使用Spring以编程方式访问属性文件？
使用Spring以编程方式访问属性文件？
提问于 2009-11-20 23:22:01
我们使用下面的代码从属性文件中注入带有属性的Spring bean。
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations" value="classpath:/my.properties"/>
</bean>
<bean id="blah" class="abc">
<property name="path" value="${the.path}"/>
</bean>有没有一种我们可以通过编程方式访问属性的方法？我正在试着在没有依赖注入的情况下做一些代码。所以我想要一些像这样的代码：
PropertyPlaceholderConfigurer props = new PropertyPlaceholderConfigurer();
props.load("classpath:/my.properties");
props.get("path");回答 13
Stack Overflow用户
回答已采纳
发布于 2009-11-20 23:29:40
Resource resource = new ClassPathResource("/my.properties");
Properties props = PropertiesLoaderUtils.loadProperties(resource);Stack Overflow用户
发布于 2012-04-18 06:39:26
如果您只想从代码中访问占位符值，则可以使用@Value注释：
@Value("${settings.some.property}")
String someValue;要从SPEL访问占位符，请使用以下语法：
#('${settings.some.property}')要将配置暴露给已关闭SPEL的视图，可以使用此技巧：
package com.my.app;
import java.util.Collection;
import java.util.Map;
import java.util.Set;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.stereotype.Component;
@Component
public class PropertyPlaceholderExposer implements Map<String, String>, BeanFactoryAware {
ConfigurableBeanFactory beanFactory;
@Override
public void setBeanFactory(BeanFactory beanFactory) {
this.beanFactory = (ConfigurableBeanFactory) beanFactory;
}
protected String resolveProperty(String name) {
String rv = beanFactory.resolveEmbeddedValue("${" + name + "}");
return rv;
}
@Override
public String get(Object key) {
return resolveProperty(key.toString());
}
@Override
public boolean containsKey(Object key) {
try {
resolveProperty(key.toString());
return true;
}
catch(Exception e) {
return false;
}
}
@Override public boolean isEmpty() { return false; }
@Override public Set<String> keySet() { throw new UnsupportedOperationException(); }
@Override public Set<java.util.Map.Entry<String, String>> entrySet() { throw new UnsupportedOperationException(); }
@Override public Collection<String> values() { throw new UnsupportedOperationException(); }
@Override public int size() { throw new UnsupportedOperationException(); }
@Override public boolean containsValue(Object value) { throw new UnsupportedOperationException(); }
@Override public void clear() { throw new UnsupportedOperationException(); }
@Override public String put(String key, String value) { throw new UnsupportedOperationException(); }
@Override public String remove(Object key) { throw new UnsupportedOperationException(); }
@Override public void putAll(Map<? extends String, ? extends String> t) { throw new UnsupportedOperationException(); }
}然后使用exposer向视图公开属性：
<bean class="org.springframework.web.servlet.view.UrlBasedViewResolver" id="tilesViewResolver">
<property name="viewClass" value="org.springframework.web.servlet.view.tiles2.TilesView"/>
<property name="attributesMap">
<map>
<entry key="config">
<bean class="com.my.app.PropertyPlaceholderExposer" />
</entry>
</map>
</property>
</bean>然后在视图中，像这样使用公开的属性：
${config['settings.some.property']}此解决方案的优势在于，您可以依赖由context:property-placeholder标记注入的标准占位符实现。
最后，如果您确实需要捕获所有占位符属性及其值，则必须通过StringValueResolver来确保占位符在属性值中按预期工作。下面的代码可以做到这一点。
package com.my.app;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;
import org.springframework.util.StringValueResolver;
public class AppConfig extends PropertyPlaceholderConfigurer implements Map<String, String> {
Map<String, String> props = new HashMap<String, String>();
@Override
protected void processProperties(ConfigurableListableBeanFactory beanFactory, Properties props)
throws BeansException {
this.props.clear();
for (Entry<Object, Object> e: props.entrySet())
this.props.put(e.getKey().toString(), e.getValue().toString());
super.processProperties(beanFactory, props);
}
@Override
protected void doProcessProperties(ConfigurableListableBeanFactory beanFactoryToProcess,
StringValueResolver valueResolver) {
super.doProcessProperties(beanFactoryToProcess, valueResolver);
for(Entry<String, String> e: props.entrySet())
e.setValue(valueResolver.resolveStringValue(e.getValue()));
}
// Implement map interface to access stored properties
@Override public Set<String> keySet() { return props.keySet(); }
@Override public Set<java.util.Map.Entry<String, String>> entrySet() { return props.entrySet(); }
@Override public Collection<String> values() { return props.values(); }
@Override public int size() { return props.size(); }
@Override public boolean isEmpty() { return props.isEmpty(); }
@Override public boolean containsValue(Object value) { return props.containsValue(value); }
@Override public boolean containsKey(Object key) { return props.containsKey(key); }
@Override public String get(Object key) { return props.get(key); }
@Override public void clear() { throw new UnsupportedOperationException(); }
@Override public String put(String key, String value) { throw new UnsupportedOperationException(); }
@Override public String remove(Object key) { throw new UnsupportedOperationException(); }
@Override public void putAll(Map<? extends String, ? extends String> t) { throw new UnsupportedOperationException(); }
}Stack Overflow用户
发布于 2009-11-20 23:29:08
我已经做到了这一点，它已经奏效了。
Properties props = PropertiesLoaderUtils.loadAllProperties("my.properties");
PropertyPlaceholderConfigurer props2 = new PropertyPlaceholderConfigurer();
props2.setProperties(props);这应该行得通。
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原文链接：
https://stackoverflow.com/questions/1771166
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