SpringBoot - 用maven-dependency-plugin插件将项目代码与依赖分开打包

雨点打透心脏的1/2处 2023-09-30 15:22 4阅读 0赞

## SpringBoot - 用maven-dependency-plugin插件将项目代码与依赖分开打包 ##

### 写在前面 ###

通常基于SpringBoot框架的项目，在发布打包时会将项目代码和所有依赖文件一起打成一个可执行的、一体化的JAR包，如果项目的依赖包很多，那么这个JAR包就会非常大，如果想把项目依赖的JAR从项目一体化的JAR包中分离出来，该怎么办呢？

#### 具体步骤 ####

###### ①. 修改打包插件 ######

将原来的打包插件：

<plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
        <version>2.4.2</version>
        <configuration>
            <executable>true</executable>
            <jvmArguments>-Dfile.encoding=UTF-8</jvmArguments>
        </configuration>
    </plugin>

替换为下面的打包插件：

<plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-jar-plugin</artifactId>
        <configuration>
            <archive>
                
                <addMavenDescriptor>false</addMavenDescriptor>
                <manifest>
                    
                    <addClasspath>true</addClasspath>
                    
                    <classpathPrefix>lib/</classpathPrefix>
                    
                    <mainClass>cn.hadoopx.servicex.ServicexApplication</mainClass>
                </manifest>
            </archive>
        </configuration>
    </plugin>

###### ②. 新增文件复制插件 ######

<plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-dependency-plugin</artifactId>
        <executions>
            <execution>
                <id>copy-lib</id>
                <phase>package</phase>
                <goals>
                    <goal>copy-dependencies</goal>
                </goals>
                <configuration>
                	
                    <outputDirectory>target/lib</outputDirectory>
                    <excludeTransitive>false</excludeTransitive>
                    <stripVersion>false</stripVersion>
                    <includeScope>runtime</includeScope>
                </configuration>
            </execution>
        </executions>
    </plugin>

###### ③. 按常规方式打包 ######

###### ④. 将项目JAR和lib目录复制到项目的部署路径下，执行启动命令 ######

![在这里插入图片描述][94295832a81b40a689d5ca9c64ee1b8b.png]

#### 常见问题 ####

###### ①. servicex-test-1.0-SNAPSHOT.jar 中没有主清单属性 ######

由于在打包插件中没有指定项目主启动类导致。

## maven-dependency-plugin插件的使用 ##

### 一、goal ###

maven-dependency-plugin插件最常用的goal有：copy、copy-dependencies、unpack、unpack-dependencies

copy：拷贝指定jar包到指定目录，与当前工程的依赖没有关系

copy-dependencies：拷贝依赖jar包到指定目录

unpack：解压指定jar包到指定目录，与当前工程的依赖没有关系

unpack-dependencies：解压依赖jar包到指定目录

### 二、copy ###

copy可以的配置的项比较多

是必须配置的，指定jar包

默认值$\{project.build.directory\}/dependency

#### 1.pom文件 ####

<?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>org.example</groupId>
        <artifactId>maven-haha</artifactId>
        <version>1.0-SNAPSHOT</version>
     
        <build>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-dependency-plugin</artifactId>
                    <version>2.8</version>
                    <configuration>
                        <artifactItems>
                            <artifactItem>
                                <groupId>junit</groupId>
                                <artifactId>junit</artifactId>
                                <version>4.11</version>
                            </artifactItem>
                        </artifactItems>
                    </configuration>
                </plugin>
            </plugins>
        </build>
    </project>

#### 2.使用dependency:copy ####

mvn clean dependency:copy

![img][]

结果:

![img][img 1]

### 三、copy-dependencies ###

#### 1.pom文件 ####

<?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>org.example</groupId>
        <artifactId>maven-haha</artifactId>
        <version>1.0-SNAPSHOT</version>
     
        <dependencies>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.13</version>
                <scope>test</scope>
            </dependency>
        </dependencies>
     
        <build>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-dependency-plugin</artifactId>
                    <version>2.8</version>
                </plugin>
            </plugins>
        </build>
    </project>

#### 2.使用dependency:copy-dependencies ####

mvn clean dependency:copy-dependencies

![img][img 2]

结果:

![img][img 3]

### 四、unpack、unpack-dependencies ###

unpack、unpack-dependencies是解压到指定目录，与copy、copy-dependencies操作类似

## spring-boot-maven-plugin 打包分离依赖lib ##

**1. 问题：** spring-boot项目，默认生成的pom使用spring-boot-maven-plugin打包，会把所有依赖项都打进jar文件中，在调试阶段需要频繁传输jar包时很痛苦。

先看spring-boot-maven-plugin官文 \[[https://docs.spring.io/spring-boot/docs/current/maven-plugin/reference/htmlsingle][https_docs.spring.io_spring-boot_docs_current_maven-plugin_reference_htmlsingle] \]，其中有一节

> **5.3.5. Dependency Exclusion**
> 
> By default, both the `repackage` and the `run` goals will include any `provided` dependencies that are defined in the project. A Spring Boot project should consider `provided` dependencies as “container” dependencies that are required to run the application.
> 
> Some of these dependencies may not be required at all and should be excluded from the executable jar. For consistency, they should not be present either when running the application.
> 
> There are two ways one can exclude a dependency from being packaged/used at runtime:
> 
>  *  Exclude a specific artifact identified by `groupId` and `artifactId`, optionally with a `classifier` if needed.
>  *  Exclude any artifact belonging to a given `groupId`.

简译： spring-boot-maven-plugin默认会把依赖都打进jar包中，如果要使用exclude排除某项/某些依赖有两种方式：1.指定groupId和artifactId, 2.指定排除groupId下的所有项。这证实了spring-boot-maven-plugin的确会把依赖和程序打在一起。但是如果要用exclude排除所有依赖项的话显然不太容易，枚举所所有groupId的工作量就不小，而且笨重，所以排除。

> Collection of artifact definitions to include. The `Include` element defines mandatory `groupId` and `artifactId` properties and an optional mandatory `groupId` and `artifactId` properties and an optional `classifier` property.
> 
> 要包含的集合。其中的Include属性定义了groupId和artifactId属性…

这里有点不清晰：includes是要包含没错，但它与“默认值”之间是什么关系？spring-boot-maven-plugin插件默认在打包的时候是将所有依赖一并打包到最终文件的（jar或war），那么如果定义了includes，是只采用includes还是所有依赖+includes还是怎样？

经过实验，含义应该是“以includes定义覆盖默认值”，即显式包含了哪些就只有哪些。如此，就可以利用这个属性实现**分离依赖**的效果:

...
    <plugin>
        <groupId>org.springframework.boot</groupId>
    	<artifactId>spring-boot-maven-plugin</artifactId>
    	<version>2.4.2</version> 
    </plugin>
    ...
     
    
    ...
    <plugin>
        <groupId>org.springframework.boot</groupId>
    	<artifactId>spring-boot-maven-plugin</artifactId>
    	<version>2.4.2</version>
    	<configuration>
    		<includes>
                
    			<include>
    				<groupId>nothing</groupId>
    				<artifactId>nothing</artifactId>
    		    </include>
    		</includes>
    	</configuration>
    </plugin>
    ...

然后再使用maven-dependency-plugin插件把依赖项拷贝到lib文件夹中，最后的pom文件build标签如下：

<build>
    		<plugins>
    			<plugin>
    				<groupId>org.apache.maven.plugins</groupId>
    				<artifactId>maven-compiler-plugin</artifactId>
    				<configuration>
    					<source>1.8</source>
    					<target>1.8</target>
    				</configuration>
    			</plugin>
     
    			<plugin>
    				<groupId>org.springframework.boot</groupId>
    				<artifactId>spring-boot-maven-plugin</artifactId>
    				<version>2.4.2</version>
    				<configuration>
    					<includes>
    						<include>
    							<groupId>haha</groupId>
    							<artifactId>haha</artifactId>
    						</include>
    					</includes>
    				</configuration>
    			</plugin>
     
    			
    			<plugin>
    				<groupId>org.apache.maven.plugins</groupId>
    				<artifactId>maven-dependency-plugin</artifactId>
    				<executions>
    					<execution>
    						<id>copy-lib</id>
    						<phase>package</phase>
    						<goals>
    							<goal>copy-dependencies</goal>
    						</goals>
    						<configuration>
    							<outputDirectory>target/lib</outputDirectory>
    							<excludeTransitive>false</excludeTransitive>
    							<stripVersion>false</stripVersion>
    							<includeScope>compile</includeScope>
    						</configuration>
    					</execution>
    				</executions>
    			</plugin>
     
    		</plugins>
    </build>

使用maven窗口的package指令打包，target结果如下：

![img][img 4] ![img][img 5]

使用java.ext.dirs指定lib路径启动,（我这里使用-Dloader.path没有加载成功）

java -jar -Djava.ext.dirs=lib xxx-0.0.1-SNAPSHOT.jar

注：这里使用java.ext.dirs有一个问题：可能有些java内在的库调用会失败，比如我这里调用到了jce.jar>javax>crypto>Mac>getInstance会失败。参考链接https://blog.csdn.net/w47\_csdn/article/details/80254459 中的一段话：

> 首先介绍下java.ext.dirs参数的使用和环境变量：java中系统属性java.ext.dirs指定的目录由ExtClassLoader加载器加载，如果您的程序没有指定该系统属性（-Djava.ext.dirs=sss/lib）那么该加载器默认加载 J A V A H O M E / l i b / e x t 目录下的所有 j a r 文件。但如果你手动指定系统属性且忘了把 JAVA\_HOME/lib/ext目录下的所有jar文件。但如果你手动指定系统属性且忘了把 JAVAHOME/lib/ext目录下的所有jar文件。但如果你手动指定系统属性且忘了把JAVA\_HOME/lib/ext路径给加上，那么ExtClassLoader不会去加载$JAVA\_HOME/lib/ext下面的jar文件，这意味着你将失去一些功能，例如java自带的加解密算法实现。

修改上述java指令，加上系统默认的ext路径$JAVA\_HOME/jre/lib/ext：

java -jar -Djava.ext.dirs=lib:$JAVA_HOME/jre/lib/ext xxx-0.0.1-SNAPSHOT.jar注意冒号做分隔符是linux，可能不同系统不一样

至此，依赖项在不变动的情况下不用重复传输，修改代码重新编译后只需要传输较小的jar包即可。

[94295832a81b40a689d5ca9c64ee1b8b.png]: https://img-blog.csdnimg.cn/94295832a81b40a689d5ca9c64ee1b8b.png
[img]: https://img-blog.csdnimg.cn/20200418190634352.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0x1Y2tfWlo=,size_16,color_FFFFFF,t_70
[img 1]: https://img-blog.csdnimg.cn/20200418190638906.png
[img 2]: https://img-blog.csdnimg.cn/20200418190806319.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0x1Y2tfWlo=,size_16,color_FFFFFF,t_70
[img 3]: https://img-blog.csdnimg.cn/20200418190816426.png
[https_docs.spring.io_spring-boot_docs_current_maven-plugin_reference_htmlsingle]: https://docs.spring.io/spring-boot/docs/current/maven-plugin/reference/htmlsingle/#goals-repackage-parameters-details-includes
[img 4]: https://img-blog.csdnimg.cn/20210219120620355.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JlaWppaHVraw==,size_16,color_FFFFFF,t_70
[img 5]: https://img-blog.csdnimg.cn/20210219120740934.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JlaWppaHVraw==,size_16,color_FFFFFF,t_70