WebJars能使Maven的依赖管理支持OSS的JavaScript库/CSS库,比如jQuery、Bootstrap等;
WebJars是将Web前端Javascript和CSS等资源打包成Java的Jar包,这样在Java Web开发中我们可以借助Maven这些依赖库的管理,保证这些Web资源版本唯一性。
基本原理如下:
With any Servlet 3 compatible container, the WebJars that are in the WEB-INF/lib directory are automatically made available as static resources.
This works because anything in a META-INF/resources directory in a JAR in WEB-INF/lib is automatically exposed as a static resource.
(1)使用 添加js或者css库
pom.xml
<dependency> <groupId>org.webjars</groupId> <artifactId>bootstrap</artifactId> <version>3.3.7-1</version> </dependency> <dependency> <groupId>org.webjars</groupId> <artifactId>jquery</artifactId> <version>3.1.1</version> </dependency>
src/main/resources/static/demo.html
<html> <head> <script src="/webjars/jquery/3.1.1/jquery.min.js"></script> <script src="/webjars/bootstrap/3.3.7-1/js/bootstrap.min.js"></script> <title>WebJars Demo</title> <link rel="stylesheet" href="/webjars/bootstrap/3.3.7-1/css/bootstrap.min.css" /> </head> <body> <div class="container"><br/> <div class="alert alert-success"> <a href="#" class="close" data-dismiss="alert" aria-label="close">×</a> Hello, <strong>WebJars!</strong> </div> </div> </body> </html>
启动应用后可以看到以下log:
2017-02-09 13:52:48.117 INFO 6188 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping :
Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
启动应用访问 http://localhost:8080/demo.html
(2)省略版本号
很少在代码中硬编码版本号,所以需要隐藏它
pom.xml添加webjars-locator
<dependency> <groupId>org.webjars</groupId> <artifactId>webjars-locator</artifactId> <version>0.31</version> </dependency>
src/main/resources/static/demo.html
将
<script src="/webjars/jquery/3.1.1/jquery.min.js"></script> <script src="/webjars/bootstrap/3.3.7-1/js/bootstrap.min.js"></script> <title>WebJars Demo</title> <link rel="stylesheet" href="/webjars/bootstrap/3.3.7-1/css/bootstrap.min.css" />
改为
<script src="/webjars/jquery/jquery.min.js"></script> <script src="/webjars/bootstrap/js/bootstrap.min.js"></script> <title>WebJars Demo</title> <link rel="stylesheet" href="/webjars/bootstrap/css/bootstrap.min.css" />
启动应用再次访问 http://localhost:8080/demo.html 结果和上边一样
扩展:
引入的开源JavaScript库/CSS库将会以jar的形式被打包进工程!
spring-boot-demo1-0.0.1-SNAPSHOT.jar\BOOT-INF\lib
bootstrap-3.3.7-1.jar
└─ META-INF
└─ resources
└─ webjars
└─ bootstrap
└─ 3.3.7-1
├─ css
| ├─ bootstrap.min.css
| ├─ bootstrap.min.css.gz # Gzip文件
...
jquery-3.1.1.jar
└─ META-INF
└─ resources
└─ webjars
└─ jquery
└─ 3.1.1
├─ jquery.min.js
...