关于xss的介绍可以看 Asp.net安全架构之1：xss（跨站脚本）和 腾讯微博的XSS攻击漏洞 网页，
具体我就讲讲Spring MVC里面的预防：
第一种方法,使用Spring MVC
web.xml加上：
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<context-param>
<param-name>defaultHtmlEscape</param-name>
<param-value>true</param-value>
</context-param>
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Forms加上：
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<spring:htmlEscape defaultHtmlEscape="true" />
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第二种方法是手动escape
例如用户可以输入：
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<script>alert();</script>
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或者输入
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<h2>abc<h2>
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,如果有异常,显然有xss漏洞。
首先添加一个jar包:commons-lang-2.5.jar,然后在后台调用这些函数：
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StringEscapeUtils.escapeHtml(string);
StringEscapeUtils.escapeJavaScript(string);
StringEscapeUtils.escapeSql(string);
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前台js调用escape函数即可。
第三种方法是后台加Filter,对每个post请求的参数过滤一些关键字,替换成安全的
例如：< > ‘ “ \ / # &
方法是实现一个自定义的HttpServletRequestWrapper，然后在Filter里面调用它，替换掉getParameter函数即可。
首先添加一个XssHttpServletRequestWrapper:
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package com.ibm.web.beans;
//
import java.util.Enumeration;
//
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
//
public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {
//
public XssHttpServletRequestWrapper(HttpServletRequest servletRequest) {
super(servletRequest);
}
//
public String[] getParameterValues(String parameter) {
String[] values = super.getParameterValues(parameter);
if (values==null) {
return null;
}
int count = values.length;
String[] encodedValues = new String[count];
for (int i = 0; i < count; i++) {
encodedValues[i] = cleanXSS(values[i]);
}
return encodedValues;
}
//
public String getParameter(String parameter) {
String value = super.getParameter(parameter);
if (value == null) {
return null;
}
return cleanXSS(value);
}
//
public String getHeader(String name) {
String value = super.getHeader(name);
if (value == null)
return null;
return cleanXSS(value);
}
//
private String cleanXSS(String value) {
//You'll need to remove the spaces from the html entities below
value = value.replaceAll("<", "& lt;").replaceAll(">", "& gt;");
value = value.replaceAll("\\(", "& #40;").replaceAll("\\)", "& #41;");
value = value.replaceAll("'", "& #39;");
value = value.replaceAll("eval\\((.*)\\)", "");
value = value.replaceAll("[\\\"\\\'][\\s]*javascript:(.*)[\\\"\\\']", "\"\"");
value = value.replaceAll("script", "");
return value;
}
}
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然后添加一个过滤器XssFilter ：
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package com.ibm.web.beans;
//
import java.io.IOException;
//
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.HttpServletResponse;
//
public class XssFilter implements Filter {
FilterConfig filterConfig = null;
//
public void init(FilterConfig filterConfig) throws ServletException {
this.filterConfig = filterConfig;
}
//
public void destroy() {
this.filterConfig = null;
}
//
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
chain.doFilter(new XssHttpServletRequestWrapper(
(HttpServletRequest) request), response);
}
}
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最后在web.xml里面配置一下，所有的请求的getParameter会被替换，如果参数里面含有敏感词会被替换掉：
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<filter>
<filter-name>XssSqlFilter</filter-name>
<filter-class>com.ibm.web.beans.XssFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>XssSqlFilter</filter-name>
<url-pattern>/*</url-pattern>
<dispatcher>REQUEST</dispatcher>
</filter-mapping>
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(这个Filter也可以防止SQL注入攻击)