如何使用 Inject 获取一次服务实例 [英] How to get once instance of service with Inject

问题描述

如何使用 Injector 获得相同的单例服务实例:

我在 bootstrap 应用程序上定义了这个服务的提供者(例如所有应用程序上的一个实例)

I define provider of this service on the bootstrap application(for one instance on the all application)

示例:

//Init application
bootstrap(AppComponent, [ROUTER_PROVIDERS, HTTP_PROVIDERS, SessionService]);

会话服务

Singleton - 这只是示例，但实际上可以是会话或 acl 服务

SessionService

Singleton - this is just example, but in real can be session or acl service

@Injectable()
export class SessionService {
    constructor() {
        console.warn("INSTANCE OF SESSION SERVICE-a");
    }
    public getInstance(instanceName: string){
        console.warn("Injected service come from component name: " + instanceName);
    }
}

SecuredHomeComponent

当我在构造函数上注入服务时只有一次服务实例(好)

@Component()
@CanActivate(AccessService.checkSession)
export class SecuredHomeComponent {
    public constructor(private testSessionService: SessionService) {
        this.testSessionService.getInstance('Component1:1'); //Test 1 - get the same instance when service is inject into contructor
    }
}

MyStaticService

我是这样尝试的，注入服务但总是得到新的服务实例但是我需要使用Injector.resolveAndCreate"直接注入例如静态方法，然后NG2创建新的服务实例(坏)

@Injectable()
export class MyStaticService {
    public static getDataFromService() {
        //That two ways is bad, bcs create new instance of my test SessionService
        //Test4
        let providers = Injector.resolve([ SessionService ]);
        let injectorFirst = Injector.fromResolvedProviders(providers);
        let testServFirst = injectorFirst.get(SessionService);
        testServFirst.getInstance('StaticService1:1');
        //Test 5
        let injectorSecond = Injector.resolveAndCreate([SessionService]);
        let testServSecond = injectorSecond.get(SessionService);
        testServSecond.getInstance('StaticService1:2');
    }
}

静态服务

例如，我需要带有静态方法的静态类如果我很好地理解文档，当想要覆盖注释的方法时canActivate必须提供静态方法的服务

Static Service

For real example, I need static class with static method If I good understand doc, when want overwrites methods for annotation canActivate must provide servise with static method

行:@CanActivate(AccessService.checkSession) 在我的SecuredHomeComponent"

Line: @CanActivate(AccessService.checkSession) in my "SecuredHomeComponent"

//Static Service - ACCESS
@Injectable()
export class AccessService {
    public static checkAccess = (next: ComponentInstruction, prev: ComponentInstruction): boolean => {        
        return AccessService.checkSession() && AccessService.checkAcl(res, priv);
    }
    public static checkSession(): boolean {
        let injectedSessionServices: SessionService; //How to inject the same instance of my SessionService?
        return injectedSessionServices.getDataFromService(); //for real service he get back checkSession from sessionService
    }
    public static checkAcl(aclResource: AclResources, aclPrivilege: AclPrivileges): boolean {
        let injectedAclServices: SessionService; //How to inject the same instance of my SessionService?
        return injectedAclServices.checkAcl(aclResource, aclPrivilege);
    }
}

推荐答案

我找到了使用一个全局服务实例的解决方案 injector 使用 getInstance() 实现了标准的单例类进入引导程序.之后可以在所有级别的应用程序上获得注入服务的简单实例.如果有人找到不同的解决方案，或者 NG2 解决了这个不同的问题，请告诉我.

I find solution with using one instance of global service injector implemented standard singleton class with getInstance() into bootstrap application. And after that can get simple instance of injected service on all level of application. If some time somebody find different solution, or NG2 resolve this different pls let me know.

非常简单的示例代码:

引导程序

//Init application
bootstrap(AppComponent, [ROUTER_PROVIDERS, MY_PROVIDERS, HTTP_PROVIDERS])
    .then((appRef) => MainInjectorService.getInstance().setInjector(appRef.injector));

我的助手主要注入器

import { Injector, Injectable } from 'angular2/src/core/di';

@Injectable()
export class MainInjectorService
{
    static instance:MainInjectorService;    
    static isCreating:Boolean = false;
    private _injector: Injector;

    constructor() {
        if (!MainInjectorService.isCreating) {
            throw new Error("You can't call new in Singleton instances!");
        }
    }

    public static getInstance() {
        if (MainInjectorService.instance == null) {
            MainInjectorService.isCreating = true;
            MainInjectorService.instance = new MainInjectorService();
            MainInjectorService.isCreating = false;
        }

        return MainInjectorService.instance;
    }

    public setInjector(injector: Injector) {
        this._injector = injector;
    }

    public getInjector(): Injector {
        return this._injector;
    }
}

我的静态类

// Access - static service 
@Injectable()
export class StaticAccessService {

    // Get service instance from global provides service
    private static _getService<T>(serviceName: any) {
        let injector: Injector = MainInjectorService.getInstance().getInjector();
        return injector.get(serviceName);
    }

    //Check access to session and acl
    public static checkAccess = (next: ComponentInstruction, prev: ComponentInstruction): boolean => {
        return StaticAccessService.checkSession() && StaticAccessService.checkAcl(next.routeData.data['res'], next.routeData.data['priv']);
    }

    // Check session access
    public static checkSession(): boolean {
        return StaticAccessService._getService(MySessionService).checkSession();
    }

    // Check session access
    public static checkAccess(res, priv): boolean {
        return StaticAccessService._getService(MyAclService).checkAccess(res, priv);
    }
}

以及如何在组件中使用

@Component()
@CanActivate(StaticAccessService.checkAccess)
export class SecuredComponent {
}

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