java非法字符过滤器

过滤项目中的非法字符,并且用其他的特殊符号过滤:

WordFilter.java

package com.easyweb.web.character;

import java.io.IOException;
import java.io.InputStream;
import java.util.Collection;
import java.util.Iterator;
import java.util.Properties;
import java.util.Random;

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;

/**
* 过来非法字符的过滤器
*
* @author leo
*
*/
public class WordFilter implements Filter {

Properties ps = new Properties(); // properties 属性文件
Collection con = null; // 非法文字集合(从properties属性文件中读取出来)
private String encoding; // 字符编码
private String[] charWorld = new String[] { "~", "@", "#", "$", "%", "^",
"&", "*" }; // 将非法文字替换成随机字符

Random input = new Random(); // 随机产生器(为上面的随机字符提供下标)

@Override
public void destroy() {

}

@Override
public void doFilter(ServletRequest request, ServletResponse response,
   FilterChain chain) throws IOException, ServletException {
  if (encoding != null) {
   request.setCharacterEncoding(encoding); // 设置 request字符编码
   request = new Request((HttpServletRequest) request);
   response.setContentType("text/html;charset=" + encoding); // 设置response字符编码
  }
  chain.doFilter(request, response);
}

/**
* 过滤器初始化参数,与读取非法字符的properties文件
*/
@Override
public void init(FilterConfig filterConfig) throws ServletException {
  encoding = filterConfig.getInitParameter("encoding");
  try {
   InputStream in = filterConfig.getServletContext().getResourceAsStream("/wordFilter.properties");
   ps.load(in);
   con = ps.values(); //得到properties中的所有value值,存入collection集合中
  } catch (IOException e) {
   e.printStackTrace();
  }
}

/**
* 过滤字符的方法
* @param param
* @return
*/
public String filter(String param) {
  // 过滤非法字符的方法
  try {
   if (param != null && param.length() > 0) {
    // 保证传入的字符串不为空和空字符串
    Iterator it = con.iterator(); // 迭代器可以把collection中的值一条一条的读出来
    if (con != null) { // 集合要被初始化
     while (it.hasNext()) {
      // 判断集合里是否还有值
      String value = (String) it.next(); // 取出该值
      if (param.indexOf(value) != -1) {
       param = param.replace(value, charWorld[input
         .nextInt(8)]); // 对非法字符词语进行替换
      }
     }
    }
   }
  } catch (Exception e) { // TODO Auto-generated catch block
   e.printStackTrace();
  }
  return param;
}

//内部类为了重写request的getParameter 和 getParameterValues
   class Request extends HttpServletRequestWrapper{
     public Request(HttpServletRequest request) {
      super(request);
   }
     @Override
     public String getParameter(String name) {
      //返回值之前先进行过滤
      return filter(super.getParameter(name));
     }
     @Override
     public String[] getParameterValues(String name) {
      //返回值之前先进行过滤
      String[] values = super.getParameterValues(name);
      for (int i = 0; i < values.length; i++) {
       values[i] = filter(values[i]);
      }
      return values;
     }
   }

}

java非法字符过滤器

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