首先，你要了解你的项目是什么 然后右击鼠标，选择底部的属性 然后在左上角选择内置路径然后添加外部jar文件添加点击应用，就这样了

首先，你要了解你的项目是什么 然后右击鼠标，选择底部的属性 然后在左上角选择内置路径然后添加外部jar文件添加点击应用，就这样了

右键单击项目。 单击Build Path。 单击“配置生成路径”。 在Libraries下面，单击Add Jar或Add External Jar。

两个选择:

1/来自项目:

2/如果你已经导入了其他jar，从“References Libraries”目录:

两者都会引导你进入这个屏幕，在这里你可以管理你的库:

以下是步骤:

click File > Import. The Import window opens. Under Select an import source, click J2EE > App Client JAR file. Click Next. In the Application Client file field, enter the location and name of the application client JAR file that you want to import. You can click the Browse button to select the JAR file from the file system. In the Application Client project field, type a new project name or select an application client project from the drop-down list. If you type a new name in this field, the application client project will be created based on the version of the application client JAR file, and it will use the default location. In the Target runtime drop-down list, select the application server that you want to target for your development. This selection affects the run time settings by modifying the class path entries for the project. If you want to add the new module to an enterprise application project, select the Add project to an EAR check box and then select an existing enterprise application project from the list or create a new one by clicking New. Note: If you type a new enterprise application project name, the enterprise application project will be created in the default location with the lowest compatible J2EE version based on the version of the project being created. If you want to specify a different version or a different location for the enterprise application, you must use the New Enterprise Application Project wizard. Click Finish to import the application client JAR file.

如果您想要更改文件系统中的项目位置，那么添加外部Jar并不明智。

最好的方法是添加jar到构建路径，这样你的项目将在导出时编译:

在项目文件夹中创建一个名为lib的文件夹。 将您需要的所有jar文件复制到此文件夹。 在eclipse中刷新您的项目。 选择所有jar文件，然后右键单击其中一个文件，选择构建路径->添加到构建路径