In-depth introduction to JVM (1)-two environments

If you really want to master the Java technology, first remember its four components: Java language, class file format, JVM and Java API.

If you have learned Java, you already know that Java has two environments: the compiling environment and the running environment. Well, we will discuss them separately.

1) compiling environment

What is the compiling environment? If JDK is installed, everything in your D:/j2sdk1.4.2 directory is your Java compiling environment.

The workflow for compiling the environment is as follows: You use Java language specifications or Java APIs to write (or automatically generate) A. Java file. Then,
Compile the javac.exe file in the environment using Java. Finally, you get a file in "class file format.

Here, you should have understood that the compiling environment is not the same as the development environment, because your. Java file may be dynamically generated at runtime.
.

2) running environment
What is the runtime environment? Your C:/program files/Java/j2re1.4.2 directory is your Java Runtime Environment.

The Java Runtime Environment is the Java platform.

The Java platform consists of JVM and Java APIs.

JVM consists of a class loader and a JVM running engine.

Let's look at the four major components of Java technology: you learn the Java language and Java API specifications and write compliantCode; Compile it with the compiling environment,
At the same time, determine whether it complies with the specifications. If yes, obtain the files in the class file format. Then, the JVM Class Loader loads these files and sends them to the JVM runtime reference.
Consumer, the engine starts consumption.