spring boot 调整日志打印情况

logging:
  level:
    com:
      alibaba:
        cloud: debug
#        nacos: debug
    org:
      springframework:
        context: debug
        cloud: debug
#        boot: debug

项目启动时打印了

properties search order:PROPERTIES->JVM->ENV->DEFAULT_SETTING

查看具体代码位置，发现位于 nacos-client 中

SearchableProperties

private List<AbstractPropertySource> sortPropertySourceDefaultOrder(
		AbstractPropertySource... propertySources) {
	final Map<SourceType, AbstractPropertySource> sourceMap = Arrays.stream(propertySources)
			.collect(Collectors.toMap(AbstractPropertySource::getType, propertySource -> propertySource));
	final List<AbstractPropertySource> collect = DEFAULT_ORDER.stream().map(sourceMap::get)
			.collect(Collectors.toList());
	LOGGER.info("properties search order:PROPERTIES->JVM->ENV->DEFAULT_SETTING");
	return collect;
}

其中 DEFAULT_ORDER 引用当前类的全局变量

private static final List<SourceType> DEFAULT_ORDER = Arrays.asList(SourceType.PROPERTIES, SourceType.JVM,
            SourceType.ENV, SourceType.DEFAULT_SETTING);

间接引用 SourceType

package com.alibaba.nacos.client.env;

enum SourceType {
    /**
     * get value from properties.
     */
    PROPERTIES,
    /**
     * get value from jvm args.
     */
    JVM,
    /**
     * get value from system environment.
     */
    ENV,
    /**
     * get value from default setting.
     */
    DEFAULT_SETTING
}

通过模板模式来对各种参数的获取

package com.alibaba.nacos.client.env;

import java.util.Properties;

abstract class AbstractPropertySource {
    
    /**
     * get property's type.
     * @return name
     */
    abstract SourceType getType();
    
    /**
     * get property, if the value can not be got by the special key, the null will be returned.
     * @param key special key
     * @return value or null
     */
    abstract String getProperty(String key);
    
    /**
     * Tests if the specified object is a key in this propertySource.
     * @param key key – possible key
     * @return true if and only if the specified object is a key in this propertySource, false otherwise.
     */
    abstract boolean containsKey(String key);
    
    /**
     * to properties.
     * @return properties
     */
    abstract Properties asProperties();
    
}

PROPERTIES

package com.alibaba.nacos.client.env;

import java.util.ArrayList;
import java.util.List;
import java.util.ListIterator;
import java.util.Properties;

class PropertiesPropertySource extends AbstractPropertySource {
    
    private final Properties properties = new Properties();
    
    private final PropertiesPropertySource parent;
    
    PropertiesPropertySource() {
        this.parent = null;
    }
    
    PropertiesPropertySource(PropertiesPropertySource parent) {
        this.parent = parent;
    }
    
    @Override
    SourceType getType() {
        return SourceType.PROPERTIES;
    }
    
    @Override
    String getProperty(String key) {
        return getProperty(this, key);
    }
    
    private String getProperty(PropertiesPropertySource propertiesPropertySource, String key) {
        final String value = propertiesPropertySource.properties.getProperty(key);
        if (value != null) {
            return value;
        }
        final PropertiesPropertySource parent = propertiesPropertySource.parent;
        if (parent == null) {
            return null;
        }
        return getProperty(parent, key);
    }
    
    @Override
    boolean containsKey(String key) {
        return containsKey(this, key);
    }
    
    boolean containsKey(PropertiesPropertySource propertiesPropertySource, String key) {
        final boolean exist = propertiesPropertySource.properties.containsKey(key);
        if (exist) {
            return true;
        }
        final PropertiesPropertySource parent = propertiesPropertySource.parent;
        if (parent == null) {
            return false;
        }
        return containsKey(parent, key);
    }
    
    @Override
    Properties asProperties() {
        List<Properties> propertiesList = new ArrayList<>(8);
        
        propertiesList = lookForProperties(this, propertiesList);
        
        Properties ret = new Properties();
        final ListIterator<Properties> iterator = propertiesList.listIterator(propertiesList.size());
        while (iterator.hasPrevious()) {
            final Properties properties = iterator.previous();
            ret.putAll(properties);
        }
        return ret;
    }
    
    List<Properties> lookForProperties(PropertiesPropertySource propertiesPropertySource, List<Properties> propertiesList) {
        propertiesList.add(propertiesPropertySource.properties);
        final PropertiesPropertySource parent = propertiesPropertySource.parent;
        if (parent == null) {
            return propertiesList;
        }
        return lookForProperties(parent, propertiesList);
    }
    
    synchronized void setProperty(String key, String value) {
        properties.setProperty(key, value);
    }
    
    synchronized void addProperties(Properties source) {
        properties.putAll(source);
    }
}

JVM

package com.alibaba.nacos.client.env;

import java.util.Properties;

class JvmArgsPropertySource extends AbstractPropertySource {
    
    private final Properties properties;
    
    JvmArgsPropertySource() {
        this.properties = System.getProperties();
    }
    
    @Override
    SourceType getType() {
        return SourceType.JVM;
    }
    
    @Override
    String getProperty(String key) {
        return properties.getProperty(key);
    }
    
    @Override
    boolean containsKey(String key) {
        return properties.containsKey(key);
    }
    
    @Override
    Properties asProperties() {
        Properties properties = new Properties();
        properties.putAll(this.properties);
        return properties;
    }
}

jvm参数通过 System.getProperties() 来获取。

ENV

package com.alibaba.nacos.client.env;

import java.util.Map;
import java.util.Properties;

class SystemEnvPropertySource extends AbstractPropertySource {
    
    private final Map<String, String> env = System.getenv();
    
    @Override
    SourceType getType() {
        return SourceType.ENV;
    }
    
    @Override
    String getProperty(String key) {
        String checkedKey = checkPropertyName(key);
        if (checkedKey == null) {
            final String upperCaseKey = key.toUpperCase();
            if (!upperCaseKey.equals(key)) {
                checkedKey = checkPropertyName(upperCaseKey);
            }
        }
        if (checkedKey == null) {
            return null;
        }
        return env.get(checkedKey);
    }
    
    /**
     * copy from https://github.com/spring-projects/spring-framework.git
     * Copyright 2002-2021 the original author or authors.
     * Since:
     * 3.1
     * Author:
     * Chris Beams, Juergen Hoeller
     */
    private String checkPropertyName(String name) {
        // Check name as-is
        if (containsKey(name)) {
            return name;
        }
        // Check name with just dots replaced
        String noDotName = name.replace('.', '_');
        if (!name.equals(noDotName) && containsKey(noDotName)) {
            return noDotName;
        }
        // Check name with just hyphens replaced
        String noHyphenName = name.replace('-', '_');
        if (!name.equals(noHyphenName) && containsKey(noHyphenName)) {
            return noHyphenName;
        }
        // Check name with dots and hyphens replaced
        String noDotNoHyphenName = noDotName.replace('-', '_');
        if (!noDotName.equals(noDotNoHyphenName) && containsKey(noDotNoHyphenName)) {
            return noDotNoHyphenName;
        }
        // Give up
        return null;
    }
    
    @Override
    boolean containsKey(String name) {
        return this.env.containsKey(name);
    }
    
    @Override
    Properties asProperties() {
        Properties properties = new Properties();
        properties.putAll(this.env);
        return properties;
    }
}

环境变量通过 System.getenv() 来获取。

DEFAULT_SETTING

package com.alibaba.nacos.client.env;

import com.alibaba.nacos.common.utils.ResourceUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.InputStream;
import java.util.Properties;

class DefaultSettingPropertySource extends AbstractPropertySource {
    
    private static final Logger LOGGER = LoggerFactory.getLogger(DefaultSettingPropertySource.class);
    
    private static final String DEFAULT_SETTING_PATH = "classpath:nacos_default_setting.properties";
    
    private final Properties defaultSetting = new Properties();
    
    DefaultSettingPropertySource() {
        try (final InputStream inputStream = ResourceUtils.getResourceUrl(DEFAULT_SETTING_PATH).openStream()) {
            defaultSetting.load(inputStream);
        } catch (Exception e) {
            LOGGER.error("load default setting failed", e);
        }
    }
    
    @Override
    SourceType getType() {
        return SourceType.DEFAULT_SETTING;
    }
    
    @Override
    String getProperty(String key) {
        return defaultSetting.getProperty(key);
    }
    
    @Override
    boolean containsKey(String key) {
        return defaultSetting.containsKey(key);
    }
    
    @Override
    Properties asProperties() {
        Properties properties = new Properties();
        properties.putAll(defaultSetting);
        return properties;
    }
}

默认设置读取 nacos_default_setting.properties 中的配置。