getClassLoader(), req.getClass().getInterfaces(), new InvocationHandler() {
      @Override
      public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        //判斷是否是getParameter方法
        //如果是，增強getParameter方法
        if (method.getName().equals("getParameter")) {
          //增強返回值
          //獲取返回值
          String value = (String) method.invoke(req, args);
          if (value != null) {
            for (String str : list) {
              if (value.contains(str)) {
                value = value.replace(str, "******");
              }
            }
          }
          return value;
        }
        return method.invoke(req, args);
      }
    });
    chain.doFilter(proxy_req, resp);
  }
  private List list = new ArrayList(); //敏感詞匯集合
  public void init(FilterConfig config) throws ServletException {
    try {
      //1、獲取文件的真實路徑
      ServletContext servletContext = config.getServletContext();
      String realPath = servletContext.getRealPath("/WEB-INF/classes/敏感詞匯.txt");
      //2、讀取文件
      BufferedReader br = new BufferedReader(new FileReader(realPath));
      //3、將文件的每一行讀取到list中
      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();
    }
  }
}