Android ndk 入门4 - C++实现

新建工程NDKTest3，新建活动MainActivity

新建MyNDK.java:

package com.zj.ndktest3;

/**
 * Created by root on 15-11-26.
 */
public class MyNDK {
    static {
        System.loadLibrary("hello-jni-c++");
    }

    public static native String hello();
}

修改activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context="com.zj.ndktest3.MainActivity">

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

</RelativeLayout>

修改MainActivity.java:

package com.zj.ndktest3;

import android.app.Activity;
import android.os.Bundle;
import android.view.Window;
import android.widget.TextView;

public class MainActivity extends Activity {
    
    private TextView mTextView;

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

        mTextView = (TextView)findViewById(R.id.text_view);
        mTextView.setText(MyNDK.hello());
    }
}

修改local.propeties，加入：

ndk.dir=/opt/android-ndk-r10e

修改gradle.properties，加入：

android.useDeprecatedNdk=true

修改app/build.gradle，加入：

android {
    defaultBuild {
            ndk {
               moduleName "hello-jni-c++"
               stl "stlport_shared"
               ldLibs "log"
        }
   }
}

点击MyNDK.java，右键->External Tools->javah，生成com_zj_ndktest3_MyNDK.h:

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class com_zj_ndktest3_MyNDK */

#ifndef _Included_com_zj_ndktest3_MyNDK
#define _Included_com_zj_ndktest3_MyNDK
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     com_zj_ndktest3_MyNDK
 * Method:    hello
 * Signature: ()Ljava/lang/String;
 */
JNIEXPORT jstring JNICALL Java_com_zj_ndktest3_MyNDK_hello
  (JNIEnv *, jclass);

#ifdef __cplusplus
}
#endif
#endif

新建main.cpp:

#include <jni.h>
#include <iostream>
#include <string.h>
#include "com_zj_ndktest3_MyNDK.h"
#include "MyLog.h"

using namespace std;

JNIEXPORT jstring JNICALL Java_com_zj_ndktest3_MyNDK_hello
        (JNIEnv *env, jclass cla) {
    LOGI("function begins");
    string ret;
    LOGI("ok");
    char s[] = "Golden Global   View,disk * desk";
    const char *d = " ,*";
    LOGI("next step is define char *p=NULL");
    char *p=NULL;
    LOGI("every thing is ok");
    p = strtok(s,d);
    int i=0;
    LOGI("previous step is ok");
    while(p){
        ret += p;
        ret += " ";
        p=strtok(NULL,d);
    }

    return env->NewStringUTF(ret.c_str());
    //return env->NewStringUTF("hello jni");
}

新建MyLog.h:

#ifndef _MYLOG_H_
#define _MYLOG_H_

#include <android/log.h>

#define TAG "test"

#define LOGV(...) __android_log_print(ANDROID_LOG_VERBOSE, TAG, __VA_ARGS__)
#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG, TAG, __VA_ARGS__)
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO, TAG, __VA_ARGS__)
#define LOGW(...) __android_log_print(ANDROID_LOG_WARN, TAG, __VA_ARGS__)
#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR, TAG, __VA_ARGS__)


#endif

新建jni/Android.mk:

LOCAL_PATH := ${call my-dir}
include $(CLEAR_VARS)
LOCAL_MODULE := hello-jni-c++
LOCAL_SRC_FILES := main.cpp
include ${BUILD_SHARED_LIBRARY}

运行：

##################################################################

网上找到两种实现C++的方法：

1.在Application.mk上加入：

APP_STL := stlport_shared

2.在app/build.gradle上加入:

android {
   defaultConfig {
       ndk {
            stl "stlport_shared"
       }
   }
}