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);
}
});
}
}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.
*
* 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.
*
* When the Configuration class is first instantiated it reads the XML document config/worldwind.xml and
* registers all the information there. The information can subsequently be retrieved via the class' various
* getValue 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.
*
* The default World Wind configuration document is config/worldwind.xml. This can be changed by setting
* the Java property gov.nasa.worldwind.config.file 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.)
*
* Additionally, an application may set another Java property, gov.nasa.worldwind.app.config.document, 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.
*
* See config/worldwind.xml for documentation on setting configuration values.
*
* 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.
*
* Note: Prior to September of 2009, configuration properties were read from the file
* config/worldwind.properties. An alternate file could be specified via the
* gov.nasa.worldwind.config.file Java property. These mechanisms remain available but are deprecated.
* World Wind no longer contains a worldwind.properties file. If worldwind.properties 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 configDocs = new ArrayList();
/** 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.
*
* 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.
*
* 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:
*
* Operating System Path Mac OS X ~/Library/Application
* Support Windows ~\\Application Data Linux, Unix,
* Solaris ~/
*
* @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:
*
* - OpenGL compatibility profile 4.x
- OpenGL compatibility profile 3.x
- OpenGL profile 1.x
* up to 3.0
*
* @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;
}
}
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。