java编译器的目标版本“jsr14”与JDK7 / 8

Question

Can anybody tell me the jsr14 target option of javac will be still available with JDK7/8?

Say,

$ javac -source 1.5 -target jsr14 Hello.java

Answer 1

We are heavily using -jsr14 in OSGi because it allows us to use generics in our API but still deploy on 1.4 environments, which are still popular in embedded. Unfortunately, they made JDK 7 not backward compatible with Java 6 and 5. Javac 1.7 ignores the generic information that is actually present in the JAR files. There is fortunately no problem at run-time as this info is ignored anyway. And it is not as if this was some undocumented feature ...

Unfortunately, people at the front often have very little regard for the people that cannot just update to the latest and the greatest. Guess Oracle really does not care about the embedded markets anymore.

We will likely now have to ship two JARs, one for the embedded and one for JDK 7. Sucks.

This is the bug report we filed: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7078419

Answer 2

The latest OpenJDK source bundle ( openjdk-7-ea-src-b130-18_feb_2011.zip ) still contains the flag in the source ( langtools/src/share/classes/com/sun/tools/javac/jvm/Target.java ), but it has never been supported, so relying on it is a bad idea.

Why do you need it?

Answer 3

That flag has been abandoned since the beta stages of 1.5. It was only included to allow the 1.5 beta compiler to bypass generics checking/parsing by default while the generics specification wasn't finalised. Once 1.5 was released, that flag became meaningless. New compiler versions may not give errors on encountering it but will most likely silently ignore it.