JVM 系统参数路径，类加载器路径

sun.boot.class.path：系统预加载的必须的一些jar，java.class.path,就是我们配置的系统变量中的classPath.采用的的是,委托模型:就是类装载器载入类是，首先请求其parent 使用起搜索路径帮忙载入，如果parent 找不到，那么才由自己依照自己的搜索路径来搜索类。其这样设计的目的是维护了动态性和安全性。

public class Property{
   public static void main(String args[]){
	String path = System.getProperty("sun.boot.class.path");
	System.out.println("path:"+path+"\n");
	String appPath = System.getProperty("java.class.path");
	System.out.println("appPath:"+appPath+"\n");
	String extdir = System.getProperty("java.ext.dirs");
	System.out.println("extdir:"+extdir+"\n");
   }
	
}

 结果：

 

path:/opt/jdk1.6.0_21/jre/lib/resources.jar:/opt/jdk1.6.0_21/jre/lib/rt.jar:/opt/jdk1.6.0_21/jre/lib/sunrsasign.jar:/opt/jdk1.6.0_21/jre/lib/jsse.jar:/opt/jdk1.6.0_21/jre/lib/jce.jar:/opt/jdk1.6.0_21/jre/lib/charsets.jar:/opt/jdk1.6.0_21/jre/classes

appPath:.:/opt/jdk1.6.0_21/lib:/opt/jdk1.6.0_21/jre/lib:

extdir:/opt/jdk1.6.0_21/jre/lib/ext:/usr/java/packages/lib/ext