XSS全稱為跨站指令碼攻擊 , 具體見百度百科

最常見的是用Filter來預防 , 就是建立一個新的httpRequest類XsslHttpServletRequestWrapper，然後重寫一些get方法（獲取引數時對引數進行XSS判斷預防）.

1 . 在web.xml中新增Filter

<filter>
       <filter-name>XssFilter</filter-name>
       <filter-class>com.xbz.filter.XssFilter</filter-class>
    </filter>
    <filter-mapping>
       <filter-name>XssFilter</filter-name>
       <url-pattern>/*</url-pattern>
    </filter-mapping>
 

2 . 編寫XssFilter類

package com.xbz.filter;

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;

public class XssFilter implements Filter{
	FilterConfig fc = null;
	
	public void destroy() {
		fc = null;
	}

	public void doFilter(ServletRequest req, ServletResponse resp,
			FilterChain fc) throws IOException, ServletException {
		fc.doFilter(new XssHttpServletRequestWrapper((HttpServletRequest)req), resp);
	}

	public void init(FilterConfig fc) throws ServletException {
		this.fc = fc;
	}

}
 

3 . 編寫XssHttpServletRequestWrapper類

package com.xbz.filter;

import java.util.HashMap;
import java.util.Map;
import java.util.regex.Pattern;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {
    public XssHttpServletRequestWrapper(HttpServletRequest request) {
        super(request);
    }

    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 Map<String, String[]> getParameterMap() {
        Map<String, String[]> map = super.getParameterMap();
        Map<String, String[]> encodedMap = new HashMap<String, String[]>();
        encodedMap.putAll(map);

        for (Map.Entry<String, String[]> entry : encodedMap.entrySet()) {
            String[] value = entry.getValue();
            String[] encodedValues = new String[value.length];
            for (int i = 0; i < value.length; i++) {
                encodedValues[i] = cleanXSS(value[i]);
            }
            encodedMap.put(entry.getKey(), encodedValues);
        }
        return encodedMap;
    }

    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) {
        if (value != null) {
            // Avoid null characters
            value = value.replaceAll("", "");
            // Avoid anything between script tags
            Pattern scriptPattern = Pattern.compile("<script>(.*?)</script>", Pattern.CASE_INSENSITIVE);
            value = scriptPattern.matcher(value).replaceAll("");
            // Avoid anything in a
            // src="http://www.yihaomen.com/article/java/..." type of
            // e­xpression
            scriptPattern = Pattern.compile("src[\r\n]*=[\r\n]*\\\'(.*?)\\\'", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
            value = scriptPattern.matcher(value).replaceAll("");
            scriptPattern = Pattern.compile("src[\r\n]*=[\r\n]*\\\"(.*?)\\\"", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
            value = scriptPattern.matcher(value).replaceAll("");
            // Remove any lonesome </script> tag
            scriptPattern = Pattern.compile("</script>", Pattern.CASE_INSENSITIVE);
            value = scriptPattern.matcher(value).replaceAll("");
            // Remove any lonesome <script ...> tag
            scriptPattern = Pattern.compile("<script(.*?)>", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
            value = scriptPattern.matcher(value).replaceAll("");
            // Avoid eval(...) e­xpressions
            scriptPattern = Pattern.compile("eval\\((.*?)\\)", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
            value = scriptPattern.matcher(value).replaceAll("");
            // Avoid e­xpression(...) e­xpressions
            scriptPattern = Pattern.compile("e­xpression\\((.*?)\\)", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
            value = scriptPattern.matcher(value).replaceAll("");
            // Avoid javascript:... e­xpressions
            scriptPattern = Pattern.compile("javascript:", Pattern.CASE_INSENSITIVE);
            value = scriptPattern.matcher(value).replaceAll("");
            // Avoid vbscript:... e­xpressions
            scriptPattern = Pattern.compile("vbscript:", Pattern.CASE_INSENSITIVE);
            value = scriptPattern.matcher(value).replaceAll("");
            // Avoid onload= e­xpressions
            scriptPattern = Pattern.compile("onload(.*?)=", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
            value = scriptPattern.matcher(value).replaceAll("");
        }
        return filter(value);
    }

    /** 
     * 過濾特殊字元 
     */
    public static String filter(String value) {
        if (value == null) {
            return null;
        }
        StringBuffer result = new StringBuffer(value.length());
        for (int i = 0; i < value.length(); ++i) {
            switch (value.charAt(i)) {
            case '<':
                result.append("<");
                break;
            case '>':
                result.append(">");
                break;
            case '"':
                result.append("\"");
                break;
            case '\'':
                result.append("'");
                break;
            case '%':
                result.append("%");
                break;
            case ';':
                result.append(";");
                break;
            case '(':
                result.append("(");
                break;
            case ')':
                result.append(")");
                break;
            case '&':
                result.append("&");
                break;
            case '+':
                result.append("+");
                break;
            default:
                result.append(value.charAt(i));
                break;
            }
        }
        return result.toString();
    }
}