org.diffkit.common.DKRuntime.java Source code

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Here is the source code for org.diffkit.common.DKRuntime.java

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/**
 * Copyright 2010-2011 Joseph Panico
 *
 * 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.
 */
package org.diffkit.common;

import java.io.File;
import java.net.URL;
import java.security.CodeSource;
import java.security.ProtectionDomain;

import org.apache.commons.io.FileUtils;
import org.apache.commons.lang.BooleanUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * @author jpanico
 */
public class DKRuntime {
    public static final String IS_TEST_PROPERTY = "isTest";
    public static final String DIFFKIT_HOME_PROPERTY = "DIFFKIT_HOME";
    private static final String CONF_DIR_NAME = "conf";
    private static final String DROPIN_DIR_NAME = "dropin";
    private static final String USER_LOG_CATEGORY_KEY = "user";
    private static final String NULL_STRING = new String();

    private static final DKRuntime _instance = new DKRuntime();

    private String _applicationName;
    private File _diffKitHome;
    private File _confDir;
    private File _dropinDir;
    private Boolean _isTest;
    private Logger _userLog;

    private DKRuntime() {
    }

    public static DKRuntime getInstance() {
        return _instance;
    }

    public File getDiffKitHome() {
        if (_diffKitHome != null)
            return _diffKitHome;
        _diffKitHome = this.findDiffKitHome();
        return _diffKitHome;
    }

    public File getConfDir() {
        if (_confDir != null)
            return _confDir;
        File home = DKRuntime.getInstance().getDiffKitHome();
        _confDir = new File(home, CONF_DIR_NAME);
        if (!_confDir.isDirectory())
            System.out.printf("no conf dir at->%s.\n", _confDir);
        return _confDir;
    }

    public File getDropinDir() {
        if (_dropinDir != null)
            return _dropinDir;
        File home = DKRuntime.getInstance().getDiffKitHome();
        _dropinDir = new File(home, DROPIN_DIR_NAME);
        if (!_dropinDir.isDirectory())
            System.out.printf("no dropin dir at->%s.\n", _dropinDir);
        return _dropinDir;
    }

    public Boolean getIsTest() {
        if (_isTest != null)
            return _isTest;
        _isTest = BooleanUtils.toBoolean(System.getProperty(IS_TEST_PROPERTY));
        return _isTest;
    }

    public void setIsTest(Boolean isTest_) {
        _isTest = isTest_;
    }

    /**
     * a 3 level cascade <br/>
     * 1) if DIFFKIT_HOME_PROPERTY Java property is set, use that. Property
     * always overrides any other setting <br/>
     * 2) if the receiver was loaded from an executable jar, and the name of that
     * jar matches (contains) the .applicationName, then use the dir that
     * (application) jar is in. <br/>
     * 3) CWD (user.dir).
     * 
     * @return always guaranteed to return a non-null value that is at least
     *         fairly credible
     */
    private File findDiffKitHome() {
        String propertyValue = System.getProperty(DIFFKIT_HOME_PROPERTY);
        if (propertyValue != null)
            return new File(propertyValue);
        File applicationLocation = this.findApplicationLocation();
        if (applicationLocation != null)
            return applicationLocation;
        return new File(System.getProperty("user.dir"));
    }

    private File findApplicationLocation() {
        String applicationName = this.getApplicationName();
        if (applicationName == null)
            return null;
        URL location = this.getClassLocation();
        if (location == null)
            return null;
        if (!location.toExternalForm().toUpperCase().contains(applicationName.toUpperCase()))
            return null;
        File applicationFile = FileUtils.toFile(location);
        return applicationFile.getParentFile();
    }

    private URL getClassLocation() {
        ProtectionDomain protectionDomain = this.getClass().getProtectionDomain();
        CodeSource codeSource = protectionDomain.getCodeSource();
        return codeSource.getLocation();
    }

    public String getApplicationName() {
        if (_applicationName == NULL_STRING)
            return null;
        return _applicationName;
    }

    public void setApplicationName(String applicationName_) {
        if (_applicationName != null)
            throw new IllegalStateException(
                    String.format("applicationName_ already assigned->%s cannot be reassigned to->%s",
                            _applicationName, applicationName_));
        if (applicationName_ == null)
            _applicationName = NULL_STRING;
        else
            _applicationName = applicationName_;
    }

    public Logger getUserLog() {
        if (_userLog != null)
            return _userLog;
        _userLog = LoggerFactory.getLogger(USER_LOG_CATEGORY_KEY);
        return _userLog;
    }
}