如何在guice中实现依赖I/O

Question

Injector injector = Guice.createInjector(
    new DatabaseModule(),
    new WebserverModule(),
    ...
);

Service databaseConnectionPool = injector.getInstance(
    Key.get(Service.class, DatabaseService.class));
databaseConnectionPool.start();
addShutdownHook(databaseConnectionPool);

Service webserver = injector.getInstance(
    Key.get(Service.class, WebserverService.class));
webserver.start();
addShutdownHook(webserver);

// I/O in the static method call; returns a module with
// the environment-based objects
EnvironmentModule environment = EnvironmentModule.configureEnvironment(args);

Injector injector = Guice.createInjector(
     environment,
     // the following connects to the database, and returns a module
     // providing the DataSource
     SQLModule.connectToDatabase());

injector = injector.createChildInjector(new BusinessLayerModule());
startTimers(injector);

injector = injector.createChildInjector(
    new ServicesModule(),
    new WebServerModule());

startServer(injector);

null

Answer 1

我的方法和你的第二种方法相似，除了儿童注射器。

首先，创建一个专门用于初始化的模块SQLModule：

Injector initInjector = Guice.createInjector(Stage.PRODUCTION, new SQLModule());
SQLService service = initInjector.getInstance(SQLService.class);
Properties initProps = service.doInit(); // for example

然后创建主模块：

Injector mainInjector = Guice.createInjector(Stage.PRODUCTION, 
                 new SQLModule(), 
                 new MainModule(initProps));
// main program here using the mainInjector