starter

SpringBoot中常见的项目名称，定义当前项目使用的所有依赖坐标，以达到减少依赖配置的目的。
就比如说web的依赖，只需要引入下面的一个依赖就可以了，这个依赖里面有很多小依赖。

  

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

  

点进去之后会看到有很多的小依赖。

<?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">
  <!-- This module was also published with a richer model, Gradle metadata,  -->
  <!-- which should be used instead. Do not delete the following line which  -->
  <!-- is to indicate to Gradle or any Gradle module metadata file consumer  -->
  <!-- that they should prefer consuming it instead. -->
  <!-- do_not_remove: published-with-gradle-metadata -->
  <modelVersion>4.0.0</modelVersion>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
  <version>2.6.3</version>
  <name>spring-boot-starter-web</name>
  <description>Starter for building web, including RESTful, applications using Spring MVC. Uses Tomcat as the default embedded container</description>
  <url>https://spring.io/projects/spring-boot</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>2.6.3</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-json</artifactId>
      <version>2.6.3</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-tomcat</artifactId>
      <version>2.6.3</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>5.3.15</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>5.3.15</version>
      <scope>compile</scope>
    </dependency>
  </dependencies>
</project>


  

parent

所有的SpringBoot项目都要继承的项目，定义了若干个坐标的版本号（依赖管理，而非依赖），已达到减少依赖冲突的目的。就是在下面协写依赖的时候，有时候可能没有版本号，其实本质上是SpringBoot已经收录了。

  

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.3</version>
    </parent>

  

引导类

SpringBoot工程提供引导类来用于启动成程序，就是run这个引导类就可以启动SpringBoot项目了，本质上这个东西就是一个大的Spring容器，然后之后写的bean都会放到这个spring里面的。

tomcat服务器

内嵌Tomcat服务器是SpringBoot辅助功能之一。

  

创建好springboot项目之后，就可以开始写第一个SpringBoot项目了。

package com.itheima;

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

@RestController
@RequestMapping("/books")
public class BookController {

    @GetMapping("/news")
    public String getId() {

        System.out.println("SpringBoot is running");

        return "SpringBoot is running";

    }

}


  

@RestController

@RestController = @ResponseBody ＋ @Controller合在一起的作用

如果只是使用@RestController注解Controller，则Controller中的方法无法返回jsp页面，配置的视图解析器InternalResourceViewResolver不起作用，返回的内容就是Return 里的内容。

例如：本来应该到success.jsp页面的，则其显示success.

如果需要返回到指定页面，则需要用 @Controller配合视图解析器InternalResourceViewResolver才行。

如果需要返回JSON，XML或自定义mediaType内容到页面，则需要在对应的方法上加上@ResponseBody注解。(@Controller + @ResponseBody)

@RequestMapping

@GetMapping
@PostMapping
@PutMapping
@DeleteMapping
@PatchMapping
@PathVariable

package com.itheima;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/books")
public class BookController {

    @GetMapping("/news")
    public String getId() {

        System.out.println("SpringBoot is running");

        return "SpringBoot is running";

    }

    @GetMapping("{id}")
    public String getById(@PathVariable Integer id) {

        System.out.println(id);

        return id + "";

    }

}


  

文章来源: blog.csdn.net，作者：花花叔叔，版权归原作者所有，如需转载，请联系作者。

原文链接：blog.csdn.net/qq_52077949/article/details/123035264