android112 c代码打印日志，

package com.itheima.ccalljava;

import android.os.Bundle;
import android.app.Activity;
import android.app.AlertDialog.Builder;
import android.view.Menu;
import android.view.View;

public class MainActivity extends Activity {
    static{
        System.loadLibrary("hello");
    }
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }


    public void click(View v){
        helloC();
    }
    
    public native void helloC();
    
    public void show(String message){
        Builder builder = new Builder(this);
        builder.setTitle("标题");
        builder.setMessage(message);
        builder.show();
    }
}

#include <jni.h>
#include <android/log.h>
#define LOG_TAG "System.out"
#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG, LOG_TAG, __VA_ARGS__)//把后面的函数重命名成前面的函数，Android.mk添加LOCAL_LDLIBS += -llog
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)


JNIEXPORT void JNICALL Java_com_itheima_ccalljava_MainActivity_helloC
  (JNIEnv * env, jobject obj){
    LOGD("hello!");//打印日志，debug级别的
    LOGI("hello!");////打印日志，info级别的
    //jclass      (*FindClass)(JNIEnv*, const char*);
    jclass clazz = (*env)->FindClass(env, "com/itheima/ccalljava/MainActivity");
    //jmethodID   (*GetMethodID)(JNIEnv*, jclass, const char*, const char*);
    jmethodID methodID = (*env)->GetMethodID(env, clazz, "show", "(Ljava/lang/String;)V");
    //void        (*CallVoidMethod)(JNIEnv*, jobject, jmethodID, ...);
    (*env)->CallVoidMethod(env, obj, methodID, (*env)->NewStringUTF(env, "是时候再黑一波小志了"));
}

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_LDLIBS += -llog

LOCAL_MODULE    := hello
LOCAL_SRC_FILES := hello.c

include $(BUILD_SHARED_LIBRARY)

APP_ABI := armeabi armeabi-v7a x86 //表示不同的平台

import java.lang.reflect.Method;


public class Demo {

    public static void main(String[] args) {
        try {
            //拿到类的字节码。Dialog是类名
            Class clazz = Demo.class.getClassLoader().loadClass("Dialog");
            //拿到方法，show是方法名，后面是方法的参数类型。
            Method method = clazz.getDeclaredMethod("show", String.class);
            //调用方法，因为method方法不是静态方法，所有clazz.newInstance()表示对象，后面是参数。
            method.invoke(clazz.newInstance(), "好久没黑小志了");
            
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}