深入浅析jni中的java接口使用

public class JNIUtil {

  static {

    System.loadLibrary("native-event");
  }

  // 注册函数
  public static native void setJniCallBack(JniCallBack callBack);

  // 解注册函数
  public static native void unJniCallBack();

  public interface JniCallBack{

    void onReceiveCInfo();

  }

}

//
// Created by 86130 on 2020/9/9.
//

#ifndef CDEMO_JNICALLBACK_H
#define CDEMO_JNICALLBACK_H


#ifdef __cplusplus
extern "C"{
#endif

//方法回调
void onReceiveMsg();


#ifdef __cplusplus
}
#endif
#endif //CDEMO_JNICALLBACK_H

#include <jni.h>
#include <malloc.h>
#include <cstring>

#include "jnicallback.h"

#ifdef __cplusplus
extern "C"{
#endif

  JavaVM *g_VM;
  jobject subscriber;

extern "C"
JNIEXPORT void JNICALL Java_com_demo_cdemo_JNIUtil_setJniCallBack(JNIEnv* env,jclass clazz, jobject call_back) {

  env->GetJavaVM(&g_VM);
  subscriber = env->NewGlobalRef(call_back);

}

extern "C"
JNIEXPORT void JNICALL Java_com_demo_cdemo_JNIUtil_unJniCallBack(JNIEnv* env, jclass clazz) {

  if (subscriber != NULL)
  {
    env->DeleteGlobalRef(subscriber);
  }
}

JNIEnv *getEnv()
{
  JNIEnv *env;
  if (g_VM ==NULL)
  {
    return NULL;
  }
  int envStat = g_VM->GetEnv((void **) &env, JNI_VERSION_1_6);
  if (envStat == JNI_EDETACHED)
  {
    if (g_VM->AttachCurrentThread(&env, NULL) != 0)
    {
      return NULL;
    }
  }
  return env;
}

jmethodID getMethodIdByNameAndSig(JNIEnv *env, const char *name, const char *sig)
{
  if (env == NULL || subscriber == NULL)
  {
    return NULL;
  }
  jclass subscriberClass = env->GetObjectClass(subscriber);
  if (subscriber == 0)
  {
    return NULL;
  }
  jmethodID methodId = env->GetMethodID(subscriberClass, name, sig);
  if (methodId == 0)
  {
    return NULL;
  }
  return methodId;
}

// 头文件方法实现
void onReceiveMsg()
{
  JNIEnv *env = getEnv();
  jmethodID onReceiveMethodId = getMethodIdByNameAndSig(env, "onReceiveCInfo", "()V");
  if (onReceiveMethodId == NULL)
  {
    return;
  }
  env->CallVoidMethod(subscriber, onReceiveMethodId);

}

#ifdef __cplusplus
}
#endif

project(Native-Activity)

cmake_minimum_required(VERSION 3.4.1)

#引入native_app_glue头文件
include_directories(F:/AndroidSdk/Sdk/ndk-bundle/sources/android/native_app_glue)

add_library(native-activity SHARED
    main.cpp
     jnicallback.cpp)

add_library(native-event SHARED jnicallback.cpp)

find_library(log-lib log)
find_library(OPENGLES3_LIBRARY GLESv3 "OpenGL ES v3.0 library")
find_library(EGL_LIBRARY EGL "EGL 1.4 library")
find_library(android-lib android)

#编译为静态库
add_library(app_glue STATIC
    android_native_app_glue.c)

target_link_libraries(native-event
    ${log-lib} #链接log库
    ${android-lib} #链接android库
    )

target_link_libraries(native-activity
    app_glue #链接静态库native_app_glue
    ${log-lib} #链接log库
    ${android-lib} #链接android库
    ${OPENGLES3_LIBRARY} #链接OpenGLES库
    ${EGL_LIBRARY} #链接EGL库
    )

package com.demo.cdemo;

import android.app.NativeActivity;
import android.content.Intent;
import android.os.Bundle;
import android.os.Looper;
import android.util.Log;
public class CdemoActivity extends NativeActivity {

  static {
    System.loadLibrary("native-activity");
  }

  boolean isFirst = false;

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

    JNIUtil.setJniCallBack(new JNIUtil.JniCallBack() {
      @Override
      public void onReceiveCInfo() {
        boolean isMain = isMainThread();
        Log.d("zzkk",
            "CdemoActivity onReceiveCInfo isMain = " + isMain);
        if (!isFirst)
        {
          isFirst = true;
          runOnUiThread(new Runnable() {
            @Override public void run() {
              Intent intent = new Intent(CdemoActivity.this
                  , MainActivity.class);
              startActivity(intent);
            }
          });
        }
      }
    });

  }

  private boolean isMainThread() {
    return Looper.getMainLooper() == Looper.myLooper();
  }

}