一，安装jdk

用yum安装JDK

1.查看yum库中都有哪些jdk版本

[root@localhost ~]# yum search java|grep jdk

ldapjdk-javadoc.x86_64 : Javadoc for ldapjdk

java-1.6.0-openjdk.x86_64 : OpenJDK Runtime Environment

java-1.6.0-openjdk-demo.x86_64 : OpenJDK Demos

java-1.6.0-openjdk-devel.x86_64 : OpenJDK Development Environment

java-1.6.0-openjdk-javadoc.x86_64 : OpenJDK API Documentation

java-1.6.0-openjdk-src.x86_64 : OpenJDK Source Bundle

java-1.7.0-openjdk.x86_64 : OpenJDK Runtime Environment

java-1.7.0-openjdk-demo.x86_64 : OpenJDK Demos

java-1.7.0-openjdk-devel.x86_64 : OpenJDK Development Environment

java-1.7.0-openjdk-javadoc.noarch : OpenJDK API Documentation

java-1.7.0-openjdk-src.x86_64 : OpenJDK Source Bundle

java-1.8.0-openjdk.x86_64 : OpenJDK Runtime Environment

java-1.8.0-openjdk-demo.x86_64 : OpenJDK Demos

java-1.8.0-openjdk-devel.x86_64 : OpenJDK Development Environment

java-1.8.0-openjdk-headless.x86_64 : OpenJDK Runtime Environment

java-1.8.0-openjdk-javadoc.noarch : OpenJDK API Documentation

java-1.8.0-openjdk-src.x86_64 : OpenJDK Source Bundle

ldapjdk.x86_64 : The Mozilla LDAP Java SDK

2.选择版本,进行安装

//选择1.7（自己需要的）版本进行安装

[root@localhost ~]# yum install java-1.7.0-openjdk

//安装完之后，默认的安装目录是在: /usr/lib/jvm/java-1.7.0-openjdk-1.7.0.75.x86_64

3.设置环境变量

[root@localhost ~]# vi /etc/profile

在profile文件中添加如下内容

#set java environment

JAVA_HOME=/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.75.x86_64

JRE_HOME=$JAVA_HOME/jre

CLASS_PATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/lib

PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin

export JAVA_HOME JRE_HOME CLASS_PATH PATH

如下图：

让修改生效

[root@localhost java]# source /etc/profile

4.验证，如下则安装成功

java -version

5.如果验证失败，安装 glibc 库(glibc 语言库，必须安装)

用sudo yum install glibc.i686命令安装好glibc之后问题就解决了。