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108 lines
3.0 KiB
108 lines
3.0 KiB
---
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Service 的绑定原理
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---
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1. 知道 bindService 的用法
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2. 了解 bindService 的大致流程
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3. bindService 涉及哪些参与者，通信过程是怎样的？
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```java
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IRemoteCaller mCaller;
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ServiceConnection mServiceConnection = new ServiceConnection(){
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@Override
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public void onServiceConnected(ComponentName name, IBinder service) {
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mCaller = IRemoteCaller.Stub.asInterface(service);
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mCaller.call();
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}
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}
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Intent service = new Intent(this, MyService.class);
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bindService(service, mServiceConnection, BIND_AUTO_CREATE);
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```
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Bind Service 总体流程：
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```java
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@Override
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boolean bindService(Intent service, ServiceConnection conn, int flags) {
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return bindServiceCommon(service, conn, flags, ...);
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}
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boolean bindServiceCommon(Intent service, ServiceConnection conn, ...) {
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IServiceConnection sd;
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// 为 ServiceConnection 接口生成一个 binder 对象，可用于跨进程传递给 AMS
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sd = mPackageInfo.getServiceDispatcher(conn, getOuterContext(), mMainThread.getHandler(), flags);
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ActivityManagerNative.getDefult().bindService(mMainThread.getApplicationThread(), service, sd, ...);
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}
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IServiceConnection getServiceDispatcher(ServiceConnection c, ...) {
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ServiceDispatcher sd = null;
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Map<ServiceConnection, ServiceDispatcher> map = mServices.get(context);
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if(map != null){
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sd = map.get(c);
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}
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if(sd == null){
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sd = new ServiceDispatcher(c, context, handler,flags);
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if(map == null){
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map = new ArrayMap<ServiceConnection, ServiceDispatcher>();
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mService.put(context, map);
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}
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map.put(c, sd);
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}
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return sd.getIServiceConnection();
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}
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ServiceDispatcher(ServiceConnection conn, ...){
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mIServiceConnection = new InnerConnection(this);
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mConnection = conn;
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}
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static class InnerConnection extends IServiceConnection.Stub {
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final WeakReference<ServiceDispatcher> mDispatcher;
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public void connected(ComponentName name, IBinder service) {
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LoadedApk.ServiceDispatcher sd = mDispatcher.get();
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if(sd != null){
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sd.connected(name, service);
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}
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}
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}
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void connected(){
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mActivityThread.post(new RunConnection(name, service, 0));
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}
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public void doConnected(ComponentName name, IBinder service) {
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old = mActiveConnections.get(name);
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if(old!=null && old.binder == service){
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return;
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}
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if(service != null){
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info = new ConnectionInfo(service);
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mActiveConnections.put(name, info);
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}else{
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mActiveConnections.remove(name);
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}
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if(old != null){
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mConnection.onServiceDisconnected(name);
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}
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if(service != null){
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mConnection.onServiceConnected(name, service);
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}
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}
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```
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```java
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// AMS#bindServiceLocked
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bindServiceLocked(IApplicationThread caller, ...){
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//...
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if((flag&Context.BIND_AUTO_CREATE)!=0){
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bringUpServiceLocked(s, );
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}
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if(s.app != null && b.intent.received){
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c.conn.connected(s.name, b.intent.binder);
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}else if(!b.intent.requested){
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requestServiceBindingLocked(s, b.intent, false);
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}
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}
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```
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