由于每个应用程序都运行在自己的进程空间，并且可以从应用程序UI运行另一个服务进程，而且经常会在不同的进程间传递对象。在Android平台，一个进程通常不能访问另一个进程的内存空间。但是android提供了AIDL可以用来进程间数据传递。
AIDL (Android Interface Definition Language) 是一种IDL 语言，用于生成可以在Android设备上两个进程之间进行进程间通信(interprocess communication, IPC)的代码。如果在一个进程中（例如Activity）要调用另一个进程中（例如Service）对象的操作，就可以使用AIDL生成可序列化的参数。
AIDL IPC机制是面向接口的，像COM或Corba一样，但是更加轻量级。它是使用代理类在客户端和实现端传递数据。
下面通过一个实例来演示AIDL,因为是进程之间数据传递，所以这里要使用建立android工程，一个是AIDL的服务端另一个是客户端.
服务端的实现步骤:
1.创建.aidl文件IMyService.aidl
package cn.com.karl.aidl;
import cn.com.karl.aidl.Person;
interface IMyService {
void savePersonInfo(in Person person);
List<Person> getAllPerson();
String sayHello();
}
因为这里用到了Peson对象，所以要创建一个person类。Person类，是一个序列化的类，这里使用Parcelable 接口来序列化，是Android提供的一个比Serializable 效率更高的序列化类。
public class Person implements Parcelable {
private String name;
private String telNumber;
private int age;
public Person() {}
public Person(Parcel pl){
name = pl.readString();
telNumber = pl.readString();
age = pl.readInt();
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getTelNumber() {
return telNumber;
}
public void setTelNumber(String telNumber) {
this.telNumber = telNumber;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(name);
dest.writeString(telNumber);
dest.writeInt(age);
}
public static final Parcelable.Creator<Person> CREATOR = new Parcelable.Creator<Person>() {
@Override
public Person createFromParcel(Parcel source) {
return new Person(source);
}
@Override
public Person[] newArray(int size) {
return new Person[size];
}
};
}
然后创建Person.aidl文件，注意这里的parcelable小写。
package cn.com.karl.aidl;
parcelable Person;
上面的IMyService.aidl保存以后会在gen的相应目录下启动生成如下代码：
Binder
package cn.com.karl.aidl;
public interface IMyService extends android.os.IInterface
{
/** Local-side IPC implementation stub class. */
public static abstract class Stub extends android.os.Binder implements cn.com.karl.aidl.IMyService
{
private static final java.lang.String DESCRIPTOR = "cn.com.karl.aidl.IMyService";
/** Construct the stub at attach it to the interface. */
public Stub()
{
this.attachInterface(this, DESCRIPTOR);
}
/**
* Cast an IBinder object into an cn.com.karl.aidl.IMyService interface,
* generating a proxy if needed.
*/
public static cn.com.karl.aidl.IMyService asInterface(android.os.IBinder obj)
{
if ((obj==null)) {
return null;
}
android.os.IInterface iin = (android.os.IInterface)obj.queryLocalInterface(DESCRIPTOR);
if (((iin!=null)&&(iin instanceof cn.com.karl.aidl.IMyService))) {
return ((cn.com.karl.aidl.IMyService)iin);
}
return new cn.com.karl.aidl.IMyService.Stub.Proxy(obj);
}
public android.os.IBinder asBinder()
{
return this;
}
@Override public boolean onTransact(int code, android.os.Parcel data, android.os.Parcel reply, int flags) throws android.os.RemoteException
{
switch (code)
{
case INTERFACE_TRANSACTION:
{
reply.writeString(DESCRIPTOR);
return true;
}
case TRANSACTION_savePersonInfo:
{
data.enforceInterface(DESCRIPTOR);
cn.com.karl.aidl.Person _arg0;
if ((0!=data.readInt())) {
_arg0 = cn.com.karl.aidl.Person.CREATOR.createFromParcel(data);
}
else {
_arg0 = null;
}
this.savePersonInfo(_arg0);
reply.writeNoException();
return true;
}
case TRANSACTION_getAllPerson:
{
data.enforceInterface(DESCRIPTOR);
java.util.List<cn.com.karl.aidl.Person> _result = this.getAllPerson();
reply.writeNoException();
reply.writeTypedList(_result);
return true;
}
case TRANSACTION_sayHello:
{
data.enforceInterface(DESCRIPTOR);
java.lang.String _result = this.sayHello();
reply.writeNoException();
reply.writeString(_result);
return true;
}
}
return super.onTransact(code, data, reply, flags);
}
private static class Proxy implements cn.com.karl.aidl.IMyService
{
private android.os.IBinder mRemote;
Proxy(android.os.IBinder remote)
{
mRemote = remote;
}
public android.os.IBinder asBinder()
{
return mRemote;
}
public java.lang.String getInterfaceDescriptor()
{
return DESCRIPTOR;
}
public void savePersonInfo(cn.com.karl.aidl.Person person) throws android.os.RemoteException
{
android.os.Parcel _data = android.os.Parcel.obtain();
android.os.Parcel _reply = android.os.Parcel.obtain();
try {
_data.writeInterfaceToken(DESCRIPTOR);
if ((person!=null)) {
_data.writeInt(1);
person.writeToParcel(_data, 0);
}
else {
_data.writeInt(0);
}
mRemote.transact(Stub.TRANSACTION_savePersonInfo, _data, _reply, 0);
_reply.readException();
}
finally {
_reply.recycle();
_data.recycle();
}
}
public java.util.List<cn.com.karl.aidl.Person> getAllPerson() throws android.os.RemoteException
{
android.os.Parcel _data = android.os.Parcel.obtain();
android.os.Parcel _reply = android.os.Parcel.obtain();
java.util.List<cn.com.karl.aidl.Person> _result;
try {
_data.writeInterfaceToken(DESCRIPTOR);
mRemote.transact(Stub.TRANSACTION_getAllPerson, _data, _reply, 0);
_reply.readException();
_result = _reply.createTypedArrayList(cn.com.karl.aidl.Person.CREATOR);
}
finally {
_reply.recycle();
_data.recycle();
}
return _result;
}
public java.lang.String sayHello() throws android.os.RemoteException
{
android.os.Parcel _data = android.os.Parcel.obtain();
android.os.Parcel _reply = android.os.Parcel.obtain();
java.lang.String _result;
try {
_data.writeInterfaceToken(DESCRIPTOR);
mRemote.transact(Stub.TRANSACTION_sayHello, _data, _reply, 0);
_reply.readException();
_result = _reply.readString();
}
finally {
_reply.recycle();
_data.recycle();
}
return _result;
}
}
static final int TRANSACTION_savePersonInfo = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0);
static final int TRANSACTION_getAllPerson = (android.os.IBinder.FIRST_CALL_TRANSACTION + 1);
static final int TRANSACTION_sayHello = (android.os.IBinder.FIRST_CALL_TRANSACTION + 2);
}
public void savePersonInfo(cn.com.karl.aidl.Person person) throws android.os.RemoteException;
public java.util.List<cn.com.karl.aidl.Person> getAllPerson() throws android.os.RemoteException;
public java.lang.String sayHello() throws android.os.RemoteException;
}
因为sub类实现了Binder接口，所以以后会使用这个类。
2.实现service类
public class RemoteService extends Service {
private LinkedList<Person> personList = new LinkedList<Person>();
@Override
public IBinder onBind(Intent intent) {
return mBinder;
}
private final IMyService.Stub mBinder = new IMyService.Stub(){
@Override
public void savePersonInfo(Person person) throws RemoteException {
if (person != null){
personList.add(person);
}
}
@Override
public List<Person> getAllPerson() throws RemoteException {
return personList;
}
@Override
public String sayHello() throws RemoteException {
// TODO Auto-generated method stub
return "欢迎你通过AIDL访问服务器端";
}
};
}
3.客户端实现步骤：
首先建立一个项目，把服务端的
然后构造客户端的activity类：
public class RemoteClientActivity extends Activity {
/** Called when the activity is first created. */
private TextView textHello,textPerson;
private IMyService myService;
private Button btnSave;
private Button btnGet;
private static Boolean mIsRemoteBound=false;
private ServiceConnection conn=new ServiceConnection() {
@Override
public void onServiceDisconnected(ComponentName name) {
// TODO Auto-generated method stub
myService=null;
}
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
// TODO Auto-generated method stub
myService=IMyService.Stub.asInterface(service);
try {
textHello.setText(myService.sayHello());
} catch (RemoteException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
};
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
textHello=(TextView) this.findViewById(R.id.textHello);
btnSave=(Button) this.findViewById(R.id.btnSave);
btnGet=(Button) this.findViewById(R.id.btnGet);
textPerson=(TextView) this.findViewById(R.id.textPerson);
if(mIsRemoteBound){
unbindService(conn);
}else{
Intent intent=new Intent("cn.com.karl.aidl.RemoteService");
bindService(intent, conn, BIND_AUTO_CREATE);
}
mIsRemoteBound = !mIsRemoteBound;
btnSave.setOnClickListener(new OnClickListener() {
private int index = 0;
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Person person = new Person();
indexindex = index + 1;
person.setName("Person" + index);
person.setAge(20);
person.setTelNumber("123456");
try {
myService.savePersonInfo(person);
} catch (RemoteException e) {
e.printStackTrace();
}
}
});
btnGet.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
List<Person> list = null;
try {
list = myService.getAllPerson();
} catch (RemoteException e) {
e.printStackTrace();
}
if (list != null){
StringBuilder text = new StringBuilder();
for(Person person : list){
text.append("\n联系人:");
text.append(person.getName());
text.append("\n年龄:");
text.append(person.getAge());
text.append("\n 电话:");
text.append(person.getTelNumber());
}
textPerson.setText(text);
}else {
Toast.makeText(RemoteClientActivity.this, "得到数据出错",
Toast.LENGTH_SHORT).show();
}
}
});
}
}
最后不要忘记注册service:
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service android:name=".RemoteService">
<intent-filter >
<action android:name="cn.com.karl.aidl.RemoteService"></action>
</intent-filter>
</service>
</application>
启动service的时候使用了隐士意图。
运行服务端工程.
服务端已经启动，然后运行客户端工程：
OK，已经从服务端得到了数据，第一句话就是从服务端得到的，下面看看，传递对象和获取对象与服务端。
点击添加联系人，然后点击获取联系人按钮：
