Windows下编译使用Android(安卓)NDK，调用SO文件

一、首先下载android-ndk，官方网站是： http://developer.android.com/tools/sdk/ndk/index.html 目前最新的版本是 android-ndk-r8e-windows-x86.zip，下载地址： http://dl.google.com/android/ndk/android-ndk-r8e-windows-x86.zip
下载后把压缩包解压出来，例如：D:\ndk，目录下的ndk-build.cmd就是用来编译的批处理命令。
这里以D:\ndk\samples\hello-jni为例，打开D:\ndk\samples\hello-jni\jni\hello-jni.c查看代码：

/* * 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. * */#include <string.h>#include /* This is a trivial JNI example where we use a native method * to return a new VM String. See the corresponding Java source * file located at: * *   apps/samples/hello-jni/project/src/com/example/hellojni/HelloJni.java */jstringJava_com_example_hellojni_HelloJni_stringFromJNI( JNIEnv* env,                                                  jobject thiz ){    return (*env)->NewStringUTF(env, "Hello from JNI !");}

因为我们是拿这个c源码文件来使用，如果迁就 Java_com_example_hellojni_HelloJni_stringFromJNI 函数名的话，在我们的android工程中java类的声明就要是： com/example/hellojni/HelloJni.java。
反之，如果我们的android工程已经创建好，并且包名是com.example.hellojni，stringFromJNI函数我们写在了MainActivity.java类里，那么这里的c函数就要修改为：Java_com_example_hellojni_MainActivity_stringFromJNI，否则在寻找函数时会找不到。

二、编译，打开cmd命令行窗口，cd进入目录： D:\ndk\samples\hello-jni，然后执行命令：D:\ndk\ndk-build.cmd（如果设置过环境变量则直接使用ndk-build.cmd）来编译hello-jni，如果没有错误会输出： Gdbserver : [arm-linux-androideabi-4.6] libs/armeabi/gdbserver Gdbsetup : libs/armeabi/gdb.setup
"Compile thumb : hello-jni <= hello-jni.c
SharedLibrary : libhello-jni.so
Install : libhello-jni.so => libs/armeabi/libhello-jni.so

编译成功会在D:\ndk\samples\hello-jni\libs\armeabi目录下生成libhello-jni.so文件。

三、创建android应用程序并使用so文件 打开eclipse创建一个android应用程序HelloJni，默认的com.example.hellojni包下面有一个MainActivity.java，在此包下添加一个HelloJni.java，

package com.example.hellojni;public class HelloJni {    public native String  stringFromJNI();        /* This is another native method declaration that is *not*          * implemented by 'hello-jni'. This is simply to show that          * you can declare as many native methods in your Java code          * as you want, their implementation is searched in the          * currently loaded native libraries only the first time          * you call them.          *          * Trying to call this function will result in a          * java.lang.UnsatisfiedLinkError exception !     */  }

MainActivity.java修改为：

package com.example.hellojni;import android.os.Bundle;import android.app.Activity;import android.view.Menu;import android.widget.TextView;import android.util.Log;public class MainActivity extends Activity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        //setContentView(R.layout.activity_main);                HelloJni jni = new HelloJni();        TextView  tv = new TextView(this);         String str = jni.stringFromJNI();        Log.d("HelloJni", str);        tv.setText(str);          setContentView(tv);    }    @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;    }    static {          System.loadLibrary("hello-jni");               }}

把编译生成的libhello-jni.so文件复制到F:\eclipse_workspace\HelloJni\libs\armeabi目录下（armeabi如果不存在则手动创建之），然后编译运行，效果图如下：

参考资料： Android Eclipse JNI 调用 .so文件加载问题： http://blog.sina.com.cn/s/blog_4d0afbdb0100m7y7.html Android NDK 生成、调用so文件： http://blog.csdn.net/vestigge/article/details/8597993

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