有一個項目需要java 1.7配合，原服務器上已安裝java 1.8，需要切換版本到java 1.7.
查看centos7支持的java版本
yum search java|grep java-1 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-accessibility.x86_64 : OpenJDK accessibility connector 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-headless.x86_64 : The OpenJDK runtime environment without 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-accessibility.x86_64 : OpenJDK accessibility connector java-1.8.0-openjdk-accessibility-debug.x86_64 : OpenJDK accessibility connector java-1.8.0-openjdk-debug.x86_64 : OpenJDK Runtime Environment with full debug on java-1.8.0-openjdk-demo.x86_64 : OpenJDK Demos java-1.8.0-openjdk-demo-debug.x86_64 : OpenJDK Demos with full debug on java-1.8.0-openjdk-devel.x86_64 : OpenJDK Development Environment java-1.8.0-openjdk-devel-debug.x86_64 : OpenJDK Development Environment with java-1.8.0-openjdk-headless.x86_64 : OpenJDK Runtime Environment java-1.8.0-openjdk-headless-debug.x86_64 : OpenJDK Runtime Environment with full java-1.8.0-openjdk-javadoc.noarch : OpenJDK API Documentation java-1.8.0-openjdk-javadoc-debug.noarch : OpenJDK API Documentation for packages java-1.8.0-openjdk-src.x86_64 : OpenJDK Source Bundle java-1.8.0-openjdk-src-debug.x86_64 : OpenJDK Source Bundle for packages with
安裝java 1.7版本
yum install java-1.7.0
使用update-alternatives 查看已安裝的java版本
update-alternatives --list libnssckbi.so.x86_64 auto /usr/lib64/pkcs11/p11-kit-trust.so ld auto /usr/bin/ld.bfd mkisofs auto /usr/bin/genisoimage print auto /usr/bin/lpr.cups java manual /usr/lib/jvm/java-1.7.0-openjdk-1.7.0.111-2.6.7.2.el7_2.x86_64/jre/bin/java jre_openjdk auto /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.111-1.b15.el7_2.x86_64/jre jre_1.8.0 auto /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.111-1.b15.el7_2.x86_64/jre jre_1.8.0_openjdk auto /usr/lib/jvm/jre-1.8.0-openjdk-1.8.0.111-1.b15.el7_2.x86_64 xinputrc auto /etc/X11/xinit/xinput.d/ibus.conf libjavaplugin.so.x86_64 auto /usr/lib64/IcedTeaPlugin.so cifs-idmap-plugin auto /usr/lib64/cifs-utils/cifs_idmap_sss.so mta auto /usr/sbin/sendmail.postfix cdrecord auto /usr/bin/wodim libwbclient.so.0.12-64 auto /usr/lib64/samba/wbclient/libwbclient.so.0.12 jre_1.7.0 auto /usr/lib/jvm/java-1.7.0-openjdk-1.7.0.111-2.6.7.2.el7_2.x86_64/jre jre_1.7.0_openjdk auto /usr/lib/jvm/jre-1.7.0-openjdk-1.7.0.111-2.6.7.2.el7_2.x86_64
看到java1.7已安裝成功，切換版本到java 1.7
update-alternatives --config java There are 2 programs which provide 'java'. Selection Command ----------------------------------------------- * 1 /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.111-1.b15.el7_2.x86_64/jre/bin/java + 2 /usr/lib/jvm/java-1.7.0-openjdk-1.7.0.111-2.6.7.2.el7_2.x86_64/jre/bin/java Enter to keep the current selection[+], or type selection number: 2
查看正在使用的java版本
java -version java version "1.7.0_111" OpenJDK Runtime Environment (rhel-2.6.7.2.el7_2-x86_64 u111-b01) OpenJDK 64-Bit Server VM (build 24.111-b01, mixed mode)
已成功切換到java 1.7版本。