# springboot_2002

**Repository Path**: manalay/springboot_2002

## Basic Information

- **Project Name**: springboot_2002
- **Description**: No description available
- **Primary Language**: Unknown
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 13
- **Created**: 2021-11-09
- **Last Updated**: 2024-12-02

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# springboot 学习

## springboot 是什么

https://spring.io/projects/spring-boot#overview

还是属于spring 体系的一个框架

但是不是新框架，而是一个集成了各种常用内容的框架。

在我们使用spring 的时候，不需要引入一堆的依赖。

相对于ssm集成内容，spring boot 省掉了大量的配置文件，省掉了tomcat

省掉了引入各种jar

## 一个简单的开始

新建一个文件夹，加入pom.xml

```
<?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.example</groupId>
    <artifactId>myproject</artifactId>
    <version>0.0.1-wangzeng</version>

    <!-- Inherit defaults from Spring Boot -->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
    </parent>

    <!-- Add typical dependencies for a web application -->
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
    </dependencies>

    <!-- Package as an executable jar -->
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>
```

#### 这里关于spring boot 的一共两个部分

```
    <!-- Inherit defaults from Spring Boot -->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
    </parent>
```

这个部分我们来看一看源码：

```
<?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>2.1.6.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>2.1.6.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>

```

以上内容 

- 定义了 Java 编译版本，如上为 1.8。
- 使用 UTF-8 格式编码
- maven源文件和目标文件编译的版本
- 执行打包操作的配置
- 自动化的资源过滤
- 自动化的插件配置

可以看到，是省掉了大量的配置，并且指定了后续内容的版本，可以在依赖引入时省略

### 第二部分

```
  <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
  </dependency>
```

源码：

```
<?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>2.1.6.RELEASE</version>
  </parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
  <version>2.1.6.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/spring-boot-starters/spring-boot-starter-web</connection>
    <developerConnection>scm:git:ssh://git@github.com/spring-projects/spring-boot.git/spring-boot-starters/spring-boot-starter-web</developerConnection>
    <url>https://github.com/spring-projects/spring-boot/spring-boot-starters/spring-boot-starter-web</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>2.1.6.RELEASE</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-json</artifactId>
      <version>2.1.6.RELEASE</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-tomcat</artifactId>
      <version>2.1.6.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>5.1.8.RELEASE</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>5.1.8.RELEASE</version>
      <scope>compile</scope>
    </dependency>
  </dependencies>
</project>

```

可以看到，指定了各种依赖

tomcat sprinMVC hibernate 验证，json 等等，一系列内容。

这两个内容，已经解决了我们项目大部分的配置管理问题。

## 创建一个项目

在建立了文件夹和pom文件之后，我们可以直接使用命令创建

> mvn package

这样我们就可以得到一个jar包了

### 使用idea 创建项目

打开后，可以选文件->new project - maven project

然后复制上面pom中的内容替换当前的pom就可以

## 编码

### 程序入口：

在所有子包之上，建立启动类，原因是启动类会扫描当前包以及当前包的子包

如果其它的代码不在当前包与子包范围，那就无法识别。

```
@SpringBootApplication
public class App{
	public static void main(String[] args) {
	    SpringApplication.run(App.class,args);
	}
}
```



代码并不复杂，一个注解，一个静态调用。

@SpringBootApplication

是一个复合注解，包括了很多内容：

```
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = { @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
		@Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
public @interface SpringBootApplication { 
	@AliasFor(annotation = EnableAutoConfiguration.class)
	Class<?>[] exclude() default {}; 
	@AliasFor(annotation = EnableAutoConfiguration.class)
	String[] excludeName() default {}; 
	@AliasFor(annotation = ComponentScan.class, attribute = "basePackages")
	String[] scanBasePackages() default {};
	@AliasFor(annotation = ComponentScan.class, attribute = "basePackageClasses")
	Class<?>[] scanBasePackageClasses() default {};

}

```

可以看到里面包括了配置读取自动扫描等等注解内容。

也可以理解 为一个简化后的注解。作用是扫描子包，扫描配置文件等操作。

## Controller

控制器  作为MVC的C的部分

可以单独使用注解了

普通的Controller如果需要返回实体或json需要指定responseBody

所以以下案例，都以RestController来完成。