日志配置热更新技术实践

这里我们定义一个LoggerRefresher，该类重写loadDefaults和loadConfiguration方法，通过JoranConfigurator加载logback配置，并在configureByApollo中添加一个apollo事件监听器，当发现logback.xml文件有变化时，重新执行configureByApollo方法刷新日志配置。

核心代码部分如下：

package com.zhoupu.zplog.refresher; 
 
import ch.qos.logback.classic.LoggerContext; 
import ch.qos.logback.classic.joran.JoranConfigurator; 
import ch.qos.logback.core.joran.spi.JoranException; 
import com.ctrip.framework.apollo.Config; 
import com.ctrip.framework.apollo.ConfigChangeListener; 
import com.ctrip.framework.apollo.ConfigService; 
import com.ctrip.framework.apollo.model.ConfigChangeEvent; 
import com.ctrip.framework.apollo.spring.config.PropertySourcesConstants; 
import org.slf4j.ILoggerFactory; 
import org.slf4j.Logger; 
import org.slf4j.LoggerFactory; 
import org.springframework.boot.SpringApplication; 
import org.springframework.boot.env.EnvironmentPostProcessor; 
import org.springframework.context.ApplicationContextInitializer; 
import org.springframework.context.ConfigurableApplicationContext; 
import org.springframework.core.Ordered; 
import org.springframework.core.env.ConfigurableEnvironment; 
import org.springframework.util.StringUtils; 
 
import javax.xml.parsers.DocumentBuilder; 
import javax.xml.parsers.DocumentBuilderFactory; 
import java.io.ByteArrayInputStream; 
import java.io.UnsupportedEncodingException; 
 
/** 
 * 
 * @author vigor 
 * @date 2019/6/14 上午11:27 
 */ 
 
public class LoggerRefresher implements ApplicationContextInitializer<ConfigurableApplicationContext>, EnvironmentPostProcessor, Ordered { 
    private static final Logger log = LoggerFactory.getLogger(LoggerRefresher.class); 
 
    private boolean loadFlag = false; 
 
    @Override 
    public void initialize(ConfigurableApplicationContext context) { 
        ConfigurableEnvironment environment = context.getEnvironment(); 
        load(environment); 
 
    } 
 
    @Override 
    public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application) { 
        load(environment); 
    } 
 
    @Override 
    public int getOrder() { 
        return 1; 
    } 
 
    private void load(ConfigurableEnvironment environment) { 
        if (!loadFlag) { 
            environment.getPropertySources().forEach(ps -> { 
                if (PropertySourcesConstants.APOLLO_BOOTSTRAP_PROPERTY_SOURCE_NAME.equals(ps.getName())) { 
                    configureByApollo(); 
                    loadFlag = true; 
                } 
            }); 
        } 
    } 
 
    private void configureByApollo() { 
        Config config = ConfigService.getConfig("logback.xml"); 
 
        String content = config.getProperty("content", ""); 
        if (StringUtils.isEmpty(content) || !validateXML(content)) { 
            return; 
        } 
 
        config.addChangeListener(new ConfigChangeListener() { 
            @Override 
            public void onChange(ConfigChangeEvent changeEvent) { 
                configureByApollo(); 
            } 
 
            @Override 
            public boolean equals(Object obj) { 
                if (this == obj) { 
                    return true; 
                } 
                if (this.getClass().equals(obj.getClass())) { 
                    return true; 
                } 
                return false; 
            } 
 
            @Override 
            public int hashCode() { 
                return 1; 
            } 
        }); 
 
        ILoggerFactory loggerFactory = LoggerFactory.getILoggerFactory(); 
        LoggerContext loggerContext = (LoggerContext) loggerFactory; 
        loggerContext.reset(); 
        JoranConfigurator configurator = new JoranConfigurator(); 
        configurator.setContext(loggerContext); 
        try { 
            configurator.doConfigure(new ByteArrayInputStream(content.getBytes("utf-8"))); 
            log.warn("*****************************logback configureByApollo success!********************************"); 
        } catch (JoranException e) { 
            e.printStackTrace(); 
        } catch (UnsupportedEncodingException e) { 
            e.printStackTrace(); 
        } 
    } 
 
    private boolean validateXML(String xml){ 
        boolean isValidated = true; 
        try { 
            DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance(); 
            DocumentBuilder builder = documentBuilderFactory.newDocumentBuilder(); 
            builder.parse(new ByteArrayInputStream(xml.getBytes("utf-8"))); 
        } catch (Exception e) { 
            log.error("apollo logback config error = {}", e); 
            isValidated = false; 
        } 
        return isValidated; 
    } 
 
} 

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