/** * 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. */ package org.apache.zeppelin.file; import java.net.URL; import java.net.HttpURLConnection; import java.io.BufferedReader; import java.io.InputStreamReader; import javax.ws.rs.core.UriBuilder; import org.slf4j.Logger; /** * Definition and HTTP invocation methods for all WebHDFS commands * */ public class HDFSCommand { /** * Type of HTTP request */ public enum HttpType { GET, PUT } /** * Definition of WebHDFS operator */ public class Op { public String op; public HttpType cmd; public int minArgs; public Op(String op, HttpType cmd, int minArgs) { this.op = op; this.cmd = cmd; this.minArgs = minArgs; } } /** * Definition of argument to an operator */ public class Arg { public String key; public String value; public Arg(String key, String value) { this.key = key; this.value = value; } } // How to connect to WebHDFS String url = null; String user = null; int maxLength = 0; Logger logger; // Define all the commands available public Op getFileStatus = new Op("GETFILESTATUS", HttpType.GET, 0); public Op listStatus = new Op("LISTSTATUS", HttpType.GET, 0); public HDFSCommand(String url, String user, Logger logger, int maxLength) { super(); this.url = url; this.user = user; this.maxLength = maxLength; this.logger = logger; } public String checkArgs(Op op, String path, Arg[] args) throws Exception { if (op == null || path == null || (op.minArgs > 0 && (args == null || args.length != op.minArgs))) { String a = ""; a = (op != null) ? a + op.op + "\n" : a; a = (path != null) ? a + path + "\n" : a; a = (args != null) ? a + args + "\n" : a; return a; } return null; } // The operator that runs all commands public String runCommand(Op op, String path, Arg[] args) throws Exception { // Check arguments String error = checkArgs(op, path, args); if (error != null) { logger.error("Bad arguments to command: " + error); return "ERROR: BAD ARGS"; } // Build URI UriBuilder builder = UriBuilder .fromPath(url) .path(path) .queryParam("op", op.op); if (args != null) { for (Arg a : args) { builder = builder.queryParam(a.key, a.value); } } java.net.URI uri = builder.build(); // Connect and get response string URL hdfsUrl = uri.toURL(); HttpURLConnection con = (HttpURLConnection) hdfsUrl.openConnection(); if (op.cmd == HttpType.GET) { con.setRequestMethod("GET"); int responseCode = con.getResponseCode(); logger.info("Sending 'GET' request to URL : " + hdfsUrl); logger.info("Response Code : " + responseCode); BufferedReader in = new BufferedReader( new InputStreamReader(con.getInputStream())); String inputLine; StringBuffer response = new StringBuffer(); int i = 0; while ((inputLine = in.readLine()) != null) { if (inputLine.length() < maxLength) response.append(inputLine); i++; if (i >= maxLength) break; } in.close(); return response.toString(); } return null; } }