Java用System讀取系統相關信息、環境變量——（六）

package Java_Test;

public class System1 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
System.out.println(System.getProperty("java.version"));
System.out.println(System.getProperty("java.vendor"));
System.out.println(System.getProperty("java.home"));
System.out.println(System.getProperty("java.library.path"));
System.out.println(System.getProperty("user.dir"));   //獲取當前類工做目錄
System.out.println(System.getProperty("os.version"));
System.out.println(System.getProperty("os.name"));
System.out.println(System.getenv("path"));
    }

}

 

補充:獲取系統全部屬性的方法

package com.test;

import java.util.Properties;

public class MyTest {
    public static void main(String[] args) {
        Properties properties = System.getProperties();
        for (Object key : properties.keySet()) {
            System.out.println(key + " : " + properties.getProperty((String) key));
        }
    }
}

源碼查看:全部的屬性都存在System的一個內部屬性Properties中，Properties是一個繼承HashTable的類

(1)System.getProperties

    public static Properties getProperties() {
        SecurityManager sm = getSecurityManager();
        if (sm != null) {
            sm.checkPropertiesAccess();
        }

        return props;
    }

 

private static Properties props;

 

 

(2)Properties是一個繼承HashTable的類

public
class Properties extends Hashtable<Object,Object> {

     private static final long serialVersionUID = 4112578634029874840L;

    protected Properties defaults;
。。。
}

 

結果:

java.runtime.name : Java(TM) SE Runtime Environment
sun.boot.library.path : C:\Program Files\Java\jdk1.7.0_80\jre\bin
java.vm.version : 24.80-b11
java.vm.vendor : Oracle Corporation
java.vendor.url : http://java.oracle.com/
path.separator : ;
java.vm.name : Java HotSpot(TM) 64-Bit Server VM
file.encoding.pkg : sun.io
user.country : CN
user.script : 
sun.java.launcher : SUN_STANDARD
sun.os.patch.level : 
java.vm.specification.name : Java Virtual Machine Specification
user.dir : E:\xiangmu\Mytest
java.runtime.version : 1.7.0_80-b15
java.awt.graphicsenv : sun.awt.Win32GraphicsEnvironment
java.endorsed.dirs : C:\Program Files\Java\jdk1.7.0_80\jre\lib\endorsed
os.arch : amd64
java.io.tmpdir : C:\Users\ADMINI~1\AppData\Local\Temp\
line.separator : 

java.vm.specification.vendor : Oracle Corporation
user.variant : 
os.name : Windows 8.1
sun.jnu.encoding : GBK
java.library.path : C:\Program Files\Java\jdk1.7.0_80\bin;C:\WINDOWS\Sun\Java\bin;C:\WINDOWS\system32;C:\WINDOWS;C:/Program Files/Java/jdk1.7.0_80/bin/../jre/bin/server;C:/Program Files/Java/jdk1.7.0_80/bin/../jre/bin;C:/Program Files/Java/jdk1.7.0_80/bin/../jre/lib/amd64;C:\oraclexe\app\oracle\product\11.2.0\server\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;E:\soft\apache-maven-3.5.3\bin;C:\WINDOWS\System32\OpenSSH\;E:\git\Git\cmd;E:\SVN\bin;C:\Users\Administrator\AppData\Local\Microsoft\WindowsApps;E:\soft\maven\apache-maven-3.3.9\bin;C:\Program Files\MySQL\MySQL Server 5.7\bin;C:\Program Files\Java\jdk1.7.0_80\bin;E:\git\Git\bin;E:\git\Git\usr\bin;E:\git\Git;C:\Program Files\Java\jdk1.7.0_80\jre\bin;D:\zdcontomcat\zdc8\lo\program;;E:\soft\eclipse\eclipse-jee-mars-1-win32-x86_64\eclipse;;.
java.specification.name : Java Platform API Specification
java.class.version : 51.0
sun.management.compiler : HotSpot 64-Bit Tiered Compilers
os.version : 6.3
user.home : C:\Users\Administrator
user.timezone : 
java.awt.printerjob : sun.awt.windows.WPrinterJob
file.encoding : UTF-8
java.specification.version : 1.7
java.class.path : E:\xiangmu\Mytest\bin;E:\xiangmu\Mytest\WebContent\WEB-INF\lib\log4j-1.2.16.jar;E:\xiangmu\Mytest\WebContent\WEB-INF\lib\slf4j-api-1.5.10.jar;E:\xiangmu\Mytest\WebContent\WEB-INF\lib\slf4j-log4j12-1.5.10.jar;E:\tomcat\apache-tomcat-7.0.88\lib\annotations-api.jar;E:\tomcat\apache-tomcat-7.0.88\lib\catalina-ant.jar;E:\tomcat\apache-tomcat-7.0.88\lib\catalina-ha.jar;E:\tomcat\apache-tomcat-7.0.88\lib\catalina-tribes.jar;E:\tomcat\apache-tomcat-7.0.88\lib\catalina.jar;E:\tomcat\apache-tomcat-7.0.88\lib\ecj-4.4.2.jar;E:\tomcat\apache-tomcat-7.0.88\lib\el-api.jar;E:\tomcat\apache-tomcat-7.0.88\lib\jasper-el.jar;E:\tomcat\apache-tomcat-7.0.88\lib\jasper.jar;E:\tomcat\apache-tomcat-7.0.88\lib\jsp-api.jar;E:\tomcat\apache-tomcat-7.0.88\lib\servlet-api.jar;E:\tomcat\apache-tomcat-7.0.88\lib\tomcat-api.jar;E:\tomcat\apache-tomcat-7.0.88\lib\tomcat-coyote.jar;E:\tomcat\apache-tomcat-7.0.88\lib\tomcat-dbcp.jar;E:\tomcat\apache-tomcat-7.0.88\lib\tomcat-i18n-es.jar;E:\tomcat\apache-tomcat-7.0.88\lib\tomcat-i18n-fr.jar;E:\tomcat\apache-tomcat-7.0.88\lib\tomcat-i18n-ja.jar;E:\tomcat\apache-tomcat-7.0.88\lib\tomcat-jdbc.jar;E:\tomcat\apache-tomcat-7.0.88\lib\tomcat-util.jar;E:\tomcat\apache-tomcat-7.0.88\lib\tomcat7-websocket.jar;E:\tomcat\apache-tomcat-7.0.88\lib\websocket-api.jar
user.name : Administrator
java.vm.specification.version : 1.7
sun.java.command : com.test.MyTest
java.home : C:\Program Files\Java\jdk1.7.0_80\jre
sun.arch.data.model : 64
user.language : zh
java.specification.vendor : Oracle Corporation
awt.toolkit : sun.awt.windows.WToolkit
java.vm.info : mixed mode
java.version : 1.7.0_80
java.ext.dirs : C:\Program Files\Java\jdk1.7.0_80\jre\lib\ext;C:\WINDOWS\Sun\Java\lib\ext
sun.boot.class.path : C:\Program Files\Java\jdk1.7.0_80\jre\lib\resources.jar;C:\Program Files\Java\jdk1.7.0_80\jre\lib\rt.jar;C:\Program Files\Java\jdk1.7.0_80\jre\lib\sunrsasign.jar;C:\Program Files\Java\jdk1.7.0_80\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.7.0_80\jre\lib\jce.jar;C:\Program Files\Java\jdk1.7.0_80\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.7.0_80\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.7.0_80\jre\classes
java.vendor : Oracle Corporation
file.separator : \
java.vendor.url.bug : http://bugreport.sun.com/bugreport/
sun.io.unicode.encoding : UnicodeLittle
sun.cpu.endian : little
sun.desktop : windows
sun.cpu.isalist : amd64

 

 補充:能夠採用System.setProperties設置系統屬性

    public static void main(String[] args) {
        System.setProperty("mykey", "myvalue");
        String property = System.getProperty("mykey");
        System.out.println(property);
        try {
            Thread.sleep(100 * 1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

 

咱們能夠在cmd窗口經過jinfo查看變量

C:\Users\Administrator>jps
1236
8544 MyTest
9384 Jps

C:\Users\Administrator>jinfo 8544
Attaching to process ID 8544, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 24.80-b11
Java System Properties:

java.runtime.name = Java(TM) SE Runtime Environment
java.vm.version = 24.80-b11
sun.boot.library.path = C:\Program Files\Java\jdk1.7.0_80\jre\bin
java.vendor.url = http://java.oracle.com/
java.vm.vendor = Oracle Corporation
path.separator = ;
file.encoding.pkg = sun.io
java.vm.name = Java HotSpot(TM) 64-Bit Server VM
sun.os.patch.level =
sun.java.launcher = SUN_STANDARD
user.script =
user.country = CN
user.dir = E:\xiangmu\Mytest
java.vm.specification.name = Java Virtual Machine Specification
java.runtime.version = 1.7.0_80-b15
mykey = myvalue

 

 

補充:System能夠獲取系統的環境變量

        // 讀取單個環境變量
        String str = System.getenv("JAVA_HOME");
        System.out.println(str);

        // 讀取全部的環境變量
        Map<String, String> getenv = System.getenv();
        for (Map.Entry<String, String> entry : getenv.entrySet()) {
            System.out.println(entry.getKey() + "========" + entry.getValue());
        }

 

結果:

C:\Program Files\Java\jdk1.7.0_80
USERPROFILE========C:\Users\Administrator
ProgramData========C:\ProgramData
PATHEXT========.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC
Classpath========.;%JAVA_HOME%\lib;%JAVA_HOME%\lib\tools.jar
JAVA_HOME========C:\Program Files\Java\jdk1.7.0_80
MAVEN_HOME========E:\soft\maven\apache-maven-3.3.9
.......

 

 

 

java的System.getProperty()方法能夠獲取的值:

java.version	Java 運行時環境版本
java.vendor	Java 運行時環境供應商
java.vendor.url	Java 供應商的 URL
java.home	Java 安裝目錄
java.vm.specification.version	Java 虛擬機規範版本
java.vm.specification.vendor	Java 虛擬機規範供應商
java.vm.specification.name	Java 虛擬機規範名稱
java.vm.version	Java 虛擬機實現版本
java.vm.vendor	Java 虛擬機實現供應商
java.vm.name	Java 虛擬機實現名稱
java.specification.version	Java 運行時環境規範版本
java.specification.vendor	Java 運行時環境規範供應商
java.specification.name	Java 運行時環境規範名稱
java.class.version	Java 類格式版本號
java.class.path	Java 類路徑
java.library.path	加載庫時搜索的路徑列表
java.io.tmpdir	默認的臨時文件路徑
java.compiler	要使用的 JIT 編譯器的名稱
java.ext.dirs	一個或多個擴展目錄的路徑
os.name	操做系統的名稱
os.arch	操做系統的架構
os.version	操做系統的版本
file.separator	文件分隔符（在 UNIX 系統中是「/」）
path.separator	路徑分隔符（在 UNIX 系統中是「:」）
line.separator	行分隔符（在 UNIX 系統中是「/n」）
user.name	用戶的帳戶名稱
user.home	用戶的主目錄
user.dir	用戶的當前工做目錄