一、使用javap反编译查看字节码指令
第一步：找到我们要反编译的类的.class文件所在的位置，我学习Concurrence的代码的class全部放在D:\Java_Program\JavaBasic\out\production\JavaBasic\Concurrence。
第二步:复制上面的路径，进入Power Shell中(Win7是cmd中，我的是Win10)
PS C:\WINDOWS\system32> cd D:\Java_Program\JavaBasic\out\production\JavaBasic\Concurrence
PS D:\Java_Program\JavaBasic\out\production\JavaBasic\Concurrence>第三步：运行下面的命令和你需要反编译的class文件名,
PS D:\Java_Program\JavaBasic\out\production\JavaBasic\Concurrence> javap -c SleepAndWait第四步：得到反编译的二进制文件结果
警告: 二进制文件SleepAndWait包含Concurrence.SleepAndWait
Compiled from "SleepAndWait.java"
public class Concurrence.SleepAndWait {
public Concurrence.SleepAndWait();
Code:
0: aload_0
1: invokespecial #1 // Method java/lang/Object."<init>":()V
4: return
public static void main(java.lang.String[]);
Code:
0: new #2 // class java/lang/Thread
3: dup
4: new #3 // class Concurrence/Thread1
7: dup
8: invokespecial #4 // Method Concurrence/Thread1."<init>":()V
11: invokespecial #5 // Method java/lang/Thread."<init>":(Ljava/lang/Runnable;)V
14: invokevirtual #6 // Method java/lang/Thread.start:()V
17: ldc2_w #7 // long 5000l
20: invokestatic #9 // Method java/lang/Thread.sleep:(J)V
23: goto 31
26: astore_1
27: aload_1
28: invokevirtual #11 // Method java/lang/InterruptedException.printStackTrace:()V
31: new #2 // class java/lang/Thread
34: dup
35: new #12 // class Concurrence/Thread2
38: dup
39: invokespecial #13 // Method Concurrence/Thread2."<init>":()V
42: invokespecial #5 // Method java/lang/Thread."<init>":(Ljava/lang/Runnable;)V
45: invokevirtual #6 // Method java/lang/Thread.start:()V
48: return
Exception table:
from to target type
17 23 26 Class java/lang/InterruptedException
}如果我们想要得到更详细的信息，可以运行下面的命令(推荐使用)
PS D:\Java_Program\JavaBasic\out\production\JavaBasic\Concurrence> javap -verbose SleepAndWait反编译得到的信息
警告: 二进制文件SleepAndWait包含Concurrence.SleepAndWait
Classfile /D:/Java_Program/JavaBasic/out/production/JavaBasic/Concurrence/SleepAndWait.class
Last modified 2018-7-28; size 798 bytes
MD5 checksum 7f5f4f64266bcbfe4ac1d2f452c8ade1
Compiled from "SleepAndWait.java"
public class Concurrence.SleepAndWait
minor version: 0
major version: 52
flags: ACC_PUBLIC, ACC_SUPER
Constant pool:
#1 = Methodref #15.#33 // java/lang/Object."<init>":()V
#2 = Class #34 // java/lang/Thread
#3 = Class #35 // Concurrence/Thread1
#4 = Methodref #3.#33 // Concurrence/Thread1."<init>":()V
#5 = Methodref #2.#36 // java/lang/Thread."<init>":(Ljava/lang/Runnable;)V
#6 = Methodref #2.#37 // java/lang/Thread.start:()V
#7 = Long 5000l
#9 = Methodref #2.#38 // java/lang/Thread.sleep:(J)V
#10 = Class #39 // java/lang/InterruptedException
#11 = Methodref #10.#40 // java/lang/InterruptedException.printStackTrace:()V
#12 = Class #41 // Concurrence/Thread2
#13 = Methodref #12.#33 // Concurrence/Thread2."<init>":()V
#14 = Class #42 // Concurrence/SleepAndWait
#15 = Class #43 // java/lang/Object
#16 = Utf8 <init>
#17 = Utf8 ()V
#18 = Utf8 Code
#19 = Utf8 LineNumberTable
#20 = Utf8 LocalVariableTable
#21 = Utf8 this
#22 = Utf8 LConcurrence/SleepAndWait;
#23 = Utf8 main
#24 = Utf8 ([Ljava/lang/String;)V
#25 = Utf8 e
#26 = Utf8 Ljava/lang/InterruptedException;
#27 = Utf8 args
#28 = Utf8 [Ljava/lang/String;
#29 = Utf8 StackMapTable
#30 = Class #39 // java/lang/InterruptedException
#31 = Utf8 SourceFile
#32 = Utf8 SleepAndWait.java
#33 = NameAndType #16:#17 // "<init>":()V
#34 = Utf8 java/lang/Thread
#35 = Utf8 Concurrence/Thread1
#36 = NameAndType #16:#44 // "<init>":(Ljava/lang/Runnable;)V
#37 = NameAndType #45:#17 // start:()V
#38 = NameAndType #46:#47 // sleep:(J)V
#39 = Utf8 java/lang/InterruptedException
#40 = NameAndType #48:#17 // printStackTrace:()V
#41 = Utf8 Concurrence/Thread2
#42 = Utf8 Concurrence/SleepAndWait
#43 = Utf8 java/lang/Object
#44 = Utf8 (Ljava/lang/Runnable;)V
#45 = Utf8 start
#46 = Utf8 sleep
#47 = Utf8 (J)V
#48 = Utf8 printStackTrace
{
public Concurrence.SleepAndWait();
descriptor: ()V
flags: ACC_PUBLIC
Code:
stack=1, locals=1, args_size=1
0: aload_0
1: invokespecial #1 // Method java/lang/Object."<init>":()V
4: return
LineNumberTable:
line 3: 0
LocalVariableTable:
Start Length Slot Name Signature
0 5 0 this LConcurrence/SleepAndWait;
public static void main(java.lang.String[]);
descriptor: ([Ljava/lang/String;)V
flags: ACC_PUBLIC, ACC_STATIC
Code:
stack=4, locals=2, args_size=1
0: new #2 // class java/lang/Thread
3: dup
4: new #3 // class Concurrence/Thread1
7: dup
8: invokespecial #4 // Method Concurrence/Thread1."<init>":()V
11: invokespecial #5 // Method java/lang/Thread."<init>":(Ljava/lang/Runnable;)V
14: invokevirtual #6 // Method java/lang/Thread.start:()V
17: ldc2_w #7 // long 5000l
20: invokestatic #9 // Method java/lang/Thread.sleep:(J)V
23: goto 31
26: astore_1
27: aload_1
28: invokevirtual #11 // Method java/lang/InterruptedException.printStackTrace:()V
31: new #2 // class java/lang/Thread
34: dup
35: new #12 // class Concurrence/Thread2
38: dup
39: invokespecial #13 // Method Concurrence/Thread2."<init>":()V
42: invokespecial #5 // Method java/lang/Thread."<init>":(Ljava/lang/Runnable;)V
45: invokevirtual #6 // Method java/lang/Thread.start:()V
48: return
Exception table:
from to target type
17 23 26 Class java/lang/InterruptedException
LineNumberTable:
line 5: 0
line 8: 17
line 11: 23
line 9: 26
line 10: 27
line 12: 31
line 13: 48
LocalVariableTable:
Start Length Slot Name Signature
27 4 1 e Ljava/lang/InterruptedException;
0 49 0 args [Ljava/lang/String;
StackMapTable: number_of_entries = 2
frame_type = 90 /* same_locals_1_stack_item */
stack = [ class java/lang/InterruptedException ]
frame_type = 4 /* same */
}
SourceFile: "SleepAndWait.java"