Opportunity to using native methods systemwide. How to call method or how it should be named?

Question

I want to use one native library for a plurality of applications. Library has compiled through android build system and now located in /system/lib/. It can be loaded in application through System.LoadLibrary("libexample"). But method in library which should be declared like

JNIEXPORT jstring JNICALL Java_application1_MainActivity_method1

turning out unusable because library should be used by several applications. And of course this several applications have their own unique names. So I tried to named my method just like

 JNIEXPORT jstring JNICALL method1

and call

public native String method1(String string);

But of course my application trying to find it as Java_application1_MainActivity_method1

How to call this method or how it should be named?

Updated:

I tried to use this(see post with green tick) tutorial to complete my project. I wrote a library for using native method:

package com.example.mylib;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;

public class MyClass extends Activity {
public native static String MyMethod(String string);
    static {
        System.loadLibrary("nativeLibrary");
    }
}

Then I trying to use it in my application:

// Some no interesting inclusions
import com.example.mylib.MyClass;

public class MainActivity extends ListActivity {
// Some no interesting code.
MyMethod(file.getAbsolutePath())
//Some no interesting code 
}

And it working as I need! But now I confused that my import com.example.mylib.MyClass; "never used" in eclipse. And if I will create image with this "Is Library" project the latest will no resolving. Any idea?

Answer 1

Yes, you can use the same JNI signature in many applications. Your class may not belong to the default package of the application, as defined in AndroidManifest.xml. So what?

---

Example:

Start with HelloJni sample from NDK (in Eclipse, use Import -> Android -> existing Android Code, and point to the ${android-ndk-root}/samples/hello-jni).

Build it and run on device or emulator.

Open a new Android Application project, call it TestCrossJni. The package name for our app will be: test.cross.jni - no relation to com.example.hellojni!

Choose "Create Activity" -> create Blank Activity.

Add new Java class to this project (src/com/example/hellojni/HelloJni.java):

package com.example.hellojni;

public class HelloJni
{
    public static String gets() {
        return stringFromJNI();
    }

    /* A native method that is implemented by the
     * 'hello-jni' native library, which is packaged
     * with this application.
     */
    private native String  stringFromJNI();

    /* this is used to load the 'hello-jni' library on application
     * startup. The library has already been unpacked into
     * /data/data/com.example.hellojni/lib/libhello-jni.so at
     * installation time by the package manager.
     */
    static {
        System.load("/data/data/com.example.hellojni/lib/libhello-jni.so");
    }
}

Edit res/layout/activity_main.xml: replace

    line 12 android:text="@string/hello_world" />

    with android:id="@+id/hello_world" />

In src/test/cross/jni/MainActivity.java, add the following after

    line 12 setContentView(R.layout.activity_main);

((android.widget.TextView)findViewById(R.id.hello_world)).setText(com.example.hellojni.HelloJni.gets());

Profit!