如何检查Java代码的汇编输出? [英] How do I check assembly output of Java code?

问题描述

我发现这个问题可以用C ++回答:
如何从中获取汇编器输出gcc中的C/C ++源代码?

I found this question that answered it for C++:
How do you get assembler output from C/C++ source in gcc?

推荐答案

Java使用字节码.最相似的是 javap ，根据链接的Oracle文档， javap 命令反汇编一个或多个类文件.其输出取决于所使用的选项.

Java uses bytecode. The most similar would be javap, per the linked Oracle documentation, the javap command disassembles one or more class files. Its output depends on the options used.

package com.stackoverflow;

class Main {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}

如果我将其编译为Main.class然后运行javap -v Main.class我会得到

If I compile that to Main.class and then run javap -v Main.class I get

Classfile /home/efrisch/workspace/StackOverflow/bin/com/stackoverflow/Main.class
  Last modified Jun 18, 2015; size 553 bytes
  MD5 checksum de4f987e783aa0f145e7245269504028
  Compiled from "Main.java"
class com.stackoverflow.Main
  minor version: 0
  major version: 52
  flags: ACC_SUPER
Constant pool:
   #1 = Class              #2             // com/stackoverflow/Main
   #2 = Utf8               com/stackoverflow/Main
   #3 = Class              #4             // java/lang/Object
   #4 = Utf8               java/lang/Object
   #5 = Utf8               <init>
   #6 = Utf8               ()V
   #7 = Utf8               Code
   #8 = Methodref          #3.#9          // java/lang/Object."<init>":()V
   #9 = NameAndType        #5:#6          // "<init>":()V
  #10 = Utf8               LineNumberTable
  #11 = Utf8               LocalVariableTable
  #12 = Utf8               this
  #13 = Utf8               Lcom/stackoverflow/Main;
  #14 = Utf8               main
  #15 = Utf8               ([Ljava/lang/String;)V
  #16 = Fieldref           #17.#19        // java/lang/System.out:Ljava/io/PrintStream;
  #17 = Class              #18            // java/lang/System
  #18 = Utf8               java/lang/System
  #19 = NameAndType        #20:#21        // out:Ljava/io/PrintStream;
  #20 = Utf8               out
  #21 = Utf8               Ljava/io/PrintStream;
  #22 = String             #23            // Hello, World!
  #23 = Utf8               Hello, World!
  #24 = Methodref          #25.#27        // java/io/PrintStream.println:(Ljava/lang/String;)V
  #25 = Class              #26            // java/io/PrintStream
  #26 = Utf8               java/io/PrintStream
  #27 = NameAndType        #28:#29        // println:(Ljava/lang/String;)V
  #28 = Utf8               println
  #29 = Utf8               (Ljava/lang/String;)V
  #30 = Utf8               args
  #31 = Utf8               [Ljava/lang/String;
  #32 = Utf8               SourceFile
  #33 = Utf8               Main.java
{
  com.stackoverflow.Main();
    descriptor: ()V
    flags:
    Code:
      stack=1, locals=1, args_size=1
         0: aload_0
         1: invokespecial #8                  // Method java/lang/Object."<init>":()V
         4: return
      LineNumberTable:
        line 3: 0
      LocalVariableTable:
        Start  Length  Slot  Name   Signature
            0       5     0  this   Lcom/stackoverflow/Main;

  public static void main(java.lang.String[]);
    descriptor: ([Ljava/lang/String;)V
    flags: ACC_PUBLIC, ACC_STATIC
    Code:
      stack=2, locals=1, args_size=1
         0: getstatic     #16                 // Field java/lang/System.out:Ljava/io/PrintStream;
         3: ldc           #22                 // String Hello, World!
         5: invokevirtual #24                 // Method java/io/PrintStream.println:(Ljava/lang/String;)V
         8: return
      LineNumberTable:
        line 5: 0
        line 6: 8
      LocalVariableTable:
        Start  Length  Slot  Name   Signature
            0       9     0  args   [Ljava/lang/String;
}
SourceFile: "Main.java"

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