如何將一個參數添加到將在組件的構造函數中作爲privider解析的服務？

Question

我有這個服務作爲提供商：

export class Print { 
 
    text: string; 
 

 
    constructor(text: string) { 
 
    this.text = text; 
 
    } 
 

 
    printText() { 
 
    //dosomething with the text; 
 
    } 
 

 
    prettifyText() { 
 
    //dosomething with the text; 
 
    } 
 
}

在我的部分，我想在角在text解析作爲參數使供應商的一個實例。

const text = 'Something to be printed'; 
 

 
export class AppComponent { 
 
    // How to parse 'text' as an argument 
 
    // to the printService when it is instantiate 
 
    // by angular componennt? 
 
    constructor(printService: Print) { 
 
    printService.prettifyText(); 
 
    printServoce.printText(); 
 
    } 
 
}

Answer 1

我以爲，問題是如何提供的構造函數值在注入（提供）服務。如果你需要的，是更高級的，想想看：

@Injectable() 
export class Print { 
text: string; 

constructor(text: string) { 
    this.text = text; 
    let injector = Injector.resolveAndCreate([HTTP_PROVIDERS]); 
    let http = injector.get(Http); 

    http 
     .get(this.text + ".json") 
     .subscribe(
      (response: any) => this.text = response.text(), // success 
      null, // error 
      () => console.log("c")// complete 
     ); 
} 
} 

注射器從angular2 /核心，HTTP和HTTP_PROVIDERS從angular2/HTTP 在您的組件裝飾：

@Component({ 
    selector : "cmp-name", 
    providers: [provide(Print, { useFactory:() => { return new 
Print("hello"); }})] 
}) 

而且在CMP名的構造

constructor(public print: Print) {} 

如果CONSOLE.LOG打印，您將獲得：

Print {text: "hello"} 

Answer 2

你必須有text可以在您的組件，一旦你做，你可以打電話給你的服務的方法：

export class AppComponent { 
    text; 
    constructor(private printService: Print, private http: Http) { 
    // you can get text through http, for example 
    this.http 
     .get('story.txt') 
     .subscribe(
     response => this.text = response.text(), // success 
     null, // error 
     () => this.print() // complete 
    ) 
    } 
    print() { 
    this.printService..printText(this.text) 
    } 
}