angular-docs-cn/aio/content/tutorial/toh-pt0.md

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# The Application Shell
## Install the Angular CLI
Install the [Angular CLI](https://github.com/angular/angular-cli), if you haven't already done so.
<code-example language="sh" class="code-shell">
npm install -g @angular/cli
</code-example>
## Create a new application
Create a new project named `angular-tour-of-heroes` with this CLI command.
<code-example language="sh" class="code-shell">
ng new angular-tour-of-heroes
</code-example>
The Angular CLI generated a new project with a default application and supporting files.
<div class="alert is-helpful">
You can add pre-packaged functionality to a new project by using the `ng add` command. The `ng add` command transforms a project by applying the schematics in the specified package.
For more information, see the [Angular CLI documentation.](https://github.com/angular/angular-cli/wiki/add "Angular CLI documentation")
Angular Material provides schematics for typical app layouts.
See the [Angular Material documentation](https://material.angular.io/guides "Angular Material documentation") for details.
</div>
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## Serve the application
Go to the project directory and launch the application.
<code-example language="sh" class="code-shell">
cd angular-tour-of-heroes
ng serve --open
</code-example>
<div class="alert is-helpful">
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The `ng serve` command builds the app, starts the development server,
watches the source files, and rebuilds the app as you make changes to those files.
The `--open` flag opens a browser to `http://localhost:4200/`.
</div>
You should see the app running in your browser.
## Angular components
The page you see is the _application shell_.
The shell is controlled by an Angular **component** named `AppComponent`.
_Components_ are the fundamental building blocks of Angular applications.
They display data on the screen, listen for user input, and take action based on that input.
## Change the application title
Open the project in your favorite editor or IDE and navigate to the `src/app` folder.
You'll find the implementation of the shell `AppComponent` distributed over three files:
1. `app.component.ts`&mdash; the component class code, written in TypeScript.
1. `app.component.html`&mdash; the component template, written in HTML.
1. `app.component.css`&mdash; the component's private CSS styles.
Open the component class file (`app.component.ts`) and change the value of the `title` property to 'Tour of Heroes'.
<code-example path="toh-pt0/src/app/app.component.ts" region="set-title" title="app.component.ts (class title property)" linenums="false">
</code-example>
Open the component template file (`app.component.html`) and
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delete the default template generated by the Angular CLI.
Replace it with the following line of HTML.
<code-example path="toh-pt0/src/app/app.component.html"
title="app.component.html (template)" linenums="false">
</code-example>
The double curly braces are Angular's *interpolation binding* syntax.
This interpolation binding presents the component's `title` property value
inside the HTML header tag.
The browser refreshes and displays the new application title.
{@a app-wide-styles}
## Add application styles
Most apps strive for a consistent look across the application.
The CLI generated an empty `styles.css` for this purpose.
Put your application-wide styles there.
Here's an excerpt from the `styles.css` for the _Tour of Heroes_ sample app.
<code-example path="toh-pt0/src/styles.1.css" title="src/styles.css (excerpt)">
</code-example>
## Final code review
The source code for this tutorial and the complete _Tour of Heroes_ global styles
are available in the <live-example></live-example>.
Here are the code files discussed on this page.
<code-tabs>
<code-pane title="src/app/app.component.ts" path="toh-pt0/src/app/app.component.ts">
</code-pane>
<code-pane title="src/app/app.component.html" path="toh-pt0/src/app/app.component.html">
</code-pane>
<code-pane
title="src/styles.css (excerpt)"
path="toh-pt0/src/styles.1.css">
</code-pane>
</code-tabs>
## Summary
* You created the initial application structure using the Angular CLI.
* You learned that Angular components display data.
* You used the double curly braces of interpolation to display the app title.