如何将属性值注入到使用注释配置的Spring Bean中？ [英] How can I inject a property value into a Spring Bean which was configured using annotations?

问题描述

我有一堆Spring bean，通过注释从类路径中获取，例如

  @Repository（personDao ）
 public class PersonDaoImpl extends AbstractDaoImpl implements PersonDao {
 //实现省略
} 
  

在Spring XML文件中，有一个 PropertyPlaceholderConfigurer

 < bean id =propertyConfigurer
 class =org.springframework.beans.factory.config.PropertyPlaceholderConfigurer> 
< property name =locationvalue =/ WEB-INF / app.properties/> 
< / bean> 
  

我想将app.properites中的一个属性注入上面显示的bean。我不能简单地做一些像

 < bean class =com.example.PersonDaoImpl > 
< property name =maxResultsvalue =$ {results.max}/> 
< / bean> 
  

由于PersonDaoImpl在Spring XML文件中不起作用（它通过注释从类路径中获取） 。我已经达到以下目的：

  @Repository（personDao）
 public class PersonDaoImpl extends AbstractDaoImpl实现PersonDao {
 
 @Resource（name =propertyConfigurer）
 protected void setProperties（PropertyPlaceholderConfigurer ppc）{
 //现在我如何访问results.max？ 
} 
} 
  

但我不清楚我如何访问属性我有兴趣从 ppc ？

解决方案

你可以这样做在Spring 3中使用EL支持。示例：

  @Value（＃{systemProperties.databaseName}）
 public void setDatabaseName（String dbName）{ ... 
 
 @Value（＃{strategyBean.databaseKeyGenerator}）
 public void setKeyGenerator（KeyGenerator kg）{...} 
  

systemProperties 是一个隐式对象， strategyBean 是一个bean名称。

另一个例子，当您想从属性对象。它还显示您可以将 @Value 应用于字段：

  @ Value（＃{myProperties ['github.oauth.clientId']}）
 private String githubOauthClientId; 
  

这是一个博客我写了一些更多的信息。

I have a bunch of Spring beans which are picked up from the classpath via annotations, e.g.

@Repository("personDao")
public class PersonDaoImpl extends AbstractDaoImpl implements PersonDao {
    // Implementation omitted
}

In the Spring XML file, there's a PropertyPlaceholderConfigurer defined:

<bean id="propertyConfigurer" 
  class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="location" value="/WEB-INF/app.properties" />
</bean> 

I want to inject one of the properties from app.properites into the bean shown above. I can't simply do something like

<bean class="com.example.PersonDaoImpl">
    <property name="maxResults" value="${results.max}"/>
</bean>

Because PersonDaoImpl does not feature in the Spring XML file (it is picked up from the classpath via annotations). I've got as far as the following:

@Repository("personDao")
public class PersonDaoImpl extends AbstractDaoImpl implements PersonDao {

    @Resource(name = "propertyConfigurer")
    protected void setProperties(PropertyPlaceholderConfigurer ppc) {
    // Now how do I access results.max? 
    }
}

But it's not clear to me how I access the property I'm interested in from ppc?

解决方案

You can do this in Spring 3 using EL support. Example:

@Value("#{systemProperties.databaseName}")
public void setDatabaseName(String dbName) { ... }

@Value("#{strategyBean.databaseKeyGenerator}")
public void setKeyGenerator(KeyGenerator kg) { ... }

systemProperties is an implicit object and strategyBean is a bean name.

One more example, which works when you want to grab a property from a Properties object. It also shows that you can apply @Value to fields:

@Value("#{myProperties['github.oauth.clientId']}")
private String githubOauthClientId;

Here is a blog post I wrote about this for a little more info.

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