判断编译的class文件JDK版本号

	public static void main(String[] args) {	
		try {
			String filename = "/home/xxx/apps/eclipse/workspace/Test/bin/com/ibm/plugin/test/MyChecker.class";
			DataInputStream in = new DataInputStream(new FileInputStream(filename));
			int magic = in.readInt();
			if (magic != 0xcafebabe) {
				System.out.println(filename + "is not a valid class!");
			}
			int minor = in.readUnsignedShort();
			int major = in.readUnsignedShort();
			System.out.println(filename + ":" + major + "." + minor);
			in.close();
		} catch (IOException e) {
			e.printStackTrace();
		}

String version = null;
		DataInputStream in = null;
		try {
			tring filename = "/home/zhujt/apps/eclipse/workspace/Test/bin/com/ibm/plugin/test/MyChecker.class";
			 in = new DataInputStream(new FileInputStream(filename));
			
			int magic = in.readInt();
			if (magic != 0xcafebabe) {
				throw new IllegalArgumentException("Wrong file format.");
			}
			
			int minor = in.readUnsignedShort();
			int major = in.readUnsignedShort();
			
			/*
			major    minor       version
			45       3           1.0
			45       3           1.1
			46       0           1.2
			47       0           1.3
			48       0           1.4
			49       0           1.5
			50       0           1.6
			*/

			if(major == 45 && minor == 3) {
				version = "1.1";
			} else if(major == 46) {
				version = "1.2";
			} else if(major == 47) {
				version = "1.3";
			} else if(major == 48) {
				version = "1.4";
			} else if(major == 49) {
				version = "1.5";
			} else if(major == 50) {
				version = "1.6";
			} 
			// Just for future use, it is not correct
			else if(major > 50) {
				version = "1.7";
			}
		} finally {
			if(in != null) {
				try {
					in.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
		
		return version;
}