java读取系统环境变量

import java.io.IOException;

import java.io.InputStream;

import java.util.Enumeration;

import java.util.Iterator;

import java.util.Map;

import java.util.Properties;

public class ReadEnv {

public static void main(String[] args) {

//getEnv();

//getProperties();

getRuntime();

}

/**

* java调用windows系统命令

* */

public static void getRuntime(){

Runtime rt = Runtime.getRuntime();

byte[] env = new byte[1000];

try {

Process process = rt.exec("cmd /c echo %classpath%");//cmd /c echo %classpath%

InputStream is = process.getInputStream();

is.read(env);

System.out.println(new String(env).trim());

} catch (IOException e) {

e.printStackTrace();

}

}

/**

* 根据System.getenv()获取

* */

public static void getEnv(){

Map<String,String> envMap = System.getenv();

Iterator<String> envitr = envMap.keySet().iterator();

while(envitr.hasNext()){

System.out.println(envMap.get(envitr.next()));

}

}

/**

* 根据System.getProperties()获取

* */

public static void getProperties(){

Properties prop = System.getProperties();

Enumeration<?> emn = prop.propertyNames();

while(emn.hasMoreElements()){

Object o = emn.nextElement();

System.out.println(o.toString()+":"+prop.getProperty(o.toString()));

}

}

}