什么是 JSR? 它的用途是什么？

JSRs are Java Specification Requests, basically change requests for the Java language, libraries and other components.

It's all part of the Java Community Process, whereby interested parties can put forward their ideas for enhancements and (hopefully) have them taken up and acted upon. The process is detailed here.

For example, the Bluetooth one you mention is tracked here and the definitive list is maintained here.

Java Specification Requests (JSRs) are the actual descriptions of proposed and final specifications for the Java platform. At any one time there are numerous JSRs moving through the review and approval process.

Java Specification Requests (JSRs) is a formal document that describes proposed specifications and technologies for adding to the Java platform.

JSRs: Java Specification Requests is a formal proposed document for specification and technical change (often we call it as change request). An individual or a organization can become a member of Java Community Process (JCP) and can develop their code as per specification mentioned in JSR. The developed technical change will go through review by JCP members and approve the same.

JSRs organized as below

• JSRs by Platform
• JSRs by Technology
• JSRs by Stage
• JSRs by Committee
• List of all JSRs

For more information about JSR 82: JavaTM APIs for Bluetooth

From the JCP FAQ:

Q: What is a Java Specification Request (JSR)?

A: A JSR is a Java Specification Request. This is the document submitted to the PMO by one or more members to propose the development of a new specification or significant revision to an existing specification. There are currently many Java technology specifications in development in the JCP program, including the next versions of Java™ Micro Edition (Java ME™), Java™ Platform Enterprise Edition (Java EE™), and Java™ Standard Edition (Java SE™). JSR also refers to the specification development efforts arising from these proposals. To see the JSRs, refer to the complete list of all JSRs.

And from this useful paper:

A Java Specification Request is the document that starts an enhancement on the Java platform. Whenever a member of the JCP program sees an opportunity to improve the platform, they create a JSR describing the opportunity and submit it for revision. The JSR then passes through a series of stages until it gets released or discarded. The following list enumerates the stages from the creation of a JSR to its release:

• Write a JSR
• Submit a JSR
• JSR Review
• EG formation
• Early Draft Review
• Public Review
• Proposed Final Draft
• Final Ballot