从NDK获取应用程序的名称 [英] get application name from NDK

问题描述

我需要从本机端事端一样，让我的Andr​​oid应用程序的名称：

I need to get name of my android application from the native side somethin like that:

 android.content.context context=(android.content.context) this;//current activiy
 Resources appR =context.getResources();
 String packageName=context.getPackageName();
 int id=appR.getIdentifier("app_name","string",packageName );
 CharSequence txt = appR.getText(id);

我的家乡code这样的：

my native code like that:

  jstring Java_com_AnalyticToolC_AnalyticToolActivity_JNISendData(JNIEnv* env,jobject entryObject,jobject contxt)
 {

   char *realAppName;
 realAppName=(char *)malloc(16 * 1024);
 jclass android_content_Context =(*env)->GetObjectClass(env, contxt);
    jmethodID midGetPackageName = (*env)->GetMethodID(env, android_content_Context, "getPackageName", "()Ljava/lang/String");
 jstring packageName=(*env)->CallObjectMethod(env, contxt, midGetPackageName);
jmethodID midGetResources = (*env)->GetMethodID(env, android_content_Context, "getResources", "()L");
    jobject jResource=(*env)->CallObjectMethod(env, context, midGetResources);

   jclass resource_Class=(*env)->GetObjectClass(env, jResource);
   jmethodID midGetIdentifier = (*env)->GetMethodID(env, resource_Class, "getIdentifier", "(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String)I");
   jstring app_name=(*env)->NewStringUTF(env,"app_name");
   jstring TypeName=(*env)->NewStringUTF(env,"string");
   int id=(*env)->CallObjectMethod(env, jResource, midGetIdentifier,app_name,TypeName,packageName);

  jmethodID midGetAppName = (*env)->GetMethodID(env, resource_Class,"getText","(I)Ljava/lang/String");
  jstring appName=(*env)->CallObjectMethod(env, jResource, midGetAppName,id);   

  realAppName=(*env)->GetStringUTFChars(env, appName, NULL);
}

和我只是传递活动，我从Java code本地methon。

and i just pass the activity to my native methon from java code.

和我没有机会用Java编写的类此code然后调用它构成了我NDK的应用
我想了很多上下文对象jobject传递给我的家乡code，但它总是崩溃。
剂量任何一个有什么想法？

and i don't have a chance to write this code in java class then call it form my NDK application I'm trying a lot to pass a context object as jobject to my native code but it always crash. dose any one have any idea?

推荐答案

用C反映Java访问是丑陋的，丑陋的，丑陋的，就像你证明。通过应用程序名称作为一个额外的字符串参数。

Reflected Java access in C is ugly, ugly, ugly, just like you've demonstrated. Pass the app name as an extra string parameter.

编辑：好，你要反思，反思你会得到

OK, you want reflection, reflection you'll get.

您的本地方法属于类 AnalyticToolActivity 。作为一个非静态类方法，它有一个在每次调用这个指针。与C ++和Java的方法，该指针明确传递作为第二个参数。该方法有两个强制性参数 - 一个的JNIEnv * 和 jobject 。第二个对应于这个的Java对象的指针。

Your native method belongs to class AnalyticToolActivity. As a nonstatic class method, it has a this pointer on every call. Unlike C++ and Java methods, this pointer is passed explicitly as the second parameter. The method has two mandatory parameters - a JNIEnv * and a jobject. The second one corresponds to the this pointer of the Java object.

所以，如果你的 AnalyticToolActivity 是活动的一个子类 - 很可能 - 在 entryObject 参数活动的一个实​​例，这意味着它的上下文的一个实例。因此，摆脱了第三个参数（ contxt ），和你的JNI code可以是这样的：

So if your AnalyticToolActivity is a subclass of Activity - quite likely - the entryObject parameter is an instance of Activity, meaning it's an instance of Context. So get rid of the third parameter (contxt), and your JNI code can go like this:

jclass android_content_Context =(*env)->GetObjectClass(env, entryObject);  //or use FindClass
jmethodID midGetPackageName = (*env)->GetMethodID(env,  android_content_Context, "getPackageName", "()Ljava/lang/String"); 
jstring packageName=(*env)->CallObjectMethod(env, entryObject, midGetPackageName); 

和等等。

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