Android反编译 -- 错误代码还原

1. setColor(-16777216)

反编译的代码中会有很多setColor(int)的情况,比如setColor(-16777216),这个值比较特别,能轻易的查到Android文档中对这个整数的定义:

public static final int BLACK.
Added in API level 1
Constant Value: -16777216 ( 0xff000000).

也就是说setColor(-16777216)-16777216对应的颜色是BLACK(0xff000000),那么其他系统未定义成某个颜色名的值呢?

1
2
3
4
5
6
7
8
9
10
11
-16777216 对应 0xff000000
-1 对应 0xffffffff
0xffffff 的值 16777215
那么对任意的 setColor(int)中的int值,我们可以:
0xffffffff+(int)+1 或 0xffffffff-(-int+1)
则对于 :setColor(-16777216)
可写成 :setColor(0xffffffff - 16777215)) 或 setColor(-16777216 + 1 + 0xffffffff))
这样,我们就不用查文档寻找特定的颜色值,也能解决任意颜色的设置。

Stackoverflow : How to set color using integer?

2.MeasureSpec.makeMeasureSpec(xx, int)

反编译的代码中MeasureSpec.makeMeasureSpec(xx, int)的第二个参数是个int类型的数,这个比较简单,直接看文档或者源码即可找到:

源码:

1
2
3
4
5
6
7
public static class MeasureSpec {
public static final int UNSPECIFIED = 0;
public static final int EXACTLY = 1073741824;
public static final int AT_MOST = -2147483648;
...
}

文档:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
public static final int AT_MOST
Added in API level 1
Measure specification mode: The child can be as large as it wants up to the specified size.
Constant Value: -2147483648 (0x80000000)
public static final int EXACTLY
Added in API level 1
Measure specification mode: The parent has determined an exact size for the child. The child is going to be given those bounds regardless of how big it wants to be.
Constant Value: 1073741824 (0x40000000)
public static final int UNSPECIFIED
Added in API level 1
Measure specification mode: The parent has not imposed any constraint on the child. It can be whatever size it wants.
Constant Value: 0 (0x00000000)

则对于:
MeasureSpec.makeMeasureSpec(xx, 0)
我们应该修改为
MeasureSpec.makeMeasureSpec(xx, View.MeasureSpec.UNSPECIFIED)

其他依次类推。

3.setVisibility(int)

这个同[2],看文档或者看源码:

1
2
3
public static final int VISIBLE = 0;
public static final int INVISIBLE = 4;
public static final int GONE = 8;

则对于:setVisibility(0) ==> setVisibility(View.VISIBLE)

其他依次类推。

4.new Runnable()...

反编译的代码中:

1
2
3
4
5
6
7
8
9
10
new Runnable() {
final /* synthetic */ AbstractButton a;
{
this.a = r1;
}
public final void run() {
this.a.xxxxx();
}
};

可直接去掉成员变量:

1
2
3
4
5
new Runnable() {
public final void run() {
xxxxx();
}
};

5.new Handler()...

[4],直接去掉成员变量:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
new Handler() {
final /* synthetic */ ButtonSave a;
{
this.a = r1;
}
public final void handleMessage(Message message) {
this.a.xxx();
}
};
//修改为
new Handler() {
public final void handleMessage(Message message) {
xxx();
}
};

6.context.getSystemService("layout_inflater")

直接看源码即可:

1
2
3
4
5
6
7
8
9
public static final String POWER_SERVICE = "power";
public static final String WINDOW_SERVICE = "window";
public static final String LAYOUT_INFLATER_SERVICE = "layout_inflater";
public static final String ACCOUNT_SERVICE = "account";
public static final String ACTIVITY_SERVICE = "activity";
public static final String ALARM_SERVICE = "alarm";
public static final String NOTIFICATION_SERVICE = "notification";
public static final String ACCESSIBILITY_SERVICE = "accessibility";
...

context.getSystemService("layout_inflater") ==> context.getSystemService(Context.LAYOUT_INFLATER_SERVICE)

其他依次类推。

7.intent.setFlags(335544320)

先看源码:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
Intent implements Parcelable, Cloneable {
public static final int FLAG_GRANT_READ_URI_PERMISSION = 1;
public static final int FLAG_GRANT_WRITE_URI_PERMISSION = 2;
public static final int FLAG_FROM_BACKGROUND = 4;
public static final int FLAG_DEBUG_LOG_RESOLUTION = 8;
public static final int FLAG_EXCLUDE_STOPPED_PACKAGES = 16;
public static final int FLAG_INCLUDE_STOPPED_PACKAGES = 32;
public static final int FLAG_ACTIVITY_NO_HISTORY = 1073741824;
public static final int FLAG_ACTIVITY_SINGLE_TOP = 536870912;
public static final int FLAG_ACTIVITY_NEW_TASK = 268435456;
public static final int FLAG_ACTIVITY_MULTIPLE_TASK = 134217728;
public static final int FLAG_ACTIVITY_CLEAR_TOP = 67108864;
public static final int FLAG_ACTIVITY_FORWARD_RESULT = 33554432;
public static final int FLAG_ACTIVITY_PREVIOUS_IS_TOP = 16777216;
public static final int FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS = 8388608;
public static final int FLAG_ACTIVITY_BROUGHT_TO_FRONT = 4194304;
public static final int FLAG_ACTIVITY_RESET_TASK_IF_NEEDED = 2097152;
public static final int FLAG_ACTIVITY_LAUNCHED_FROM_HISTORY = 1048576;
public static final int FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET = 524288;
public static final int FLAG_ACTIVITY_NO_USER_ACTION = 262144;
public static final int FLAG_ACTIVITY_REORDER_TO_FRONT = 131072;
public static final int FLAG_ACTIVITY_NO_ANIMATION = 65536;
public static final int FLAG_ACTIVITY_CLEAR_TASK = 32768;
public static final int FLAG_ACTIVITY_TASK_ON_HOME = 16384;
public static final int FLAG_RECEIVER_REGISTERED_ONLY = 1073741824;
public static final int FLAG_RECEIVER_REPLACE_PENDING = 536870912;
public static final int FLAG_RECEIVER_FOREGROUND = 268435456;

那么对于intent.setFlags(int);int值是上面四种之一的话就比较简单,例如:

intent.setFlags(536870912); ==> intent.setFlags(PendingIntent.FLAG_NO_CREATE);

但是遇到一个比较特别的:intent.setFlags(335544320);

源码里根本没有这样一个值啊,其实intent.setFlags( A | B )是可以使用|(或运算)的,那么:

1
2
3
4
5
6
7
10000000000000000000000000000 = 268435456
| |
100000000000000000000000000 = 67108864
10100000000000000000000000000 = 335544320
即 268435456 | 67108864 = 335544320

从而:

intent.setFlags(335544320);==>

intent.setFlags( FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_CLEAR_TOP )

或者

intent.setFlags( FLAG_RECEIVER_FOREGROUND | FLAG_ACTIVITY_CLEAR_TOP )

Codota 中搜索intent.setFlags(335544320);看到的是第一种情况,结合intent.setFlags()的用法,应该也是第一种情况。

相关资料:

http://farwmarth.com/2013/04/23/android%20反编译和代码解读/

PS:

本文已整理到Github上,欢迎提交更多代码!

你可以关注的我 GithubCSDN微博