java屏蔽关键字_替换禁用语（指定关键字）的过滤器（StopWordsFilter）

功能描述

将请求响应中所有的禁用关键字替换掉之后再输出。

使用方法

在 java web 项目的 web.xml 文件中添加如下代码。

StopWordsFilter

com.hmw.filter.StopWordsFilter

需要禁用的关键字，一个关键字占一行

keys

QQ

百度

七一五

StopWordsFilter

*.jsp

过滤器源码

ReplaceKeyWordFilter.java

package com.hmw.filter;

import java.io.IOException;

import java.io.PrintWriter;

import java.util.HashSet;

import java.util.Iterator;

import java.util.Set;

import java.util.StringTokenizer;

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.HttpServletResponse;

/**

* 替换关键字的滤器

*

* @author 何明旺

*/

public class StopWordsFilter implements Filter {

private Set keyWords = new HashSet();

/**

* 将需要进行替换的关键字添加到一个定义好的 Set 中

*/

@Override

public void init(FilterConfig config) throws ServletException {

String keys = config.getInitParameter("keys");

StringTokenizer tokenizer = new StringTokenizer(keys);

String token = null;

while (tokenizer.hasMoreTokens()) {

token = tokenizer.nextToken();

if(token != null && token.length() > 0){

keyWords.add(tokenizer.nextToken());

}

}

}

@Override

public void doFilter(ServletRequest request, ServletResponse response,

FilterChain chain) throws ServletException, IOException {

CharArrayWrapper responseWrapper = new CharArrayWrapper(

(HttpServletResponse) response);

// 调用请求资源(使用自己包装的 responseWrapper)

chain.doFilter(request, responseWrapper);

// 取得响应字符串

String responseString = responseWrapper.toString();

// 将需要替换的关键字用“**”替换掉

Iterator iter = keyWords.iterator();

while (iter.hasNext()) {

responseString = replace(responseString, iter.next(), "**");

}

// 修改响应头信息中的 Content-Length

response.setContentLength(responseString.length());

PrintWriter out = response.getWriter();

out.write(responseString);

}

@Override

public void destroy() {

}

/**

* 将字符串中的所有的指定子字符串替换掉

* @param mainString 需要进行替换的字符串

* @param orig 需要被替换的子串

* @param replacement 替换后的新串

* @return 返回替换后的字符串

*/

public static String replace(String mainString, String orig, String replacement) {

String result = "";

int oldIndex = 0;

int index = 0;

int origLength = orig.length();

while ((index = mainString.indexOf(orig, oldIndex)) != -1) {

result = result + mainString.substring(oldIndex, index) + replacement;

oldIndex = index + origLength;

}

result = result + mainString.substring(oldIndex);

return result;

}

}

CharArrayWrapper.java

package com.hmw.filter;

import java.io.CharArrayWriter;

import java.io.PrintWriter;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpServletResponseWrapper;

/**

* A response wrapper that takes everything the client would normally output and

* saves it in one big character array.

*/

public class CharArrayWrapper extends HttpServletResponseWrapper {

private CharArrayWriter charWriter;

/**

* Initializes wrapper.

*

* First, this constructor calls the parent constructor. That call is

* crucial so that the response is stored and thus setHeader, *setStatus,

* addCookie, and so forth work normally.

*

* Second, this constructor creates a CharArrayWriter that will be used to

* accumulate the response.

*/

public CharArrayWrapper(HttpServletResponse response) {

super(response);

charWriter = new CharArrayWriter();

}

/**

* When servlets or JSP pages ask for the Writer, don't give them the real

* one. Instead, give them a version that writes into the character array.

* The filter needs to send the contents of the array to the client (perhaps

* after modifying it).

*/

@Override

public PrintWriter getWriter() {

return new PrintWriter(charWriter);

}

/**

* Get a String representation of the entire buffer.

*

* Be sure not to call this method multiple times on the same

* wrapper. The API for CharArrayWriter does not guarantee that it

* "remembers" the previous value, so the call is likely to make a new

* String every time.

*/

@Override

public String toString() {

return charWriter.toString();

}

/** Get the underlying character array. */

public char[] toCharArray() {

return charWriter.toCharArray();

}

}