1. Service的数据结构
2. LoadedApk
final ArrayMap<Context, ArrayMap<ServiceConnection, LoadedApk.ServiceDispatcher>> mServices
bindService(intent, serviceConnection,BIND_AUTO_CREATE);
LoadedApk 中的mServices保存了当前进程bindService的连接信息，以Context为Key保存了当前Context对应的ArrayMap<ServiceConnection, LoadedApk.ServiceDispatcher>
ServiceConnection 对应了ServiceDispatcher中的IServiceConnection.Stub，是一个Binder的服务端，bindeS ervice的时候会将这个Binder传递给AMS, AMS持有其代理端，也就是ConnectionRecord中的conn变量
3. ConnectionRecord
/**
* Description of a single binding to a service.
*/
final class ConnectionRecord {
final AppBindRecord binding; // The application/service binding.
final ActivityRecord activity; // If non-null, the owning activity.
final IServiceConnection conn; // The client connection.
ConnectionRecord描述了一个bindService的连接
conn : IServiceConnection在AMS中的代理端
activity : 绑定Service的Activity
4. AppBindRecord
/**
* An association between a service and one of its client applications.
*/
final class AppBindRecord {
final ServiceRecord service; // The running service.
final IntentBindRecord intent; // The intent we are bound to.
final ProcessRecord client; // Who has started/bound the service.
final ArraySet<ConnectionRecord> connections = new ArraySet<>();
// All ConnectionRecord for this client.
记录了一个Service与其关联的Client信息
client : 记录了绑定当前Service的客户端进程的信息
connections: 记录了某一个客户端进程与当前Service的所有bind连接信息
一个进程中可能会有多个地方绑定同一个Service，所以一个进程会有多个ConnectionRecord信息
5. IntentBindRecord
/**
* A particular Intent that has been bound to a Service.
*/
final class IntentBindRecord {
/** The running service. */
final ServiceRecord service;
/** The intent that is bound.*/
final Intent.FilterComparison intent; //
/** All apps that have bound to this Intent. */
final ArrayMap<ProcessRecord, AppBindRecord> apps
= new ArrayMap<ProcessRecord, AppBindRecord>();
/** Binder published from service. */
IBinder binder;
绑定一个Service的时候需要一个intent参数，所以IntentBindRecord就是来记录一个Intent与其对应的Service的关系
apps: 由于同一个intent，可能有多个不同的进程来bind该service，故采用其成员变量apps来记录使用该intent绑定Service的所有client进程.
binder : service发布过程，调用publishServiceLocked()来赋值的IBinder对象；也就是bindService后的onBinder()方法 的返回值（作target进程的binder服务）的代理对象。简单来说就是onServiceConnected()的第二个参数。
6. ServiceRecord
/**
* A running application service.
*/
final class ServiceRecord extends Binder implements ComponentName.WithComponentName {
final ActivityManagerService ams;
final ComponentName name; // service component.
final String shortName; // name.flattenToShortString().
final Intent.FilterComparison intent;
// original intent used to find service.
final ServiceInfo serviceInfo;
// all information about the service.
ApplicationInfo appInfo;
// information about service's app.
final int userId; // user that this service is running as
final String packageName; // the package implementing intent's component
final String processName; // process where this component wants to run
final Runnable restarter; // used to schedule retries of starting the service
final long createRealTime; // when this service was created
final ArrayMap<Intent.FilterComparison, IntentBindRecord> bindings
= new ArrayMap<Intent.FilterComparison, IntentBindRecord>();
// All active bindings to the service.
final ArrayMap<IBinder, ArrayList<ConnectionRecord>> connections
= new ArrayMap<IBinder, ArrayList<ConnectionRecord>>();
// IBinder -> ConnectionRecord of all bound clients
ProcessRecord app; // where this service is running or null.
ProcessRecord isolatedProc; // keep track of isolated process, if requested
boolean isForeground; // is service currently in foreground mode?
int foregroundId; // Notification ID of last foreground req.
Notification foregroundNoti; // Notification record of foreground state.
ServiceRecord记录了AMS中某一个运行的Service信息，是AMS管理Service的基本单位， ServiceRecord继承于Binder对象,作为Binder IPC的Bn端；Binder将其传递到Service进程的Bp端， 保存在Service.mToken, 即ServiceRecord的代理对象。
- ServiceInfo : 记录了AndroidManifest.xml中Service相关的信息
- userId : 当前Service是那个user启动的
- app : 记录了当前Service所属进程的相关信息
- isForeground : 记录了当前Service是否是一个前台进程
- bindings : 一个Service可以被其他的进程用不同的Intent来绑定，所以bindings记录了绑定在当前Service上的所有的Intent以及气对应的IntentBindRecord信息.
总结：一个Service可以被其他进程用不同的Intent来绑定
使用同一个Intent绑定Service的可能是多个不同的进程
每个进程中有可能有多个地方bind这个服务，所以有多个Connection连接
- connections:记录IServiceConnection以及所有对应client的ConnectionRecord
- startRequested：代表service是否由startService方式所启动的
- startService()，则startRequested=true;
- stopService()或stopSelf()，则startRequested=false;
8. ActiveServices
ActiveServices是AMS中负责管理Service的类, 他变量mService是ServiceMap类型, ServiceMap中保存了运行的Service信息ServiceRecord.
有两种保存方式
- mServicesByName: 以CompomentName为key保存了ServiceReocord
- mServicesByIntent: 以Intent为Key保存了ServiceRecord
mPendingService: 表示正在等待进程启动的ServiceRecord信息
9. ProcessRecord
// all ServiceRecord running in this process
final ArraySet<ServiceRecord> services = new ArraySet<>();
// services that are currently executing code (need to remain foreground).
final ArraySet<ServiceRecord> executingServices = new ArraySet<>();
// All ConnectionRecord this process holds
final ArraySet<ConnectionRecord> connections = new ArraySet<>();
- services保存了当前进程中所有正在运行的Service信息
- executingServices 保存了所有当前进程中正在执行Service生命周期的Service信息
- connections 保存了当前进程中所有绑定其他Service的连接信息
