例：

form.component.ts：

@Component({
  selector: 'form1-component',template: `
    <h3>Form 1</h3>
        <textarea [(ngModel)]="input"></textarea>
        <button (click)="save(input)">Save</button>
  `,})
export class Form1 {
  input: any;

  constructor(private appState: AppState){

  }

  save(val){
    this.appState.setData(val);
  }
}

shared.service.ts：

@Injectable()
export class AppState {
  public formData;

  setData(value){
    this.formData = value;
  }

  getData(){
    return this.formData;
  }
}

other.component.ts：

@Component({
  selector: 'summary',template: `
    <h3>Summary From Form 1</h3>
    <div>{{data}}</div>
  `,})
export class Summary {
  data: any;

  constructor(private appState: AppState){
    this.data = this.appState.getData();
  }
}

Plunker demo