Introduction to System Properties Properties in Java System.getProperty() Parameters Daquan

There is such a method getProperties() in the System class in the JDK documentation. The following parameters are available for use in the detailed introduction of this method:

java.version  Java runtime environment version

java.vendor  Java runtime environment vendor

java.vendor.url  Java vendor URL

java.home  Java installation directory

java.vm.specification.version  Java Virtual Machine Specification Version

java.vm.specification.vendor  Java Virtual Machine Specification Vendor

java.vm.specification.name  Java Virtual Machine specification name

java.vm.version  Java Virtual Machine implementation version

java.vm.vendor  Java Virtual Machine Implementation Vendor

java.vm.name  Java virtual machine implementation name

java.specification.version  Java Runtime Environment specification version

java.specification.vendor  Java Runtime Environment Specification Vendor

java.specification.name  Java Runtime Environment specification name

java.class.version  Java class format version number

java.class.path  Java class path

java.library.path  A list of paths searched when loading libraries

java.io.tmpdir  default temporary file path

java.compiler  The name of the JIT compiler to use

java.ext.dirs  Path to one or more extension directories

os.name  the name of the operating system

os.arch  operating system architecture

os.version  The version of the operating system

file.separator  file separator ("/" on UNIX systems)

path.separator  path separator (":" on UNIX systems)

line.separator  行分隔符（在 UNIX 系统中是“/n”）

user.name  用户的账户名称

user.home  用户的主目录

user.dir  用户的当前工作目录

下面是针对这些参数进行的一个测试，代码如下：

import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Properties;
import java.util.Set;
public class MyJavaMain {

	public static void main(String[] args) throws Exception {

		//通过StringBuilder来构建要输出的内容
		StringBuilder sb = new StringBuilder();
		sb.append("Java 运行时环境版本:"+System.getProperty("java.version")+"\n");
		sb.append("Java 运行时环境供应商:"+System.getProperty("java.vendor")+"\n");
		sb.append("Java 供应商的URL:"+System.getProperty("java.vendor.url")+"\n");
		sb.append("Java 安装目录:"+System.getProperty("java.home")+"\n");
		sb.append("Java 虚拟机规范版本:"+System.getProperty("java.vm.specification.version")+"\n");
		sb.append("Java 类格式版本号:"+System.getProperty("java.class.version")+"\n");
		sb.append("Java类路径："+System.getProperty("java.class.path")+"\n");
		sb.append("加载库时搜索的路径列表:"+System.getProperty("java.library.path")+"\n");
		sb.append("默认的临时文件路径:"+System.getProperty("java.io.tmpdir")+"\n");
		sb.append("要使用的 JIT 编译器的名称:"+System.getProperty("java.compiler")+"\n");
		sb.append("一个或多个扩展目录的路径:"+System.getProperty("java.ext.dirs")+"\n");
		sb.append("操作系统的名称:"+System.getProperty("os.name")+"\n");
		sb.append("操作系统的架构:"+System.getProperty("os.arch")+"\n");
		sb.append("操作系统的版本:"+System.getProperty("os.version")+"\n");
		sb.append("文件分隔符（在 UNIX 系统中是“/”）:"+System.getProperty("file.separator")+"\n");
		sb.append("路径分隔符（在 UNIX 系统中是“:”）:"+System.getProperty("path.separator")+"\n");
		sb.append("行分隔符（在 UNIX 系统中是“/n”）:"+System.getProperty("line.separator")+"\n");
		sb.append("用户的账户名称:"+System.getProperty("user.name")+"\n");
		sb.append("用户的主目录:"+System.getProperty("user.home")+"\n");
		sb.append("用户的当前工作目录:"+System.getProperty("user.dir")+"\n");
	
		//新建一个文件，如果该文件不存在则创建一个
		File file = new File("c:\\t.txt");
		if( !file.exists()){
			file.createNewFile();
		}
		OutputStream ous = new FileOutputStream(file);
	
		//获取系统的属性
		Properties ps = System.getProperties();
		//获得系统属性中的键值
		Set<String> set = ps.stringPropertyNames();
		for(String name: set){
			sb.append(name + " : " +ps.getProperty(name) + "\n");
			System.out.println(name + " : " +ps.getProperty(name) );
		}
		ous.write(sb.toString().getBytes());
		ous.close();

		System.out.println(System.getProperty("os.name"));
		System.out.println(System.getProperty("os.version"));
		System.out.println("Java运行时环境版本:"+System.getProperty("java.version"));
		System.out.println("Java 运行时环境供应商:"+System.getProperty("java.vendor"));
		System.out.println("Java 供应商的URL:"+System.getProperty("java.vendor.url"));
		System.out.println("Java 安装目录:"+System.getProperty("java.home"));
		System.out.println("Java 虚拟机规范版本:"+System.getProperty("java.vm.specification.version"));
		System.out.println("Java 类格式版本号:"+System.getProperty("java.class.version"));
		System.out.println("Java 类路径："+System.getProperty("java.class.path"));
		System.out.println("加载库时搜索的路径列表:"+System.getProperty("java.library.path"));
		System.out.println("默认的临时文件路径:"+System.getProperty("java.io.tmpdir"));
		System.out.println("要使用的 JIT 编译器的名称:"+System.getProperty("java.compiler"));
		System.out.println("一个或多个扩展目录的路径:"+System.getProperty("java.ext.dirs"));
		System.out.println("操作系统的名称:"+System.getProperty("os.name"));
		System.out.println("操作系统的架构:"+System.getProperty("os.arch"));
		System.out.println("操作系统的版本:"+System.getProperty("os.version"));
		System.out.println("文件分隔符（在 UNIX 系统中是“/”）:"+System.getProperty("file.separator"));
		System.out.println("路径分隔符（在 UNIX 系统中是“:”）:"+System.getProperty("path.separator"));
		System.out.println("行分隔符（在 UNIX 系统中是“/n”）:"+System.getProperty("line.separator"));
		System.out.println("用户的账户名称:"+System.getProperty("user.name"));
		System.out.println("用户的主目录:"+System.getProperty("user.home"));
		System.out.println("用户的当前工作目录: "+System.getProperty("user.dir"));
	
		InetAddress netAddress = getInetAddress();
		System.out.println("host ip:" + getHostIp(netAddress));
		System.out.println("host name:" + getHostName(netAddress));
	}

	/**
	* 获取本地主机
	* @return 
	*/
	public static InetAddress getInetAddress() {
		try {
			return InetAddress.getLocalHost();
		} catch (UnknownHostException e) {
			System.out.println("unknown host!");
		}
		return null;
	} 

	/**
	* 通过InetAddress获取本地Ip
	* @param netAddress
	* @return 
	*/
	public static String getHostIp(InetAddress netAddress) {
		if (null == netAddress) {
			return null;
		}
		String ip = netAddress.getHostAddress();
		return ip;
	}

	/**
	* 通过InetAddress获取本地主机的名字
	* @param netAddress
	* @return 
	*/
	public static String getHostName(InetAddress netAddress) {
		if (null == netAddress) {
			return null;
		}
		String name = netAddress.getHostName();
		return name;
	}
}

然而在Android系统中，却要使用另一种方法才能遍历获得系统的一些属性

Properties ps = System.getProperties();
Set<Entry<Object, Object>> set = ps.entrySet();
for(Entry<Object, Object> ent : set){
	Log.v("ent", "key:" + ent.getKey() + " |value: " + ent.getValue());
}