javaweb使用过滤器防止图片盗链 ------请求头referer的使用

在web.xml文件中如下配置：

 

1.  
   <filter>
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   <filter-name>SimpleFilter</filter-name>
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   <filter-class>cn.SimpleFilter</filter-class>
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   </filter>
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   <filter-mapping>
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   <filter-name>SimpleFilter</filter-name>
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   <url-pattern>/images/*</url-pattern>
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   </filter-mapping>

 

在servlet过滤器代码如下：

 

1.  
   package cn;
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3.  
   import java.io.IOException;
4.  
    
5.  
   import javax.servlet.Filter;
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   import javax.servlet.FilterChain;
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   import javax.servlet.FilterConfig;
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   import javax.servlet.ServletException;
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   import javax.servlet.ServletRequest;
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    import javax.servlet.ServletResponse;
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    import javax.servlet.http.HttpServlet;
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    import javax.servlet.http.HttpServletRequest;
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    import javax.servlet.http.HttpServletResponse;
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15.  
    public class SimpleFilter extends HttpServlet implements Filter {
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    private static final long serialVersionUID = 1L;
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    private FilterConfig filterConfig;
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    public void init(FilterConfig config) {
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    this.filterConfig = config;
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    }
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    public void doFilter(ServletRequest req, ServletResponse res,
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    FilterChain chain) throws ServletException, IOException {
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    HttpServletRequest request = (HttpServletRequest) req;
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    HttpServletResponse response = (HttpServletResponse) res;
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    // 禁止缓存
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    response.setHeader("Cache-Control", "no-store");
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    response.setHeader("Pragrma", "no-cache");
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    response.setDateHeader("Expires", 0);
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    // 链接来源地址
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    String referer = request.getHeader("referer");
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    System.out.println("refer is"+referer);
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    System.out.println("serverName is"+request.getServerName());
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    if (referer == null || !referer.contains(request.getServerName())) {
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    /**
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    * 如果 链接地址来自其他网站，则返回错误图片
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    */
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    request.getRequestDispatcher("/error.jsp").forward(request, response);
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    } else {
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    /**
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    * 图片正常显示
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    */
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    chain.doFilter(request, response);
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    }
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    }
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50.  
    public void destroy() {
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    this.filterConfig = null;
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    }
53.  
     
54.  
    }