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new 2825fefc0e Update logging.md (#2112)
2825fefc0e is described below
commit 2825fefc0ef9d057cbaa5bafcbab7c516b4131c1
Author: ethic-233 <[email protected]>
AuthorDate: Thu Feb 9 16:17:37 2023 +0800
Update logging.md (#2112)
---
.../observability/logging.md | 162 ++++++++++++++++++++-
1 file changed, 161 insertions(+), 1 deletion(-)
diff --git
a/content/zh/docs3-v2/java-sdk/advanced-features-and-usage/observability/logging.md
b/content/zh/docs3-v2/java-sdk/advanced-features-and-usage/observability/logging.md
index c4f0de8423..2bc207b035 100644
---
a/content/zh/docs3-v2/java-sdk/advanced-features-and-usage/observability/logging.md
+++
b/content/zh/docs3-v2/java-sdk/advanced-features-and-usage/observability/logging.md
@@ -5,4 +5,164 @@ linkTitle: "日志管理"
weight: 3
no_list: true
hide_summary: true
----
\ No newline at end of file
+---
+
+在 Dubbo 框架内所有的日志输出都是通过 LoggerFactory 这个静态工厂类来获得 Logger 的对象实体，并且抽离了一个
LoggerAdapter 用于对接第三方日志框架，所以就有了JDKLoggerAdapter, Log4jLoggerAdapter,
SLF4JLoggerAdapter等一些实现子类，分别对接了不同 Log 第三方实现。既然 Dubbo 能够支持这么多log实现，那么这些实现在 Dubbo
中优先级是在呢么样的呢？这里的优先级是只未配置指定的 logger 提供方的情况下，由 Dubbo 框架自己选择。优先级如下：
+
+| 第三方日志框架 | 优先级 |
+| ------------------------------------- |
------------------------------------------ |
+| Log4j | 最高（默认就用这个） |
+| SLF4J | 次高（上面没有采用这个） |
+| Common Logging(jcl就是common logging) | 次低（Log4j和SLF4J在项目中均没有就用这个） |
+| JDK log | 最低（最后的选择） |
+
+Dubbo 日志的调用方式，针对不同的日志打印系统，采用统一的 API 调用及输出，如：
+
+```java
+/**
+ * ChannelListenerDispatcher
+ */
+public class ChannelHandlerDispatcher implements ChannelHandler {
+
+ private static final ErrorTypeAwareLogger logger =
LoggerFactory.getErrorTypeAwareLogger(ChannelHandlerDispatcher.class);
+```
+
+Dubbo 采用的日志输出方式是首先从 dubbo.application.logger
系统变量中获取属性值，来判断到底采用哪种日志输出方式，如果没设置则按照默认的加载顺序加载相应的日志输出类，直到成功加载：
+
+顺序为：log4jLogger > slf4jLogger > JclLogger > JdkLogger
+
+LoggerFactory 在类加载过程中变量的初始化过程：
+
+```java
+// search common-used logging frameworks
+static {
+ String logger = System.getProperty("dubbo.application.logger", "");
+ switch (logger) {
+ case Slf4jLoggerAdapter.NAME:
+ setLoggerAdapter(new Slf4jLoggerAdapter());
+ break;
+ case JclLoggerAdapter.NAME:
+ setLoggerAdapter(new JclLoggerAdapter());
+ break;
+ case Log4jLoggerAdapter.NAME:
+ setLoggerAdapter(new Log4jLoggerAdapter());
+ break;
+ case JdkLoggerAdapter.NAME:
+ setLoggerAdapter(new JdkLoggerAdapter());
+ break;
+ case Log4j2LoggerAdapter.NAME:
+ setLoggerAdapter(new Log4j2LoggerAdapter());
+ break;
+ default:
+ List<Class<? extends LoggerAdapter>> candidates = Arrays.asList(
+ Log4jLoggerAdapter.class,
+ Slf4jLoggerAdapter.class,
+ Log4j2LoggerAdapter.class,
+ JclLoggerAdapter.class,
+ JdkLoggerAdapter.class
+ );
+ boolean found = false;
+ // try to use the first available adapter
+ for (Class<? extends LoggerAdapter> clazz : candidates) {
+ try {
+ LoggerAdapter loggerAdapter =
clazz.getConstructor().newInstance();
+ loggerAdapter.getLogger(LoggerFactory.class);
+ if (loggerAdapter.isConfigured()) {
+ setLoggerAdapter(loggerAdapter);
+ found = true;
+ break;
+ }
+ } catch (Exception | LinkageError ignored) {
+ // ignore
+ }
+ }
+ if (found) {
+ break;
+ }
+
+ System.err.println("Dubbo: Unable to find a proper configured
logger to log out.");
+ for (Class<? extends LoggerAdapter> clazz : candidates) {
+ try {
+ LoggerAdapter loggerAdapter =
clazz.getConstructor().newInstance();
+ loggerAdapter.getLogger(LoggerFactory.class);
+ setLoggerAdapter(loggerAdapter);
+ found = true;
+ break;
+ } catch (Throwable ignored) {
+ // ignore
+ }
+ }
+ if (found) {
+ System.err.println("Dubbo: Using default logger: " +
loggerAdapter.getClass().getName() + ". " +
+ "If you cannot see any log, please configure
-Ddubbo.application.logger property to your preferred logging framework.");
+ } else {
+ System.err.println("Dubbo: Unable to find any available logger
adapter to log out. Dubbo logs will be ignored. " +
+ "Please configure -Ddubbo.application.logger property and
add corresponding logging library to classpath.");
+ }
+ }
+}
+```
+
+上面这段静态块是在LoggerFactory里面，说明只要LoggerFactory类一加载就会去选择对应的日志提供方。大家可能会发现对日志的提供方其实是可以通过配置来指定的，因为静态块一开始是从当前jvm环境中获取dubbo.application.logger，这个参数是同java
-Ddubbo.application.logger=xxxx去指定的，如果是放在容器里面，就需要配置在容器启动的jvm参数里面。
+
+## 使用Log4j来提供日志输出
+
+你不用做过多的处理就可以开启dubbo的日志，因为dubbo默认就是使用log4j。你唯一需要做的就是配置一个name是"com.alibaba.dubbo"的logger就可以了，然后关联到对应的appender。如下：
+
+```xml
+<appender name="dubboAppender"
class="org.apache.log4j.DailyRollingFileAppender">
+ <param name="File" value="E:/dubbo.log" />
+ <param name="DatePattern" value="'.'yyyy-MM-dd'.log'" />
+ <layout class="org.apache.log4j.PatternLayout">
+ <param name="ConversionPattern"
+ value="[%d{MMdd HH:mm:ss SSS\} %-5p] [%t] %c{3\} - %m%n" />
+ </layout>
+</appender>
+<logger name="com.alibaba.dubbo" additivity="false">
+ <priority value ="info"/>
+ <appender-ref ref="dubboAppender" />
+</logger>
+```
+
+## 使用logback来提供日志输出
+
+这种情况，默认是看不到dubbo的日志输出的，除非出现异常，被你当前系统的日志框架拦截住了。我这里就拿当前使用最多的日志框架logback来做示例。我们知道logback天生和slf4j进行了集成，所以要在项目里面使用logback，调用slf4j暴露的接口就可以。所以要把dubbo的日志输出切换到logback，也就变成了切换到slf4j了。
+
+```xml
+<timestamp key="byDate" datePattern="yyyyMMdd"/>
+ <!-- dubbo log -->
+ <appender name="dubboRolling"
class="ch.qos.logback.core.rolling.RollingFileAppender">
+ <Encoding>UTF-8</Encoding>
+ <file>${LOG_HOME_DUBBO}/MTP-DUBBO.log</file>
+ <rollingPolicy
class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
+
<fileNamePattern>${LOG_HOME_DUBBO}/DEMO-%d{yyyy-MM-dd}.%i-DUBBO.zip</fileNamePattern>
+ <maxHistory>30</maxHistory>
+ <TimeBasedFileNamingAndTriggeringPolicy
class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
+ <MaxFileSize>100MB</MaxFileSize>
+ </TimeBasedFileNamingAndTriggeringPolicy>
+ </rollingPolicy>
+ <encoder>
+ <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level
%logger{36} - %msg%n</pattern>
+ <immediateFlush>true</immediateFlush>
+ </encoder>
+ </appender>
+ <logger name="com.alibaba.dubbo" level="DEBUG">
+ <appender-ref ref="dubboRolling"/>
+ </logger>
+```
+
+Dubbo 也可以将日志信息记录或者保存到文件中。
+
+1. 使用`accesslog`输出到`log4j`
+
+```xml
+<dubbo:protocol accesslog="true" name="dubbo" port="20880"/>
+<dubbo:protocol accesslog="true" name="rmi" port="1099" />
+```
+
+2. 输出到文件
+
+```xml
+<dubbo:protocol accesslog="http://localhost/log.txt"; name="dubbo"
port="20880"/>
+<dubbo:protocol accesslog="http://localhost/log2.txt"; name="rmi" port="1099" />
+```
