Java Basics Introduction Essay (1) JavaSE Edition

Java Basics Introduction Essay (1) JavaSE Edition 1. Three technical architectures of the Java language: J2SE (java 2 Platform Standard Edition): Standard Edition is a solution for developing ordinary desktop and business applications. This technical system is the basis of the other two and can complete the development of some desktop applications. It was renamed JavaSE after Java 5.0 version.
　J2EE (java 2 Platform EnterPRise Edition): Enterprise Edition is a set of solutions for developing applications in enterprise environments. The technologies included in this technical system such as Servlet jsp are mainly aimed at Web application development, Java 5.0 After the version was renamed JavaEE.
　 J2ME (java 2 Platform Micro Edition): small version, is a solution for the development of electronic consumer products and embedded devices. This technology system is mainly used in small electronic consumer products, such as applications in mobile phones, etc., Java 5.0 After the version, the name was changed to JavaME.
　2. Characteristics of the Java language: Cross-platform: Using the JVM (java virtual machine) installed on your own platform, the same code can be executed between different operating systems, which is also known as Java's good portability.
　3.java development environment: jre: the running environment of java, including java virtual machine (JVM) and the core class libraries required for java programs, etc. If you just want to run a developed java program, you only need to install jre on your computer That’s it. (jre=JVM+class library)
　jdk: It is provided for java developers to use, which includes java development tools and jre. So after installing jdk, you no longer need to install jre separately. The development tools include: compilation tool (javac.exe), packaging tool (jar.exe), etc. (jdk=jre+java development tool)
　To put it simply: use jdk to develop a java program and hand it over to jre to run.
　4.java Configure environment variables and temporary environment variables: To configure environment variables, please refer to JDK installation and environment variable configuration. The system variables configured here, if you are only a user, you can set JAVA_HOME and JAVA_HOME in user variables. Pay attention to setting the Path path. It is necessary to write JAVA_HOME to the front, so that it can be called first and prevent other java configurations in the system;
The temporary environment variables are set as follows:
How to set the temporary environment variables, here D: java is the installation directory bin where jdk is located Under this command, temporary environment variables only apply to the current cmd.

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