测试环境： MyEclipse  V8.6 

java项目打jar包分为2种情况： 
建议选择第二种（简单） 
一、java项目没有导入第三方jar包 
这时候打包就比较简单： 
1. 首先在MyEclipse中打开项目， 右键点击项目，选择“Export”； 
2. 选择Java/JAR file，Next； 
3. Select the resources to export中可以选择你想要包含的项目文件夹，一些不必要的文件夹就无需放进去了，免得增大空间； 
这里有几个选项： 
    * Export generated class files and resources 表示只导出生成的.class文件和其他资源文件 
    * Export all output folders for checked projects 表示导出选中项目的所有文件夹 
    * Export java source file and resouces 表示导出的jar包中将包含你的源代码*.java，如果你不想泄漏源代码，那么就不要选这项了 
    * Export refactorings for checked projects 把一些重构的信息文件也包含进去 
在Select the export destination中选择导出的jar的路径，Next. 
4. 下一页可以选择是否导出那些含有警告warning或者错误errors的*.class文件。一般不用理他，Next 
5. 下一个页面里可以对项目做一些配置。（如果项目没有引入第三方jar包，这项我们采用系统默认的选项就OK，Main class一定要设置成为你项目的那个主方法入口类） 
    * Generate the manifest file是系统帮我们自动生成MANIFEST.MF文件，如果你的项目没有引用其他class-path，那可以选择这一项。 
    * Use existing mainfest from workspace。这是可以选择我们自定义的.MF文件，格式如上所写。 
    * Seal content。要封装整个jar或者指定的包packet 
    * Main class。这里可以选择你的程序入口，将来打包出来的jar就是你这个入口类的执行结果。 
最后Finish，搞定。 ...... 
二、java项目有导入第三方Jar包 
1，右击项目，单击export=》java=》选第三个,Runnable Jar file (可执行的jar文件),Next， 
2，选择launch configuration（程序入口配置），Exportdestination（导出目标） 
Library handing：   选择第一个 引用的jar包会整合到项目中去。 
                    选择第二个 引用的jar包会单独放在项目根目录下（推荐）。 
                    选择第三个 引用的jar包会单独放在一个文件夹下，这个文件夹和导出的jar放在同一目录下， 
finish。 


遇到的问题： 
（网络来源）为什么export-->runnable jar file的launch configuration没有东西可以选择?对于这个问题，网上答案少之又少，我来制造些内容吧。 
为什么MyEclipse8.5的export-->runnable jar file-->的launch configuration里面没有可以选择的东西了，其实是要把你要打包成jar文件的工程的main方法运行一次，比如main方法在A类里，运行一次A就有了 
   我是看见下面这段，试了一下弄出来的，喜欢的人仔细研究一下  Creating a Java application launch configuration 
When you choose Run >Run As >Java Application to launch your class, you are running your class using a generic Java Application launch configuration that derives most of the launch parameters from your Java project and your workbench preferences.  In some cases, you will want to override the derived parameters or specify additional arguments. 
You do this by creating your own Java Application launch configuration. 
Select or from the workbench menu bar.  This opens a dialog that lets you create, modify, and delete launch configurations of different types. 
Select Java Application in the left hand list of launch configuration types, and press the New button in the toolbar. This will create a new launch configuration for a Java application. The tabs on the right hand side allow you control specific aspects of the launch. 
The Main tab defines the class to be launched. Enter the name of the project containing the class to launch in the project field, and the fully qualified name of the main class in the Main class field. Check the Stop in main checkbox if you want the program to stop in the main method whenever the program is launched in debug mode. 
Note:  You do not have to specify a project, but doing so allows a default classpath, source lookup path, and JRE to be chosen. 
The Arguments tab defines the arguments to be passed to the application and to the virtual machine (if any). You can also specify the working directory to be used by the launched application. 
The JRE tab defines the JRE used to run or debug the application. You can select a JRE from the already defined JREs, or define a new JRE. 
The Classpath tab defines the location of class files used when running or debugging an application. By default, the user and bootstrap class locations are derived from the associated project's build path. You may override these settings here. 
The Source tab defines the location of source files used to display source when debugging a Java application. By default, these settings are derived from the associated project's build path. You may override these settings here. 
The Environment tab defines the environment variable values to use when running or debugging a Java application. By default, the environment is inherited from the Eclipse runtime. You may override or append to the inherited environment. 
The Common tab defines general information about the launch configuration.  You may choose to store the launch configuration in a specific file and specify which perspectives become active when the launch configuration is launched.

转载自：http://vincentboy.iteye.com/blog/1735826