StderrApp.java
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上传日期:2018-01-08
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文件大小:2k
- /**
- * 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.hadoop.streaming;
- import java.io.*;
- /**
- * Output an arbitrary number of stderr lines before or after
- * consuming the keys/values from stdin.
- */
- public class StderrApp
- {
- /**
- * Print preWriteLines to stderr, pausing sleep ms between each
- * output, then consume stdin and echo it to stdout, then write
- * postWriteLines to stderr.
- */
- public static void go(int preWriteLines, int sleep, int postWriteLines) throws IOException {
- BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
- String line;
-
- while (preWriteLines > 0) {
- --preWriteLines;
- System.err.println("some stderr output before reading input, "
- + preWriteLines + " lines remaining, sleeping " + sleep);
- try {
- Thread.sleep(sleep);
- } catch (InterruptedException e) {}
- }
-
- while ((line = in.readLine()) != null) {
- System.out.println(line);
- }
-
- while (postWriteLines > 0) {
- --postWriteLines;
- System.err.println("some stderr output after reading input, lines remaining "
- + postWriteLines);
- }
- }
- public static void main(String[] args) throws IOException {
- if (args.length < 3) {
- System.err.println("Usage: StderrApp PREWRITE SLEEP POSTWRITE");
- return;
- }
- int preWriteLines = Integer.parseInt(args[0]);
- int sleep = Integer.parseInt(args[1]);
- int postWriteLines = Integer.parseInt(args[2]);
-
- go(preWriteLines, sleep, postWriteLines);
- }
- }