worldwind学习笔记-1-Configuration

做的一个小的cs程序中一直嵌套worldwind使用，由于使用的是worldwind的java版，结果cs程序也一直是用java的swing开发的，swing在几年前确实很强大，但是现在给人感觉蛮没落的，几乎很少见到swing开发的软件了，不过还好，我们的用户不考虑我们使用什么系统，也可以吹吹牛逼说，我们的程序可以在mac下，linux下，windows下运行，当然，事实也确实如此。

不过我们使用worldwind一直局限在使用它的功能上，一直没能深入进去研究其架构等，我觉得，ww这款sdk功能真的很强大啊，但是我们只用到了collada下的东西做模型，surfaceImage做贴图，animation做3D云，surface下还用了写东西，用来简单的画画图形，画画path等，当然，我们也使用了OpelGL中的一些功能，画了爆炸，降雨等效果，但是我感觉都不是很理想，显然，OpenGL是基础，这个也得会，才能看懂worldwind中的一些代码。

好了，一些基础信息介绍完毕，我想开始去深入挖掘下ww内的东西，尝试学习他，而不仅仅是使用它。

我选择使用HelloWorldWind.java这个类作为入口，因为它只有一个最基本的球，通过阅读代码去学习，我觉得还是可以有较快的进步的。

先来看下这个类的代码。

package gov.nasa.worldwindx;import gov.nasa.worldwind.BasicModel;import gov.nasa.worldwind.Configuration;import gov.nasa.worldwind.awt.WorldWindowGLCanvas;public class HelloWorldWind{    // An inner class is used rather than directly subclassing JFrame in the main class so    // that the main can configure system properties prior to invoking Swing. This is    // necessary for instance on OS X (Macs) so that the application name can be specified.    private static class AppFrame extends javax.swing.JFrame    {        public AppFrame()        {                     this.setDefaultCloseOperation(EXIT_ON_CLOSE);            WorldWindowGLCanvas wwd = new WorldWindowGLCanvas();            wwd.setPreferredSize(new java.awt.Dimension(1000, 800));            this.getContentPane().add(wwd, java.awt.BorderLayout.CENTER);                         wwd.setModel(new BasicModel());            this.pack();        }    }    public static void main(String[] args)    {        if (Configuration.isMacOS())        {            System.setProperty("com.apple.mrj.application.apple.menu.about.name", "Hello World Wind");        }        final AppFrame app=new AppFrame();        java.awt.EventQueue.invokeLater(new Runnable()        {            public void run()            {                // Create an AppFrame and immediately make it visible. As per Swing convention, this                // is done within an invokeLater call so that it executes on an AWT thread.                                app.setVisible(true);            }        });    }}

代码非常的简单，就是构建了一个JFrame，然后调用awt包中的EventQueue来执行，之所以setvisible是单独执行的，是因为worldwind底层要调用jogl，从而用opengl画图。这个代码我曾尝试将app.setVisible拿出来执行，而不是放在EventQueue里面。这种情况在win32下可以正常，在win64下就不正常，按照EventQueue的解释（awt是单线程的所有awt的组件只能在事件处理线程中访问，从而保证组件状态的可确定性）。。。。。这一块我只想说四个字：不觉明历。。。。貌似是和Java内存模型中的，所谓的无关对象的执行顺序会重排也有一定的关系吧。谁能给点这方面的建议就好了。。

再贴一段别人的解释：使用eventqueue.invokelater()好处是显而易见的，这个方法调用完毕后，它会被销毁，因为匿名内部类是作为临时变量存在的，给它分配的内存在此时会被释放。这个对于只需要在一个地方使用时可以节省内存，而且这个类是不可以被其它的方法或类使用的，只能被EventQueue.invokeLater()来使用。但如果你需要一个在很多地方都能用到的类，而不是只在某一个类里面或者方法里用的话，定义成匿名内部类显然是不可取的。 是，runnable是跟线程相关的类。
swingutilities.invokelater()和eventqueue.invokelater(),后者可以不干扰到事件分发线程.SwingUtilities版只是一个薄薄的封装方法，它直接转而调用 EventQueue.invokeLater。因为Swing框架本身经常调用SwingUtilities，使用SwingUtilities可以减少程序引入的类。

对于如此多的概念，我感觉好无力，还是看Main里面干嘛了吧。

if (Configuration.isMacOS()) 第一句，判断是不是苹果的操作系统，我不是苹果机，爱我吊事。。。不过，Configuration却是一个非常非常重要的东西，它是不可忽略的。

Configuration的代码如下。

/* * Copyright (C) 2012 United States Government as represented by the Administrator of the * National Aeronautics and Space Administration. * All Rights Reserved. */package gov.nasa.worldwind;import gov.nasa.worldwind.avlist.AVKey;import gov.nasa.worldwind.geom.Angle;import gov.nasa.worldwind.util.*;import org.w3c.dom.*;import javax.media.opengl.GLProfile;import javax.xml.xpath.*;import java.io.*;import java.util.*;import java.util.logging.Level;/** * This class manages the initial World Wind configuration. It reads World Wind configuration files and registers their * contents. Configurations files contain the names of classes to create at run-time, the initial model definition, * including the globe, elevation model and layers, and various control quantities such as cache sizes and data * retrieval timeouts. * <p/> * The Configuration class is a singleton, but its instance is not exposed publicly. It is addressed only via static * methods of the class. It is constructed upon first use of any of its static methods. * <p/> * When the Configuration class is first instantiated it reads the XML document <code>config/worldwind.xml</code> and * registers all the information there. The information can subsequently be retrieved via the class' various * <code>getValue</code> methods. Many World Wind start-up objects query this information to determine the classes to * create. For example, the first World Wind object created by an application is typically a {@link * gov.nasa.worldwind.awt.WorldWindowGLCanvas}. During construction that class causes World Wind's internal classes to * be constructed, using the names of those classes drawn from the Configuration singleton, this class. * <p/> * The default World Wind configuration document is <code>config/worldwind.xml</code>. This can be changed by setting * the Java property <code>gov.nasa.worldwind.config.file</code> to a different file name or a valid URL prior to * creating any World Wind object or invoking any static methods of World Wind classes, including the Configuration * class. When an application specifies a different configuration location it typically does so in its main method prior * to using World Wind. If a file is specified its location must be on the classpath. (The contents of application and * World Wind jar files are typically on the classpath, in which case the configuration file may be in the jar file.) * <p/> * Additionally, an application may set another Java property, <code>gov.nasa.worldwind.app.config.document</code>, to a * file name or URL whose contents contain configuration values to override those of the primary configuration document. * World Wind overrides only those values in this application document, it leaves all others to the value specified in * the primary document. Applications usually specify an override document in order to specify the initial layers in the * model. * <p/> * See <code>config/worldwind.xml</code> for documentation on setting configuration values. * <p/> * Configuration values can also be set programatically via {@link Configuration#setValue(String, Object)}, but they are * not retroactive so affect only Configuration queries made subsequent to setting the value. * <p/> * <em>Note:</em> Prior to September of 2009, configuration properties were read from the file * <code>config/worldwind.properties</code>. An alternate file could be specified via the * <code>gov.nasa.worldwind.config.file</code> Java property. These mechanisms remain available but are deprecated. * World Wind no longer contains a <code>worldwind.properties</code> file. If <code>worldwind.properties</code> or its * replacement as specified through the Java property exists at run-time and can be found via the classpath, * configuration values specified by that mechanism are given precedence over values specified by the new mechanism. * * @version $Id: Configuration.java 1171 2013-02-11 21:45:02Z dcollins $ * @author Tom Gaskins */public class Configuration // Singleton{    public static final String DEFAULT_LOGGER_NAME = "gov.nasa.worldwind";    private static final String CONFIG_PROPERTIES_FILE_NAME = "config/worldwind.properties";    private static final String CONFIG_FILE_PROPERTY_KEY = "gov.nasa.worldwind.config.file";    private static final String CONFIG_WW_DOCUMENT_KEY = "gov.nasa.worldwind.config.document";    private static final String CONFIG_WW_DOCUMENT_NAME = "config/worldwind.xml";    private static final String CONFIG_APP_DOCUMENT_KEY = "gov.nasa.worldwind.app.config.document";    private static Configuration ourInstance = new Configuration();    private static Configuration getInstance()    {        return ourInstance;    }    private final Properties properties;    private final ArrayList<Document> configDocs = new ArrayList<Document>();    /** Private constructor invoked only internally. */    private Configuration()    {        this.properties = initializeDefaults();        // Load the app's configuration if there is one        try        {            String appConfigLocation = System.getProperty(CONFIG_APP_DOCUMENT_KEY);            if (appConfigLocation != null)                this.loadConfigDoc(System.getProperty(CONFIG_APP_DOCUMENT_KEY)); // Load app's config first        }        catch (Exception e)        {            Logging.logger(DEFAULT_LOGGER_NAME).log(Level.WARNING, "Configuration.ConfigNotFound",                System.getProperty(CONFIG_APP_DOCUMENT_KEY));            // Don't stop if the app config file can't be found or parsed        }        try        {            // Load the default configuration            this.loadConfigDoc(System.getProperty(CONFIG_WW_DOCUMENT_KEY, CONFIG_WW_DOCUMENT_NAME));            // Load config properties, ensuring that the app's config takes precedence over wwj's            for (int i = this.configDocs.size() - 1; i >= 0; i--)            {                this.loadConfigProperties(this.configDocs.get(i));            }        }        catch (Exception e)        {            Logging.logger(DEFAULT_LOGGER_NAME).log(Level.WARNING, "Configuration.ConfigNotFound",                System.getProperty(CONFIG_WW_DOCUMENT_KEY));        }        // To support old-style configuration, read an existing config properties file and give the properties        // specified there precedence.        this.initializeCustom();    }    private void loadConfigDoc(String configLocation)    {        if (!WWUtil.isEmpty(configLocation))        {            Document doc = WWXML.openDocument(configLocation);            if (doc != null)            {                this.configDocs.add(doc);//                this.loadConfigProperties(doc);            }        }    }    private void insertConfigDoc(String configLocation)    {        if (!WWUtil.isEmpty(configLocation))        {            Document doc = WWXML.openDocument(configLocation);            if (doc != null)            {                this.configDocs.add(0, doc);                this.loadConfigProperties(doc);            }        }    }    private void loadConfigProperties(Document doc)    {        try        {            XPath xpath = WWXML.makeXPath();            NodeList nodes = (NodeList) xpath.evaluate("/WorldWindConfiguration/Property", doc, XPathConstants.NODESET);            if (nodes == null || nodes.getLength() == 0)                return;            for (int i = 0; i < nodes.getLength(); i++)            {                Node node = nodes.item(i);                String prop = xpath.evaluate("@name", node);                String value = xpath.evaluate("@value", node);                if (WWUtil.isEmpty(prop))// || WWUtil.isEmpty(value))                    continue;                this.properties.setProperty(prop, value);            }        }        catch (XPathExpressionException e)        {            Logging.logger(DEFAULT_LOGGER_NAME).log(Level.WARNING, "XML.ParserConfigurationException");        }    }    private Properties initializeDefaults()    {        Properties defaults = new Properties();        java.util.TimeZone tz = java.util.Calendar.getInstance().getTimeZone();        if (tz != null)            defaults.setProperty(AVKey.INITIAL_LONGITUDE,                Double.toString(                    Angle.fromDegrees(180.0 * tz.getOffset(System.currentTimeMillis()) / (12.0 * 3.6e6)).degrees));        return defaults;    }    private void initializeCustom()    {        // IMPORTANT NOTE: Always use the single argument version of Logging.logger in this method because the non-arg        // method assumes an instance of Configuration already exists.        String configFileName = System.getProperty(CONFIG_FILE_PROPERTY_KEY, CONFIG_PROPERTIES_FILE_NAME);        try        {            java.io.InputStream propsStream = null;            File file = new File(configFileName);            if (file.exists())            {                try                {                    propsStream = new FileInputStream(file);                }                catch (FileNotFoundException e)                {                    Logging.logger(DEFAULT_LOGGER_NAME).log(Level.FINEST, "Configuration.LocalConfigFileNotFound",                        configFileName);                }            }            if (propsStream == null)            {                propsStream = this.getClass().getResourceAsStream("/" + configFileName);            }            if (propsStream != null)                this.properties.load(propsStream);        }        // Use a named logger in all the catch statements below to prevent Logger from calling back into        // Configuration when this Configuration instance is not yet fully instantiated.        catch (IOException e)        {            Logging.logger(DEFAULT_LOGGER_NAME).log(Level.SEVERE, "Configuration.ExceptionReadingPropsFile", e);        }    }    public static void insertConfigurationDocument(String fileName)    {        getInstance().insertConfigDoc(fileName);    }    /**     * Return as a string the value associated with a specified key.     *     * @param key          the key for the desired value.     * @param defaultValue the value to return if the key does not exist.     *     * @return the value associated with the key, or the specified default value if the key does not exist.     */    public static synchronized String getStringValue(String key, String defaultValue)    {        String v = getStringValue(key);        return v != null ? v : defaultValue;    }    /**     * Return as a string the value associated with a specified key.     *     * @param key the key for the desired value.     *     * @return the value associated with the key, or null if the key does not exist.     */    public static synchronized String getStringValue(String key)    {        Object o = getInstance().properties.getProperty(key);        return o != null ? o.toString() : null;    }    /**     * Return as an Integer the value associated with a specified key.     *     * @param key          the key for the desired value.     * @param defaultValue the value to return if the key does not exist.     *     * @return the value associated with the key, or the specified default value if the key does not exist or is not an     *         Integer or string representation of an Integer.     */    public static synchronized Integer getIntegerValue(String key, Integer defaultValue)    {        Integer v = getIntegerValue(key);        return v != null ? v : defaultValue;    }    /**     * Return as an Integer the value associated with a specified key.     *     * @param key the key for the desired value.     *     * @return the value associated with the key, or null if the key does not exist or is not an Integer or string     *         representation of an Integer.     */    public static synchronized Integer getIntegerValue(String key)    {        String v = getStringValue(key);        if (v == null)            return null;        try        {            return Integer.parseInt(v);        }        catch (NumberFormatException e)        {            Logging.logger().log(Level.SEVERE, "Configuration.ConversionError", v);            return null;        }    }    /**     * Return as an Long the value associated with a specified key.     *     * @param key          the key for the desired value.     * @param defaultValue the value to return if the key does not exist.     *     * @return the value associated with the key, or the specified default value if the key does not exist or is not a     *         Long or string representation of a Long.     */    public static synchronized Long getLongValue(String key, Long defaultValue)    {        Long v = getLongValue(key);        return v != null ? v : defaultValue;    }    /**     * Return as an Long the value associated with a specified key.     *     * @param key the key for the desired value.     *     * @return the value associated with the key, or null if the key does not exist or is not a Long or string     *         representation of a Long.     */    public static synchronized Long getLongValue(String key)    {        String v = getStringValue(key);        if (v == null)            return null;        try        {            return Long.parseLong(v);        }        catch (NumberFormatException e)        {            Logging.logger().log(Level.SEVERE, "Configuration.ConversionError", v);            return null;        }    }    /**     * Return as an Double the value associated with a specified key.     *     * @param key          the key for the desired value.     * @param defaultValue the value to return if the key does not exist.     *     * @return the value associated with the key, or the specified default value if the key does not exist or is not an     *         Double or string representation of an Double.     */    public static synchronized Double getDoubleValue(String key, Double defaultValue)    {        Double v = getDoubleValue(key);        return v != null ? v : defaultValue;    }    /**     * Return as an Double the value associated with a specified key.     *     * @param key the key for the desired value.     *     * @return the value associated with the key, or null if the key does not exist or is not an Double or string     *         representation of an Double.     */    public static synchronized Double getDoubleValue(String key)    {        String v = getStringValue(key);        if (v == null)            return null;        try        {            return Double.parseDouble(v);        }        catch (NumberFormatException e)        {            Logging.logger().log(Level.SEVERE, "Configuration.ConversionError", v);            return null;        }    }    /**     * Return as a Boolean the value associated with a specified key.     * <p/>     * Valid values for true are '1' or anything that starts with 't' or 'T'. ie. 'true', 'True', 't' Valid values for     * false are '0' or anything that starts with 'f' or 'F'. ie. 'false', 'False', 'f'     *     * @param key          the key for the desired value.     * @param defaultValue the value to return if the key does not exist.     *     * @return the value associated with the key, or the specified default value if the key does not exist or is not a     *         Boolean or string representation of an Boolean.     */    public static synchronized Boolean getBooleanValue(String key, Boolean defaultValue)    {        Boolean v = getBooleanValue(key);        return v != null ? v : defaultValue;    }    /**     * Return as a Boolean the value associated with a specified key.     * <p/>     * Valid values for true are '1' or anything that starts with 't' or 'T'. ie. 'true', 'True', 't' Valid values for     * false are '0' or anything that starts with 'f' or 'F'. ie. 'false', 'False', 'f'     *     * @param key the key for the desired value.     *     * @return the value associated with the key, or null if the key does not exist or is not a Boolean or string     *         representation of an Boolean.     */    public static synchronized Boolean getBooleanValue(String key)    {        String v = getStringValue(key);        if (v == null)            return null;        if (v.trim().toUpperCase().startsWith("T") || v.trim().equals("1"))        {            return true;        }        else if (v.trim().toUpperCase().startsWith("F") || v.trim().equals("0"))        {            return false;        }        else        {            Logging.logger().log(Level.SEVERE, "Configuration.ConversionError", v);            return null;        }    }    /**     * Determines whether a key exists in the configuration.     *     * @param key the key of interest.     *     * @return true if the key exists, otherwise false.     */    public static synchronized boolean hasKey(String key)    {        return getInstance().properties.contains(key);    }    /**     * Removes a key and its value from the configuration if the configuration contains the key.     *     * @param key the key of interest.     */    public static synchronized void removeKey(String key)    {        getInstance().properties.remove(key);    }    /**     * Adds a key and value to the configuration, or changes the value associated with the key if the key is already in     * the configuration.     *     * @param key   the key to set.     * @param value the value to associate with the key.     */    public static synchronized void setValue(String key, Object value)    {        getInstance().properties.put(key, value.toString());    }    // OS, user, and run-time specific system properties. //    /**     * Returns the path to the application's current working directory.     *     * @return the absolute path to the application's current working directory.     */    public static String getCurrentWorkingDirectory()    {        String dir = System.getProperty("user.dir");        return (dir != null) ? dir : ".";    }    /**     * Returns the path to the application user's home directory.     *     * @return the absolute path to the application user's home directory.     */    public static String getUserHomeDirectory()    {        String dir = System.getProperty("user.home");        return (dir != null) ? dir : ".";    }    /**     * Returns the path to the operating system's temp directory.     *     * @return the absolute path to the operating system's temporary directory.     */    public static String getSystemTempDirectory()    {        String dir = System.getProperty("java.io.tmpdir");        return (dir != null) ? dir : ".";    }    /**     * Returns the path to the current user's application data directory. The path returned depends on the operating     * system on which the Java Virtual Machine is running. The following table provides the path for all supported     * operating systems:     * <p/>     * <table> <tr><th>Operating System</th><th>Path</th></tr> <tr><td>Mac OS X</td><td>~/Library/Application     * Support</td></tr> <tr><td>Windows</td><td>~\\Application Data</td></tr> <tr><td>Linux, Unix,     * Solaris</td><td>~/</td></tr> </table>     *     * @return the absolute path to the current user's application data directory.     */    public static String getCurrentUserAppDataDirectory()    {        if (isMacOS())        {            // Return a path that Mac OS X has designated for app-specific data and support files. See the following URL            // for details:            // http://developer.apple.com/library/mac/#documentation/FileManagement/Conceptual/FileSystemProgrammingGUide/MacOSXDirectories/MacOSXDirectories.html#//apple_ref/doc/uid/TP40010672-CH10-SW1            return getUserHomeDirectory() + "/Library/Application Support";        }        else if (isWindowsOS())        {            return getUserHomeDirectory() + "\\Application Data";        }        else if (isLinuxOS() || isUnixOS() || isSolarisOS())        {            return getUserHomeDirectory();        }        else        {            String msg = Logging.getMessage("generic.UnknownOperatingSystem");            Logging.logger().fine(msg);            return null;        }    }    /**     * Determines whether the operating system is a Mac operating system.     *     * @return true if the operating system is a Mac operating system, otherwise false.     */    public static boolean isMacOS()    {        String osName = System.getProperty("os.name");        return osName != null && osName.toLowerCase().contains("mac");    }    /**     * Determines whether the operating system is Windows operating system.     *     * @return true if the operating system is a Windows operating system, otherwise false.     */    public static boolean isWindowsOS()    {        String osName = System.getProperty("os.name");        return osName != null && osName.toLowerCase().contains("windows");    }    /**     * Determines whether the operating system is Windows XP operating system.     *     * @return true if the operating system is a Windows XP operating system, otherwise false.     */    public static boolean isWindowsXPOS()    {        String osName = System.getProperty("os.name");        return osName != null && osName.toLowerCase().contains("windows") && osName.contains("xp");    }    /**     * Determines whether the operating system is Windows Vista operating system.     *     * @return true if the operating system is a Windows Vista operating system, otherwise false.     */    public static boolean isWindowsVistaOS()    {        String osName = System.getProperty("os.name");        return osName != null && osName.toLowerCase().contains("windows") && osName.contains("vista");    }    /**     * Determines whether the operating system is Windows 7 operating system.     *     * @return true if the operating system is a Windows Vista operating system, otherwise false.     */    public static boolean isWindows7OS()    {        String osName = System.getProperty("os.name");        return osName != null && osName.toLowerCase().contains("windows") && osName.contains("7");    }    /**     * Determines whether the operating system is Linux operating system.     *     * @return true if the operating system is a Linux operating system, otherwise false.     */    public static boolean isLinuxOS()    {        String osName = System.getProperty("os.name");        return osName != null && osName.toLowerCase().contains("linux");    }    /**     * Determines whether the operating system is Unix operating system.     *     * @return true if the operating system is a Unix operating system, otherwise false.     */    public static boolean isUnixOS()    {        String osName = System.getProperty("os.name");        return osName != null && osName.toLowerCase().contains("unix");    }    /**     * Determines whether the operating system is Solaris operating system.     *     * @return true if the operating system is a Solaris operating system, otherwise false.     */    public static boolean isSolarisOS()    {        String osName = System.getProperty("os.name");        return osName != null && osName.toLowerCase().contains("solaris");    }    /**     * Returns the version of the Java virtual machine.     *     * @return the Java virtual machine version.     */    public static float getJavaVersion()    {        float ver = 0f;        String s = System.getProperty("java.specification.version");        if (null == s || s.length() == 0)            s = System.getProperty("java.version");        try        {            ver = Float.parseFloat(s.trim());        }        catch (NumberFormatException ignore)        {        }        return ver;    }    /**     * Returns the highest OpenGL profile available on the current graphics device that is compatible with World Wind.     * The returned profile favors hardware acceleration over software acceleration. With JOGL version 2.0-rc11, this     * returns the highest available profile from the following list:     * <p/>     * <ul> <li>OpenGL compatibility profile 4.x</li> <li>OpenGL compatibility profile 3.x</li> <li>OpenGL profile 1.x     * up to 3.0</li> </ul>     *     * @return the highest compatible OpenGL profile.     */    public static GLProfile getMaxCompatibleGLProfile()    {        return GLProfile.getMaxFixedFunc(true); // Favor a hardware rasterizer.    }    /**     * Returns a specified element of an XML configuration document.     *     * @param xpathExpression an XPath expression identifying the element of interest.     *     * @return the element of interest if the XPath expression is valid and the element exists, otherwise null.     *     * @throws NullPointerException if the XPath expression is null.     */    public static Element getElement(String xpathExpression)    {        XPath xpath = WWXML.makeXPath();        for (Document doc : getInstance().configDocs)        {            try            {                Node node = (Node) xpath.evaluate(xpathExpression, doc.getDocumentElement(), XPathConstants.NODE);                if (node != null)                    return (Element) node;            }            catch (XPathExpressionException e)            {                return null;            }        }        return null;    }}

很轻松的在前几行就可以看到，这是单列的，整个程序就此一家，别无他处，所有的方法几乎都是static声明的，外部可以直接调用。

    private static Configuration getInstance()    {        return ourInstance;    }

其所返回的ourInstance在这个方法的上面声明的，也是static的，并且调用了私有的构造参数初始化。

构造函数中首先就是先给Properties初始化，这个对象是util包中的，用于存储一些属性变量。

private Properties initializeDefaults()    {        Properties defaults = new Properties();        java.util.TimeZone tz = java.util.Calendar.getInstance().getTimeZone();        if (tz != null)            defaults.setProperty(AVKey.INITIAL_LONGITUDE,                Double.toString(                    Angle.fromDegrees(180.0 * tz.getOffset(System.currentTimeMillis()) / (12.0 * 3.6e6)).degrees));        return defaults;    }

这段代码，给defaults增加了一个开始的经纬度，这个经纬度，是根据当前程序所运行的国家的时区以及当前时间，以及180分成12个时区，每个时区所分的时间等信息计算得到的，我的结果是120°。

之后它在try中开始载入配置文件：

String appConfigLocation = System.getProperty(CONFIG_APP_DOCUMENT_KEY);
            if (appConfigLocation != null)
                this.loadConfigDoc(System.getProperty(CONFIG_APP_DOCUMENT_KEY));

appConfiguration的结果是null，所以不执行哈。

再然后有一个 this.loadConfigDoc(System.getProperty(CONFIG_WW_DOCUMENT_KEY, CONFIG_WW_DOCUMENT_NAME));

追一下System的源代码，里面还有一层，最终找到这样的代码

public String getProperty(String key, String defaultValue) {
        String val = getProperty(key);
        return (val == null) ? defaultValue : val;
    }

loadConfigDoc这个方法，是读取xml文件的，这个里面深入下，可以看到有趣的东西，就是

public static Document openDocument(Object docSource)    {        if (docSource == null || WWUtil.isEmpty(docSource))        {            String message = Logging.getMessage("nullValue.DocumentSourceIsNull");            throw new IllegalArgumentException(message);        }        if (docSource instanceof URL)        {            return openDocumentURL((URL) docSource);        }        else if (docSource instanceof InputStream)        {            return openDocumentStream((InputStream) docSource);        }        else if (docSource instanceof File)        {            return openDocumentFile(((File) docSource).getPath(), null);        }        else if (!(docSource instanceof String))        {            String message = Logging.getMessage("generic.UnrecognizedSourceType", docSource.toString());            throw new IllegalArgumentException(message);        }        String sourceName = (String) docSource;        URL url = WWIO.makeURL(sourceName);        if (url != null)            return openDocumentURL(url);        return openDocumentFile(sourceName, null);    }

比较牛的代码啊，是吧？！类似于工厂模式，按照传过来的不同的对象，用不同的方式去打开，都返回Document的实例，而且通过最后一句if判断是不是String，如果是String，就用URL的方式打开。读取XML文件是个老生长谈的问题，这里他用的JAXP读取的，不过百度说：由于问题太多，从JDK1.7开始删除该功能。

之后呢，要把刚读到的Document对象用loadConfigProperties方法，把里面的内容放入property对象中，就实现了系统的初始化。

注意，构造函数中最后一句的this.initializeCustom();没有啥意思了，是老版本中读取配置文件的，也可以用来自定义一些内容。