类文件中第5,6,7,8四个字节是jDK版本号信息,其中5,6为小版本号;7,8为大版本号。
大版本好对应JDK版本如下:
J2SE 8 = 52 (0x34 hex),
J2SE 7 = 51 (0x33 hex),J2SE 6.0 = 50 (0x32 hex),
J2SE 5.0 = 49 (0x31 hex),
JDK 1.4 = 48 (0x30 hex),
JDK 1.3 = 47 (0x2F hex),
JDK 1.2 = 46 (0x2E hex),
JDK 1.1 = 45 (0x2D hex).