Manual installation and configuration of the Java environment

Manual installation and configuration of the Java environment

1. Theoretical Basis
1.1 Related Concepts
JDK-the abbreviation of Java Development Kit. It is a product for Java developers and is the core of Java, including the Java Runtime Environment JRE, Java tools, and Java base class libraries.
JRE-is the abbreviation of Java Runtime Environment. It is a set of environments required to run JAVA programs, including JVM standard implementation and Java core class libraries.
JVM is the abbreviation of Java Virtual Machine (java Virtual Machine). It is the core of cross-platform implementation in Java and can run software programs written in Java.
1.2 correlation

As shown in:
1) JVM-JVM is called a JAVA virtual machine. It is responsible for parsing the java bytecode (*. class file) and is the lowest layer of the JAVA architecture.
2) JRE-is based on JVM Virtual Machine + additional JRE class library
3) JDK-a JAVA Development Tool + JRE environment based on some columns
Note: JRE class library must be called when JVM parses a JAVA bytecode File
1.3. JDK directory structure

As shown in:
1) JDK root directory-the official recommended absolute path is as follows:
/Usr/java/jdk1.7.0 _ 80/

2) The jre root directory is located in the JDK and directory. The absolute path is as follows:
/Usr/java/jdk1.7.0 _ 80/jre

3) The jre class library is located in the jre and directory. The absolute path is as follows:

/Usr/java/jdk1.7.0 _ 80/jre/lib

4) The JVM root directory is located in the jre root directory. The absolute path is as follows:
/Usr/java/jdk1.7.0 _ 80/jre/bin

1.4. JDK system environment variable definition
Refer to the JDK directory structure. Therefore, the four system environment variables during JAVA runtime are defined as follows:
Export JAVA_HOME =/usr/java/jdk1.7.0 _ 80/
Export JRE_HOME =$ {JAVA_HOME}/jre
Export CLASSPATH =. :$ {JAVA_HOME}/lib :$ {JRE_HOME}/lib
Export PATH =$ {JAVA_HOME}/bin: $ PATH

Note: For specific settings, see the Practice section.
2. Practice
2.1 Environment
Hostname = java.cmdschool.org
Ipaddress = 10.168.0.x
2.2 download JDK
1) download JAVA (newer java)
Http://www.java.com/zh_CN/download/manual.jsp
2) JAVA file (download the old java version)
Http://www.Oracle.com/technetwork/java/javase/archive-139210.html
2.3 configure JDK
2.3.1 create a java directory
Mkdir/usr/java

2.3.2. Decompress
Cd/usr/java
Tar zxvf jdk1.x.x_xx.tar.gz
Cd jdk1.x. x_xx

2.3.2 configure Environment Variables

Vim/etc/profile

Add the following content at the end:
Export JAVA_HOME =/usr/java/jdk1.x. x_xx
Export JRE_HOME =$ {JAVA_HOME}/jre
Export CLASSPATH =. :$ {JAVA_HOME}/lib :$ {JRE_HOME}/lib
Export PATH =$ {JAVA_HOME}/bin: $ PATH

NOTE: If only one user's environment becomes effective, write the configuration in the following file:
1 vim ~ /. Bashrc

2.3.3. Configuration takes effect
Source/etc/profile

2.3.4 Test Environment Variables
Java-version

Reference:
1) download JAVA (newer java)
Http://www.java.com/zh_CN/download/manual.jsp
2) JAVA file (download the old java version)
Http://www.oracle.com/technetwork/java/javase/archive-139210.html
Http://www.oracle.com/technetwork/java/javase/downloads/jdk7-downloads-1880260.html
3) official installation tutorial for JAVA

Basic installation:
Http://www.java.com/zh_CN/download/help/linux_install.xml
Environment Variable Configuration:
Http://www.java.com/zh_CN/download/help/path.xml
4) unofficial JAVA reference


5) JAVA uninstall
Http://www.java.com/zh_CN/download/help/linux_uninstall.xml

 

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