How to solve the problems of SpringBoot official website construction and quick startup

SpringBoot Overview

SpringBoot is a brand new framework provided by the Pivotal team and is designed to be used with To simplify the initial construction and development process of Spring applications.

Everyone has experienced the SpringBoot program. Let’s look back and see what the main function of SpringBoot is to simplify the construction and development process of Spring .

OriginalSpring There are the following problems in environment construction and development:

• Cumbersome configuration dependencies

• Settings Cumbersome

SpringBoot The advantage of the program happens to be automatic configuration for the shortcomings of Spring

• . This is used to solve the problem of cumbersome program configuration in Spring

• ##starting dependencies. This is used to solve

  Spring the problem of cumbersome program dependency settings

• auxiliary functions (built-in server,...). When we started the

  SpringBoot program, we neither used the local tomcat nor the tomcat plug-in, but used the SpringBoot built-in server.

Next let’s talk about the starting dependencies of

SpringBoot

Starting dependencies

We use

Spring Initializr The pom.xml configuration file of the Maven project created in the method automatically generates many dependencies containing starter, as shown below

These dependencies are startup dependencies. Next, let’s explore how they are implemented.

Exploring the parent project

From the above file, we can see that a parent project is specified. We enter the parent project and find that another parent project is specified in the parent project, as shown in the figure below

Then enter the parent project. In this project, we can see the configuration content structure as shown below

The properties tag in the above picture defines the versions that each technical software depends on, which avoids us considering version compatibility issues when using different software technologies. In properties we find the versions of servlet and mysql as shown below

dependencyManagement# The ## tag is for dependency version locking, but the corresponding dependency is not imported; if our project needs that dependency, we only need to introduce the groupid and artifactId of the dependency. There is no need to define the version .

The

build tag also locks the plug-in version, as shown below

After reading the parent project

After configuring pom.xml, it is not difficult to understand why none of our project’s dependencies are configured version.

Exploring dependencies

The following dependencies are configured in

pom.xml in the project we created

Enter the dependency and check the dependencies of

pom.xml and you will find that it introduces the following dependencies

which introduces

spring-web and spring-webmvc are dependent on each other. This is why our project can still use the annotations in springMVC without relying on these two packages.

and relies on

spring-boot-starter-tomcat. From the name, we can basically confirm that tomcat is internally dependent, so our project can start normally.

Conclusion: If you need to use technology in the future, you only need to introduce the starting dependencies corresponding to the technology

Summary

starter

• Common project names in SpringBoot define all project coordinates used by the current project to reduce dependency configuration

parent

• The projects to be inherited by all

  SpringBoot projects define several coordinate version numbers (dependency management, not dependency) to reduce dependencies Conflicting Purpose

• spring-boot-starter-parent (2.5.0) and spring-boot-starter-parent (2.4.6) have a total of 57 coordinates Different versions

Actual development

When using arbitrary coordinates, only write G and A in GAV, V is provided by SpringBoot

G：groupid

A：artifactId

V：version

If a coordinate error occurs, specify the version again (be careful of version conflicts)

Program startup

Every SpringBoot program created contains a class similar to the following. We call this class the boot class

@SpringBootApplication
public class Springboot01QuickstartApplication {
    
    public static void main(String[] args) {
        SpringApplication.run(Springboot01QuickstartApplication.class, args);
    }
}

Note:

• SpringBoot When creating a project, use the jar packaging method

• SpringBoot The boot class is the entry point of the project. Running the main method can start the project

because we configured ## in pom.xml #spring-boot-starter-web depends on it, and this dependency knows through previous learning that it depends on tomcat, so running the main method can use tomcat Start our project.

Switch web server

Now we start the project using the

tomcat server, can we use jetty# instead of tomcat ## Server, jetty When we maven are advanced, we will talk about the server used by maven private servers. To switch the web server, you need to exclude the default tomcat server. How to exclude it? Using the exclusion tag <pre class="brush:xml;">&lt;dependency&gt; &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt; &lt;artifactId&gt;spring-boot-starter-web&lt;/artifactId&gt; &lt;exclusions&gt; &lt;exclusion&gt; &lt;artifactId&gt;spring-boot-starter-tomcat&lt;/artifactId&gt; &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt; &lt;/exclusion&gt; &lt;/exclusions&gt; &lt;/dependency&gt;</pre> Now can we run the bootstrap class? Try running it. The printed log information is as follows

The program stopped directly. Why? That's because if the

tomcat

server is excluded, there will be no server in the program. So at this time not only the tomcat server must be excluded, but also the jetty server must be introduced. In pom.xml, because the starting dependency of jetty is <pre class="brush:xml;">&lt;dependency&gt; &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt; &lt;artifactId&gt;spring-boot-starter-jetty&lt;/artifactId&gt; &lt;/dependency&gt;</pre>, run the boot class again. You can see in the log information that

is used. jetty

Server

Summary:

By switching the server, it is not difficult for us to find that we are using SpringBoot
When changing technology, you only need to import the starting dependencies of the technology.

Comparison between spring and springboot

After we finished the introductory case in the previous article, we can find that there is a big difference between the two:

Coordinates

• Spring

  The coordinates in the program need to be written by yourself, and there are many coordinates

• SpringBoot

  The coordinates in the program are automatically generated by checking when we create the project

web3.0 configuration class

• Spring

  The program needs to write this configuration class by itself. Everyone has written this configuration class before, and it must feel very complicated

• SpringBoot

  The program does not need to be written by ourselves

Configuration Class

• Spring/SpringMVC

  The configuration class of the program needs to be written by yourself. The SpringBoot program does not need to be written.

Note: The

Spring Initializr

based on Idea requires an Internet connection to quickly build the SpringBoot project.

Official website construction project

The reason why the

SpringBoot

project can be quickly built in the entry case is because Idea uses the provided by the official website Quickly build the components of the SpringBoot project. So how to build projects on the official website? Build through the following stepsEnter the SpringBoot official website

Enter the

SpringBoot

official website and drag it to the bottom to see the following content

Then click

Spring Initializr

The hyperlink will jump to the following page

Does the content of this page look familiar? The interface is basically the same as the one we use

Idea

to quickly build the SpringBoot project. Enter the corresponding information on the above pageSelect dependencies

Select

Spring Web

You can click the ADD DEPENDENCIES... CTRL B button in the upper right corner of the picture above , the following interface will appear<p><img src="https://img.php.cn/upload/article/000/887/227/168376831282036.png" alt="How to solve the problems of SpringBoot official website construction and quick startup"></p> <h4>生成工程</h4> <p>以上步骤完成后就可以生成 <code>SpringBoot 工程了。在页面的最下方点击 GENERATE CTRL + 回车 按钮生成工程并下载到本地，如下图所示

打开下载好的压缩包可以看到工程结构和使用 Idea 生成的一模一样，如下图

而打开 pom.xml 文件，里面也包含了父工程和 Spring Web 的依赖。

通过上面官网的操作，我们知道 Idea 中快速构建 SpringBoot 工程其实就是使用的官网的快速构建组件，那以后即使没有 Idea 也可以使用官网的方式构建 SpringBoot 工程。

SpringBoot工程快速启动

问题引入

以后我们和前端开发人员协同开发，而前端开发人员需要测试前端程序就需要后端开启服务器，这就受制于后端开发人员。为了摆脱这个受制，前端开发人员尝试着在自己电脑上安装 Tomcat 和 Idea ，在自己电脑上启动后端程序，这显然不现实。

我们后端可以将 SpringBoot 工程打成 jar 包，该 jar 包运行不依赖于 Tomcat 和 Idea 这些工具也可以正常运行，只是这个 jar 包在运行过程中连接和我们自己程序相同的 Mysql 数据库即可。这样就可以解决这个问题，如下图

那现在问题是如何打包呢？

打包

由于我们在构建 SpringBoot 工程时已经在 pom.xml 中配置了如下插件

<plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
</plugin>

所以我们只需要使用 Maven 的 package 指令打包就会在 target 目录下生成对应的 Jar 包。

注意：该插件必须配置，不然打好的 jar 包也是有问题的。

启动

进入 jar 包所在位置，在 命令提示符 中输入如下命令

java -jar 包名.jar

执行上述命令就可以看到 SpringBoot 运行的日志信息

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