# 用Spring boot 生成Java项目
Date: 2020-12-16


学习java, 尝试用了spring boot创建了一个项目， 使用是maven配置, spring boot 提供很多的模板， 创建项目非常方便， 这让我想起了visual studio 点击几下鼠标自动生成模板代码。

### 项目创建

使用[spring的initializr](https://start.spring.io/) 选择一下就可以生成代码

我的配置:

- Project : Maven Project
- Language : Java
- Spring Boot : 2.4.1
- Dependencies: Spring Web 创建一个web项目 Spring Boot Actuator 提供健康检查功能 Lombok: 通过注释说明生成代码需要安装相关插件
- Java : 11
- Packaging :jar

#### 相关代码 :

- 自动生成代码如下:

```java
package com.garlicspace.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@RestController 
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}
```

- 通过"/hello"文根实现页面输出"hello World!"

```java
package com.garlicspace.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
@RestController 
public class DemoApplication {

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

    @RequestMapping("/hello")
    public String hello(){
        return "hello World!";
    }
}
```

`cmd`运行:

```
F:\spring\helloworld\demo>curl http://localhost:8080/hello
hello World!
F:\spring\helloworld\demo>curl http://localhost:8080/actuator/health
{"status":"UP"}
```

#### maven配置:

pom.xml 文件中使用parent标签配置

```java
<?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>2.4.1</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.garlicspace</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>11</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </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>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>
```

本地repository相关目录下查找到相关配置信息

以下是我的路径

```C
c:\Users\garlic\.m2\repository\org\springframework\boot\spring-boot-starter-parent\2.4.1
```

```C
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-dependencies</artifactId>
    <version>2.4.1</version>
  </parent>
  <artifactId>spring-boot-starter-parent</artifactId>
  <packaging>pom</packaging>
  <name>spring-boot-starter-parent</name>
  <description>Parent pom providing dependency and plugin management for applications built with Maven</description>
  <properties>
    <java.version>1.8</java.version>
    <resource.delimiter>@</resource.delimiter>
    <maven.compiler.source>${java.version}</maven.compiler.source>
    <maven.compiler.target>${java.version}</maven.compiler.target>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
  </properties>
  <url>https://spring.io/projects/spring-boot</url>
... 
   <resources>
      <resource>
        <directory>${basedir}/src/main/resources</directory>
        <filtering>true</filtering>
        <includes>
          <include>**/application*.yml</include>
          <include>**/application*.yaml</include>
          <include>**/application*.properties</include>
        </includes>
      </resource>
      <resource>
        <directory>${basedir}/src/main/resources</directory>
        <excludes>
          <exclude>**/application*.yml</exclude>
          <exclude>**/application*.yaml</exclude>
          <exclude>**/application*.properties</exclude>
        </excludes>
      </resource>
    </resources>

```

配置内容:

- Java 1.8作为默认编译器级别。
- UTF-8源编码。
- 继承`spring-boot-dependencies`
- 使用repackage执行ID 执行repackage目标。
- 资源过滤。
- 插件配置
- application.properties和application.yml的合理资源过滤，包括特定于配置文件的文件（例如，application-dev.properties和application-dev.yml）

```
C:\Users\garlic\.m2\repository\org\springframework\boot\spring-boot-dependencies\2.4.1
```

`spring-boot-dependencies` 文件中中存放了打包好的依赖的版本。

```C
...
<properties>
<activemq.version>5.15.9</activemq.version>
<antlr2.version>2.7.7</antlr2.version>
<appengine-sdk.version>1.9.73</appengine-sdk.version>
<artemis.version>2.6.4</artemis.version>
<aspectj.version>1.9.2</aspectj.version>
<assertj.version>3.11.1</assertj.version>
<atomikos.version>4.0.6</atomikos.version>
<bitronix.version>2.1.4</bitronix.version>
<build-helper-maven-plugin.version>3.0.0</build-helper-maven-plugin.version>
<byte-buddy.version>1.9.12</byte-buddy.version>
<caffeine.version>2.6.2</caffeine.version>
<cassandra-driver.version>3.6.0</cassandra-driver.version>
<classmate.version>1.4.0</classmate.version>
<commons-codec.version>1.11</commons-codec.version>
<commons-dbcp2.version>2.5.0</commons-dbcp2.version>
<commons-lang3.version>3.8.1</commons-lang3.version>
<commons-pool.version>1.6</commons-pool.version>
<commons-pool2.version>2.6.1</commons-pool2.version>
<couchbase-cache-client.version>2.1.0</couchbase-cache-client.version>
<couchbase-client.version>2.7.4</couchbase-client.version>
...
```

当然也可以不使用默认的配置，通过`dependencyManagement`将其依赖导入

```C
    <!--<parent>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-parent</artifactId>
       <version>2.4.1</version>
       <relativePath/> lookup parent from repository
    </parent> -->
...
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.4.1</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>

    </dependencyManagement>
...
```

- 验证

```
F:\spring\helloworld\demo>curl http://localhost:8080/hello
hello World!
F:\spring\helloworld\demo>curl http://localhost:8080/actuator/health
{"status":"UP"}

```

### 参考引用

极客时间《玩转Spring全家桶》 [https://segmentfault.com/a/1190000018854658](https://segmentfault.com/a/1190000018854658) Photo by Steve Johnson from Pexels