Introduction

I would like to write a sample program in Spring Boot. For reference, [Introduction to Spring](https://www.amazon.co.jp/Spring%E5%BE%B9%E5%BA%95%E5%85%A5%E9%96%80- Spring-Framework% E3% 81% AB% E3% 82% 88% E3% 82% 8BJava% E3% 82% A2% E3% 83% 97% E3% 83% AA% E3% 82% B1% E3% 83% BC% E3% 82% B7% E3% 83% A7% E3% 83% B3% E9% 96% 8B% E7% 99% BA-% E6% A0% AA% E5% BC% 8F% E4% BC% 9A % E7% A4% BENTT% E3% 83% 87% E3% 83% BC% E3% 82% BF / dp / 4798142476). We will create the conference room reservation system introduced here.

Java installation

Let's install Java. There are various versions, but this time we will use OpenJDK 8. If you are using WSL2, you can download it with the following command.

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$ sudo apt install openjdk-8-jdk

Then set the environment variables. First, let's check where Java was installed.

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$ dpkg -L openjdk-8-jdk

***Abbreviation
/usr/lib/jvm/java-8-openjdk-amd64
***Abbreviation

There are a lot of them, but you can specify JAVA_HOME in / usr / lib / jvm / java-8-openjdk-amd64. Now that we know the path, set the environment variables.

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$ sudo vi /etc/profile

/etc/Add the following to profile.
export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64
export PATH=$PATH:$JAVA_HOME/bin
export CLASSPATH=.:$JAVA_HOME/jre/lib:$JAVA_HOME/lib:$JAVA_HOME/lib/tools.jar

Use the following command to reflect the bash settings and check that the installation has been completed.

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$ source /etc/profile
$ java -version
openjdk version "1.8.0_265"
OpenJDK Runtime Environment (build 1.8.0_265-8u265-b01-0ubuntu2~20.04-b01)
OpenJDK 64-Bit Server VM (build 25.265-b01, mixed mode)

Now you can use Java.

Maven installation

Next, install Maven. Gradle seems to be more popular as a build tool, but due to adult circumstances, I use good old Maven. This is the only command.

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$ sudo apt install maven

Let's check the installation.

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$ mvn -v
Apache Maven 3.6.3
Maven home: /usr/share/maven
Java version: 1.8.0_265, vendor: Private Build, runtime: /usr/lib/jvm/java-8-openjdk-amd64
Default locale: en, platform encoding: UTF-8
OS name: "linux", version: "4.19.104-microsoft-standard", arch: "amd64", family: "unix"

Start Spring-Boot sample

Now let's create a Spring Boot sample project. First, create a suitable directory. In my case, I did the following.

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$ cd ~
$ mkdir web-app
$ cd web-app

Create a sample project with the following command.

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$ mvn archetype:generate

***Omission***

Choose a number or apply filter (format: [groupId:]artifactId, case sensitive contains): 1672:

How about. A lot of English comes out and I'm afraid, but you can ignore it. mvn archetype: generate is a command to create a project interactively. Let's select the sample to be used this time. Try typing spring-boot.

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Choose a number or apply filter (format: [groupId:]artifactId, case sensitive contains): : spring-boot

There are fewer options than before. (78 in my environment) This time, let's use ʻorg.springframework.boot: spring-boot-sample-tomcat-archetype (Spring Boot Tomcat Sample) . In this sample, Tomcat is built in, so you can run Jar as it is. In my environment, it was displayed as 68:, so enter 68`. (You should be able to specify the name)

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***Abbreviation
68: remote -> org.springframework.boot:spring-boot-sample-tomcat-archetype (Spring Boot Tomcat Sample)
***Abbreviation
Choose a number or apply filter (format: [groupId:]artifactId, case sensitive contains): : 68

I can speak a lot of English again, but please don't turn down. You can ignore it. Next you will be asked the following.

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***Abbreviation
Define value for property 'groupId': com.rocorock
Define value for property 'artifactId': mvn-spring
Define value for property 'version' 1.0-SNAPSHOT: :
Define value for property 'package' com.rocorock: :
Confirm properties configuration:
groupId: com.rocorock
artifactId: mvn-spring
version: 1.0-SNAPSHOT
package: com.rocorock
 Y: : y

Maven requires you to specify groupId, ʻartifactId, version, package. It is used in the package name. I think that essentially anything is OK. If you press Enter as it is, version and package` will be reflected without permission. I will not post an explanation of Maven setting items this time, but if you want to know about Maven, I recommend this book. [Introduction to Java Build Tools](https://www.amazon.co.jp/Java%E3%83%93%E3%83%AB%E3%83%89%E3%83%84%E3%83%BC % E3% 83% AB% E5% 85% A5% E9% 96% 80-Maven-Gradle-SBT-Bazel% E5% AF% BE% E5% BF% 9C / dp / 4798049387) If the following message is displayed on the console, it is successful.

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[INFO] ----------------------------------------------------------------------------
[INFO] Using following parameters for creating project from Archetype: spring-boot-sample-tomcat-archetype:1.0.2.RELEASE
[INFO] ----------------------------------------------------------------------------
[INFO] Parameter: groupId, Value: com.rocorock
[INFO] Parameter: artifactId, Value: mvn-spring
[INFO] Parameter: version, Value: 1.0-SNAPSHOT
[INFO] Parameter: package, Value: com.rocorock
[INFO] Parameter: packageInPathFormat, Value: com/rocorock
[INFO] Parameter: package, Value: com.rocorock
[INFO] Parameter: version, Value: 1.0-SNAPSHOT
[INFO] Parameter: groupId, Value: com.rocorock
[INFO] Parameter: artifactId, Value: mvn-spring
[INFO] Project created from Archetype in dir: /home/tomoya/web-app/mvn-spring
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  02:26 min
[INFO] Finished at: 2020-09-06T16:51:46+09:00
[INFO] ------------------------------------------------------------------------

Let's package the resulting file.

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$ cd mvn-spring
$ mvn package

***Abbreviation

Results :

Failed tests:
  SampleTomcatApplicationTests.testHome:53 expected:<Hello [World]> but was:<Hello [DESKTOP-F147IF8]>
  NonAutoConfigurationSampleTomcatApplicationTests.testHome:82 expected:<Hello [World]> but was:<Hello [DESKTOP-F147IF8]>

Tests run: 2, Failures: 2, Errors: 0, Skipped: 0

[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  4.461 s
[INFO] Finished at: 2020-09-06T16:52:06+09:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.15:test (default-test) on project mvn-spring: There are test failures.
[ERROR]
[ERROR] Please refer to /home/tomoya/web-app/mvn-spring/target/surefire-reports for the individual test results.
[ERROR] -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException

I got BUILD FAILURE. Let's check the console.

Failed tests:
  SampleTomcatApplicationTests.testHome:53 expected:<Hello [World]> but was:<Hello [DESKTOP-F147IF8]>
  NonAutoConfigurationSampleTomcatApplicationTests.testHome:82 expected:<Hello [World]> but was:<Hello [DESKTOP-F147IF8]>

Apparently the test is failing. ʻExpected: <Hello [World]> but was: <Hello [DESKTOP-F147IF8]>`, so let's fix the code so that it returns'Hello World'. (Why is it a sample but throws an error ...) First, check the test code.

`SampleTomcatApplicationTests.java`


/*
 * Copyright 2012-2014 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.rocorock.tomcat;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.test.IntegrationTest;
import org.springframework.boot.test.SpringApplicationConfiguration;
import org.springframework.boot.test.TestRestTemplate;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.test.annotation.DirtiesContext;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.test.context.web.WebAppConfiguration;

import static org.junit.Assert.assertEquals;

/**
 * Basic integration tests for demo application.
 * 
 * @author Dave Syer
 */
@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = SampleTomcatApplication.class)
@WebAppConfiguration
@IntegrationTest("server.port:0")
@DirtiesContext
public class SampleTomcatApplicationTests {

	@Value("${local.server.port}")
	private int port;

	@Test
	public void testHome() throws Exception {
		ResponseEntity<String> entity = new TestRestTemplate().getForEntity(
				"http://localhost:" + this.port, String.class);
		assertEquals(HttpStatus.OK, entity.getStatusCode());
		assertEquals("Hello World", entity.getBody());
	}

}

Since assertEquals ("Hello World ", entity.getBody ()) is a test with an error, modify it so that this test passes.

`HelloWorldService.java`


/*
 * Copyright 2012-2013 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.rocorock.tomcat.service;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component
public class HelloWorldService {

	@Value("${name:World}")
	private String name;

	public String getHelloMessage() {
		return "Hello World"; //Modification place
	}

}

This time, I solidified it as "Hello World" to avoid the test. In essence, it has not been solved, but it will not start unless it works for the time being, so I will proceed as it is. Let's package it again.

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$ mvn package

***Abbreviation
[INFO] Building jar: /home/tomoya/web-app/mvn-spring/target/mvn-spring-1.0-SNAPSHOT.jar
[INFO]
[INFO] --- spring-boot-maven-plugin:1.0.2.RELEASE:repackage (default) @ mvn-spring ---
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  4.288 s
[INFO] Finished at: 2020-09-06T17:00:47+09:00
[INFO] ------------------------------------------------------------------------

This time it was successful. If successful, a new target folder will be created. The executable jar is stored here. Let's move it immediately.

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$ ls
pom.xml  src  target
$ java -jar target/mvn-spring-1.0-SNAPSHOT.jar

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.0.2.RELEASE)

2020-09-06 17:01:19.928  INFO 5988 --- [           main] c.r.tomcat.SampleTomcatApplication       : Starting SampleTomcatApplication on DESKTOP-F147IF8 with PID 5988 (/home/tomoya/web-app/mvn-spring/target/mvn-spring-1.0-SNAPSHOT.jar started by tomoya in /home/tomoya/web-app/mvn-spring)
2020-09-06 17:01:19.951  INFO 5988 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@414be896: startup date [Sun Sep 06 17:01:19 JST 2020]; root of context hierarchy

You'll see a fun startup script. Tomcat starts on port 8080 by default, so let's access it. Type http: // localhost: 8080 in your browser. If you see Hello World, you are successful. Press Ctrl + C on the console to stop Tomcat and you're done.

At the end

I said that I would create a conference room reservation app, but I finished running the Tomcat sample ... I would like to extend and develop this sample from the next time onwards! (If you get frustrated, it may not be an article)

Try Spring Boot 1 (Environment construction ~ Tomcat startup)

Introduction

Java installation

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Maven installation

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Start Spring-Boot sample

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SampleTomcatApplicationTests.java

HelloWorldService.java

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At the end

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`SampleTomcatApplicationTests.java`

`HelloWorldService.java`

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