How to run two browsers (Firefox) with Java plugins in Windows (7) having different versions (1.6 and 1.7)?

Question

For an old KVM switch I need to run a browser with Java 1.6. But for all other cases I want to use the latest Java browser plugin which is 1.7.

On Linux I can create two profiles and put in each a symbolic link to the Java plugins. By this I can easily create two profiles: one for Java 1.6 and on for Java 1.7.

How to achieve the same on Windows?

It seems to me that the Java version which should be run in the browser is taken form a registry key. This makes it impossible to have two browsers with two different Java plugins on the same machine. How to work around this limitation/design error?

There is already a similar question about IE and Java 1.5/1.6 but it has also no answer.

Solution

Use a portable Firefox together with a portable version of Java 1.6 as second browser.
This way, you can still use your primary installed Firefox together with your installed Java 1.7

You need 3 things:

1. Firefox Portable: The launcher FirefoxPortable.exe automatically detects portable Java versions
2. jPortable: PortableApps.com is hosting a portable version of Java on sourceforge.net.
   There we find archives for older Java versions including some Java 1.6 versions » Yeah!

3. When extracting jPortable and Firefox Portable you have to set up the correct installation paths. Otherwise Firefox cannot detect Java 1.6.

   [...]--+--\ CommonFiles \ Java \ bin \ java.exe
          |
          +--\ Firefox \ FirefoxPortable.exe
   

   As you see, the Firefox launcher jumps one folder level up and looks for a folder called CommonFiles and loads all plugins placed inside

_{proof screen}

---

It's possible you will see both Java versions in Firefox Portable under Addons » Plugins. Just disable Java 1.7 so your second browser will only use 1.6

Comments

[CodeManX]

Worked pretty well, but only like 10 minutes, then you're asked to pay $20 per month for the service :(

[Marco]

Set "plugin.scan.plid.all" to "false" in your portable firefox. This will prevent firefox from using the "MozillaPlugins" registry entry.