Android通过NDK获取Keystore签名值

防止别人反编译自已的游戏再修改然后发布，我们可以用在so文件中用Keystore签名值来加密一些参数。

这里只提供NDK获取Keystore签名值代码

package com.boyaa.ndk;

import android.content.Context;

public class RegionGames {
	static {
		try {
			System.loadLibrary("boyaaregiongames");
		} catch (Throwable e) {
			e.printStackTrace();
		}
	}

	public static native String getSign(Context ctx);
}

#include <jni.h>
#include<android/log.h>
#include <string.h>
#include <unistd.h>

extern "C"
JNIEXPORT jstring JNICALL Java_com_boyaa_ndk_RegionGames_signData(JNIEnv *env, jclass jcl,
		jobject context_object) {
	jclass context_class = env->GetObjectClass(context_object);

		//context.getPackageManager()
		jmethodID methodId = env->GetMethodID(context_class, "getPackageManager", "()Landroid/content/pm/PackageManager;");
		jobject package_manager_object = env->CallObjectMethod(context_object, methodId);
	    if (package_manager_object == NULL) {
	    	__android_log_print(ANDROID_LOG_INFO, "JNITag","getPackageManager() Failed!");
	        return NULL;
	    }

	    //context.getPackageName()
	    methodId = env->GetMethodID(context_class, "getPackageName", "()Ljava/lang/String;");
		jstring package_name_string = (jstring)env->CallObjectMethod(context_object, methodId);
		if (package_name_string == NULL) {
			__android_log_print(ANDROID_LOG_INFO, "JNITag","getPackageName() Failed!");
			return NULL;
		}

		env->DeleteLocalRef(context_class);

		//PackageManager.getPackageInfo(Sting, int)
		jclass pack_manager_class = env->GetObjectClass(package_manager_object);
		methodId = env->GetMethodID(pack_manager_class, "getPackageInfo", "(Ljava/lang/String;I)Landroid/content/pm/PackageInfo;");
		env->DeleteLocalRef(pack_manager_class);
		jobject package_info_object = env->CallObjectMethod(package_manager_object, methodId, package_name_string, 64);
		if (package_info_object == NULL) {
			__android_log_print(ANDROID_LOG_INFO, "JNITag","getPackageInfo() Failed!");
			return NULL;
		}

		env->DeleteLocalRef(package_manager_object);

		//PackageInfo.signatures[0]
		jclass package_info_class = env->GetObjectClass(package_info_object);
		jfieldID fieldId = env->GetFieldID(package_info_class, "signatures", "[Landroid/content/pm/Signature;");
		env->DeleteLocalRef(package_info_class);
		jobjectArray signature_object_array = (jobjectArray)env->GetObjectField(package_info_object, fieldId);
		if (signature_object_array == NULL) {
			__android_log_print(ANDROID_LOG_INFO, "JNITag","PackageInfo.signatures[] is null");
			return NULL;
		}
		jobject signature_object = env->GetObjectArrayElement(signature_object_array, 0);

		env->DeleteLocalRef(package_info_object);

		//Signature.toCharsString()
		jclass signature_class = env->GetObjectClass(signature_object);
		methodId = env->GetMethodID(signature_class, "toCharsString", "()Ljava/lang/String;");
		env->DeleteLocalRef(signature_class);
		jstring signature_string = (jstring) env->CallObjectMethod(signature_object, methodId);

		return signature_string;
}