1. 错误1：打 jar 包执行，报错，找不到 类库的 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)

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

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

原因：选错了 launch configuration，自然就找不到 main方法，选择时要选择那个包括 main 方法的 类作为 launch

3. 错误3：

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

如下代码，eclipse export 导出 jar 包之后，执行 无法找到路径：

因为路径变成了如下的形式：file:/F:/remoteLogin.jar!/com/diantusoft/image/login_button.png

所以 java -jar remoteLogin.jar 执行时，是如法找到图片的。

解决方法：

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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() 来获取图片，就不会发生因路径变化找不到图片的问题。