Java tutorial
package org.apache.blur.gui; /** * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import java.io.File; import java.io.FileInputStream; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.io.IOUtils; @SuppressWarnings("serial") public class LogServlet extends HttpServlet { private final String _dir; public LogServlet(String dir) { _dir = dir; } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String filename = request.getParameter("file"); response.setContentType("text/plain"); response.setHeader("Content-disposition", "attachment; filename=" + filename); if (filename.contains("/")) { throw new IOException("Filename [" + filename + "] with '/' is not allowed."); } File file = new File(new File(_dir), filename); if (!file.exists()) { throw new IOException("Filename [" + filename + "] doe snot exist."); } FileInputStream input = new FileInputStream(file); ServletOutputStream outputStream = response.getOutputStream(); IOUtils.copy(input, outputStream); input.close(); outputStream.flush(); } }