简介
相信很多人都接触spring框架很长时间了，每次搭建spring框架的时候都需要配置好多的jar、xml，做很多繁琐重复的配置，稍微不留神就会出现各种各样的问题，每次调试真的是香菇、蓝瘦啊。
spring boot的出现帮助我们彻底解决了这些jar的依赖，只需要很少的配置就可以完成我们的开发工作，我们可以把自己的应用打包成jar，使用java -jar来运行spring web应用，spring boot集成了很多的web容器，后面都会慢慢讲到这些，今天我们就开始使用spring boot完成一个最简单的web应用。
使用maven构建项目
spring官网提供了了一个非常方便的地址来帮助我们创建spring boot项目，http://start.spring.io/ ，输入相关参数点击 Generate Project 即可下载自动生成的压缩包。
该项目采用maven构建，加压后直接使用自己的IDE导入maven工程即可
1，打开pom文件就可以看到新的项目比传统的spring mvc项目的pom文件接口清晰了很多
1 <parent> 2 <groupId>org.springframework.boot</groupId> 3 <artifactId>spring-boot-starter-parent</artifactId> 4 <version>1.4.1.RELEASE</version> 5 </parent>
第一个地方是多了上面的代码，这个spring boot会自动帮我门引入一些约定的配置，查看源码得知
1 <?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"> 2 <modelVersion>4.0.0</modelVersion> 3 <parent> 4 <groupId>org.springframework.boot</groupId> 5 <artifactId>spring-boot-dependencies</artifactId> 6 <version>1.4.1.RELEASE</version> 7 <relativePath>../../spring-boot-dependencies</relativePath> 8 </parent> 9 <artifactId>spring-boot-starter-parent</artifactId> 10 <packaging>pom</packaging> 11 <name>Spring Boot Starter Parent</name> 12 <description>Parent pom providing dependency and plugin management for applications 13 built with Maven</description> 14 <url>http://projects.spring.io/spring-boot/</url> 15 <organization> 16 <name>Pivotal Software, Inc.</name> 17 <url>http://www.spring.io</url> 18 </organization> 19 <properties> 20 <java.version>1.6</java.version> 21 <resource.delimiter>@</resource.delimiter> <!-- delimiter that doesn't clash with Spring ${} placeholders --> 22 <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> 23 <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> 24 <maven.compiler.source>${java.version}</maven.compiler.source> 25 <maven.compiler.target>${java.version}</maven.compiler.target> 26 </properties> 27 <dependencyManagement> 28 <dependencies> 29 <dependency> 30 <groupId>org.springframework</groupId> 31 <artifactId>spring-core</artifactId> 32 <version>${spring.version}</version> 33 <exclusions> 34 <exclusion> 35 <groupId>commons-logging</groupId> 36 <artifactId>commons-logging</artifactId> 37 </exclusion> 38 </exclusions> 39 </dependency> 40 </dependencies> 41 </dependencyManagement> 42 <build> 43 <!-- Turn on filtering by default for application properties --> 44 <resources> 45 <resource> 46 <directory>${basedir}/src/main/resources</directory> 47 <filtering>true</filtering> 48 <includes> 49 <include>**/application*.yml</include> 50 <include>**/application*.properties</include> 51 </includes> 52 </resource> 53 <resource> 54 <directory>${basedir}/src/main/resources</directory> 55 <excludes> 56 <exclude>**/application*.yml</exclude> 57 <exclude>**/application*.properties</exclude> 58 </excludes> 59 </resource> 60 </resources> 61 <pluginManagement> 62 <plugins> 63 <!-- Apply more sensible defaults for user projects --> 64 <plugin> 65 <groupId>org.apache.maven.plugins</groupId> 66 <artifactId>maven-failsafe-plugin</artifactId> 67 <executions> 68 <execution> 69 <goals> 70 <goal>integration-test</goal> 71 <goal>verify</goal> 72 </goals> 73 </execution> 74 </executions> 75 </plugin> 76 <plugin> 77 <groupId>org.apache.maven.plugins</groupId> 78 <artifactId>maven-jar-plugin</artifactId> 79 <configuration> 80 <archive> 81 <manifest> 82 <mainClass>${start-class}</mainClass> 83 <addDefaultImplementationEntries>true</addDefaultImplementationEntries> 84 </manifest> 85 </archive> 86 </configuration> 87 </plugin> 88 <plugin> 89 <groupId>org.apache.maven.plugins</groupId> 90 <artifactId>maven-surefire-plugin</artifactId> 91 <configuration> 92 <includes> 93 <include>**/*Tests.java</include> 94 <include>**/*Test.java</include> 95 </includes> 96 <excludes> 97 <exclude>**/Abstract*.java</exclude> 98 </excludes> 99 </configuration> 100 </plugin> 101 <plugin> 102 <groupId>org.apache.maven.plugins</groupId> 103 <artifactId>maven-war-plugin</artifactId> 104 <configuration> 105 <failOnMissingWebXml>false</failOnMissingWebXml> 106 <archive> 107 <manifest> 108 <mainClass>${start-class}</mainClass> 109 <addDefaultImplementationEntries>true</addDefaultImplementationEntries> 110 </manifest> 111 </archive> 112 </configuration> 113 </plugin> 114 <plugin> 115 <groupId>org.codehaus.mojo</groupId> 116 <artifactId>exec-maven-plugin</artifactId> 117 <configuration> 118 <mainClass>${start-class}</mainClass> 119 </configuration> 120 </plugin> 121 <plugin> 122 <groupId>org.apache.maven.plugins</groupId> 123 <artifactId>maven-resources-plugin</artifactId> 124 <version>2.6</version> 125 <configuration> 126 <delimiters> 127 <delimiter>${resource.delimiter}</delimiter> 128 </delimiters> 129 <useDefaultDelimiters>false</useDefaultDelimiters> 130 </configuration> 131 </plugin> 132 <plugin> 133 <groupId>pl.project13.maven</groupId> 134 <artifactId>git-commit-id-plugin</artifactId> 135 <version>2.1.11</version> 136 <executions> 137 <execution> 138 <goals> 139 <goal>revision</goal> 140 </goals> 141 </execution> 142 </executions> 143 <configuration> 144 <verbose>true</verbose> 145 <dateFormat>yyyy-MM-dd'T'HH:mm:ssZ</dateFormat> 146 <generateGitPropertiesFile>true</generateGitPropertiesFile> 147 <generateGitPropertiesFilename>${project.build.outputDirectory}/git.properties</generateGitPropertiesFilename> 148 </configuration> 149 </plugin> 150 <!-- Support our own plugin --> 151 <plugin> 152 <groupId>org.springframework.boot</groupId> 153 <artifactId>spring-boot-maven-plugin</artifactId> 154 <executions> 155 <execution> 156 <goals> 157 <goal>repackage</goal> 158 </goals> 159 </execution> 160 </executions> 161 <configuration> 162 <mainClass>${start-class}</mainClass> 163 </configuration> 164 </plugin> 165 <!-- Support shade packaging (if the user does not want to use our plugin) --> 166 <plugin> 167 <groupId>org.apache.maven.plugins</groupId> 168 <artifactId>maven-shade-plugin</artifactId> 169 <dependencies> 170 <dependency> 171 <groupId>org.springframework.boot</groupId> 172 <artifactId>spring-boot-maven-plugin</artifactId> 173 <version>1.4.1.RELEASE</version> 174 </dependency> 175 </dependencies> 176 <configuration> 177 <keepDependenciesWithProvidedScope>true</keepDependenciesWithProvidedScope> 178 <createDependencyReducedPom>true</createDependencyReducedPom> 179 <filters> 180 <filter> 181 <artifact>*:*</artifact> 182 <excludes> 183 <exclude>META-INF/*.SF</exclude> 184 <exclude>META-INF/*.DSA</exclude> 185 <exclude>META-INF/*.RSA</exclude> 186 </excludes> 187 </filter> 188 </filters> 189 </configuration> 190 <executions> 191 <execution> 192 <phase>package</phase> 193 <goals> 194 <goal>shade</goal> 195 </goals> 196 <configuration> 197 <transformers> 198 <transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer"> 199 <resource>META-INF/spring.handlers</resource> 200 </transformer> 201 <transformer implementation="org.springframework.boot.maven.PropertiesMergingResourceTransformer"> 202 <resource>META-INF/spring.factories</resource> 203 </transformer> 204 <transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer"> 205 <resource>META-INF/spring.schemas</resource> 206 </transformer> 207 <transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/> 208 <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer"> 209 <mainClass>${start-class}</mainClass> 210 </transformer> 211 </transformers> 212 </configuration> 213 </execution> 214 </executions> 215 </plugin> 216 </plugins> 217 </pluginManagement> 218 </build> 219 </project>
spring boot默认帮我引入的jdk版本是1.6，如果需要改动，则在自己pom文件中直接重写<java.version>1.6</java.version>即可。
还可以看到它已经帮我们引入了spring-core和commons-logging包
继续往下看可以发现一些属性文件他也帮我定义好了规则，不需要我们自己在xml中定义了，已经一些maven插件的定义这里就不一一说明 ，具体插件是做什么用的，各位可以看下maven的相关知识。
第二个改变的地方是
1 <dependency> 2 <groupId>org.springframework.boot</groupId> 3 <artifactId>spring-boot-starter</artifactId> 4 </dependency> 5 6 <dependency> 7 <groupId>org.springframework.boot</groupId> 8 <artifactId>spring-boot-starter-test</artifactId> 9 <scope>test</scope> 10 </dependency> 11 12 <dependency> 13 <groupId>org.springframework.boot</groupId> 14 <artifactId>spring-boot-starter-web</artifactId> 15 </dependency>
spring-boot-starter:核心模块，包括自动配置支持、日志
spring-boot-starter-test ：测试模块，包括JUnit、Hamcrest、Mockito
spring-boot-starter-web ：开发web项目依赖
代码编写
说了这么多的配置，来让我们创建第一个class吧
@Controller @EnableAutoConfiguration @RequestMapping("/ctr") public class SampleController { @RequestMapping("/getStr") @ResponseBody String home(){ return "Hello World"; } @RequestMapping("/info") @ResponseBody public Map<String,String> getInfo(){ Map<String, String> map = new HashMap<>(); map.put("name", "jack"); return map; } public static void main(String[] args) { SpringApplication.run(SampleController.class,args); } }
到此为止，我们的第一个spring 的web项目就结束了，直接运行main方法，浏览器中输入：http://127.0.0.1:8080/ctr/info 可以看到运行结果 {"name": "jack"}
怎么样，是不是很神奇，没有启动任何的web容器，只需要执行main方法就可以运行我们的web项目了，而且配置就这么简单任性。