详解使用Spring Boot开发Restful程序

一、简介

spring boot是由pivotal团队提供的全新框架，其设计目的是用来简化新spring应用的初始搭建以及开发过程。该框架使用了特定的方式来进行配置，从而使开发人员不再需要定义样板化的配置。通过这种方式，boot致力于在蓬勃发展的快速应用开发领域（rapid application development）成为领导者。

多年以来，spring io平台饱受非议的一点就是大量的xml配置以及复杂的依赖管理。在去年的springone 2gx会议上，pivotal的cto adrian colyer回应了这些批评，并且特别提到该平台将来的目标之一就是实现免xml配置的开发体验。boot所实现的功能超出了这个任务的描述，开发人员不仅不再需要编写xml，而且在一些场景中甚至不需要编写繁琐的import语句。在对外公开的beta版本刚刚发布之时，boot描述了如何使用该框架在140个字符内实现可运行的web应用，从而获得了极大的关注度，该样例发表在tweet上。

spring boot不生成代码，且完全不需要xml配置。其主要目标如下：

1. 为所有的spring开发工作提供一个更快、更广泛的入门经验。
2. 开箱即用，你也可以通过修改默认值来快速满足你的项目的需求。
3. 提供了一系列大型项目中常见的非功能性特性，如嵌入式服务器、安全、指标，健康检测、外部配置等。
   

spring boot官网:

二、开发环境准备

ide：intellij idea

官网地址：

jdk：1.8

maven

数据库：mysql

我将以一个用户积分系统为例，开发一个restful风格的服务端

三、第一个restful程序

1.新建一个普通maven工程

创建项目完成后目录结构如下图所示

2.在pom文件中加入对spring-boot的依赖

<?xml version="1.0" encoding="utf-8"?>
<project xmlns="http://maven.apache.org/pom/4.0.0"
   xmlns:xsi="http://www.w3.org/2001/xmlschema-instance"
   xsi:schemalocation="http://maven.apache.org/pom/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 <modelversion>4.0.0</modelversion>

 <groupid>com.bluecoffee</groupid>
 <artifactid>mapp</artifactid>
 <version>1.0-snapshot</version>

 <parent>
  <groupid>org.springframework.boot</groupid>
  <artifactid>spring-boot-starter-parent</artifactid>
  <version>1.4.1.release</version>
  <relativepath /> <!-- lookup parent from repository -->
 </parent>

 <properties>
  <project.build.sourceencoding>utf-8</project.build.sourceencoding>
  <java.version>1.8</java.version>
 </properties>


 <dependencies>
  <dependency>
   <groupid>org.springframework.boot</groupid>
   <artifactid>spring-boot-starter-web</artifactid>
  </dependency>

  <dependency>
   <groupid>org.springframework.boot</groupid>
   <artifactid>spring-boot-starter-test</artifactid>
   <scope>test</scope>
  </dependency>
 </dependencies>

 <build>
  <plugins>
   <plugin>
    <groupid>org.springframework.boot</groupid>
    <artifactid>spring-boot-maven-plugin</artifactid>
   </plugin>
  </plugins>
 </build>
</project>

3.新建一个restcontroller来接收客户端的请求，我们来模拟一个登录请求

package com.yepit.mapp.rest;

import org.springframework.boot.autoconfigure.enableautoconfiguration;
import org.springframework.context.annotation.configuration;
import org.springframework.web.bind.annotation.*;

/**
 * created by qianlong on 16/7/20.
 */
@restcontroller
public class usercontroller {

 @requestmapping(value = "/users/{username}",method = requestmethod.get,consumes="application/json")
 public string getuser(@pathvariable string username, @requestparam string pwd){
  return "welcome,"+username;
 }}

1. 关键字@restcontroller代表这个类是用restful风格来访问的，如果是普通的web页面访问跳转时，我们通常会使用@controller
2. value = "/users/{username}" 代表访问的url是"http://host:port/users/实际的用户名"
3. method = requestmethod.get 代表这个http请求必须是以get方式访问
4. consumes="application/json" 代表数据传输格式是json
5. @pathvariable将某个动态参数放到url请求路径中
6. @requestparam指定了请求参数名称
   

4.新建启动restful服务端的启动类

package com.yepit.mapp;

import org.springframework.boot.springapplication;
import org.springframework.boot.autoconfigure.springbootapplication;

/**
 * created by qianlong on 16/7/20.
 */
@springbootapplication
public class mapprunapplication {

 public static void main(string[] args) {
  springapplication.run(mapprunapplication.class, args);
 }
}

5.执行mapprunapplication的main方法启动restful服务，可以看到控制台有如下输出

 . ____   _   __ _ _
 /\\\\ / ___'_ __ _ _(_)_ __ __ _ \\ \\ \\ \\
( ( )\\___ | '_ | '_| | '_ \\/ _` | \\ \\ \\ \\
 \\\\/ ___)| |_)| | | | | || (_| | ) ) ) )
 ' |____| .__|_| |_|_| |_\\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: spring boot ::  (v1.3.3.release)

2016-07-20 16:49:43.334 info 2106 --- [   main] com.yepit.mapp.mapprunapplication  : starting mapprunapplication on bogon with pid 2106 (/users/qianlong/workspace/spring-boot-samples/target/classes started by qianlong in /users/qianlong/workspace/spring-boot-samples)
2016-07-20 16:49:43.338 info 2106 --- [   main] com.yepit.mapp.mapprunapplication  : no active profile set, falling back to default profiles: default
2016-07-20 16:49:43.557 info 2106 --- [   main] ationconfigembeddedwebapplicationcontext : refreshing org.springframework.boot.context.embedded.annotationconfigembeddedwebapplicationcontext@543e710e: startup date [wed jul 20 16:49:43 cst 2016]; root of context hierarchy
2016-07-20 16:49:44.127 info 2106 --- [   main] o.s.b.f.s.defaultlistablebeanfactory  : overriding bean definition for bean 'beannameviewresolver' with a different definition: replacing [root bean: class [null]; scope=; abstract=false; lazyinit=false; autowiremode=3; dependencycheck=0; autowirecandidate=true; primary=false; factorybeanname=org.springframework.boot.autoconfigure.web.errormvcautoconfiguration$whitelabelerrorviewconfiguration; factorymethodname=beannameviewresolver; initmethodname=null; destroymethodname=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/web/errormvcautoconfiguration$whitelabelerrorviewconfiguration.class]] with [root bean: class [null]; scope=; abstract=false; lazyinit=false; autowiremode=3; dependencycheck=0; autowirecandidate=true; primary=false; factorybeanname=org.springframework.boot.autoconfigure.web.webmvcautoconfiguration$webmvcautoconfigurationadapter; factorymethodname=beannameviewresolver; initmethodname=null; destroymethodname=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/web/webmvcautoconfiguration$webmvcautoconfigurationadapter.class]]
2016-07-20 16:49:44.658 info 2106 --- [   main] s.b.c.e.t.tomcatembeddedservletcontainer : tomcat initialized with port(s): 8080 (http)
2016-07-20 16:49:44.672 info 2106 --- [   main] o.apache.catalina.core.standardservice : starting service tomcat
2016-07-20 16:49:44.673 info 2106 --- [   main] org.apache.catalina.core.standardengine : starting servlet engine: apache tomcat/8.0.32
2016-07-20 16:49:44.759 info 2106 --- [ost-startstop-1] o.a.c.c.c.[tomcat].[localhost].[/]  : initializing spring embedded webapplicationcontext
2016-07-20 16:49:44.759 info 2106 --- [ost-startstop-1] o.s.web.context.contextloader   : root webapplicationcontext: initialization completed in 1207 ms
2016-07-20 16:49:44.972 info 2106 --- [ost-startstop-1] o.s.b.c.e.servletregistrationbean  : mapping servlet: 'dispatcherservlet' to [/]
2016-07-20 16:49:44.977 info 2106 --- [ost-startstop-1] o.s.b.c.embedded.filterregistrationbean : mapping filter: 'characterencodingfilter' to: [/*]
2016-07-20 16:49:44.978 info 2106 --- [ost-startstop-1] o.s.b.c.embedded.filterregistrationbean : mapping filter: 'hiddenhttpmethodfilter' to: [/*]
2016-07-20 16:49:44.978 info 2106 --- [ost-startstop-1] o.s.b.c.embedded.filterregistrationbean : mapping filter: 'httpputformcontentfilter' to: [/*]
2016-07-20 16:49:44.978 info 2106 --- [ost-startstop-1] o.s.b.c.embedded.filterregistrationbean : mapping filter: 'requestcontextfilter' to: [/*]
2016-07-20 16:49:45.184 info 2106 --- [   main] s.w.s.m.m.a.requestmappinghandleradapter : looking for @controlleradvice: org.springframework.boot.context.embedded.annotationconfigembeddedwebapplicationcontext@543e710e: startup date [wed jul 20 16:49:43 cst 2016]; root of context hierarchy
2016-07-20 16:49:45.251 info 2106 --- [   main] s.w.s.m.m.a.requestmappinghandlermapping : mapped "{[/users],methods=[get],consumes=[application/json]}" onto public java.lang.string com.yepit.mapp.rest.usercontroller.getuser(java.lang.string,java.lang.string)
2016-07-20 16:49:45.253 info 2106 --- [   main] s.w.s.m.m.a.requestmappinghandlermapping : mapped "{[/error]}" onto public org.springframework.http.responseentity<java.util.map<java.lang.string, java.lang.object>> org.springframework.boot.autoconfigure.web.basicerrorcontroller.error(javax.servlet.http.httpservletrequest)
2016-07-20 16:49:45.254 info 2106 --- [   main] s.w.s.m.m.a.requestmappinghandlermapping : mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.modelandview org.springframework.boot.autoconfigure.web.basicerrorcontroller.errorhtml(javax.servlet.http.httpservletrequest,javax.servlet.http.httpservletresponse)
2016-07-20 16:49:45.275 info 2106 --- [   main] o.s.w.s.handler.simpleurlhandlermapping : mapped url path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.resourcehttprequesthandler]
2016-07-20 16:49:45.275 info 2106 --- [   main] o.s.w.s.handler.simpleurlhandlermapping : mapped url path [/**] onto handler of type [class org.springframework.web.servlet.resource.resourcehttprequesthandler]
2016-07-20 16:49:45.306 info 2106 --- [   main] o.s.w.s.handler.simpleurlhandlermapping : mapped url path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.resourcehttprequesthandler]
2016-07-20 16:49:45.380 info 2106 --- [   main] o.s.j.e.a.annotationmbeanexporter  : registering beans for jmx exposure on startup
2016-07-20 16:49:45.462 info 2106 --- [   main] s.b.c.e.t.tomcatembeddedservletcontainer : tomcat started on port(s): 8080 (http)
2016-07-20 16:49:45.467 info 2106 --- [   main] com.yepit.mapp.mapprunapplication  : started mapprunapplication in 2.573 seconds (jvm running for 3.187)

我们可以看到服务器是tomcat，端口为8080

6.验证

推荐大家使用google的postman插件来模拟请求

在发起请求前，请注意需要在headers中设置content-type为application/json

到此一个基本的restful风格的服务端就已经完成了，全部编码时间不会超过5分钟！

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。