Ubuntu 下部署 SpringBoot

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第一步：下载 Idea

我这次是一切从 0 开始的，所以 Idea 也是电脑上也是没有，安装过程就不水文了，不会的去网上搜一下，教程一大把。
PoJie 教程也可以去网上搜，我 Idea 下载的是目前官方最新版（2021.1.3 Ultimate x64），PoJie 教程亲测今日可用（2021.7.12）
多说一句，2021 版的 Idea 第一次用，默认的关键字颜色变了，挺好看的~

第二步：新建 SpringBoot 项目

这一步也不水文了，网上教程太多了。

这里把 pom.xml 文件、包结构、新增的控制器代码贴一下

pom.xml

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.2</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

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

在这里插入图片描述

第三步：打包 .jar 文件

在这里插入图片描述

第四步：在 Ubuntu 上部署 .jar 包

mkdir demo 命令创建一个名为 demo 的命令
cd demo 命令进入该目录

nohup java -jar demo-0.0.1-SNAPSHOT.jar 命令启动 jar 包。

nohup xxx & ：是 no hang up 的缩写，意为不挂起，用于在系统后台不断运行命令，退出终端不会影响程序的运行
运行完之后会生成一个 nohup.out 文件，里面是启动过程的一些日志
打开 nohup.out 文件，如果正常启动的话，会看到类似这样的输出
```
Started DemoApplication in xxx seconds
```

但是，我就没那么幸运了，我遇到的是这样的

    .   ____          _            __ _ _
    /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
    ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
    \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
    '  |____| .__|_| |_|_| |_\__, | / / / /
    =========|_|==============|___/=/_/_/_/
    :: Spring Boot ::                (v2.5.2)

    2021-07-14 22:42:22.087  INFO 39193 --- [           main] com.example.demo.DemoApplication         : Starting DemoApplication v0.0.1-SNAPSHOT using Java 1.8.0_291 on iZwz92d94t8mb03s9z327hZ with PID 39193 (/opt/xiaodudu/demo/demo-0.0.1-SNAPSHOT.jar started by root in /opt/xiaodudu/demo)
    2021-07-14 22:42:22.090  INFO 39193 --- [           main] com.example.demo.DemoApplication         : No active profile set, falling back to default profiles: default
    2021-07-14 22:42:23.276  INFO 39193 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
    2021-07-14 22:42:23.291  INFO 39193 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
    2021-07-14 22:42:23.291  INFO 39193 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.48]
    2021-07-14 22:42:23.345  INFO 39193 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
    2021-07-14 22:42:23.345  INFO 39193 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1141 ms
    2021-07-14 22:42:23.673  WARN 39193 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.context.ApplicationContextException: Failed to start bean 'webServerStartStop'; nested exception is org.springframework.boot.web.server.PortInUseException: Port 8080 is already in use
    2021-07-14 22:42:23.677  INFO 39193 --- [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
    2021-07-14 22:42:23.691  INFO 39193 --- [           main] ConditionEvaluationReportLoggingListener : 

    Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
    2021-07-14 22:42:23.713 ERROR 39193 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : 

    ***************************
    APPLICATION FAILED TO START
    ***************************

    Description:

    Web server failed to start. Port 8080 was already in use.

    Action:

    Identify and stop the process that's listening on port 8080 or configure this application to listen on another port.

Port 8080 was already in use. 端口被占用，是比较常见的一个异常。

执行 netstat -anp | grep 8080 查看占用端口的程序 pid。（netstat 有很多参数，可以使用 netstat -h 查询）

root@iZwz92d94t8mb03s9z327hZ:~# netstat -anp | grep 8080
tcp6       0      0 :::8080                 :::*                    LISTEN      19032/java

执行 kill -9 xxxxx 命令终止该程序

root@iZwz92d94t8mb03s9z327hZ:~# kill -9 19032

重新执行 nohup xxx & 命令部署 jar 程序。(nohup.out 是否删除可以自己决定，删除就是重新生成，不删除就是追加内容)

root@iZwz92d94t8mb03s9z327hZ:/opt/xiaodudu/demo# nohup java -jar demo-0.0.1-SNAPSHOT.jar &
[1] 39342
root@iZwz92d94t8mb03s9z327hZ:/opt/xiaodudu/demo# nohup: ignoring input and appending output to 'nohup.out'

查看 nohup.out 文件

     .   ____          _            __ _ _
    /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
    ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
    \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
    '  |____| .__|_| |_|_| |_\__, | / / / /
    =========|_|==============|___/=/_/_/_/
    :: Spring Boot ::                (v2.5.2)

    2021-07-14 23:05:16.089  INFO 39342 --- [           main] com.example.demo.DemoApplication         : Starting DemoApplication v0.0.1-SNAPSHOT using Java 1.8.0_291 on iZwz92d94t8mb03s9z327hZ with PID 39342 (/opt/xiaodudu/demo/demo-0.0.1-SNAPSHOT.jar started by root in /opt/xiaodudu/demo)
    2021-07-14 23:05:16.093  INFO 39342 --- [           main] com.example.demo.DemoApplication         : No active profile set, falling back to default profiles: default
    2021-07-14 23:05:17.228  INFO 39342 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
    2021-07-14 23:05:17.239  INFO 39342 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
    2021-07-14 23:05:17.240  INFO 39342 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.48]
    2021-07-14 23:05:17.300  INFO 39342 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
    2021-07-14 23:05:17.300  INFO 39342 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1095 ms
    2021-07-14 23:05:17.755  INFO 39342 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
    2021-07-14 23:05:17.764  INFO 39342 --- [           main] com.example.demo.DemoApplication         : Started DemoApplication in 2.338 seconds (JVM running for 2.769)