直接注入

Bean直接注入示例：

@Bean("blankDisc1")
@Profile("dev")
@Primary
public BlankDisc getDevBlankDiscPrimary() {
	BlankDisc blankDisc = new BlankDisc();
	blankDisc.setTitle("Sgt. Pepper's Lonely Hearts Club Band dev Primary");
	List<String> tracks = new ArrayList<>();
	tracks.add("Sgt. Pepper's Lonely Hearts Club Band track dev Primary");
	blankDisc.setTracks(tracks);
	return blankDisc;
}

XML直接注入示例：

<bean id="blankDisc"
	class="com.zachary.soundsystem.impl.BlankDisc"
	p:title="Sgt. Pepper's Lonely Hearts Club Band"
	p:tracks-ref="trackList" />

注入外部的值

創建app.properties文件

disc.title=Sgt. Pepper's Lonely Hearts Club Band
disc.artist=The Beatles

重Environment中獲取外部注入值

@Configuration
@PropertySource("classpath:app.properties")
public class RuntimeInjectCompactDiscConfig {
	
	@Autowired
	Environment env;
	
	@Bean
	public BlankDisc setBlankDisc() {
		BlankDisc blankDisc = new BlankDisc();
		blankDisc.setTitle(env.getProperty("disc.title"));
		blankDisc.setArtist(env.getProperty("disc.artist"));
		blankDisc.setTracks(new ArrayList<>());
		return blankDisc;
	}

}

Environment中方法：

• String getProperty(String key)：返回一個String類型值
• String getProperty(String key, String defaultValue)：返回一個String類型值，沒有值時取默認值
• T getProperty(String key, Class type)：返回一個指定類型的值
• T getPropety(String key, Class type, T defaultValue)：返回一個指定類型的值，沒有時取默認值
• String getRequiredProperty(String key)：返回一個String類型的值，沒有定義時拋IllegalStateExceptio異常
• T getRequiredProperty(String key, Class targetType)：返回一個指定類型的值，沒有定義時拋IllegalStateExceptio異常
• boolean containsProperty(String key)：判斷某個屬性是否存在
• String[] getActiveProfiles()：返回**的profile名稱的數組
• String[] getDefaultProfiles()：返回默認profile名稱的數組
• boolean acceptsProfiles(Profiles profiles)：如果environment支持給定的profile，返回true

小知識：Environment 除了可以注入外，還可以從ConditionContext中獲得。

解析占位符 “&{…}”

為了使用占位符，我們需要配置一個PropertyPlacehokderConfigurer bean或者PropertySourcesPlaceholderConfigurer bean。從Spring3.1開始，推薦使用PropertySourcesPlaceholderConfigrer，因為它是基于Spring Environment及其屬性源解析占位符。

@Bean在Java中配置PropertySourcesPlaceholderConfigrer

示例的代碼：

@Bean
static PropertySourcesPlaceholderConfigurer placeholderConfigurer() {
	return new PropertySourcesPlaceholderConfigurer();
}

XML配置PropertySourcesPlaceholderConfigrer

context命名空間

xmlns:context="http://www.springframework.org/schema/context"
http://www.springframework.org/schema/context
https://www.springframework.org/schema/context/spring-context.xsd

示例代碼：

<?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"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd 
        http://www.springframework.org/schema/context
		https://www.springframework.org/schema/context/spring-context.xsd">
	
	<context:property-placeholder/>
</beans>

Java解析占位符

代碼示例

@Bean
@Qualifier("setBlankDisc2")
public BlankDisc setBlankDisc2(@Value("${disc.title}") String title, @Value("${disc.artist}") String aritst) {
	BlankDisc blankDisc = new BlankDisc();
	blankDisc.setTitle(title + "setBlankDisc2");
	blankDisc.setArtist(aritst + "setBlankDisc2");
	blankDisc.setTracks(new ArrayList<>());
	return blankDisc;
}

XML解析占位符

代碼示例
xml

<?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:p="http://www.springframework.org/schema/p"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:util="http://www.springframework.org/schema/util"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd 
        http://www.springframework.org/schema/util 
        https://www.springframework.org/schema/util/spring-util.xsd
        http://www.springframework.org/schema/context
		https://www.springframework.org/schema/context/spring-context.xsd">

	<context:property-placeholder/>
	
	<util:list id="trackList">
		<value>Sgt. Pepper's Lonely Hearts Club Band</value>
		<value>Sgt. Pepper's Lonely Hearts Club Band2</value>
		<value>Sgt. Pepper's Lonely Hearts Club Band3</value>
		<value>Sgt. Pepper's Lonely Hearts Club Band4</value>
	</util:list>
	
	<bean id="blankDisc"
		class="com.zachary.soundsystem.impl.BlankDisc"
		p:title="${disc.title}"
		p:artist="${disc.artist}"
		p:tracks-ref="trackList" />
</beans>

java配置類

@Configuration
@PropertySource("classpath:app.properties")
@ImportResource("classpath:cd-config.xml")
public class RuntimeInjectCompactDiscConfig {

	@Autowired
	Environment env;
}

測試類

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes=RuntimeInjectCompactDiscConfig.class)
public class RuntimeInjectCompactDiscConfigTest {

	@Autowired
	BlankDisc blankDisc;
	
	@Test
	public void setBlankDiscTest() {
		blankDisc.play();
	}
}