/*
* Copyright 2001-2004 The Apache Software Foundation.
*
* Licensed 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 org.apache.commons.digester.Digester;
import org.apache.commons.digester.plugins.PluginRules;
import org.apache.commons.digester.plugins.PluginCreateRule;
import java.io.*;
/**
* This is the "main" class for this example.
* <p>
* It can be run via <code>java Pipeline config-file-name</code>.
* <p>
* The specified config file is parsed using the Apache Commons Digester.
* This config file specifies an input file to be read, a number of
* user-defined transform classes to be instantiated and configured from
* the config file, and an output file.
* <p>
* The contents of the input file is then passed to the transform objects,
* and the output written to the output file.
* <p>
* Why not try writing your own transform classes, and plugging them in.
* Note that they can configure themselves from the main config file in
* any manner the Digester supports, without changing a line of this
* application.
*/
public class Pipeline {
private String source;
private String dest;
private Transform transformer;
public static void main(String[] args) {
if (args.length != 1) {
System.err.println("usage: pipeline config-file");
System.exit(-1);
}
String configFile = args[0];
Digester digester = new Digester();
PluginRules rc = new PluginRules();
digester.setRules(rc);
digester.addObjectCreate("pipeline", Pipeline.class);
digester.addCallMethod("pipeline/source", "setSource", 1);
digester.addCallParam("pipeline/source", 0, "file");
PluginCreateRule pcr = new PluginCreateRule(Transform.class);
digester.addRule("pipeline/transform", pcr);
digester.addSetNext("pipeline/transform", "setTransform");
digester.addCallMethod("pipeline/destination", "setDest", 1);
digester.addCallParam("pipeline/destination", 0, "file");
Pipeline pipeline = null;
try {
pipeline = (Pipeline) digester.parse(configFile);
}
catch(Exception e) {
System.err.println("oops exception occurred during parse.");
e.printStackTrace();
System.exit(-1);
}
try {
pipeline.execute();
}
catch (Exception e) {
System.err.println("oops exception occurred during pipeline execution.");
e.printStackTrace();
System.exit(-1);
}
}
public void setSource(String source) {
this.source = source;
}
public void setDest(String dest) {
this.dest = dest;
}
public void setTransform(Transform transformer) {
this.transformer = transformer;
}
private void execute() throws IOException {
FileReader inRaw = new FileReader(source);
FileWriter out = new FileWriter(dest);
BufferedReader in = new BufferedReader(inRaw);
while(true) {
String inStr = in.readLine();
if (inStr==null)
break;
String outStr = transformer.transform(inStr);
out.write(outStr);
out.write('\n');
}
inRaw.close();
out.close();
System.out.println(
"Contents of file " + source + " have been transformed, and"
+ " written to file " + dest + ".");
}
}