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android studio 修改jni-demo控制led

笙烛 2022-02-22 阅读 44

android studio 修改jni-demo控制led,做来玩玩
cpp:

#include <jni.h>
#include <string>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/gpio.h>
#include <android/log.h>
#define  LOG_TAG    "gpio jni"
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)
#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)
extern "C" {
            JNIEXPORT jstring JNICALL Java_com_example_testjni_MainActivity_stringFromJNI(
                    JNIEnv *env,
                    jobject /* this */) {
                std::string hello = "Hello from C++";
                return env->NewStringUTF(hello.c_str());
            }

             JNIEXPORT void JNICALL Java_com_example_testjni_MainActivity_gpioctlFromJNI(JNIEnv *env,jobject,jint i) {
               //  system("chmod 0666 /sys/class/leds/LEDGREEN/brightness"); //给权限
                // LOGI("chmod 0666 /sys/class/leds/LEDGREEN/brightness");
                if(i==1)
                   system("echo 0 > /sys/class/leds/LEDGREEN/brightness"); //red
               else
                    system("echo 1 > /sys/class/leds/LEDGREEN/brightness"); //blue
             }

java:

package com.example.testjni;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import android.widget.Button;
import com.example.testjni.databinding.ActivityMainBinding;

public class MainActivity extends AppCompatActivity {
    int i=1;
    private Button button;
    // Used to load the 'testjni' library on application startup.
    static {
        System.loadLibrary("testjni");
    }

    private ActivityMainBinding binding;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        binding = ActivityMainBinding.inflate(getLayoutInflater());
        setContentView(binding.getRoot());


        button=(Button)findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                // Example of a call to a native method
                button.setText(stringFromJNI());
                i=~i;
                gpioctlFromJNI(i);
            }
        });

    }

    /**
     * A native method that is implemented by the 'testjni' native library,
     * which is packaged with this application.
     */
    public native String stringFromJNI();
    public native void gpioctlFromJNI(int i);
}

xml:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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=".MainActivity">
    <Button
        android:id="@+id/button"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_constraintTop_toTopOf="parent"
        android:textAllCaps="false"
        android:text="确认"/>
</androidx.constraintlayout.widget.ConstraintLayout>
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