[root@BlueSkytv2.0]#java
Usage:gij[OPTION]...CLASS[ARGS]...
toinvokeCLASS.main,or
gij-jar[OPTION]...JARFILE[ARGS]...
toexecuteajarfile
Try`gij--help'formoreinformation.
于是:
[root@BlueSkytv2.0]#whichjava
/usr/bin/java
[root@BlueSkysoftware]#ls/usr/bin/java-l
lrwxrwxrwx1rootroot2201-1521:23/usr/bin/java->/etc/alternatives/java
[root@BlueSkysoftware]#ll/etc/alternatives/java
lrwxrwxrwx1rootroot3505-1013:48/etc/alternatives/java->/usr/lib/jvm/jre-1.4.2-gcj/bin/java
查看alternatives的帮助;
[root@BlueSkysoftware]#alternatives--help
替换选择(alternatives)的版本1.3.30-版权(C)1997-2000RedHat,Inc.
在GNU公共许可的条款下,本软件可以被自由发行。
用法:alternatives--install<link><name><path><priority>
[--initscript<service>]
[--slave<link><name><path>]*
alternatives--remove<name><path>
alternatives--auto<name>
alternatives--config<name>
alternatives--display<name>
alternatives--set<name><path>
公用选项:--verbose--test--help--usage--version
--altdir<directory>--admindir<directory>
下面先安装jre1.5.0_09,此版本可以到sun的公司网站上下得;
[root@BlueSkysoftware]#rpm-ivhjre-1_5_0_09-linux-i586.rpm
Preparing...###########################################[100%]
1:jre###########################################[100%]
[root@BlueSkysoftware]#/usr/java/jre1.5.0_09/bin/java
Usage:java[-options]class[args...]
(toexecuteaclass)
orjava[-options]-jarjarfile[args...]
(toexecuteajarfile)
whereoptionsinclude:
-d32usea32-bitdatamodelifavailable
-d64usea64-bitdatamodelifavailable
-clienttoselectthe"client"VM
-servertoselectthe"server"VM
-hotspotisasynonymforthe"client"VM[deprecated]
ThedefaultVMisclient.
-cp<classsearchpathofdirectoriesandzip/jarfiles>
-classpath<classsearchpathofdirectoriesandzip/jarfiles>
A:separatedlistofdirectories,JARarchives,
andZIParchivestosearchforclassfiles.
-D<name>=<value>
setasystemproperty
-verbose[:class|gc|jni]
enableverboseoutput
-versionprintproductversionandexit
-version:<value>
requirethespecifiedversiontorun
-showversionprintproductversionandcontinue
-jre-restrict-search|-jre-no-restrict-search
include/excludeuserprivateJREsintheversionsearch
-?-helpprintthishelpmessage
-Xprinthelponnon-standardoptions
-ea[:<packagename>...|:<classname>]
-enableassertions[:<packagename>...|:<classname>]
enableassertions
-da[:<packagename>...|:<classname>]
-disableassertions[:<packagename>...|:<classname>]
disableassertions
-esa|-enablesystemassertions
enablesystemassertions
-dsa|-disablesystemassertions
disablesystemassertions
-agentlib:<libname>[=<options>]
loadnativeagentlibrary<libname>,e.g.-agentlib:hprof
seealso,-agentlib:jdwp=helpand-agentlib:hprof=help
-agentpath:<pathname>[=<options>]
loadnativeagentlibrarybyfullpathname
-javaagent:<jarpath>[=<options>]
loadJavaprogramminglanguageagent,seejava.lang.instrument
接着,使用alternatives工具增加这个版本;
[root@BlueSkysoftware]#alternatives--install/usr/bin/javajava/usr/java/jre1.5.0_09/bin/java300
[root@BlueSkysoftware]#alternatives--configjava
共有2个程序提供“java”。
选择命令
-----------------------------------------------
*1/usr/lib/jvm/jre-1.4.2-gcj/bin/java
2/usr/java/jre1.5.0_09/bin/java
按Enter来保存当前选择[+],或键入选择号码:2
[root@BlueSkysoftware]#java
Usage:java[-options]class[args...]
(toexecuteaclass)
orjava[-options]-jarjarfile[args...]
(toexecuteajarfile)
whereoptionsinclude:
-d32usea32-bitdatamodelifavailable
-d64usea64-bitdatamodelifavailable
-clienttoselectthe"client"VM
-servertoselectthe"server"VM
-hotspotisasynonymforthe"client"VM[deprecated]
ThedefaultVMisclient.
-cp<classsearchpathofdirectoriesandzip/jarfiles>
-classpath<classsearchpathofdirectoriesandzip/jarfiles>
A:separatedlistofdirectories,JARarchives,
andZIParchivestosearchforclassfiles.
-D<name>=<value>
setasystemproperty
-verbose[:class|gc|jni]
enableverboseoutput
-versionprintproductversionandexit
-version:<value>
requirethespecifiedversiontorun
-showversionprintproductversionandcontinue
-jre-restrict-search|-jre-no-restrict-search
include/excludeuserprivateJREsintheversionsearch
-?-helpprintthishelpmessage
-Xprinthelponnon-standardoptions
-ea[:<packagename>...|:<classname>]
-enableassertions[:<packagename>...|:<classname>]
enableassertions
-da[:<packagename>...|:<classname>]
-disableassertions[:<packagename>...|:<classname>]
disableassertions
-esa|-enablesystemassertions
enablesystemassertions
-dsa|-disablesystemassertions
disablesystemassertions
-agentlib:<libname>[=<options>]
loadnativeagentlibrary<libname>,e.g.-agentlib:hprof
seealso,-agentlib:jdwp=helpand-agentlib:hprof=help
-agentpath:<pathname>[=<options>]
loadnativeagentlibrarybyfullpathname
-javaagent:<jarpath>[=<options>]
loadJavaprogramminglanguageagent,seejava.lang.instrument
查看效果:
[root@BlueSkysoftware]#alternatives--displayjava
java-状态是手工。
链接目前指向/usr/java/jre1.5.0_09/bin/java
/usr/lib/jvm/jre-1.4.2-gcj/bin/java-优先度1420
从keytool:/usr/lib/jvm/jre-1.4.2-gcj/bin/keytool
从rmiregistry:/usr/lib/jvm/jre-1.4.2-gcj/bin/rmiregistry
从jre_exports:/usr/lib/jvm-exports/jre-1.4.2-gcj
从jre:/usr/lib/jvm/jre-1.4.2-gcj
/usr/java/jre1.5.0_09/bin/java-优先度300
从keytool:(null)
从rmiregistry:(null)
从jre_exports:(null)
从jre:(null)
当前“最佳”版本是/usr/lib/jvm/jre-1.4.2-gcj/bin/java。
更换Java版本
本文介绍如何使用alternatives工具在Linux系统中切换不同的Java版本,并详细记录了安装Sun的Java版本并将其设置为默认版本的过程。
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