Table of contents

1. What is Spring Boot?

Learning the Spring framework is to simplify Java development, and SpringBoot was born to simplify Spring development

Advantages of Spring Boot:

1. Rapid integration framework: you can quickly add external jar packages and directly add the required dependencies to the project

In the past, it was necessary to open the warehouse search framework first, correspond to the version, assign the dependent content, and paste it into the dependency of the .pom file, and the version is easy to mismatch, and errors will occur

Directly check the required dependencies to help us complete these tedious tasks

2. Run and deploy the program directly, built-in running container, no need to install some plug-ins

3. Quickly deploy projects, start and run projects without external containers

4. Can be developed using annotations, no xml configuration files are required

5. Support more monitoring indicators to better observe the operation of the project

2. Creation of SpringBoot project

IDEA create project

The professional version of IDEA does not require the installation of plug-ins

In the community version of IDEA, you need to install the plug-in first to create a SpringBoot project. The SpringBootHelper plug-in below version 2022 is free

Click to create new project

Plugin installed successfully

Once the plugin is installed, the project can be created

Click Spring Initializr

SDK, choose a stable version of JDK, such as version 1.8

In the initialization selection box, you need to pull the official data of spring, which needs to be connected to the Internet

There is a loading time in the middle, and the next interface will appear, which is pulling data

Then the project parameter settings appear:

Click next to select the springboot version and dependencies

Click next, select the name and path

Then select Maven Support

load the whole project

It is slow to create a project for the first time, because you need to download these jar packages, and create it again, you will directly use the local jar package, and it will be very fast

If an error is reported, or the dependency cannot be loaded, there is a high probability that Maven's domestic source is wrong, and the configuration needs to be checked

Click to run, run successfully

The console prints the time-consuming project startup, which proves that it has run successfully

Web version create project

Let's learn how to create a SpringBoot project on the web version

Jump to this interface

Select the same as our above configuration requirements

Then add dependencies, search for dependencies

Search to add three more commonly used dependencies

Click to download the project locally

This is equivalent to a project package. After decompressing it, it can be loaded into IDEA. Every time you can use this file to decompress to get the project, you can modify some information in pom.xml

Open it with IDEA after decompression

Also need to add framework support

After loading the dependencies, click Run

3. Use of Spring Boot

Project directory structure

All files of the project can be seen in the directory structure

The .mnv file is not needed, IDEA already has a visual Maven command window tool

HELP.md is a help document, which comes with the project after creating it, and does not need it

mvnw is used in the linux environment, and .cmd is used in the windows environment. You can use these commands to operate the project, and you can use IDEA's visual tools to operate

These four files are unnecessary. They can be deleted, and the project can start normally after deletion.

We explain the remaining directories:

Open the target file, which is the .class file required by the JVM to run, and can also be deleted, because a target file will be generated every time the project is started

test

Let's test the springboot project

The test class should be written under the demo or under the demo subpackage

Spring will only scan whether the classes under the package where the startup class is located are annotated, and will not scan other places. Create classes in other packages, and add class annotations will not be scanned! This is Spring's agreement

Remember to write the @Controller annotation, otherwise the class will not be loaded into spring

@Controller
@ResponseBody //当前类的所有方法都是返回非静态页面数据
public class Test {
    @RequestMapping("/sayHello")//=@Webservlet(/url)
    public String sayHello(){
        return "Hello World";
    }
}

After starting the project, access it in the browser

Creation and use of SpringBoot