1.javac 编译器的使用
Javac -d destdir srcFile
Javac -d . srcFile 路径为当前的路径
2. javap 反编译的简单应用
C:\>javap -help
用法: javap <options> <classes>
其中, 可能的选项包括:
-help --help -? 输出此用法消息
-version 版本信息
-v -verbose 输出附加信息
-l 输出行号和本地变量表
-public 仅显示公共类和成员
-protected 显示受保护的/公共类和成员
-package 显示程序包/受保护的/公共类
和成员 (默认)
-p -private 显示所有类和成员
-c 对代码进行反汇编
-s 输出内部类型签名
-sysinfo 显示正在处理的类的
系统信息 (路径, 大小, 日期, MD5 散列)
-constants 显示静态最终常量
-classpath <path> 指定查找用户类文件的位置
-bootclasspath <path> 覆盖引导类文件的位置
javap -c
D:\com\company>javap -c TestIncrease.class
Compiled from "TestIncrease.java"
public class com.company.TestIncrease {
public com.company.TestIncrease();
Code:
0: aload_0
1: invokespecial #1 // Method java/lang/Object."<init>":()V
4: return
public static void main(java.lang.String[]);
Code:
0: iconst_0
1: istore_1
2: getstatic #2 // Field java/lang/System.out:Ljava/io/PrintStream;
5: new #3 // class java/lang/StringBuilder
8: dup
9: invokespecial #4 // Method java/lang/StringBuilder."<init>":()V
12: ldc #5 // String
14: invokevirtual #6 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
17: iload_1
18: invokevirtual #7 // Method java/lang/StringBuilder.append:(I)Ljava/lang/StringBuilder;
21: invokevirtual #8 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
24: invokevirtual #9 // Method java/io/PrintStream.println:(Ljava/lang/String;)V
27: iconst_0
28: istore_2
29: iload_2
30: bipush 10
32: if_icmpge 44
35: iinc 1, 1
38: iinc 2, 1
41: goto 29
44: getstatic #2 // Field java/lang/System.out:Ljava/io/PrintStream;
47: new #3 // class java/lang/StringBuilder
50: dup
51: invokespecial #4 // Method java/lang/StringBuilder."<init>":()V
54: ldc #5 // String
56: invokevirtual #6 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
59: iload_1
60: invokevirtual #7 // Method java/lang/StringBuilder.append:(I)Ljava/lang/StringBuilder;
63: invokevirtual #8 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
66: invokevirtual #9 // Method java/io/PrintStream.println:(Ljava/lang/String;)V
69: return
}
Javap -v
D:\com\company>javap -v TestIncrease.class
Classfile /D:/com/company/TestIncrease.class
Last modified 2019-5-18; size 729 bytes
MD5 checksum 51f06c604a0a6412c3417539347b40ed
Compiled from "TestIncrease.java"
public class com.company.TestIncrease
minor version: 0
major version: 52
flags: ACC_PUBLIC, ACC_SUPER
Constant pool:
#1 = Methodref #11.#21 // java/lang/Object."<init>":()V
#2 = Fieldref #22.#23 // java/lang/System.out:Ljava/io/PrintStream;
#3 = Class #24 // java/lang/StringBuilder
#4 = Methodref #3.#21 // java/lang/StringBuilder."<init>":()V
#5 = String #25 //
#6 = Methodref #3.#26 // java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
#7 = Methodref #3.#27 // java/lang/StringBuilder.append:(I)Ljava/lang/StringBuilder;
#8 = Methodref #3.#28 // java/lang/StringBuilder.toString:()Ljava/lang/String;
#9 = Methodref #29.#30 // java/io/PrintStream.println:(Ljava/lang/String;)V
#10 = Class #31 // com/company/TestIncrease
#11 = Class #32 // java/lang/Object
#12 = Utf8 <init>
#13 = Utf8 ()V
#14 = Utf8 Code
#15 = Utf8 LineNumberTable
#16 = Utf8 main
#17 = Utf8 ([Ljava/lang/String;)V
#18 = Utf8 StackMapTable
#19 = Utf8 SourceFile
#20 = Utf8 TestIncrease.java
#21 = NameAndType #12:#13 // "<init>":()V
#22 = Class #33 // java/lang/System
#23 = NameAndType #34:#35 // out:Ljava/io/PrintStream;
#24 = Utf8 java/lang/StringBuilder
#25 = Utf8
#26 = NameAndType #36:#37 // append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
#27 = NameAndType #36:#38 // append:(I)Ljava/lang/StringBuilder;
#28 = NameAndType #39:#40 // toString:()Ljava/lang/String;
#29 = Class #41 // java/io/PrintStream
#30 = NameAndType #42:#43 // println:(Ljava/lang/String;)V
#31 = Utf8 com/company/TestIncrease
#32 = Utf8 java/lang/Object
#33 = Utf8 java/lang/System
#34 = Utf8 out
#35 = Utf8 Ljava/io/PrintStream;
#36 = Utf8 append
#37 = Utf8 (Ljava/lang/String;)Ljava/lang/StringBuilder;
#38 = Utf8 (I)Ljava/lang/StringBuilder;
#39 = Utf8 toString
#40 = Utf8 ()Ljava/lang/String;
#41 = Utf8 java/io/PrintStream
#42 = Utf8 println
#43 = Utf8 (Ljava/lang/String;)V
{
public com.company.TestIncrease();
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
public static void main(java.lang.String[]);
descriptor: ([Ljava/lang/String;)V
flags: ACC_PUBLIC, ACC_STATIC
Code:
stack=3, locals=3, args_size=1
0: iconst_0
1: istore_1
2: getstatic #2 // Field java/lang/System.out:Ljava/io/PrintStream;
5: new #3 // class java/lang/StringBuilder
8: dup
9: invokespecial #4 // Method java/lang/StringBuilder."<init>":()V
12: ldc #5 // String
14: invokevirtual #6 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
17: iload_1
18: invokevirtual #7 // Method java/lang/StringBuilder.append:(I)Ljava/lang/StringBuilder;
21: invokevirtual #8 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
24: invokevirtual #9 // Method java/io/PrintStream.println:(Ljava/lang/String;)V
27: iconst_0
28: istore_2
29: iload_2
30: bipush 10
32: if_icmpge 44
35: iinc 1, 1
38: iinc 2, 1
41: goto 29
44: getstatic #2 // Field java/lang/System.out:Ljava/io/PrintStream;
47: new #3 // class java/lang/StringBuilder
50: dup
51: invokespecial #4 // Method java/lang/StringBuilder."<init>":()V
54: ldc #5 // String
56: invokevirtual #6 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
59: iload_1
60: invokevirtual #7 // Method java/lang/StringBuilder.append:(I)Ljava/lang/StringBuilder;
63: invokevirtual #8 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
66: invokevirtual #9 // Method java/io/PrintStream.println:(Ljava/lang/String;)V
69: return
LineNumberTable:
line 6: 0
line 8: 2
line 11: 27
line 13: 35
line 11: 38
line 17: 44
line 19: 69
StackMapTable: number_of_entries = 2
frame_type = 253 /* append */
offset_delta = 29
locals = [ int, int ]
frame_type = 250 /* chop */
offset_delta = 14
}
SourceFile: "TestIncrease.java"