Java防止xss攻击

首先说一下思路，防止这种类似于注入攻击，就是使用拦截器（Filter）处理特殊字符或过滤特殊字符

今天介绍一个方法，利用覆盖Servlet的getParameter方法达到处理特殊字符的目的来解决（防止）Xss攻击

web.xml

<filter>
<filter-name>XssEscape</filter-name>
<filter-class>www.ablanxue.com.filter.XssFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>XssEscape</filter-name>
<url-pattern>/*</url-pattern>
<dispatcher>REQUEST</dispatcher>
</filter-mapping>

Filter类（XssFilter. Java ）

package www.ablanxue.com.filter;

import java.io.IOException;

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;

public class XssFilter implements javax.servlet.Filter {

@Override
public void destroy() {
// TODO Auto-generated method stub

}

@Override
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain filterChain) throws IOException, ServletException {

XssHttpServletRequestWrapper xssRequest = new XssHttpServletRequestWrapper((HttpServletRequest) request);
filterChain.doFilter(xssRequest, response);
}

@Override
public void init(FilterConfig arg0) throws ServletException {
// TODO Auto-generated method stub

}

}

最关键的类（XssHttpServletRequestWrapper.java）

继承servlet的HttpServletRequestWrapper，并重写相应的几个有可能带xss攻击的方法

package www.ablanxue.com.filter;

import java.io.StringReader;
import java.io.StringWriter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import com.blogspot.radialmind.html.HTMLParser;
import com.blogspot.radialmind.xss.XSSFilter;

public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {

HttpServletRequest orgRequest = null;

public XssHttpServletRequestWrapper(HttpServletRequest request) {
super(request);
orgRequest = request;
}

/**
* 覆盖getParameter方法，将参数名和参数值都做xss过滤。
* 如果需要获得原始的值，则通过super.getParameterValues(name)来获取
* getParameterNames,getParameterValues和getParameterMap也可能需要覆盖
*/
@Override
public String getParameter(String name) {
String value = super.getParameter(xssEncode(name));
if (value != null) {
value = xssEncode(value);
}
return value;
}

/**
* 覆盖getHeader方法，将参数名和参数值都做xss过滤。
* 如果需要获得原始的值，则通过super.getHeaders(name)来获取
* getHeaderNames 也可能需要覆盖
*/
@Override
public String getHeader(String name) {

String value = super.getHeader(xssEncode(name));
if (value != null) {
value = xssEncode(value);
}
return value;
}

/**
* 将容易引起xss漏洞的半角字符直接替换成全角字符
*
* @param s
* @return
*/
private static String xssEncode(String s) {

if (s == null || s.isEmpty()) {
return s;
}

StringReader reader = new StringReader(s);
StringWriter writer = new StringWriter();
try {
HTMLParser.process(reader, writer, new XSSFilter(), true);

String result = writer.toString();

System.out.println("xssEncode-------------------------" + s + " = " + result);

return result;
} catch (NullPointerException e) {
return s;
} catch (Exception ex) {
ex.printStackTrace();
}

return null;

}

/**
* 获取最原始的request
*
* @return
*/
public HttpServletRequest getOrgRequest() {
return orgRequest;
}

/**
* 获取最原始的request的静态方法
*
* @return
*/
public static HttpServletRequest getOrgRequest(HttpServletRequest req) {
if (req instanceof XssHttpServletRequestWrapper) {
return ((XssHttpServletRequestWrapper) req).getOrgRequest();
}

return req;
}
}

依赖jar包百度网盘下载xssProtect-0.1.jarantlr-runtime-3.0.1.jar
转载注明本文地址：http://www.ablanxue.com/shtml/201502/26346_1.shtml

通过重写getParameter()等方法，实现简单的过滤，从而防止Xss攻击