String t=Thread.currentThread().getContextClassLoader().getResource("").getPath();
     

   System.out.println(t);
        

int num=t.indexOf(".metadata");
        

System.out.println(num);   //这里输出-1     
      

  String path=t.substring(1,num).replace('/', '\\')+"CBDParkingSystem\\WebContent\\img";
         System.out.println(path);

下面是报错-----------》》》：

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: -2
    at java.lang.String.substring(Unknown Source)
    at com.lovo.dao.test.ExternalContractsTest.main(ExternalContractsTest.java:77)
/C:/Users/Administrator/Desktop/CBDParkingSystem/build/classes/
-1