Ubuntu NDK配置与JNI demo

NDK配置

1.下载最新版本NDK(android-ndk-r9d-linux-x86_64.tar.bz2)

下载网页:http://developer.android.com/tools/sdk/ndk/index.html

2.拷贝下载文件到环境配置目录解压，解压方式

tar -jxvf android-ndk-r9d-linux-x86_64.tar.bz2

3.控制台进入到账户根目录，编辑.bashrc文件(vi .bashrc)

4.新建环境变量(主要最后一个文件夹为ndk解压后的文件夹名）

export NDK_HOME=/home/lchd/work/tools/android-ndk-r9-linux

5.在PATH中添加改环境

export PATH=$PATH:$NDK_HOME:.

6.退出控制台，重新进入控制台

输入 ndk-build 查看错误提示

Android NDK: Could not find application project directory !
Android NDK: Please define the NDK_PROJECT_PATH variable to point to it.

出现以上错误，恭喜你，环境配置OK

JNI demo

src源代码结构图

./src

├── ./src/com

│   └── ./src/com/example

│       └── ./src/com/example/testedittext

│           └── ./src/com/example/testedittext/MainActivity.java

└── ./src/jni

└── ./src/jni/helloworld.java

/src/com/example/testedittext/MainActivity.java

package com.example.testedittext;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Button;
import android.widget.Toast;

import jni.helloworld;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        System.loadLibrary("helloworld");
        Toast.makeText(this, "xx " + new helloworld().dispHelloWorld(), Toast.LENGTH_SHORT).show();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

}

　/src/jni/helloworld.java

package jni;

public class helloworld {
    public native String dispHelloWorld();
}

JNI文件目录

├── ./jni

│   ├── ./jni/Android.mk

│   └── ./jni/helloworld.c

/jni/Android.mk

# Copyright (C) 2009 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE    := helloworld
LOCAL_SRC_FILES := helloworld.c

include $(BUILD_SHARED_LIBRARY)

/jni/helloworld.c

#include <jni.h>
#include <stdio.h>
JNIEXPORT jstring JNICALL Java_jni_helloworld_dispHelloWorld(JNIEnv *env,
		jobject obj) {
	char* cstr = "helloworld111";
	return (**env).NewStringUTF(env, cstr);
}

在项目根目录运行ndk-build 生成以下文件

├── ./libs

│   ├── ./libs/android-support-v4.jar

│   └── ./libs/armeabi

│       └── ./libs/armeabi/libhelloworld.so

├── ./obj

│   └── ./obj/local

│       └── ./obj/local/armeabi

│           ├── ./obj/local/armeabi/libhelloworld.so

│           └── ./obj/local/armeabi/objs

│               └── ./obj/local/armeabi/objs/helloworld

│                   ├── ./obj/local/armeabi/objs/helloworld/helloworld.o

│                   └── ./obj/local/armeabi/objs/helloworld/helloworld.o.d

运行android程序，正确谈出toast xx helloworld111.