AIDL+NDK访问NDK数据

最新推荐文章于 2024-03-28 11:58:30 发布

原创最新推荐文章于 2024-03-28 11:58:30 发布 · 777 阅读

CC 4.0 BY-SA版权

本文详细探讨了如何通过AIDL（Android Interface Definition Language）在Android应用中与NDK（Native Development Kit）进行数据交换。内容涵盖AIDL的基本概念、创建过程以及在NDK模块中处理数据的方法，旨在帮助开发者实现更高效的应用层与底层通信。

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第一个app：

AIDL：

package net.bwie.monthexam;


interface IGetCppStringInterface {

    String getCppString();

}

c++：

#include <jni.h>
#include <string>


extern "C"
JNIEXPORT jstring JNICALL
Java_net_bwie_monthexam_MainActivity_stringFromJNI(
        JNIEnv *env,
jobject /* this */) {
std::string hello = "Hello from C++";
return env->NewStringUTF(hello.c_str());
}

extern "C"
JNIEXPORT jstring JNICALL
Java_net_bwie_monthexam_service_GetCppStringService_stringFromJNI2(
        JNIEnv *env,
        jobject /* this */) {
    std::string hello = "Hello from C++";
    return env->NewStringUTF(hello.c_str());
}

<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="net.bwie.monthexam.MainActivity">

<TextView
    android:id="@+id/sample_text"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Hello World!"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent"/>

</RelativeLayout>

<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="net.bwie.monthexam.MainActivity">

<TextView
    android:id="@+id/sample_text"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Hello World!"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent"/>

</RelativeLayout>

public class GetCppStringService extends Service {

    // 静态代码块中加载C++库
    static {
        System.loadLibrary("native-lib");
    }

    class MyBinder extends IGetCppStringInterface.Stub {

        @Override
        public String getCppString() throws RemoteException {
            return stringFromJNI2();
        }
    }

    @Override
    public IBinder onBind(Intent intent) {
        return new MyBinder();
    }

    // C++的方法，记得用native修饰
    public native String stringFromJNI2();

}

/**
 * AIDL服务端、NDK环境搭建
 * 使用AIDL访问当前服务端中C++的字符串
 */
public class MainActivity extends AppCompatActivity {

    // 静态代码块中加载C++库
    static {
        System.loadLibrary("native-lib");
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Example of a call to a native method
        TextView tv = (TextView) findViewById(R.id.sample_text);
        tv.setText(stringFromJNI());
    }

    // C++的方法，记得用native修饰
    public native String stringFromJNI();
}

aidlclient 项目2：

<LinearLayout
    android:orientation="vertical"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="net.bwie.aidlclient.MainActivity">

    <Button
        android:id="@+id/get_cpp_string_btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="获取服务端中的C++字符串"/>

    <TextView
        android:id="@+id/text_view"
        android:text="asdasdasd"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

</LinearLayout>

**
 * 初始化视图
 * 绑定服务端的Service
 * 通过接口ServiceConnection获取aidl实例
 * 按钮中使用aidl实例获取服务端中C++的字符串
 */
public class MainActivity extends AppCompatActivity implements View.OnClickListener, ServiceConnection {

    protected Button mGetCppStringBtn;
    protected TextView mTextView;

    private IGetCppStringInterface mIGetCppStringInterface;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        super.setContentView(R.layout.activity_main);
        initView();

        bindService();
    }

    @Override
    public void onClick(View view) {
        if (view.getId() == R.id.get_cpp_string_btn) {

            try {
                String cppString = mIGetCppStringInterface.getCppString();
                mTextView.setText(cppString);
            } catch (RemoteException e) {
                e.printStackTrace();
                Toast.makeText(this, "错误", Toast.LENGTH_SHORT).show();
            }

        }
    }

    private void initView() {
        mGetCppStringBtn = (Button) findViewById(R.id.get_cpp_string_btn);
        mGetCppStringBtn.setOnClickListener(MainActivity.this);
        mTextView = (TextView) findViewById(R.id.text_view);
    }

    private void bindService() {
        Intent intent = new Intent("get_cpp_action");
        intent.setPackage("net.bwie.monthexam");
        boolean isBindSuccessful = bindService(intent, this, Context.BIND_AUTO_CREATE);
        Toast.makeText(this, "是否成功："+ isBindSuccessful, Toast.LENGTH_SHORT).show();
    }


    @Override
    public void onServiceConnected(ComponentName name, IBinder iBinder) {
        mIGetCppStringInterface = IGetCppStringInterface.Stub.asInterface(iBinder);
    }

    @Override
    public void onServiceDisconnected(ComponentName name) {

    }
}

package net.bwie.monthexam;


interface IGetCppStringInterface {

    String getCppString();

}