冒号后缺少 空格.这应该有效:

You are missing a space after the colon. This should work:

Manifest-Version: 1.0
Created-By: 1.7.0_51
Permissions: sandbox
Application-Name: MyFarmingBusiness
Application-Library-Allowable-Codebase: http://mycompany.com/version_4/myapplet/
Caller-Allowable-Codebase: www.mycompany.com
Codebase: www.mycompany.com

注意 Application-Library-Allowable-Codebase: 和 Caller-Allowable-Codebase: 条目之后的额外 空格.

Note the additional space after the Application-Library-Allowable-Codebase: and Caller-Allowable-Codebase: entry.

根据 jar 文件规范、值定义为:

值:空格 *otherchar 换行符 *continuation

value: SPACE *otherchar newline *continuation

如果添加空格，它会按预期工作.

If you add the spaces, it works as expected.