The role of the Java Basic Class library package

Tools.jar: Tool library, it has nothing to do with the underlying class library used in our program.

The JRE library contains jar files (jdk1.6): Resources.jar, Rt.jar, Jsse.jar, Jce.jar, Charsets.jar, Dnsns.jar, Localedata.jar A total of 10 jar files, where Resource.jar is a resource bundle (picture, properties file); Rt.jar is a run-time package

java.*, javax.* bag, org.* pack :

1, as part of the API public interface of J2SE, operating system-independent can be run on all Java platforms;

2, different JDK version will remain compatible will not easily change, provide API documentation and source code (SRC.ZIP).

sun.* Package :

1, not part of the API expose interface, the program that calls the Sun package does not ensure that all Java platforms are working, and that implementations in different operating systems may not be the same.

2, different JDK version of the Sun package classes may also change irregularly, so the class in the sun.* package does not provide API documentation and source code.

1. Rt.jar
Rt.jar defaults to the bootstrap classes (the RunTime classes that comprise the Java platform's core API) in root ClassLoader's loading path.

2. Tools.jar

Tools.jar is used when the system compiles a class, that is, when the javac is executed.

Javac Xxx.java

is actually running

Java-calsspath=%java_home%\lib\tools.jar Xx.xxx.Main Xxx.java

Javac is the encapsulation of the above command, so Tools.jar doesn't have to be added to Classpath.

3. Dt.jar
Dt.jar is a class library of operating environments, mainly swing's packages that are best added when used with swing.

4.sunjce_provider.jar Encryption and decryption

5.charsets.jar--Character conversion classes.

6.localedata.jar--Locale data for java.text and Java.util.

7.jce.jar was also added and decrypted.

The role of the Java Basic Class library package