Serving Web Content with Spring MVC

This guide walks you through the process of creating a "hello world" web site with Spring.

What you’ll build

You’ll build an application that has a static home page, and also will accept HTTP GET requests at:

http://localhost:8080/greeting

and respond with a web page displaying HTML. The body of the HTML contains a greeting:

"Hello, World!"

You can customize the greeting with an optional name parameter in the query string:

http://localhost:8080/greeting?name=User

The name parameter value overrides the default value of "World" and is reflected in the response:

"Hello, User!"

What you’ll need

How to complete this guide

Like most Spring Getting Started guides, you can start from scratch and complete each step, or you can bypass basic setup steps that are already familiar to you. Either way, you end up with working code.

To start from scratch, move on to Build with Gradle.

To skip the basics, do the following:

When you’re finished, you can check your results against the code in gs-serving-web-content/complete.

Build with Gradle

 

Build with Maven

 

Build with your IDE

 

Create a web controller

In Spring’s approach to building web sites, HTTP requests are handled by a controller. You can easily identify these requests by the @Controller annotation. In the following example, the GreetingController handles GET requests for /greeting by returning the name of a View, in this case, "greeting". A View is responsible for rendering the HTML content:

src/main/java/hello/GreetingController.java

package hello;

import org.springframework.stereotype.Controller;

import org.springframework.ui.Model;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestParam;

@Controller

public class GreetingController {

    @RequestMapping("/greeting")

    public String greeting(@RequestParam(value="name", required=false, defaultValue="World") String name, Model model) {

        model.addAttribute("name", name);

        return "greeting";

    }

}

This controller is concise and simple, but there’s plenty going on. Let’s break it down step by step.

The @RequestMapping annotation ensures that HTTP requests to /greeting are mapped to the greeting() method.

  The above example does not specify GET vs. PUT, POST, and so forth, because @RequestMapping maps all HTTP operations by default. Use @RequestMapping(method=GET) to narrow this mapping.

@RequestParam binds the value of the query String parameter name into the nameparameter of the greeting() method. This query String parameter is not required; if it is absent in the request, the defaultValue of "World" is used. The value of the name parameter is added to a Model object, ultimately making it accessible to the view template.

The implementation of the method body relies on a view technology, in this case Thymeleaf, to perform server-side rendering of the HTML. Thymeleaf parses the greeting.html template below and evaluates the th:text expression to render the value of the ${name} parameter that was set in the controller.

src/main/resources/templates/greeting.html

<!DOCTYPE HTML>

<html xmlns:th="http://www.thymeleaf.org">

<head>

    <title>Getting Started: Serving Web Content</title>

    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />

</head>

<body>

    <p th:text="'Hello, ' + ${name} + '!'" />

</body>

</html>

Developing web apps

A common feature of developing web apps is coding a change, restarting your app, and refreshing the browser to view the change. This entire process can eat up a lot of time. To speed up the cycle of things, Spring Boot comes with a handy module known as spring-boot-devtools.

  • Enable hot swapping

  • Switches template engines to disable caching

  • Enables LiveReload to refresh browser automatically

  • Other reasonable defaults based on development instead of production

Make the application executable

Although it is possible to package this service as a traditional WAR file for deployment to an external application server, the simpler approach demonstrated below creates a standalone application. You package everything in a single, executable JAR file, driven by a good old Java main() method. Along the way, you use Spring’s support for embedding the Tomcat servlet container as the HTTP runtime, instead of deploying to an external instance.

src/main/java/hello/Application.java

package hello;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication

public class Application {

    public static void main(String[] args) {

        SpringApplication.run(Application.class, args);

    }

}

@SpringBootApplication is a convenience annotation that adds all of the following:

  • @Configuration tags the class as a source of bean definitions for the application context.

  • @EnableAutoConfiguration tells Spring Boot to start adding beans based on classpath settings, other beans, and various property settings.

  • Normally you would add @EnableWebMvc for a Spring MVC app, but Spring Boot adds it automatically when it sees spring-webmvc on the classpath. This flags the application as a web application and activates key behaviors such as setting up a DispatcherServlet.

  • @ComponentScan tells Spring to look for other components, configurations, and services in the the hello package, allowing it to find the controllers.

The main() method uses Spring Boot’s SpringApplication.run() method to launch an application. Did you notice that there wasn’t a single line of XML? No web.xml file either. This web application is 100% pure Java and you didn’t have to deal with configuring any plumbing or infrastructure.

Build an executable JAR

You can run the application from the command line with Gradle or Maven. Or you can build a single executable JAR file that contains all the necessary dependencies, classes, and resources, and run that. This makes it easy to ship, version, and deploy the service as an application throughout the development lifecycle, across different environments, and so forth.

If you are using Gradle, you can run the application using ./gradlew bootRun. Or you can build the JAR file using ./gradlew build. Then you can run the JAR file:

java -jar build/libs/gs-serving-web-content-0.1.0.jar

If you are using Maven, you can run the application using ./mvnw spring-boot:run. Or you can build the JAR file with ./mvnw clean package. Then you can run the JAR file:

java -jar target/gs-serving-web-content-0.1.0.jar
  The procedure above will create a runnable JAR. You can also opt to build a classic WAR file instead.

Logging output is displayed. The app should be up and running within a few seconds.

Test the App

Now that the web site is running, visit http://localhost:8080/greeting, where you see:

"Hello, World!"

Provide a name query string parameter with http://localhost:8080/greeting?name=User. Notice how the message changes from "Hello, World!" to "Hello, User!":

"Hello, User!"

This change demonstrates that the @RequestParam arrangement in GreetingController is working as expected. The name parameter has been given a default value of "World", but can always be explicitly overridden through the query string.

Add a Home Page

Static resources, like HTML or JavaScript or CSS, can easily be served from your Spring Boot application just be dropping them into the right place in the source code. By default Spring Boot serves static content from resources in the classpath at "/static" (or "/public"). The index.html resource is special because it is used as a "welcome page" if it exists, which means it will be served up as the root resource, i.e. at http://localhost:8080/ in our example. So create this file:

src/main/resources/static/index.html

<!DOCTYPE HTML>

<html>

<head>

    <title>Getting Started: Serving Web Content</title>

    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />

</head>

<body>

    <p>Get your greeting <a href="/greeting">here</a></p>

</body>

</html>

and when you restart the app you will see the HTML at http://localhost:8080/.

springboot Serving Web Content with Spring MVC的更多相关文章

  1. Java Web系列：Spring MVC基础

    1.Web MVC基础 MVC的本质是表现层模式,我们以视图模型为中心,将视图和控制器分离出来.就如同分层模式一样,我们以业务逻辑为中心,把表现层和数据访问层代码分离出来是一样的方法.框架只能在技术层 ...

  2. springboot学习笔记：5.spring mvc(含FreeMarker+layui整合)

    Spring Web MVC框架(通常简称为"Spring MVC")是一个富"模型,视图,控制器"的web框架. Spring MVC允许你创建特定的@Con ...

  3. 【WEB】初探Spring MVC框架

    Spring MVC框架算是当下比较流行的Java开源框架.但实话实说,做了几年WEB项目,完全没有SpringMVC实战经验,乃至在某些交流场合下被同行严重鄙视“奥特曼”了.“心塞”的同时,只好默默 ...

  4. intellij idea 12 搭建maven web项目 freemarker + spring mvc

    配置spring mvc ,写这篇文章的时候spring已经出了4.0 这里还是用稳定的3.2.7.RELEASE,先把spring和freemarker配置好 1.spring mvc配置 在web ...

  5. 二十一、MVC的WEB框架（Spring MVC）

    一.基于注解方式配置 1.首先是修改IndexContoller控制器类 1.1.在类前面加上@Controller:表示这个类是一个控制器 1.2.在方法handleRequest前面加上@Requ ...

  6. 二十、MVC的WEB框架（Spring MVC）

    一.Spring MVC 运行原理:客户端请求提交到DispatcherServlet,由DispatcherServlet控制器查询HandlerMapping,找到并分发到指定的Controlle ...

  7. Java Web 学习(8) —— Spring MVC 之文件上传与下载

    Spring MVC 之文件上传与下载 上传文件 表单: <form action="upload" enctype="multipart/form-data&qu ...

  8. Java Web 学习(7) —— Spring MVC 之国际化

    Spring MVC 之国际化 i18n 与 l10n internationalization:国际化,以 i 开头,以 n 结尾,中间 18 个字母,简称 i18n. localization:本 ...

  9. Java Web 学习(4) —— Spring MVC 概览

    Spring MVC 概览 一. Spring MVC Spring MVC 是一个包含了 Dispatcher Servlet 的 MVC 框架. Dispatcher Servlet 实现了 : ...

随机推荐

  1. Entity Framework 代码先行

    一.什么是Code First 为了支持以设计为中心的开发流程,EF还更多地支持以代码为中心 (code-centric) ,我们称为代码优先的开发,代码优先的开发支持更加优美的开发流程,它允许你在不 ...

  2. SharePoint中新创建的Web Application在浏览器中报404错误

    问题描述:在安装完成SharePoint 2010后,进入Central Administration,创建一个新的Web Application,可以正常创建,但访问时却返回404. 平台环境:Wi ...

  3. 获取form对象

    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/ ...

  4. 又一个半成品库 weblog rpc client

    我基本上属于半成品专业户,去看我的github就知道. 下午又撸了一个weblog rpc client库,而这又一次证明了一个有技术但没有产品能力的程序员是没有卵用的. 因为当做好了库的雏形,但与具 ...

  5. MyEclipse10查看Struts2源码及Javadoc文档

    1:查看Struts2源码 (1):Referenced Libraries >struts2-core-2.1.6.jar>右击>properties. (2):Java Sour ...

  6. 从零开始学 Java - Windows 下安装 JDK

    关于未来 "我要死在火星.在我死去的时候能够想着人类能有一个美好的未来--有可持续的能源,同时能够殖民其他的星球来避免人类灭绝的最坏可能." 官网下载 直接打开官网:http:// ...

  7. ABP中使用OAuth2(Resource Owner Password Credentials Grant模式)

    ABP目前的认证方式有两种,一种是基于Cookie的登录认证,一种是基于token的登录认证.使用Cookie的认证方式一般在PC端用得比较多,使用token的认证方式一般在移动端用得比较多.ABP自 ...

  8. gif jpg bmp png的区别

    PNG格式图片因其高保真性.透明性及文件大小较小等特性,被广泛应用于网页设计.平面设计中.网络通讯中因受带宽制约,在保证图片清晰.逼真的前提下,网页中不可能大范围的使用文件较大的bmp.jpg格式文件 ...

  9. JS高程3.基本概念（6）函数

    1.ECMAScript中的函数使用function关键字来声明. eg: function sum (num1,num2){ alert(num1+num2); } sum(3,7); 注意: 在有 ...

  10. 如何使用grunt压缩js文件

    jQuery在使用grunt,bootstrap在使用grunt,百度UEditor在使用grunt,你没有理由不学.不用! 1. 前言 各位web前端开发人员,如果你现在还不知道grunt或者听说过 ...