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Tool version compatibility problem
I'm learning SSM(H) In the process of , A lot of configuration work needs to be done , In fact, many configuration behaviors are only means , Not the end . Based on this consideration , Simplify what should be simplified , The omission of the omission , Developers only care about providing business functionality , This is it. SpringBoot.
Correct
In other words ,SpringBoot It can be simply seen as a simplified 、 Developed as agreed SSM(H). The development speed has been greatly improved . But what , Better still SSM(H) Basis of , Otherwise, it uses Spring MVC,Mybatis,Hibernate Place , Or feel confused . notes ： In parentheses (H) express Hibernate. Step 2 : about SpringBoot edition Step 3 : about IDE Step 4 : about STS plug-in unit Step 5 : Run... First , See the effect , Learn again Step 6 : Imitation and troubleshooting Step 7 : about Tomcat Step 8 : Create project Step 9 : Enter project parameters Step 10 : pom.xml Step 11 : Application.java Step 12 : HelloController.java Step 13 : Run and test
Try to use JDK8 32 edition , lower than 8 Definitely not , higher than 8 Schrodinger BUG, Try to use 8, Please download JDK8：
Download and configure JDK environment
Eclipse Also try to use the information provided by the webmaster , Avoid problems caused by environmental reasons ： Eclipse notes ： JDK8 64 Bit version is the same as that provided by the current project jar Package incompatible , Please use Provided by the station master 32 Bit .
This series of tutorials uses 1.5.9.RELEASE, Now there are updates Springboot 2.x Version .
Their usage is similar , But there are still some differences . I hope the students will be here first 1.5.9.RELEASE Study on the basis of 、 master 、 After proficiency , If you are still interested , Then switch to 2.x Version on . What I want to emphasize here is , If you switch to... Now 2.x Version , And the running webmaster is currently springboot The code in the series of Textbooks , Unexpected mistakes will occur , Finally, it creates obstacles to your study . So the stationmaster shouted at the top of his voice 3 sentence ： Do not modify the version number at will ！ Do not modify the version number at will ！ Do not modify the version number at will ！
At present, the mainstream development tool is Eclipse and IDEA, So separate , The current knowledge points are Eclipse, The next knowledge point is IDEA.
Eclipse Provides a dedicated development SpringBoot The plug-in is called Spring Tool Suite. This plug-in is installed using foreign sources , Installation is too laggy , At least dozens of minutes .
and SpringBoot application , It's essentially a Java program , Its style is maven style , So it's another Maven project , Next, we'll follow maven Just create it as a project . Don't be overshadowed by fancy plug-ins .
The old rule , First download the runnable project in the upper right corner , Configure to run , After confirming availability , Then learn what steps have been taken to achieve this effect .
This is a maven project , Eclipse Import maven Project approach , Please refer to the following steps ： stay Eclipse Import in maven project Then run the class ： com.how2java.springboot.Application Main method of Then visit the address : http://127.0.0.1:8080/hello You can see the effect as shown in the figure . notes ： this maven The project uses a lot jar Bag , If not jar Package download slow , You can use the library I'm using : Used by the station master maven Warehouse , It's just a little big ~
After ensuring that the runnable project can run correctly , Then strictly follow the steps in the tutorial , Imitate the code again .
The imitation process inevitably has code differences , As a result, the expected operation results cannot be obtained , At this moment, by comparison The correct answer ( Runnable project ) And your own code , To locate the problem . In this way , Learning is effective , Troubleshooting is efficient , It can obviously improve the learning speed , Across all the barriers on the way to learning . It is recommended to use diffmerge Software , Compare folders . Put your own project folder , Compare with my runnable project folder . This software is awesome , You can know which two files in the folder are wrong , And clearly marked Here is a green installation and use tutorial ： diffmerge Download and use tutorials
Run... First , See the effect , Learn again Successful students , It may be a little strange . It's a... that's clearly running web program , Why the startup mode is not startup tomcat？ It's a start Java Class Main method ？
This is because of this com.how2java.springboot.Application The main method of the class puts tomcat Embedded , There is no need to start manually tomcat What happened .
Then start from 0 Start creating this project .
Create a new one first maven project Menu -> File -> New -> Other -> Maven -> Maven -> Maven Project -> New Maven Project Tick this Create a simple project (skip archetype selection), See ,Springboot It's a simple maven project notes ： Before creating the project , To put Run... First , See the effect , Learn again The program started in step returns first , Otherwise there will be problems .
Then enter these values in the red box in the parameter
Use the following pom.xml The contents of the project cover pom.xml.
After covering , Right click on the item ->Maven->Update Project Update the project . this pom.xml It specifies the... Required for the current project jar Bag . notes ： this maven The project uses a lot jar Bag , If not jar Package download slow , You can use the library I'm using : Used by the station master maven Warehouse , It's just a little big ~
<?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.how2java</groupId> <artifactId>springboot</artifactId> <version>0.0.1-SNAPSHOT</version> <name>springboot</name> <description>springboot</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.9.RELEASE</version> </parent> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> </dependencies> <properties> <java.version>1.8</java.version> </properties> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>
establish Application.java, Its annotation @SpringBootApplication It means that this is a SpringBoot application , Running its main method will start tomcat, The default port is 8080
package com.how2java.springboot; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; @SpringBootApplication public class Application { public static void main(String[] args) { SpringApplication.run(Application.class, args); } }
package com.how2java.springboot;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
Then create the controller class HelloController, This class is Spring MVC An ordinary controller in .
@RestController yes spring4 New notes in , yes @ResponseBody and @Controller Abbreviation for .
package com.how2java.springboot.web; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; @RestController public class HelloController { @RequestMapping("/hello") public String hello() { return "Hello Spring Boot!"; } }
package com.how2java.springboot.web;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class HelloController {
@RequestMapping("/hello")
public String hello() {
return "Hello Spring Boot!";
}
}
Then run
Application.java, Then visit the address
http://127.0.0.1:8080/hello You can see the test results
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2021-07-24
Could not calculate build plan Problem solving
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2020-11-03
Eclipse Go ahead Maven Environment configuration uses
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qq2880668 Jump to the problem location Answer time ：2021-03-05
and idea It's almost the same , find maven Installation path , find setting.xml File ( It has to be changed into Alibaba's remote warehouse , Or the original download is too slow ), Find library
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2020-08-26
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HelloController Remember to put it in Application Under the consent directory
2020-05-12
I don't know how to run ,,,, It's a choice maven build Are you
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