浏览器无法关联JNLP文件至Java Web Start问题咨询（Java 9相关）

Hey there, let’s break down your questions clearly—this is a super common pain point when shifting from Java 8 to Java 9, so I’ve got you covered:

1. Did Java 9 introduce a mechanism change for JNLP file handling? #

Absolutely. Java 9 brought intentional shifts to how Java Web Start (JWS) interacts with the system, and this directly impacts file associations.

2. Does the Java 9 installer no longer associate JNLP files with javaws.exe? #

That’s exactly what’s happening. Unlike Java 8 (and older versions) where the installer automatically set .jnlp files to open with javaws.exe, Java 9’s installer skips this step by default. This isn’t a bug—it’s a deliberate choice tied to broader platform changes.

3. Is this related to deprecation mechanisms? #

You nailed it. Java Web Start was officially deprecated in Java 9 and fully removed in Java 11. As part of this phase-out, Oracle and OpenJDK distributions scaled back automatic integration features like file associations to signal that JWS is being retired.

Extra Context for Firefox & IE11 Users #

• Firefox: Even before Java 9, Firefox had started restricting NPAPI plugins (which JWS relied on for seamless integration). With Java 9’s lack of automatic association, users now have to manually select javaws.exe when opening .jnlp files for the first time, or set it as the default via Windows file association settings.
• IE11: While IE11 still supports some legacy plugin paths, Java 9’s removal of automatic association means users will either need to manually link .jnlp files to javaws.exe or launch it directly via command line (e.g., javaws.exe C:\path\to\your\file.jnlp).

Quick Workarounds #

• To set manual associations on Windows: Right-click a .jnlp file → Open with → Choose another app → Check "Always use this app to open .jnlp files" → Browse to your Java 9 installation’s bin folder (typically C:\Program Files\Java\jdk-9.x.x\bin) and select javaws.exe.
• If you’re recommending Java 9 to avoid Java 8 Update 161/162 bugs, keep in mind JWS’s end-of-life status. Long-term, consider migrating to alternatives like self-contained Java apps or web-based tools that don’t depend on JWS.

内容的提问来源于stack exchange，提问作者Marcus