如何替换掉系统默认的Java

Question

如题所述

Answer 1

系统自带的JDK
[root@master ~]# java -version
java version "1.5.0"
gij (GNU libgcj) version 4.4.7 20120313 (Red Hat 4.4.7-3)

Copyright (C) 2007 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.1234567

自己配置的jdk
[hadoop@master ~]$ echo $JAVA_HOME
/usr/java/jdk1.8.0_60
123

但是系统默认的用的是系统自带的jdk，下面切换到安装的jdk版本
[root@master ~]# alternatives --install /usr/bin/java java /usr/java/jdk1.8.0_60/bin/java 300
[root@master ~]# alternatives --config java

There are 2 programs which provide 'java'.

Selection Command
-----------------------------------------------
*+ 1 /usr/lib/jvm/jre-1.5.0-gcj/bin/java
2 /usr/java/jdk1.8.0_60/bin/java

Enter to keep the current selection[+], or type selection number: 2
123456789101112

系统自带的jdk时，是带gij的，输入java命令如下：
[root@master ~]# java -version
java version "1.5.0"
gij (GNU libgcj) version 4.4.7 20120313 (Red Hat 4.4.7-3)

Copyright (C) 2007 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
12345678

自己安装的jdk，输入java命令如下：
[root@master ~]# java -version
java version "1.8.0_60"
Java(TM) SE Runtime Environment (build 1.8.0_60-b27)
Java HotSpot(TM) 64-Bit Server VM (build 25.60-b23, mixed mode)