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Hibernate example source code file (Jdk.java)

This example Hibernate source code file (Jdk.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Hibernate tags/keywords

bufferedreader, file, file, inputstreamreader, io, ioexception, is_dos, java, javaversion, javaversion, jdk, jdk, runtimeexception, string, string

The Hibernate Jdk.java source code

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2011, Red Hat Inc. or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Inc.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */

package org.hibernate.gradle.util;

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;

import org.apache.tools.ant.taskdefs.condition.Os;
import org.apache.tools.ant.util.FileUtils;

/**
 * Models path information for a particular JDK install.
 * <p/>
 * Copied largely from {@link org.gradle.util.Jvm} and {@link org.apache.tools.ant.util.JavaEnvUtils}.  The main
 * difference is that those classes are static, based solely on the reported "java.home" sys prop.  Also, Ant's
 * JavaEnvUtils allows for use of either a JRE or JDK; we do not care about allowing for a JRE-only set up here.
 *
 *
 * @author Steve Ebersole
 */
public class Jdk {
	private static final boolean IS_DOS = Os.isFamily( "dos" );
	private static final FileUtils FILE_UTILS = FileUtils.getFileUtils();

	private final File jdkHome;
	private final JavaVersion version;
    public Jdk(){
        this(System.getenv( "JAVA_HOME" ));
    }

	public Jdk(File jdkHome) {
		this.jdkHome = jdkHome;
		if ( !jdkHome.exists() ) {
			throw new IllegalArgumentException( "Invalid path specified for JDK home; " + jdkHome.getAbsolutePath() + " did not exist" );
		}
		this.version = determineJdkVersion();
	}

	public Jdk(String jdkHomePath) {
		this( new File( jdkHomePath ) );
	}

    public File getJavaExecutable() {
        return new File( getJdkExecutable( "java" ) );
    }

	public File getJavacExecutable() {
		return new File( getJdkExecutable( "javac" ) );
	}

    public File getJavadocExecutable() {
        return new File( getJdkExecutable( "javadoc" ) );
    }

	public JavaVersion getVersion() {
		return version;
	}

	protected String getJdkExecutable(String command) {
		File executable = findInDir( jdkHome + "/bin", command );

		if ( executable == null ) {
			executable = findInDir( jdkHome + "/../bin", command );
		}

		if ( executable != null ) {
			return executable.getAbsolutePath();
		}
		else {
			// Unfortunately on Windows java.home doesn't always refer
			// to the correct location, so we need to fall back to
			// assuming java is somewhere on the PATH.
			return addExtension( command );
		}
	}

	private static File findInDir(String dirName, String commandName) {
		File dir = FILE_UTILS.normalize(dirName);
		File executable = null;
		if (dir.exists()) {
			executable = new File(dir, addExtension(commandName));
			if (!executable.exists()) {
				executable = null;
			}
		}
		return executable;
	}

	private static String addExtension(String command) {
		// This is the most common extension case - exe for windows and OS/2,
		// nothing for *nix.
		return command + (IS_DOS ? ".exe" : "");
	}

	private JavaVersion determineJdkVersion() {
		String javaVersionString = extractFromSunJdk();
		if ( javaVersionString == null ) {
			throw new RuntimeException( "Could not determine Java version" );
		}
		return new JavaVersion( javaVersionString );
	}

	private String extractFromSunJdk() {
		String version = null;
		final String key = "java version \"";
		try {
			final File javaCommand = getJavaExecutable();
			Process javaProcess = Runtime.getRuntime().exec( javaCommand.getAbsolutePath() + " -version" );

			try {
				BufferedReader br = new BufferedReader( new InputStreamReader( javaProcess.getErrorStream() ) );
				String line;
				while ( (line = br.readLine()) != null) {
					if ( version == null && line.startsWith( key ) ) {
						version = line.substring( key.length(), line.length() - 1 );
					}
				}
				br.close();

				br = new BufferedReader( new InputStreamReader( javaProcess.getInputStream() ) );
				while ( (line = br.readLine()) != null) {
					if ( version == null && line.startsWith( key ) ) {
						version = line.substring( key.length(), line.length() - 1 );
					}
				}
				br.close();
			}
			finally {
				javaProcess.destroy();
			}
		}
		catch ( IOException e ) {
			throw new RuntimeException( "Unable to determine Java version", e );
		}
		return version;
	}
}

Other Hibernate examples (source code examples)

Here is a short list of links related to this Hibernate Jdk.java source code file:

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