angular-docs-cn/modules/@angular/common/src/location/location_strategy.ts

/**
 * @license
 * Copyright Google Inc. All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import {InjectionToken} from '@angular/core';
import {LocationChangeListener} from './platform_location';

/**
 * `LocationStrategy` is responsible for representing and reading route state
 * from the browser's URL. Angular provides two strategies:
 * {@link HashLocationStrategy} and {@link PathLocationStrategy}.
 *
 * This is used under the hood of the {@link Location} service.
 *
 * Applications should use the {@link Router} or {@link Location} services to
 * interact with application route state.
 *
 * For instance, {@link HashLocationStrategy} produces URLs like
 * `http://example.com#/foo`, and {@link PathLocationStrategy} produces
 * `http://example.com/foo` as an equivalent URL.
 *
 * See these two classes for more.
 *
 * @stable
 */
export abstract class LocationStrategy {
  abstract path(includeHash?: boolean): string;
  abstract prepareExternalUrl(internal: string): string;
  abstract pushState(state: any, title: string, url: string, queryParams: string): void;
  abstract replaceState(state: any, title: string, url: string, queryParams: string): void;
  abstract forward(): void;
  abstract back(): void;
  abstract onPopState(fn: LocationChangeListener): void;
  abstract getBaseHref(): string;
}


/**
 * The `APP_BASE_HREF` token represents the base href to be used with the
 * {@link PathLocationStrategy}.
 *
 * If you're using {@link PathLocationStrategy}, you must provide a provider to a string
 * representing the URL prefix that should be preserved when generating and recognizing
 * URLs.
 *
 * ### Example
 *
 * ```typescript
 * import {Component, NgModule} from '@angular/core';
 * import {APP_BASE_HREF} from '@angular/common';
 *
 * @NgModule({
 *   providers: [{provide: APP_BASE_HREF, useValue: '/my/app'}]
 * })
 * class AppModule {}
 * ```
 *
 * @stable
 */
export const APP_BASE_HREF = new InjectionToken<string>('appBaseHref');