Android 从硬件到应用：一步一步向上爬 6 -- 编写APP测试框架层硬件服务(完)

创建Android Application工程：使用Eclipse的Android插件ADT创建Android工程，工程名称为Gpio，创建完成后将工程目录拷贝到packages/apps/文件夹下，并删除工程目录下的gen文件夹，不删除的话会造成类重复的错误。

src/com/android/gpio/Gpio.java：

package com.android.gpio;
import com.android.gpio.R;
import android.app.Activity;
import android.os.ServiceManager;
import android.os.Bundle;
import android.os.IGpioService;
import android.os.RemoteException;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;  

public class Gpio extends Activity implements OnClickListener {
private final static String LOG_TAG = "com.android.Gpio";
private IGpioService gpioService = null;  

private Button setButton = null;
private Button clearButton = null;  

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	setContentView(R.layout.main);  

	gpioService = IGpioService.Stub.asInterface(
	ServiceManager.getService("gpio"));  

	setButton = (Button)findViewById(R.id.button_set);
	clearButton = (Button)findViewById(R.id.button_clear);  

	setButton.setOnClickListener(this);
	clearButton.setOnClickListener(this);
}  

@Override
public void onClick(View v) {
	if(v.equals(setButton)) {
	try{
		int val='1';
		gpioService.setVal(val);
	} catch (RemoteException e){
		Log.e(LOG_TAG,"setting value");
	}
	}
	else if(v.equals(clearButton)) {
	try{
		int val='0';
		gpioService.setVal(val);
	   } catch (RemoteException e){
		Log.e(LOG_TAG,"setting value");
	   }
	   }
	}
}  

布局res/layout/main.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:orientation="vertical"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent">  

   <Button
       android:id="@+id/button_clear"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:text="@string/clear"
       android:textStyle="bold"
       android:layout_marginTop="140dp"/>
   <Button
       android:id="@+id/button_set"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:text="@string/set"
       android:textStyle="bold"
       android:layout_marginTop="0dp"/>
</LinearLayout>  

字符串res/values/strings.xml：

<?xml version="1.0" encoding="utf-8"?>
<resources>
   <string name="app_name">GPIO</string>
   <string name="set">Set</string>
   <string name="clear">Clear</string>
</resources>  

AndroidManifest.xml：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
  package="com.android.gpio"
  android:versionCode="1"
  android:versionName="1.0">
  <application android:icon="@drawable/ic_launcher" android:label="@string/app_name">
    <activity android:name=".Gpio"
              android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
  </application>
</manifest>   

编辑工程目录下Android.mk：

LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE_TAGS := optional
LOCAL_SRC_FILES := $(call all-subdir-java-files)
LOCAL_PACKAGE_NAME := Gpio
LOCAL_CERTIFICATE := platform
include $(BUILD_PACKAGE)
include $(call all-makefiles-under,$(LOCAL_PATH))

编辑build/target/product/generic_no_telephony.mk：

在PRODUCT_PACKAGES := \ 后加入Gpio \

编译工程会生成Gpio.apk

make TARGET_PRODUCT=am335xevm_sk -j8 OMAPES=4.x 

到这一步一切准备工作都已就绪，开始更新目标板am335evm的文件系统：(左为host，右为evm)

out/target/product/am335xevm_sk/system/app/Gpio.apk                 ==>   rootfs/

out/target/product/am335xevm_sk/system/framework/services.jar       ==>   rootfs/system/framework/

out/target/product/am335xevm_sk/system/framework/framework.jar      ==>   rootfs/system/framework/

out/target/product/am335xevm_sk/obj/lib/libandroid_servers.so       ==>   rootfs/system/lib/

out/target/product/am335xevm_sk/obj/lib/gpio.default.so             ==>   rootfs/system/lib/hw/

确保rootfs下 ueventd.rc 已经添加：(Android 从硬件到应用：一步一步向上爬 3 -- 硬件抽象层访问硬件驱动 提到)

/dev/AdrIO                0666   root       root

启动，安装Gpio.apk，打开GPIO：

现象：

点击"Set"按钮：     D1灯亮    

点击"Clear"按钮：   D1灯灭

可见编写的APP通过调用硬件服务已经成功操作了AM335寄存器，改变AM335X_GPIO_LED4的电平，通过N沟MOS器件控制LED D1的亮灭。