Go语言视频零基础入门到精通

javalearner

一个过滤敏感词的filter,看书学到的,小结之:    原理是将内容输出到response时,response将其缓存起来,在filter中替换,然后再输出到客户端浏览器.因为默认的response不能缓存输出内容,因此要自定义response,可以通过扩展HttpServletResponseWrapper 获得, import java.io.CharArrayWriter;
import java.io.IOException;
import java.io.PrintWriter; import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper; public class HttpCharacterResponseWrapper extends HttpServletResponseWrapper {  private CharArrayWriter charArrayWriter = new CharArrayWriter();  public HttpCharacterResponseWrapper(HttpServletResponse response) {
   super(response);
  }  @Override
  public PrintWriter getWriter() throws IOException {
   return new PrintWriter(charArrayWriter);
  }  public CharArrayWriter getCharArrayWriter() {
   return charArrayWriter;
  }
}  filter需要将自定义的response传到servlet中,代码如下: public class OutputReplaceFilter implements Filter {  private Properties pp = new Properties();  public void init(FilterConfig config) throws ServletException {
   String file = config.getInitParameter("file");
   String realPath = config.getServletContext().getRealPath(file);
   try {
    pp.load(new FileInputStream(realPath));
   } catch (IOException e) {
   }
  }  public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {   // 自定义的 response
   HttpCharacterResponseWrapper response = new HttpCharacterResponseWrapper(
     (HttpServletResponse) res);   // 提交给 Servlet 或者下一个 Filter
   chain.doFilter(req, response);   // 得到缓存在自定义 response 中的输出内容
   String output = response.getCharArrayWriter().toString();   // 修改，替换
   for (Object obj : pp.keySet()) {
    String key = (String) obj;
    output = output.replace(key, pp.getProperty(key));
   }
   // 输出
   PrintWriter out = res.getWriter();
   out.write(output);
   out.println("<!-- Generated at " + new java.util.Date() + " -->");
  }  public void destroy() {
  }