java -jar 執行 eclipse export 的 jar 包報錯處理

1. 錯誤1：打 jar 包執行，報錯，找不到 類庫的 jar 包

F:\>java -jar remoteLogin.jar
Exception in thread "AWT-EventQueue-0" java.lang.NoClassDefFoundError: com/alibaba/fastjson/JSON
at com.diantusoft.LoginWindow.getFingerPrintFromDB(LoginWindow.java:819)
at com.diantusoft.LoginWindow.login(LoginWindow.java:630)
at com.diantusoft.LoginWindow.access$8(LoginWindow.java:577)
at com.diantusoft.LoginWindow$13.mouseClicked(LoginWindow.java:509)
at java.awt.Component.processMouseEvent(Component.java:6528)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6290)
at java.awt.Container.processEvent(Container.java:2234)
at java.awt.Component.dispatchEventImpl(Component.java:4881)
at java.awt.Container.dispatchEventImpl(Container.java:2292)
at java.awt.Component.dispatchEvent(Component.java:4703)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4898)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4542)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4462)
at java.awt.Container.dispatchEventImpl(Container.java:2278)
at java.awt.Window.dispatchEventImpl(Window.java:2750)
at java.awt.Component.dispatchEvent(Component.java:4703)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:751)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:702)
at java.awt.EventQueue$3.run(EventQueue.java:696)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86)
at java.awt.EventQueue$4.run(EventQueue.java:724)
at java.awt.EventQueue$4.run(EventQueue.java:722)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:721)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
Caused by: java.lang.ClassNotFoundException: com.alibaba.fastjson.JSON
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)

解決方法：Use Export -> Java -> Runnable JAR File instead Export -> Java -> JAR File on your project (right mouse click).

2. 錯誤2: Could not find main method from given launch configuration

原因：選錯了 launch configuration，自然就找不到 main方法，選擇時要選擇那個包括 main 方法的 類作為 launch

3. 錯誤3：

	public static ImageIcon getPicture2(String name) {
		ImageIcon icon = new ImageIcon(PictureUtil.class.getClassLoader()
								.getResource("com/diantusoft/image/" + name));
		return icon;
	}

如下代碼，eclipse export 導出 jar 包之后，執行 無法找到路徑：

因為路徑變成了如下的形式：file:/F:/remoteLogin.jar!/com/diantusoft/image/login_button.png

所以 java -jar remoteLogin.jar 執行時，是如法找到圖片的。

解決方法：

	private static PictureUtil instance = new PictureUtil();
	
	private PictureUtil(){}
	
	
	public static PictureUtil getInstance(){
		return instance;
	}

	public ImageIcon getPicture(String name){
		URL url = this.getClass().getResource(name);
		
		if(url != null){	
			return new ImageIcon(url);
		}			
	}

也就是使用 this.getClass().getResource() 來獲取圖片，就不會發生因路徑變化找不到圖片的問題。