Go: Android Development: Read app signatures with JNI

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In order to prevent the anti-compilation, it is intended to write the key code in so (such as add decryption), in so add to determine whether the APK package signature is consistent code, to avoid so two times packaging. In fact, using JNI to read the signature is the reflection mechanism of java.

First look at how Java reads the signature:

1 Try {2       PackageInfo info = Context.getpackagemanager (). Getpackageinfo (Context.getpackagename (), +); 3       Signature sign = info.signatures[0]; 4       LOG.I ("Test", "Hashcode:" + Sign.hashcode ()); 5     Catch (namenotfoundexception e) {6      e.printstacktrace (); 7     }

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Then we implement the JNI C language, and we also need to pass the context:

1 intGetsignhashcode (JNIENV *env, Jobject context) {2   //class of the context3Jclass Context_clazz = (*env)Getobjectclass (env, context);4   //get the ID of the Getpackagemanager method5Jmethodid Methodid_getpackagemanager = (*env)Getmethodid (env, Context_clazz,6"Getpackagemanager", "() Landroid/content/pm/packagemanager;");7  8   //Get Packagemanager Object9Jobject Packagemanager = (*env)Callobjectmethod (env, context,Ten Methodid_getpackagemanager); One //    //Get Packagemanager class AJclass Pm_clazz = (*env)Getobjectclass (env, packagemanager); -   //get the ID of the Getpackageinfo method -Jmethodid methodid_pm = (*env)->getmethodid (env, Pm_clazz, "Getpackageinfo", the"(ljava/lang/string;i) Landroid/content/pm/packageinfo;"); - // - //    //get the ID of the Getpackagename method -Jmethodid Methodid_pack = (*env)Getmethodid (env, Context_clazz, +"Getpackagename", "() ljava/lang/string;"); -   +   //get the current app's package name AJstring application_package = (*env)Callobjectmethod (env, context, at methodid_pack); -   Const Char*str = (*env)->getstringutfchars (env, application_package, 0); -__android_log_print (Android_log_debug, "JNI", "PackageName:%s\n", str); -   -   //Get PackageInfo -Jobject PackageInfo = (*env)Callobjectmethod (env, Packagemanager, inMETHODID_PM, Application_package, 64); -   toJclass Packageinfo_clazz = (*env)Getobjectclass (env, packageinfo); +Jfieldid fieldid_signatures = (*env)Getfieldid (env, Packageinfo_clazz, -"Signatures", "[Landroid/content/pm/signature;"]); theJobjectarray Signature_arr = (Jobjectarray) (*env),Getobjectfield (env, * PackageInfo, fieldid_signatures); $   //Take the first element out of the signature arrayPanax NotoginsengJobject signature = (*env)->getobjectarrayelement (env, Signature_arr, 0); -   //Read Signature's hashcode theJclass Signature_clazz = (*env)Getobjectclass (env, signature); +Jmethodid Methodid_hashcode = (*env)Getmethodid (env, Signature_clazz, A"Hashcode", "() I"); theJint hashcode = (*env)Callintmethod (env, signature, methodid_hashcode); +__android_log_print (Android_log_debug, "JNI", "Hashcode:%d\n", hashcode); -   returnhashcode; $}

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The second parameter, Jobject, is not the default parameter of the JNI function, but the incoming context instance.

Go: Android Development: Read app signatures with JNI