为什么我们需要Java和Applet中的JNLP文件？

Question

1. Why do we need JNLP file?
2. What is the advantage of it?
3. Can we run applet without signing it on browser?

Answer 1

Why do we need JNLP file?

For some of the things that launching via JWS brings to an applet, read the info. tag on JNLP (& chase the links).

Can we run applet without signing it on browser?

Does that make sense in your head? To me, it sounds like nonsense.

Whether code is signed is unrelated to whether it is deployed using Java Web Start.

The browser has (little or) nothing to do with code signing.

But guessing one meaning. Code can be deployed as either a standard embedded applet or by web start, as either signed or unsigned.

Answer 2

JNLP allows you to do many more things than specifying where application files should be downloaded. Given the presence of a JNLP client, there is a wide range of features that could be supported by the JNLP protocol, as follows:

1. A richer client environment at runtime. Developers can use a new API that leverages the underlying JNLP Client, allowing standard runtime services to access system resources.
2. A secure deployment solution. End users can trust a reliable JNLP Client because it will not allow any harmful behavior by client applications.
3. Versioning and incremental updates. Each resource can be tagged with a version id and managed accordingly. Incremental updates are obtained using the JARDiff format.
4. Multiple JREs management and automatic installation of additional JREs and optional packages.
5. Offline operation. Deployed applications can work even without a connection with the deployment server. Even if it is a somewhat minimal feature, it is widely used in practice.
6. Automatic installation of native code/libraries. Some Java programs may need some platform-specific support for running.
7. JNLP Client management console. Although not part of the specifications, the JNLP Client is providing to end users a form of graphical configuration console (for instance, the management console of Java Web Start).
8. The capability of using platform-dependent facilities such as shortcuts, accelerators, and the like. Deployed applications are integrated on the native OS—providing shortcuts and launching scripts or other platform-dependent mechanisms So your Java application will look like a native application with a little effort.