使用maven的profile切换项目各环境的参数

Java后端开发经常需要面对管理多套环境，一般有三种环境：开发，测试，生产。

各个环境之间的参数各不相同，比如MySQL、Redis等不同环境的host不一样，若每个环境都手动替换环境很容易出错，Maven profile正是提供了配置多种环境的功能。

创建一个与resource文件夹同级的文件夹，我这里取名叫profiles 

src/main/profiles/dev 目录对应开发环境的配置项目
src/main/profiles/beta 目录对应测试环境的配置项目
src/main/profiles/gray 目录对应灰度环境的配置项目
src/main/profiles/prd 目录对应生产环境的配置项目

接下来就是配置maven profile，如下，设定dev是默认激活的profile，此外根据具体的环境名称引入对应的资源文件夹。

<profiles>
    <profile>
        <!-- 本地开发环境 -->
        <id>dev</id>
        <properties>
            <!-- 这里的属性名是随便取的，可以在后续配置中引用 -->
            <profiles.dir>dev</profiles.dir>
        </properties>
        <!-- 是否默认 -->
        <activation>
            <activeByDefault>true</activeByDefault>
        </activation>
    </profile>

    <profile>
        <!-- beta环境 -->
        <id>beta</id>
        <properties>
            <profiles.dir>beta</profiles.dir>
        </properties>
    </profile>

    <profile>
        <!-- 灰度环境 -->
        <id>gray</id>
        <properties>
            <profiles.dir>gray</profiles.dir>
        </properties>
    </profile>
    
    <profile>
        <!-- 生产环境 -->
        <id>prod</id>
        <properties>
            <profiles.dir>prod</profiles.dir>
        </properties>
    </profile>
</profiles>

 activeByDefault标签的值为true的话表示默认的profile，使用mvn install命令起作用的就是它，这里为dev

resources标签定义要包含的资源，在下面的配置下package阶段会把resources文件夹里的 ${profiles.activation}/* 文件打包

这里的${profiles.activation}由命令maven的-P选项指定，例：mvn install -Pbeta 就是打包 beta/* 即beta目录下的所有文件 

<build>
    <finalName>${project.artifactId}</finalName>
    <resources>
        <!-- 这里的resource配置的是需要导入到项目的资源文件夹 -->
        <resource>
            <directory>src/main/resources</directory>
        </resource>
        <!-- 这里的${profiles.dir}是你上面配置的属性值，用于动态替换，比如打包的时候输入的是-Pdev则这里就是的${profiles.dir}就是dev的值 -->
        <resource>
            <directory>src/main/profiles/${profiles.dir}</directory>
        </resource>
    </resources>
</build>

如果要把这些文件放在spring容器中呢？

在war包中这些文件就是在classpath中。

<bean id="propertyConfigurer"
      class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="ignoreUnresolvablePlaceholders" value="true"/>
    <property name="locations">
        <list>
            <value>classpath:environment.properties</value>
            <value>classpath:jdbc.properties</value>
        </list>
    </property>
</bean>

使用maven的打包命令并且指定使用那个文件夹做为资源文件 

mvn clean package -Dmaven.test.skip=true -Pbeta

注意最后一个-P beta，maven会激活项目下的pom.xml配置的<profiles>标签下id为test。

maven命令选项

[root@winner_0715 bin]# mvn --help

usage: mvn [options] [<goal(s)>] [<phase(s)>]

Options:
 -am,--also-make                        If project list is specified, also
                                        build projects required by the
                                        list
 -amd,--also-make-dependents            If project list is specified, also
                                        build projects that depend on
                                        projects on the list
 -B,--batch-mode                        Run in non-interactive (batch)
                                        mode
 -b,--builder <arg>                     The id of the build strategy to
                                        use.
 -C,--strict-checksums                  Fail the build if checksums don't
                                        match
 -c,--lax-checksums                     Warn if checksums don't match
 -cpu,--check-plugin-updates            Ineffective, only kept for
                                        backward compatibility
 -D,--define <arg>                      Define a system property
 -e,--errors                            Produce execution error messages
 -emp,--encrypt-master-password <arg>   Encrypt master security password
 -ep,--encrypt-password <arg>           Encrypt server password
 -f,--file <arg>                        Force the use of an alternate POM
                                        file (or directory with pom.xml).
 -fae,--fail-at-end                     Only fail the build afterwards;
                                        allow all non-impacted builds to
                                        continue
 -ff,--fail-fast                        Stop at first failure in
                                        reactorized builds
 -fn,--fail-never                       NEVER fail the build, regardless
                                        of project result
 -gs,--global-settings <arg>            Alternate path for the global
                                        settings file
 -h,--help                              Display help information
 -l,--log-file <arg>                    Log file to where all build output
                                        will go.
 -llr,--legacy-local-repository         Use Maven 2 Legacy Local
                                        Repository behaviour, ie no use of
                                        _remote.repositories. Can also be
                                        activated by using
                                        -Dmaven.legacyLocalRepo=true
 -N,--non-recursive                     Do not recurse into sub-projects
 -npr,--no-plugin-registry              Ineffective, only kept for
                                        backward compatibility
 -npu,--no-plugin-updates               Ineffective, only kept for
                                        backward compatibility
 -nsu,--no-snapshot-updates             Suppress SNAPSHOT updates
 -o,--offline                           Work offline
 -P,--activate-profiles <arg>           Comma-delimited list of profiles
                                        to activate
 -pl,--projects <arg>                   Comma-delimited list of specified
                                        reactor projects to build instead
                                        of all projects. A project can be
                                        specified by [groupId]:artifactId
                                        or by its relative path.
 -q,--quiet                             Quiet output - only show errors
 -rf,--resume-from <arg>                Resume reactor from specified
                                        project
 -s,--settings <arg>                    Alternate path for the user
                                        settings file
 -T,--threads <arg>                     Thread count, for instance 2.0C
                                        where C is core multiplied
 -t,--toolchains <arg>                  Alternate path for the user
                                        toolchains file
 -U,--update-snapshots                  Forces a check for missing
                                        releases and updated snapshots on
                                        remote repositories
 -up,--update-plugins                   Ineffective, only kept for
                                        backward compatibility
 -V,--show-version                      Display version information
                                        WITHOUT stopping build
 -v,--version                           Display version information
 -X,--debug                             Produce execution debug output