@Input

Declares a data-bound input property.Angular automatically updates data-bound properties during change detection.

在Angular2官方文件裡有一段示例程式碼（https://angular.cn/docs/ts/latest/guide/ngmodule.html）

@Component({
  selector: 'bank-account',
  template: `
    Bank Name: {{bankName}}
    Account Id: {{id}}
  `
})
class BankAccount {
  @Input() bankName: string;
  @Input('account-id') id: string;
  // this property is not bound, and won't be automatically updated by Angular
  normalizedBankName: string;
}
@Component({
  selector: 'app',
  template: `
    <bank-account bank-name="RBC" account-id="4747"></bank-account>
  `,
  directives: [BankAccount]
})
class App {}
bootstrap(App);
 

Bank Name: RBC

Account Id: 4747

為BankAccount類聲明瞭兩個輸入屬性，並在<bank-account>標籤中為其賦值。

在這裡還要注意兩點：

1）單向屬性繫結

<bank-account bank-name="RBC" account-id="4747"></bank-account>

如果輸入屬性不是字串而是一個類，則注意要為檢視目標加上［］，比如：

<bank-account [bankUser]="user"></bank-account>
 

@Input() bankName: string;

@Input('bank-name'): string;