Java basics to obtain system properties and environment variables

public static void main(String[] args) {  
        //属性  
        System.out.println("系统属性......");  
        Properties props = System.getProperties();  
        Set<Object> sets = props.keySet();  
        for (Object objKey : sets) {  
            System.out.println("属性名：【"+objKey+"】\n属性值:"+props.getProperty((String) objKey)+"\n");  
        }  
          
          
        //环境变量  
        System.out.println("\n\n环境变量......");  
        Map<String, String> env = System.getenv();  
        Set<String> keySet = env.keySet();  
        for (String key : keySet) {  
            System.out.println("【"+key+"】\t:\t【"+env.get(key)+"】\n");  
        }  
          
    }