springboot初探---spring-boot-starter-web究竟干了啥

上一篇已经简单介绍了启动类的部分,这一篇主要讨论一下springboot引入的哪些依赖java

咱们都知道想用springboot作一个web应用,首先要作的是引入相关依赖,两步操做:git

一、添加spring-boot-starter-parentgithub

二、引入spring-boot-starter-webweb

至此全部关于web的依赖所有应用完毕spring

之前咱们在用spring的时候,还须要添加不少依赖,包括spring-webmvc、spring-context、spring-bean等等,为何到springboot就只须要这两个了呢?apache

如今来一探究竟json

先从spring-boot-starter-parent开始,先贴一下源码tomcat

<?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>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-dependencies</artifactId>
        <version>2.1.1.RELEASE</version>
        <relativePath>../../spring-boot-dependencies</relativePath>
    </parent>
    <artifactId>spring-boot-starter-parent</artifactId>
    <packaging>pom</packaging>
    <name>Spring Boot Starter Parent</name>
    <description>Parent pom providing dependency and plugin management for applications
		built with Maven</description>
    <url>https://projects.spring.io/spring-boot/#/spring-boot-starter-parent</url>
    <properties>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <resource.delimiter>@</resource.delimiter>
        <maven.compiler.source>${java.version}</maven.compiler.source>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.target>${java.version}</maven.compiler.target>
    </properties>
    <build>
        <resources>
            <resource>
                <filtering>true</filtering>
                <directory>${basedir}/src/main/resources</directory>
                <includes>
                    <include>**/application*.yml</include>
                    <include>**/application*.yaml</include>
                    <include>**/application*.properties</include>
                </includes>
            </resource>
            <resource>
                <directory>${basedir}/src/main/resources</directory>
                <excludes>
                    <exclude>**/application*.yml</exclude>
                    <exclude>**/application*.yaml</exclude>
                    <exclude>**/application*.properties</exclude>
                </excludes>
            </resource>
        </resources>
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.jetbrains.kotlin</groupId>
                    <artifactId>kotlin-maven-plugin</artifactId>
                    <version>${kotlin.version}</version>
                    <executions>
                        <execution>
                            <id>compile</id>
                            <phase>compile</phase>
                            <goals>
                                <goal>compile</goal>
                            </goals>
                        </execution>
                        <execution>
                            <id>test-compile</id>
                            <phase>test-compile</phase>
                            <goals>
                                <goal>test-compile</goal>
                            </goals>
                        </execution>
                    </executions>
                    <configuration>
                        <jvmTarget>${java.version}</jvmTarget>
                        <javaParameters>true</javaParameters>
                    </configuration>
                </plugin>
                <plugin>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <configuration>
                        <parameters>true</parameters>
                    </configuration>
                </plugin>
                <plugin>
                    <artifactId>maven-failsafe-plugin</artifactId>
                    <executions>
                        <execution>
                            <goals>
                                <goal>integration-test</goal>
                                <goal>verify</goal>
                            </goals>
                        </execution>
                    </executions>
                    <configuration>
                        <classesDirectory>${project.build.outputDirectory}</classesDirectory>
                    </configuration>
                </plugin>
                <plugin>
                    <artifactId>maven-jar-plugin</artifactId>
                    <configuration>
                        <archive>
                            <manifest>
                                <mainClass>${start-class}</mainClass>
                                <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
                            </manifest>
                        </archive>
                    </configuration>
                </plugin>
                <plugin>
                    <artifactId>maven-war-plugin</artifactId>
                    <configuration>
                        <archive>
                            <manifest>
                                <mainClass>${start-class}</mainClass>
                                <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
                            </manifest>
                        </archive>
                    </configuration>
                </plugin>
                <plugin>
                    <groupId>org.codehaus.mojo</groupId>
                    <artifactId>exec-maven-plugin</artifactId>
                    <configuration>
                        <mainClass>${start-class}</mainClass>
                    </configuration>
                </plugin>
                <plugin>
                    <artifactId>maven-resources-plugin</artifactId>
                    <configuration>
                        <delimiters>
                            <delimiter>${resource.delimiter}</delimiter>
                        </delimiters>
                        <useDefaultDelimiters>false</useDefaultDelimiters>
                    </configuration>
                </plugin>
                <plugin>
                    <groupId>pl.project13.maven</groupId>
                    <artifactId>git-commit-id-plugin</artifactId>
                    <executions>
                        <execution>
                            <goals>
                                <goal>revision</goal>
                            </goals>
                        </execution>
                    </executions>
                    <configuration>
                        <verbose>true</verbose>
                        <dateFormat>yyyy-MM-dd'T'HH:mm:ssZ</dateFormat>
                        <generateGitPropertiesFile>true</generateGitPropertiesFile>
                        <generateGitPropertiesFilename>${project.build.outputDirectory}/git.properties</generateGitPropertiesFilename>
                    </configuration>
                </plugin>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                    <executions>
                        <execution>
                            <id>repackage</id>
                            <goals>
                                <goal>repackage</goal>
                            </goals>
                        </execution>
                    </executions>
                    <configuration>
                        <mainClass>${start-class}</mainClass>
                    </configuration>
                </plugin>
                <plugin>
                    <artifactId>maven-shade-plugin</artifactId>
                    <executions>
                        <execution>
                            <phase>package</phase>
                            <goals>
                                <goal>shade</goal>
                            </goals>
                            <configuration>
                                <transformers>
                                    <transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
                                        <resource>META-INF/spring.handlers</resource>
                                    </transformer>
                                    <transformer implementation="org.springframework.boot.maven.PropertiesMergingResourceTransformer">
                                        <resource>META-INF/spring.factories</resource>
                                    </transformer>
                                    <transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
                                        <resource>META-INF/spring.schemas</resource>
                                    </transformer>
                                    <transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
                                    <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                        <mainClass>${start-class}</mainClass>
                                    </transformer>
                                </transformers>
                            </configuration>
                        </execution>
                    </executions>
                    <dependencies>
                        <dependency>
                            <groupId>org.springframework.boot</groupId>
                            <artifactId>spring-boot-maven-plugin</artifactId>
                            <version>2.1.1.RELEASE</version>
                        </dependency>
                    </dependencies>
                    <configuration>
                        <keepDependenciesWithProvidedScope>true</keepDependenciesWithProvidedScope>
                        <createDependencyReducedPom>true</createDependencyReducedPom>
                        <filters>
                            <filter>
                                <artifact>*:*</artifact>
                                <excludes>
                                    <exclude>META-INF/*.SF</exclude>
                                    <exclude>META-INF/*.DSA</exclude>
                                    <exclude>META-INF/*.RSA</exclude>
                                </excludes>
                            </filter>
                        </filters>
                    </configuration>
                </plugin>
                <plugin>
                    <groupId>org.eclipse.m2e</groupId>
                    <artifactId>lifecycle-mapping</artifactId>
                    <version>1.0.0</version>
                    <configuration>
                        <lifecycleMappingMetadata>
                            <pluginExecutions>
                                <pluginExecution>
                                    <pluginExecutionFilter>
                                        <groupId>org.codehaus.mojo</groupId>
                                        <artifactId>flatten-maven-plugin</artifactId>
                                        <versionRange>[1.0.0,)</versionRange>
                                        <goals>
                                            <goal>flatten</goal>
                                        </goals>
                                    </pluginExecutionFilter>
                                    <action>
                                        <ignore/>
                                    </action>
                                </pluginExecution>
                                <pluginExecution>
                                    <pluginExecutionFilter>
                                        <groupId>org.apache.maven.plugins</groupId>
                                        <artifactId>maven-checkstyle-plugin</artifactId>
                                        <versionRange>[3.0.0,)</versionRange>
                                        <goals>
                                            <goal>check</goal>
                                        </goals>
                                    </pluginExecutionFilter>
                                    <action>
                                        <ignore/>
                                    </action>
                                </pluginExecution>
                            </pluginExecutions>
                        </lifecycleMappingMetadata>
                    </configuration>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>

首先看到的是spring-boot-starter-parent竟然还有parent,这个先稍后再说。springboot

而后看到的是<build>标签,这里定义了哪些会被打包到jar里,指定了一堆plugin来帮助打包和编译mvc

plugin有兴趣的能够研究,重点说一下配置文件的指定。

看到.yml、.yaml,.properties三种格式配置文件,当一个工程的resources下同时存在这三种文件时,优先加载的是.properties文件,为何这么说呢,由于spring有个覆盖原则,后边的配置会覆盖掉前边,就算先加载.yml文件的内容,只要是相同的配置,依然会被后边的覆盖掉,可是不一样的配置会被保留。

什么意思呢?举个例来讲明一下,如今项目里有这样一个controller和三个配置文件

properties文件里下的内容是

yaml文件里内容是

yml文件里的内容是

然而最终启动时用的端口是

访问接口打印的是

说明properties>yml>yaml,另外不一样路径也有不同的优先级-file:/config/>-file:./>-classpath:/config/>-classpath:/

固然,有其余方式指定配置文件,有机会单独详细介绍

 

 

下面是spring-boot-starter-web的pom文件这里只是引入了springweb项目须要用的依赖,并无什么好说的。

<?xml version="1.0" encoding="UTF-8"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starters</artifactId>
    <version>2.1.9.RELEASE</version>
  </parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
  <version>2.1.9.RELEASE</version>
  <name>Spring Boot Web Starter</name>
  <description>Starter for building web, including RESTful, applications using Spring
		MVC. Uses Tomcat as the default embedded container</description>
  <url>https://projects.spring.io/spring-boot/#/spring-boot-parent/spring-boot-starters/spring-boot-starter-web</url>
  <organization>
    <name>Pivotal Software, Inc.</name>
    <url>https://spring.io</url>
  </organization>
  <licenses>
    <license>
      <name>Apache License, Version 2.0</name>
      <url>https://www.apache.org/licenses/LICENSE-2.0</url>
    </license>
  </licenses>
  <developers>
    <developer>
      <name>Pivotal</name>
      <email>info@pivotal.io</email>
      <organization>Pivotal Software, Inc.</organization>
      <organizationUrl>https://www.spring.io</organizationUrl>
    </developer>
  </developers>
  <scm>
    <connection>scm:git:git://github.com/spring-projects/spring-boot.git</connection>
    <developerConnection>scm:git:ssh://git@github.com/spring-projects/spring-boot.git</developerConnection>
    <url>https://github.com/spring-projects/spring-boot</url>
  </scm>
  <issueManagement>
    <system>Github</system>
    <url>https://github.com/spring-projects/spring-boot/issues</url>
  </issueManagement>
  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter</artifactId>
      <version>2.1.9.RELEASE</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-json</artifactId>
      <version>2.1.9.RELEASE</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-tomcat</artifactId>
      <version>2.1.9.RELEASE</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.hibernate.validator</groupId>
      <artifactId>hibernate-validator</artifactId>
      <version>6.0.17.Final</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>5.1.10.RELEASE</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>5.1.10.RELEASE</version>
      <scope>compile</scope>
    </dependency>
  </dependencies>
</project>

 

 

 

至此就是spring-boot-start-web的所有内容

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