一、用placeholder给bean运行时注入值的步骤
Spring取得placeholder的值是用${...}
1.声明placeholder bean
(1)java方式
In order to use placeholder values, you must configure either a PropertyPlaceholder-
Configurer bean or a PropertySourcesPlaceholderConfigurer bean. Starting with
Spring 3.1, PropertySourcesPlaceholderConfigurer is preferred because it resolves
placeholders against the Spring Environment and its set of property sources.
The following @Bean method configures PropertySourcesPlaceholderConfigurer
in Java configuration:
@Bean
public
static PropertySourcesPlaceholderConfigurer placeholderConfigurer() {
return new PropertySourcesPlaceholderConfigurer();
}
(2)xml方式
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:c="http://www.springframework.org/schema/c"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd"> <context:property-placeholder
location="com/soundsystem/app.properties" /> <bean class="com.soundsystem.BlankDisc"
c:_0 = "${disc.title}"
c:_1 = "${disc.artist}"/> </beans>
2.注入
1.在java文件中用 @Value
如构造函数
public BlankDisc(
@Value("${disc.title}") String title,
@Value("${disc.artist}") String artist) {
this.title = title;
this.artist = artist;
}
2.xml
<bean id="sgtPeppers"
class="soundsystem.BlankDisc"
c:_title="${disc.title}"
c:_artist="${disc.artist}" />