如何使用注释在Spring 4中重新加载属性文件？

Question

我有一个简单的应用程序,我使用几个属性文件来获取其他用户编辑的内容(链接到网站等).

我加载属性的类看起来像这样:

@Configuration
@PropertySource("classpath:salestipsWhitelist.properties")
public class SalestipsWhitelist {

@Autowired
Environment env;

public Environment getEnv() {
    return env;
}

public void setEnv(Environment env) {
    this.env = env;
}

@Bean
   public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
      return new PropertySourcesPlaceholderConfigurer();
   }
}

一些属性文件:

UPS_MPP_M_L=True
UPS_MPP_M_M=True
UPS_MPP_M_MP=True
UPS_MPP_M_S=True

这工作正常,但如果我对属性文件进行更改,我必须重新加载应用程序以可视化所做的任何更改.

如果我将位置移动到磁盘而不是类路径,是否有可能定期或手动重新加载？我不希望在更改时自动完成此操作,因为我想控制何时完成/更新.

Answer 1

这是一种享受.需要Java 7,Apache commons日志记录,Apache commons lang(v2.6)和Apache commons配置:

package corejava.reloadTest;

import org.apache.commons.configuration.ConfigurationException;
import org.apache.commons.configuration.PropertiesConfiguration;
import org.apache.commons.configuration.reloading.FileChangedReloadingStrategy;

public class MyApplicationProperties {
    private static PropertiesConfiguration configuration = null;

    static {
        try {
            configuration = new PropertiesConfiguration("test.properties");
        } catch (ConfigurationException e) {
            e.printStackTrace();
        }
        configuration.setReloadingStrategy(new FileChangedReloadingStrategy());
    }

    public static synchronized String getProperty(final String key) {
        return (String) configuration.getProperty(key);
    }
}

并测试它:

package corejava.reloadTest;

public class TestReloading {
    public static void main(String[] args) {
        while (true) {
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(MyApplicationProperties.getProperty("key"));
        }
    }
}

更改test.properties时的输出是这样的(test.props的原始内容是key = value,后来更改为key = value1 mid-program execution):

value
value
value
value
value
Jan 17, 2015 2:05:26 PM org.apache.commons.configuration.PropertiesConfiguration reload
INFO: Reloading configuration. URL is file:/D:/tools/workspace   /AutoReloadConfigUsingApacheCommons/resources/test.properties
value1
value1
value1

你也可以考虑官方Spring框架参考文档可 刷新的bean,使用像Groovy这样的DSL.

Answer 2

需要重写PropertyPlaceholderConfigurer以重新加载新属性

您需要重写processProperties方法以使StringValueResolver包含属性的内容变为可加载.这是我的代码

import java.io.IOException;
import java.util.Properties;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;
import org.springframework.util.PropertyPlaceholderHelper;
import org.springframework.util.PropertyPlaceholderHelper.PlaceholderResolver;
import org.springframework.util.StringValueResolver;


public class ReloadablePropertyPlaceholderConfigurer 
                                    extends PropertyPlaceholderConfigurer {

    private ReloadablePlaceholderResolvingStringValueResolver reloadableValueResolver;


    public void reloadProperties() throws IOException {
        Properties props = mergeProperties();
        this.reloadableValueResolver.refreshProperties(props);
    }


    @Override
    protected void processProperties(ConfigurableListableBeanFactory beanFactoryToProcess, Properties props)
            throws BeansException {
        this.reloadableValueResolver = new ReloadablePlaceholderResolvingStringValueResolver(props);
        StringValueResolver valueResolver = this.reloadableValueResolver;
        this.doProcessProperties(beanFactoryToProcess, valueResolver);
    }


    private class ReloadablePlaceholderResolvingStringValueResolver 
            implements StringValueResolver {

        private final PropertyPlaceholderHelper helper;
        private final ReloadablePropertyPlaceholderConfigurerResolver resolver;

        public ReloadablePlaceholderResolvingStringValueResolver(Properties props) {
            this.helper = new PropertyPlaceholderHelper(placeholderPrefix, placeholderSuffix, valueSeparator, ignoreUnresolvablePlaceholders);
            this.resolver = new ReloadablePropertyPlaceholderConfigurerResolver(props);
        }

        @Override
        public String resolveStringValue(String strVal) throws BeansException {
            String value = this.helper.replacePlaceholders(strVal, this.resolver);
            return (value.equals(nullValue) ? null : value);
        }

        private void refreshProperties(Properties props){
            this.resolver.setProps(props);
        }
    }

    private class ReloadablePropertyPlaceholderConfigurerResolver 
            implements PlaceholderResolver {

        private Properties props;
        private ReloadablePropertyPlaceholderConfigurerResolver(Properties props) {
            this.props = props;
        }

        @Override
        public String resolvePlaceholder(String placeholderName) {
            return ReloadablePropertyPlaceholderConfigurer.this.resolvePlaceholder(placeholderName, props, SYSTEM_PROPERTIES_MODE_FALLBACK);
        }

        public void setProps(Properties props) {
            this.props = props;
        }
   }
}

这里是properties-config.xml.all 的配置.所有这些属性都可以在运行时作为原型bean重新加载.

<bean id="propertyConfigurer" class="com.cn21.mail189.analysis.commons.expand.ReloadablePropertyPlaceholderConfigurer">
    <property name="ignoreUnresolvablePlaceholders" value="true" />
    <property name="locations">
        <list>
            <!-- database config -->
            <value>classpath:spring/dbconfig.properties</value>
            <!-- app config -->
            <value>classpath:spring/app.properties</value>
            <!-- some other config -->
            <value>classpath:xxxx.properties</value>
        </list>
    </property>
</bean>`