Description of the JDK directory:
Bin: Storage of Java related development tools
DB: As the name implies, the lightweight database included with the JRE
Include: an interface file that calls system resources
Operating Environment of Jre:java
LIB: The Core class Library
Src.zip:java's Open source code
JVM: Refers to a Java Virtual machine (role: Explaining the class file and notifying the system what to do, the Java virtual machine is not cross-platform, because different systems have different machine codes)
Jre;java's operating environment, including Java Virtual machines and core class libraries, for users
Jdk:java's development toolset, including JRE and Java development tools, for developers
Path: For the console to be able to find environment variable information under any path
Java_home: Avoid frequent changes to the PATH environment variable information
Classpath: Sets the path information where the class file is located (no configuration required above JDK5.0)
Command:
Javac: Start the Java compiler to compile the specified Java source files
Java: Start the Java Virtual machine to interpret and execute the corresponding class file
Initial knowledge of Java development