Http://playkid.blog.163.com/blog/static/56287260201372113842153/JDK (Java Development Kit) is a product for Java developers, Is the core of the entire Java, including the Java Runtime Environment JRE, Java Tools, and the Java base Class library. Java Runtime Environment (JRE) is a collection of environments necessary to run Java programs, including the JVM standard implementation and the Java Core Class library. The JVM is the abbreviation for Java Virtual machine (Java VM), the most central part of the entire Java implementation cross-platform, capable of running software programs written in the Java language. In the history of computer development languages, no language has ever been supported by so many vendors as Java, with so many development tools.
JDK (Java development Kit)The JDK is the Java SDK and is the product of Sun Microsystems for Java developers. The JDK contains the JRE, in the JDK installation directory, there is a directory named JRE, there are two folders Bin and Lib, where it can be considered that the bin is the jvm,lib in the JVM is required to work the class library, and the JVM and Lib are called the JRE. The JDK is the core of the entire Java, including the Java Runtime Environment JRE (Java Runtime envirnment), a stack of Java tools (JAVAC/JAVA/JDB, etc.), and a Java-based class library (that is, the Java API includes Rt.jar). ①se (J2SE), Standard Edition, is a version we typically use, starting with JDK 5.0 and renaming Java SE. ②ee (EE), Enterprise Edition, Corporate Edition, uses this JDK to develop the Java EE application, starting with JDK 5.0, and renaming it to the JavaScript. ③me (J2ME), Micro Edition, is primarily used for Java applications on mobile devices and embedded devices, starting with JDK 5.0 and renaming Java ME. Pyramid structure jdk=jre+jvm+ Other running Java programs generally require the user's computer to install the JRE environment (Java Runtime Environment), there is no Jre,java program can not run, and no Java program, the JRE is useless.
Java Runtime Environment (JRE)is an essential running environment for running programs written in the Java language. It is also through which Java developers are able to publish their own programs to the user and let them use them. The RE contains Java Virtual machine (JVM), runtime class libraries, and Java Application Launcher, which are the necessary components for running Java programs. Unlike the familiar JDK, the JRE is a Java runtime environment, not a development environment, so it does not contain any development tools, such as compilers and debuggers, but is intended for users who use Java programs.
JVM (Java Virtual machine)Is the Java virtual machine that we often say, it is the entire Java implementation cross-platform of the most core part, all Java programs will be compiled into a. class file, this class file can be executed on the virtual machine. This means that class does not directly correspond to the machine's operating system, but rather interacts with the operating system indirectly by the virtual machine, which interprets the program to the local system for execution. Only the JVM cannot be executed as class, because the JVM needs to invoke the class library lib that is required to interpret the class, and the JRE contains the Lib class library. The JVM masks information that is relevant to the operating system platform, allowing Java programs to run without modification on multiple platforms by generating only the target code (bytecode) that runs on the Java virtual machine.
The relationship between JDK, JRE, and JVM
