終端切換到 <sdk>/tools/ 目錄下執行 Android 命令就可以把AVD Manager 打開了。 可是，如果你沒有添加 <sdk>/tools 到你的環境變量中時，輸入 android 回車後終端只會提示你
android：找不到命令
而只要在android前加上 ./ 就可以解決問題：
./android
更簡單的辦法是將 <sdk>/tools 路徑添加進 PATH 環境變量。可以添加進用戶級環境變量，也可以添加到系統環境變量中。通過命令或編輯文件均可，在這裡我只提供一個辦法，打開終端，輸入：
sudo gedit /etc/environment
回車，在PATH=”………………….”的雙引號中追加上：
:<sdk>/tools:<sdk>/platform-tools
比如：
:/opt/android-sdk/tools:/opt/android-sdk/platform-tools
注意，:是分隔符。
重啟一下或者 source /etc/environment(立即生效) 在終端輸入 android 回車就會有反應了。
下載Android NDK ： http://developer.android.com/sdk/ndk/index.html
echo 解壓縮得到android-ndk-r6b目錄，即可。 tar -jxvf android-ndk-r6b-linux-x86.tar.bz2
也將其路徑加入到source路徑中
經過了上述步驟，在命令行下敲：
ndk-bulid
彈出如下的錯誤，而不是說ndk-build not found，就說明ndk環境已經安裝成功了。
Android NDK: Could not find application project directory !
Android NDK: Please define the NDK_PROJECT_PATH variable to point to it.
/home/braincol/workspace/android/android-ndk-r5/build/core/build-local.mk:85: *** Android NDK: Aborting . Stop.
二、代碼的編寫
1.首先是寫java代碼
建立一個Android應用工程HelloJni，創建HelloJni.java文件：
HelloJni.java :
/*
* 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.
*/
package
com.example.hellojni;
import
android.app.Activity;
import
android.widget.TextView;
import
android.os.Bundle;
public
class
HelloJni extends
Activity
{
/** Called when the activity is first created. */
@Override
public
void
onCreate(Bundle savedInstanceState)
{
super
.onCreate(savedInstanceState);
/* Create a TextView and set its content.
* the text is retrieved by calling a native
* function.
*/
TextView tv = new
TextView(this
);
tv.setText( stringFromJNI() );
setContentView(tv);
}
/* A native method that is implemented by the
* 'hello-jni' native library, which is packaged
* with this application.
*/
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 !
*/
public
native
String unimplementedStringFromJNI();
/* this is used to load the 'hello-jni' library on application
* startup. The library has already been unpacked into
* /data/data/com.example.HelloJni/lib/libhello-jni.so at
* installation time by the package manager.
*/
static
{
System.loadLibrary("hello-jni"
);
}
}這段代碼很簡單，注釋也很清晰，這裡只提兩點：:
static{
System.loadLibrary("hello-jni" );
}
表明程序開始運行的時候會加載hello-jni, static區聲明的代碼會先於onCreate方法執行。如果你的程序中有多個類，而且如果HelloJni這個類不是你應用程序的入口，那麼 hello-jni（完整的名字是libhello-jni.so）這個庫會在第一次使用HelloJni這個類的時候加載。
public native String stringFromJNI();
public native String unimplementedStringFromJNI();
可以看到這兩個方法的聲明中有 native 關鍵字， 這個關鍵字表示這兩個方法是本地方法，也就是說這兩個方法是通過本地代碼（C/C++）實現的，在java代碼中僅僅是聲明。
用eclipse編譯該工程，生成相應的.class文件，這步必須在下一步之前完成，因為生成.h文件需要用到相應的.class文件。
