热部署原理和实例

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public interface IApplication {
 
public void init();
 
public void execute();
 
public void destory();
 
}

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public ClassLoader createClassLoader(ClassLoader parentClassLoader, String... folders) {
 
List<url> jarsToLoad = new ArrayList<url>();
for (String folder : folders) {
List<string> jarPaths = scanJarFiles(folder);
 
for (String jar : jarPaths) {
 
try {
File file = new File(jar);
jarsToLoad.add(file.toURI().toURL());
 
} catch (MalformedURLException e) {
e.printStackTrace();
}
}
}
 
URL[] urls = new URL[jarsToLoad.size()];
jarsToLoad.toArray(urls);
 
return new URLClassLoader(urls, parentClassLoader);
}
</string></url></url>

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<apps>
<app>
<name>TestApplication1</name>
<file>com.ijavaboy.app.TestApplication1</file>
</app>
<app>
<name>TestApplication2</name>
<file>com.ijavaboy.app.TestApplication2</file>
</app>
</apps>

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public void createApplication(String basePath, AppConfig config){
String folderName = basePath + GlobalSetting.JAR_FOLDER + config.getName();
ClassLoader loader = this.jarLoader.createClassLoader(ApplicationManager.class.getClassLoader(), folderName);
 
try {
Class<!--?--> appClass = loader.loadClass(config.getFile());
 
IApplication app = (IApplication)appClass.newInstance();
 
app.init();
 
this.apps.put(config.getName(), app);
 
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}

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public void loadAllApplications(String basePath){
 
for(AppConfig config : this.configManager.getConfigs()){
this.createApplication(basePath, config);
}
}

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public class TestApplication1 implements IApplication{
 
@Override
public void init() {
System.out.println("TestApplication1-->init");
}
 
@Override
public void execute() {
System.out.println("TestApplication1-->do something");
}
 
@Override
public void destory() {
System.out.println("TestApplication1-->destoryed");
}
 
}

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<app>
<name>TestApplication1</name>
<file>com.ijavaboy.app.TestApplication1</file>
</app>

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public void fileChanged(FileChangeEvent event) throws Exception {
 
String ext = event.getFile().getName().getExtension();
if(!"jar".equalsIgnoreCase(ext)){
return;
}
 
String name = event.getFile().getName().getParent().getBaseName();
 
ApplicationManager.getInstance().reloadApplication(name);
 
}

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public void reloadApplication(String name){
IApplication oldApp = this.apps.remove(name);
 
if(oldApp == null){
return;
}
 
oldApp.destory();	//call the destroy method in the user's application
 
AppConfig config = this.configManager.getConfig(name);
if(config == null){
return;
}
 
createApplication(getBasePath(), config);
}

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public void initMonitorForChange(String basePath){
try {
this.fileManager = VFS.getManager();
 
File file = new File(basePath + GlobalSetting.JAR_FOLDER);
FileObject monitoredDir = this.fileManager.resolveFile(file.getAbsolutePath());
FileListener fileMonitorListener = new JarFileChangeListener();
this.fileMonitor = new DefaultFileMonitor(fileMonitorListener);
this.fileMonitor.setRecursive(true);
this.fileMonitor.addFile(monitoredDir);
this.fileMonitor.start();
System.out.println("Now to listen " + monitoredDir.getName().getPath());
 
} catch (FileSystemException e) {
e.printStackTrace();
}
}

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public static void main(String[] args){
 
Thread t = new Thread(new Runnable() {
 
@Override
public void run() {
ApplicationManager manager = ApplicationManager.getInstance();
manager.init();
}
});
 
t.start();
 
while(true){
try {
Thread.sleep(300);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}