Java编译过程详解：生成字节码文件的技术解析与应用20201012

javap -verbose Hello

Java代码&＃xff1a;

public class Hello {

public static void main(String[] args) {

System.out.println("hello world");

}

}

生成的字节码如下&＃xff1a;

&＃96;&＃96;&＃96;Classfile /Users/jessen/learning/JAVA-000/Week_01/demo1/Hello.class

Last modified 2020-10-12; size 415 bytes

MD5 checksum f78738196756e74f31907b064c1ee653

Compiled from "Hello.java"

public class Hello

minor version: 0

major version: 52

flags: ACC_PUBLIC, ACC_SUPER

Constant pool:

#1 &＃61; Methodref          #6.#15        // java/lang/Object."":()V

#2 &＃61; Fieldref          #16.#17        // java/lang/System.out:Ljava/io/PrintStream;

#3 &＃61; String            #18            // hello world

#4 &＃61; Methodref          #19.#20        // java/io/PrintStream.println:(Ljava/lang/String;)V

#5 &＃61; Class              #21            // Hello

#6 &＃61; Class              #22            // java/lang/Object

#7 &＃61; Utf8

#8 &＃61; Utf8              ()V

#9 &＃61; Utf8              Code

#10 &＃61; Utf8              LineNumberTable

#11 &＃61; Utf8              main

#12 &＃61; Utf8              ([Ljava/lang/String;)V

#13 &＃61; Utf8              SourceFile

#14 &＃61; Utf8              Hello.java

#15 &＃61; NameAndType        #7:#8          // "":()V

#16 &＃61; Class              #23            // java/lang/System

#17 &＃61; NameAndType        #24:#25        // out:Ljava/io/PrintStream;

#18 &＃61; Utf8              hello world

#19 &＃61; Class              #26            // java/io/PrintStream

#20 &＃61; NameAndType        #27:#28        // println:(Ljava/lang/String;)V

#21 &＃61; Utf8              Hello

#22 &＃61; Utf8              java/lang/Object

#23 &＃61; Utf8              java/lang/System

#24 &＃61; Utf8              out

#25 &＃61; Utf8              Ljava/io/PrintStream;

#26 &＃61; Utf8              java/io/PrintStream

#27 &＃61; Utf8              println

#28 &＃61; Utf8              (Ljava/lang/String;)V

{

public Hello();

descriptor: ()V

flags: ACC_PUBLIC

Code:

stack&＃61;1, locals&＃61;1, args_size&＃61;1

0: aload_0

1: invokespecial #1                  // Method java/lang/Object."":()V

4: return

LineNumberTable:

line 2: 0

public static void main(java.lang.String[]);

descriptor: ([Ljava/lang/String;)V

flags: ACC_PUBLIC, ACC_STATIC

Code:

stack&＃61;2, locals&＃61;1, args_size&＃61;1

0: getstatic    #2                  // Field java/lang/System.out:Ljava/io/PrintStream;

3: ldc          #3                  // String hello world

5: invokevirtual #4                  // Method java/io/PrintStream.println:(Ljava/lang/String;)V

8: return

LineNumberTable:

line 4: 0

line 5: 8

}

SourceFile: "Hello.java"&＃96;&＃96;&＃96;