如何保证Spring bean的订单? PropertyPlaceHolder问题 [英] How to guarantee Spring bean order? PropertyPlaceHolder issue

问题描述

我正在使用spring进行非常简单的小型服务. 要配置数据库连接，我有一个DataSource bean，并且使用了一个使用.

I have a very simple and small service which I am using spring. To configure the database connection I have a DataSource bean and I use a "datasource.properties" file that is loaded using .

交易是Spring在读取属性文件之前初始化了数据源bean，这样，数据源bean尝试使用"$ {datasource.driver}"驱动程序.

The deal is that Spring is initializing the datasource bean before reading the properties file and this way, the datasource bean is trying use the "${datasource.driver}" driver.

如何保证在初始化数据源bean之前已加载属性?

How can I guarantee that the properties are loaded before initializing the datasource bean?

请参见下面的一段代码:

See a piece of code below:

<context:property-placeholder location="classpath:config/datasource.properties"/>
<import resource="classpath:spring/spring-*.xml"/>

<bean id="bdsDatasource"    class="com.mchange.v2.c3p0.ComboPooledDataSource"   destroy-method="close">
    <property name="driverClass"    value="${datasource.bds.driver}" />
    <property name="jdbcUrl"        value="${datasource.bds.url}" />
    <property name="user"           value="${datasource.bds.user}" />
    <property name="password"       value="${datasource.bds.password}" />
</bean>

推荐答案

if

• property-placeholder用于同一应用上下文中，并且
• <import resource="classpath:spring/spring-*.xml"/>没有自己的property-placeholder，该property-placeholder会覆盖import语句之前定义的property-placeholder，并且
• datasource.properties确实有一个datasource.bds.driver

if

• property-placeholder is used in the same app context, and
• <import resource="classpath:spring/spring-*.xml"/> does not have its own property-placeholder that overrides the one defined before the import statement, and
• datasource.properties really has a datasource.bds.driver

bdsDatasource的${datasource.bds.driver}应该没有问题的解决.

bdsDatasource's ${datasource.bds.driver} should be resolved with no problems.

有一个 是另一个property-placeholder，它覆盖了import语句之前定义的那个，这里有两个尝试:

there is another property-placeholder somewhere that overrides the one defined before the import statement, here are two things to try:

• 在导入语句之后定义property-placeholder :

<import resource="classpath:spring/spring-*.xml"/>
<context:property-placeholder location="classpath:config/datasource.properties"/>

<bean id="bdsDatasource"    class="com.mchange.v2.c3p0.ComboPooledDataSource"   destroy-method="close">
    <property name="driverClass"    value="${datasource.bds.driver}" />
    <property name="jdbcUrl"        value="${datasource.bds.url}" />
    <property name="user"           value="${datasource.bds.user}" />
    <property name="password"       value="${datasource.bds.password}" />
</bean>

• 将order属性添加到property-placeholder:
• add an order attribute to the property-placeholder:

<context:property-placeholder 
    location="classpath:config/datasource.properties" 
    order="0"/>

可能会覆盖多个property-placeholder bean的顺序

to potentially override the order of several property-placeholder beans

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