查看JAR 的JDK 版本

You test the JDK version of your JAR with following code.

 

 

public class JDKVersion {
  private static final int JAVA_CLASS_MAGIC = 0xCAFEBABE;
  
  public static void main(String[] args){        
    try {               
     DataInputStream dis = new DataInputStream(new FileInputStream("C:\\LJ\\test\\BusiLegalVehicle.class"));
     int magic = dis.readInt();
     if(magic == JAVA_CLASS_MAGIC){
      int minorVersion = dis.readUnsignedShort();
      int majorVersion = dis.readUnsignedShort();
      
//      Java 1.2 uses major version 46
//      Java 1.3 uses major version 47
//      Java 1.4 uses major version 48
//      Java 5 uses major version 49
//      Java 6 uses major version 50
//      Java 7 uses major version 51  
      
      System.out.println("ClassVersionTest.main() " + majorVersion + "." + minorVersion);
      }
      }catch (FileNotFoundException e){
       // TODO Auto-generated catch block
        e.printStackTrace();
       } catch (IOException e){
       // TODO Auto-generated catch block
        e.printStackTrace();
       }
   }
}