通过JVM 参数 实现spring 应用的二进制代码与配置分离。

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分离的好处就不说了。说下分离的思路。通过JVM 参数-D 添加 config.path 的property 到系统中。系统通过System.getProperty(config.path)得到配置文件的目录。然后通过spring的filecontext 加载。例子如下

来看下启动类

public class App 
{

  
    public static FileSystemXmlApplicationContext fileSystemXmlApplicationContext = null;
    
    static {
        if(System.getProperty("os.name").toLowerCase().contains("windows")){
            fileSystemXmlApplicationContext=new FileSystemXmlApplicationContext(System.getProperty("config.path").toString()+"\applicationContext_rules.xml");
        }else{
            fileSystemXmlApplicationContext=new FileSystemXmlApplicationContext(System.getProperty("config.path").toString()+"/applicationContext_rules.xml");
        }
    }
        

    public static void main( String[] args ) throws RuleEngineException, MqttException {
        
        EventRuleService eventRuleTransaction = fileSystemXmlApplicationContext.getBean(EventRuleService.class);
     
        System.out.println("test");
    }
}

System.getProperty("config.path").toString()+"\applicationContext_rules.xml" 这里就实现了代码与配置分离。接下来，在 applicationContext_rules.xml 文件中，还有诸如数据库，事务，mybatis mapper文件等的外链。都可以通过
取得config.path实现动态配置。
看例子

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:aop="http://www.springframework.org/schema/aop" xmlns:mybatis="http://mybatis.org/schema/mybatis-spring"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd http://mybatis.org/schema/mybatis-spring http://mybatis.org/schema/mybatis-spring.xsd">

    <context:property-placeholder 
            ignore-unresolvable="true" location="file:${config.path}/config.properties"/>
    <!--
    <context:property-placeholder
            ignore-unresolvable="true" location="classpath*:config.properties"/>
    -->

    <context:component-scan base-package="com.iot.aws" use-default-filters="true" annotation-config="true" >
    </context:component-scan>
    <bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor"/>
    <!-- db config 加载配置属性文件 -->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource"
          destroy-method="close">
        <property name="url" value="${jdbc.url}"/>
        <property name="driverClassName" value="${jdbc.driver}"/>
        <property name="username" value="${jdbc.user}"/>
        <property name="password" value="${jdbc.password}"/>
    </bean>

    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"></property>
    </bean>

    <tx:advice id="txAdvice" transaction-manager="transactionManager">
        <tx:attributes >
            <tx:method name="delete*" propagation="REQUIRED" read-only="false"  />
            <tx:method name="insert*" propagation="REQUIRED" read-only="false"/>
            <tx:method name="update*" propagation="REQUIRED" read-only="false"/>
            <tx:method name="find*" propagation="REQUIRED" read-only="true"/>
            <tx:method name="select*" propagation="REQUIRED" read-only="true"/>
            <tx:method name="get*" propagation="REQUIRED" read-only="true"/>
            <tx:method name="make*" propagation="SUPPORTS" read-only="false"/>
        </tx:attributes>
    </tx:advice>

    <aop:config proxy-target-class="true">
        <aop:pointcut expression="execution(* com.iot.aws.service.*.*(..))" id="serviceCutPoint"/>
        <aop:advisor advice-ref="txAdvice" pointcut-ref="serviceCutPoint"/>
    </aop:config>
  
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"></property>
        <property name="configLocation" value="file:${config.path}/mybatis-config.xml"></property>

        <!--mybatis配置文件自动扫描路径-->
        <property name="mapperLocations">
            <array>
                <value>file:${config.path}/mappers/*.xml</value>
            </array>
        </property>
    </bean>

    <mybatis:scan base-package="com.iot.aws.common.mapper" />


</beans>

在spring 中，可以通过${config.path} 获取JVM 添加的属性。通过上面的配置，所以的配置文件和mapper 映射文件都定位到相同的目录。

最后在启动应用的时候加入java -Dconfig.path="d:xxxxxyyyy" 然后将所有的配置文件和属性文件放到对应的目录中就可以了。