PathLocationStrategy

功能：利用URL储存当前应用的本地数据。

概况：

 class PathLocationsStrategy extends LocationsStrategy{       constructor(_platformLocation: PlatformLocation, href?:     string)onPopState(fn: LocationChangeListener) : voidgetBaseHref() : stringprepareExternalUrl(internal: string) : stringpath(includeHash?: boolean) : stringpushState(state: any, title: string, url: string, queryParams: string)replaceState(state: any, title: string, url: string, queryParams: string)forward() : voidback() : void}

类描述：
PathLocationStrategy 就是LocationStrategy被用于配置Location的一种服务，用于表示浏览器URL路径中状态。

如果你正在使用PathLocationStrategy,你必须提供一个APP_BASE_HREF或者增加一个基础元素给到文档。当生成以及识别URL时，这个URL的前缀将会被预存。

我们举一个实例，如果你提供一个/my/app的APP_BASE_HREF并且调用了location.go(‘/foo’)。浏览器URL就会编程example.com/my/app/foo.

类似的，如果你添加

import {Location, LocationStrategy, PathLocationStrategy} from '@angular/common';import {Component} from '@angular/core';@Component({  selector: 'path-location',  providers: [Location, {provide: LocationStrategy, useClass: PathLocationStrategy}],  template: `    <h1>PathLocationStrategy</h1>    Current URL is: <code>{{location.path()}}</code><br>    Normalize: <code>/foo/bar/</code> is: <code>{{location.normalize('foo/bar')}}</code><br>  `})export class PathLocationComponent {  location: Location;  constructor(location: Location) { this.location = location; }}

注解：@Injectable();
构造函数：constructor(_platformLocation: PlatformLocation, href?: string)