jni不通过线程c回调java的函数

整个工程的项目如下：

1、项目的思路是在activity中启动MyService这个服务，在服务中调用

JniScsManger类中的本地方法startNativeScsService，在

startNativeScsService的c代码实现中回调JniScsManger中的scsConnectStatus方法。
下面我们来看下两种代码的实现：

package com.cetcs.ecmapplication.jni.scs;

import android.app.Service;

import android.content.Intent;

import android.os.IBinder;

public class MyService extends Service {

    public MyService() {

    }

    @Override

    public IBinder onBind(Intent intent) {

        // TODO: Return the communication channel to the service.

        throw new UnsupportedOperationException("Not yet implemented");

    }

    @Override

    public void onCreate() {

        super.onCreate();

        JniScsManger.getInstances().startNativeScsService();

    }

}

activity的代码：

package im.weiyuan.com.jni2;

import android.content.Intent;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.widget.Toast;

import com.cetcs.ecmapplication.jni.scs.JniScsManger;

import com.cetcs.ecmapplication.jni.scs.MyService;

public class MainActivity extends AppCompatActivity {

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        Intent intent = new Intent(MainActivity.this, MyService.class);

        startService(intent);

    }

}

package com.cetcs.ecmapplication.jni.scs;

import android.util.Log;

/**

 * Created by wei.yuan on 2017/6/7.

 */

public class JniScsManger {

    static {

        System.loadLibrary("jniscs");

    }

    private  static JniScsManger jniScsManger = null;

    private JniScsManger(){

    }

    public static JniScsManger getInstances(){

        if(jniScsManger == null){

            jniScsManger = new JniScsManger();

        }

        return  jniScsManger;

    }

    public native int startNativeScsService();

    public  void  scsConnectStatus(int status,String reason){

        Log.d("123456",""+status+","+reason);

    }

    public  void getScsStatus(){

        Log.d("123456",""+",");

    }

    public int onProgressCallBack(long total, long already) {

        //自行执行回调后的操作

        Log.d("123456",""+"onProgressCallBack");

        System.out.println("total123456:"+total);

        System.out.println("already:"+already);

        return 1;

    }

}

我们来看看本地native层实现的代码：

第一种方式：

//

// Created by wei.yuan on 2017/6/7.

//

#include <android/log.h>

#include <string.h>

#include <stdio.h>

#include <pthread.h>

#include <time.h>

#include <dlfcn.h>

#include <jni.h>

#include <stdio.h>

#include <stdlib.h>

#include <dlfcn.h>

#include <time.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <dlfcn.h>

#include <assert.h>

#include <android\log.h>

#include <errno.h>

#include <pthread.h>

#include "com_cetcs_ecmapplication_jni_scs_JniScsManger.h"

//动态链接库路径

#define LIB_SCS_PATH "libServerCenter.so"

#define LOG_TAG "SCS123456"

#define LOGI_JniSCS(...)  __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)

JNIEXPORT jint JNICALL Java_com_cetcs_ecmapplication_jni_scs_JniScsManger_startNativeScsService(JNIEnv * env, jobject jobj){

    LOGI_JniSCS("start native ServerCenterService");

    //jobj对象就是java层调用startNativeScsService的对象，那个类调用startNativeScsService对应的jobj就是那个对象

    jclass javaClass = (*env)->FindClass(env, "com/cetcs/ecmapplication/jni/scs/JniScsManger");

    if (javaClass == ) {

              LOGI_JniSCS("Unable to find class");

            return;

        }

        //获取要回调的方法ID

        jmethodID javaCallbackId = (*env)->GetMethodID(env, javaClass,"scsConnectStatus", "(ILjava/lang/String;)V");

        if (javaCallbackId == NULL) {

             LOGI_JniSCS("Unable to find method:onProgressCallBack");

            return;

        }

        //执行回调,注意第二个参数是jobj，不是javaClass

            (*env)->CallVoidMethod(env, jobj, javaCallbackId,,(*env)->NewStringUTF(env, "Hello from JNI000.0.0.!"));

    return ;

}

第二种方式：

//

// Created by wei.yuan on 2017/6/7.

//

#include <android/log.h>

#include <string.h>

#include <stdio.h>

#include <pthread.h>

#include <time.h>

#include <dlfcn.h>

#include <jni.h>

#include <stdio.h>

#include <stdlib.h>

#include <dlfcn.h>

#include <time.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <dlfcn.h>

#include <assert.h>

#include <android\log.h>

#include <errno.h>

#include <pthread.h>

#include "com_cetcs_ecmapplication_jni_scs_JniScsManger.h"

//动态链接库路径

#define LIB_SCS_PATH "libServerCenter.so"

#define LOG_TAG "SCS123456"

#define LOGI_JniSCS(...)  __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)

JNIEXPORT jint JNICALL Java_com_cetcs_ecmapplication_jni_scs_JniScsManger_startNativeScsService(JNIEnv * env, jobject jobj){

    LOGI_JniSCS("start native ServerCenterService");

    //jobj对象就是java层调用startNativeScsService的对象，那个类调用startNativeScsService对应的jobj就是那个对象

    jclass javaClass = (*env)->GetObjectClass(env, jobj);

    if (javaClass == ) {

              LOGI_JniSCS("Unable to find class");

            return;

        }

        //获取要回调的方法ID

        jmethodID javaCallbackId = (*env)->GetMethodID(env, javaClass,"scsConnectStatus", "(ILjava/lang/String;)V");

        if (javaCallbackId == NULL) {

             LOGI_JniSCS("Unable to find method:onProgressCallBack");

            return;

        }

        //执行回调,注意第二个参数是jobj，不是javaClass

            (*env)->CallVoidMethod(env, jobj, javaCallbackId,,(*env)->NewStringUTF(env, "Hello from JNI000.0.0.!"));

    return ;

}

注意点：

FindClass是通过传java中完整的类名来查找java的class， 而GetObjectClass是通过传入jni中的一个java的引用来获取该引用的类型。 前者要求你必须知道完整的类名，后者要求在Jni有一个类的引用。
上面中传入的

(JNIEnv * env, jobject jobj)中的jobj就是调用startNativeScsService的对象，就是JniScsManger的一个对象实例。

FindClass是通过类名获得该对象的实例，

GetObjectClass是获得该对象的一个引用。

现在增加一个需求：
我们在上传新增加一个类：

我们要在startNativeScsService的c代码实现中回调Sb中的scsConnectStatus方法如何实现了，我们来看c层的代码

package com.cetcs.ecmapplication.jni.scs;

import android.util.Log;

/**

 * Created by wei.yuan on 2017/6/26.

 */

public class Sb {

    public  void  scsConnectStatus(int status,String reason){

        Log.d("123456",""+status+","+reason);

    }

}

//

// Created by wei.yuan on 2017/6/7.

//

#include <android/log.h>

#include <string.h>

#include <stdio.h>

#include <pthread.h>

#include <time.h>

#include <dlfcn.h>

#include <jni.h>

#include <stdio.h>

#include <stdlib.h>

#include <dlfcn.h>

#include <time.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <dlfcn.h>

#include <assert.h>

#include <android\log.h>

#include <errno.h>

#include <pthread.h>

#include "com_cetcs_ecmapplication_jni_scs_JniScsManger.h"

//动态链接库路径

#define LIB_SCS_PATH "libServerCenter.so"

#define LOG_TAG "SCS123456"

#define LOGI_JniSCS(...)  __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)

JNIEXPORT jint JNICALL Java_com_cetcs_ecmapplication_jni_scs_JniScsManger_startNativeScsService(JNIEnv * env, jobject jobj){

    LOGI_JniSCS("start native ServerCenterService");

    //jobj对象就是java层调用startNativeScsService的对象，那个调用startNativeScsService对应的jobj就是那个对象

    jclass javaClass = (*env)->FindClass(env, "com/cetcs/ecmapplication/jni/scs/Sb");

    if (javaClass == ) {

        LOGI_JniSCS("Unable to find class");

        return;

    }

    //构造Sb这个对象

    jmethodID constructor = (*env)->GetMethodID(env, javaClass, "<init>", "()V");

    //获取要回调的方法ID

    jmethodID javaCallbackId = (*env)->GetMethodID(env, javaClass,"scsConnectStatus", "(ILjava/lang/String;)V");

    if (javaCallbackId == NULL) {

        LOGI_JniSCS("Unable to find method:onProgressCallBack");

        return;

    }

    jobject obj = (*env)->NewObject(env, javaClass, constructor);

    //执行回调,注意第二个参数是obj，不是jobj

    (*env)->CallVoidMethod(env, obj, javaCallbackId,,(*env)->NewStringUTF(env, "Hello from JNI000.0.0.!0..22"));

    return ;

}

程序代码的下载地址是：

https://pan.baidu.com/s/1gfosrp5