原标题：Android去掉/混淆Log，反编译都看不到

出发点：

当然是由于编程习惯太好，打了一堆中文log，其实只是想给测试看。然而如果包被反编译，看log基本都能理解流程了，有点尴尬。所以此文主要探究proguard配置，以去除log。

以下过程示例，来自于这段代码。

publicclassMainActivityextendsAppCompatActivity{

privatestaticfinalString TAG = "MainActivity";

privateString a = "a";

privateString b = "b";

@Override

protectedvoidonCreate(Bundle savedInstanceState){

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

Log.d(TAG, "This is"+ a + b);

}

}

啥都不配置的情况下，反编译的smali代码如下：

# virtual methods

. method publiconCreate(Landroid/os/Bundle;)V

.locals 2

invoke-super {p0, p1}, Landroid/support/v7/app/c;->onCreate(Landroid/os/Bundle;)V

constp1, 0x7f09001b

invoke- virtual{p0, p1}, Lcom/rentee/logremove/MainActivity;->setContentView(I)V

const- stringp1, "MainActivity"

new-instance v0, Ljava/lang/StringBuilder;

const- stringv1, "This is"

invoke-direct {v0, v1}, Ljava/lang/StringBuilder;->(Ljava/lang/String;)V

iget- objectv1, p0, Lcom/rentee/logremove/MainActivity;->m:Ljava/lang/String;

invoke- virtual{v0, v1}, Ljava/lang/StringBuilder;->append(Ljava/lang/String;)Ljava/lang/StringBuilder;

iget- objectv1, p0, Lcom/rentee/logremove/MainActivity;->n:Ljava/lang/String;

invoke- virtual{v0, v1}, Ljava/lang/StringBuilder;->append(Ljava/lang/String;)Ljava/lang/StringBuilder;

invoke- virtual{v0}, Ljava/lang/StringBuilder;->toString()Ljava/lang/String;

move-result- objectv0

invoke- static{p1, v0}, Landroid/util/Log;->d(Ljava/lang/String;Ljava/lang/String;)I

return- void

.end method

很明显，整条字符串拼接过程是由StringBuilder完成的。

1.在build.gradle配置proguard-android-optimize.txt，因为默认的proguard-android.txt优化开关是关了的，而proguard的assumenosideeffects、

assumenoexternalsideeffects配置是需要开启优化开关的。

buildTypes{

release{

minifyEnabledtrue

proguardFiles getDefaultProguardFile( 'proguard-android-optimize.txt'), 'proguard-rules.pro'

}

}

在proguard-rules.pro文件中配置assumenosideeffects。这是网上的通用大解。

-assumenosideeffects classandroid.util.Log{

publicstaticbooleanisLoggable(java.lang.String, int);

publicstaticintv(...);

publicstaticinti(...);

publicstaticintw(...);

publicstaticintd(...);

publicstaticinte(...);

}

不过也的确存在一个问题，就是去除不干净，反编译后，smail如下：

# virtual methods

. method publiconCreate(Landroid/os/Bundle;)V

.locals 1

invoke-super {p0, p1}, Landroid/support/v7/app/c;->onCreate(Landroid/os/Bundle;)V

constp1, 0x7f09001b

invoke- virtual{p0, p1}, Lcom/rentee/logremove/MainActivity;->setContentView(I)V

new-instance p1, Ljava/lang/StringBuilder;

const- stringv0, "This is"

invoke-direct {p1, v0}, Ljava/lang/StringBuilder;->(Ljava/lang/String;)V

iget- objectv0, p0, Lcom/rentee/logremove/MainActivity;->m:Ljava/lang/String;

invoke- virtual{p1, v0}, Ljava/lang/StringBuilder;->append(Ljava/lang/String;)Ljava/lang/StringBuilder;

iget- objectv0, p0, Lcom/rentee/logremove/MainActivity;->n:Ljava/lang/String;

invoke- virtual{p1, v0}, Ljava/lang/StringBuilder;->append(Ljava/lang/String;)Ljava/lang/StringBuilder;

return- void

.end method

Log的相关代码没了，但是还是有StringBuilder的拼接过程在，这个从根本上解决不了问题。

2.进化版，proguard 6.0以上版本新增了assumenoexternalsideeffects和assumenoexternalreturnvalues，这两个属性6.0才引入，Android自带proguard-gradle插件并没有这么新，所以要在工程项目根目录配置如下strategy，强制将progurad指定到6.0以上版本。

build {

configurations.all {

resolutionStrategy {

force "net.sf.proguard:proguard-gradle:6.0.3"

}

}

}

然后在progaurd-rules.txt文件中增加如下配置：

-assumenoexternalsideeffects classjava.lang.StringBuilder{

publicjava.lang.StringBuilder();

publicjava.lang.StringBuilder( int);

publicjava.lang.StringBuilder(java.lang.String);

publicjava.lang. StringBuilder append(java.lang.Object);

publicjava.lang. StringBuilder append(java.lang.String);

publicjava.lang. StringBuilder append(java.lang.StringBuffer);

publicjava.lang. StringBuilder append(char[]);

publicjava.lang. StringBuilder append(char[], int, int);

publicjava.lang. StringBuilder append(boolean);

publicjava.lang. StringBuilder append(char);

publicjava.lang. StringBuilder append(int);

publicjava.lang. StringBuilder append(long);

publicjava.lang. StringBuilder append(float);

publicjava.lang. StringBuilder append(double);

publicjava.lang. String toString();

}

-assumenoexternalreturnvalues publicfinalclassjava.lang.StringBuilder{

publicjava.lang. StringBuilder append(java.lang.Object);

publicjava.lang. StringBuilder append(java.lang.String);

publicjava.lang. StringBuilder append(java.lang.StringBuffer);

publicjava.lang. StringBuilder append(char[]);

publicjava.lang. StringBuilder append(char[], int, int);

publicjava.lang. StringBuilder append(boolean);

publicjava.lang. StringBuilder append(char);

publicjava.lang. StringBuilder append(int);

publicjava.lang. StringBuilder append(long);

publicjava.lang. StringBuilder append(float);

publicjava.lang. StringBuilder append(double);

}

这段配置的作用是，去除返回值无用的StringBuilder的相关操作，由于在第2点配置后，Log相关代码被去除，所以Log中的字符串拼接也是无用的，会被去除。配置后smali代码是：

# virtual methods

. method publiconCreate(Landroid/os/Bundle;)V

.locals 0

invoke-super {p0, p1}, Landroid/support/v7/app/c;->onCreate(Landroid/os/Bundle;)V

constp1, 0x7f09001b

invoke- virtual{p0, p1}, Lcom/rentee/logremove/MainActivity;->setContentView(I)V

return- void

.end method

是的，一句都没有了，干干净净，爽！