traceid打印到log里如何修改log4j2.xml

要将 traceid 打印到 log4j2.xml 中，可以按照以下步骤进行操作：

1. 在 log4j2.xml 中添加一个 MDC Pattern Layout，例如：

<PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss.SSS} [%t] %-5level %logger{36} - %X{traceId} - %msg%n"/>

其中 `%X{traceId}` 表示输出 MDC 中名为 traceId 的键对应的值。

2. 在代码中设置 traceId 的值，例如：

import org.apache.logging.log4j.ThreadContext;

// 在需要设置 traceId 的地方调用
ThreadContext.put("traceId", "your-trace-id");

这样，在输出日志时就会将 traceId 对应的值打印出来了。需要注意的是，这里的 traceId 可以是任何你想要输出的值，只要在代码中将其设置到 MDC 中即可。

相关问题

怎么把mapper生成的sql打印出来

在使用Mybatis时，可以通过设置日志级别来打印出mapper生成的SQL语句。具体步骤如下：

1. 在log4j.properties或logback.xml等日志配置文件中，将Mybatis的日志级别设置为DEBUG或TRACE级别，例如：

log4j.logger.org.apache.ibatis=DEBUG

2. 在Mybatis的配置文件中，添加如下配置：

<configuration>
  ...
  <settings>
    ...
    <setting name="logImpl" value="LOG4J"/>
    ...
  </settings>
  ...
</configuration>

其中，logImpl属性指定了Mybatis使用的日志实现框架，在本例中指定为log4j。

3. 在执行查询时，可以通过在日志中查看到Mybatis生成的SQL语句。例如：

public interface UserMapper {
    @Select("select * from user where id = #{id}")
    User getUserById(int id);
}

SqlSession session = sqlSessionFactory.openSession();
try {
    UserMapper mapper = session.getMapper(UserMapper.class);
    User user = mapper.getUserById(1);
    System.out.println(user);
} finally {
    session.close();
}

在控制台中，可以看到类似以下的输出：

DEBUG [main] - o.a.i.t.JdbcTransaction.openConnection() - Opening JDBC Connection
DEBUG [main] - o.a.i.t.JdbcTransaction.getTransactionLog() - ==>  Preparing: select * from user where id = ?
DEBUG [main] - o.a.i.t.JdbcTransaction.getTransactionLog() - ==> Parameters: 1(Integer)
DEBUG [main] - o.a.i.t.JdbcTransaction.openConnection() - Created connection 1031165799.
DEBUG [main] - o.a.i.t.JdbcTransaction.getTransactionLog() - <==    Columns: id, username, password
DEBUG [main] - o.a.i.t.JdbcTransaction.getTransactionLog() - <==        Row: 1, test, 123456
DEBUG [main] - o.a.i.t.JdbcTransaction.closeConnection() - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@7afbc479]

其中，Preparing后面的语句即为Mybatis生成的SQL语句，Parameters后面的值为SQL语句中的参数。

<?xml version="1.0" encoding="utf-8" ?> <nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.nlog-project.org/schemas/NLog.xsd NLog.xsd" autoReload="true" throwExceptions="false" internalLogLevel="Off" internalLogFile="c:\temp\nlog-internal.log"> <!-- optional, add some variables https://github.com/nlog/NLog/wiki/Configuration-file#variables --> <variable name="myvar" value="myvalue"/> <!-- See https://github.com/nlog/nlog/wiki/Configuration-file for information on customizing logging rules and outputs. --> <targets> <!-- add your targets here See https://github.com/nlog/NLog/wiki/Targets for possible targets. See https://github.com/nlog/NLog/wiki/Layout-Renderers for the possible layout renderers. --> <!-- Write events to a file with the date in the filename. <target xsi:type="File" name="f" fileName="${basedir}/logs/${shortdate}.log" layout="${longdate} ${uppercase:${level}} ${message}" /> --> <target xsi:type="File" name="f" fileName="logs/${shortdate}.log" archiveFileName="logs/archive.{#}.log" archiveEvery="Day" archiveNumbering="Rolling" maxArchiveFiles="30" concurrentWrites="true" keepFileOpen="false" encoding="utf-8"> <layout xsi:type="CsvLayout" delimiter="auto" withHeader="true" > <column name="time" layout="${longdate:universalTime=false}" /> <column name="threadid" layout="${threadid}"/> <column name="level" layout="${level:upperCase=true}"/> <column name="callsite" layout="${callsite:includeSourcePath=true}" /> <column name="message" layout="${message}" /> <column name="stacktrace" layout="${callsite:includeSourcePath=true}" /> <column name="exception" layout="${exception:format=ToString}"/> </layout> </target> <target xsi:type="File" name="c" layout="${threadid} ${uppercase:${level}} ${message} ${callsite} ${exception:format=tostring}" /> </targets> <rules> <!-- add your logging rules here --> <!-- Write all events with minimal level of Debug (So Debug, Info, Warn, Error and Fatal, but not Trace) to "f" <logger name="*" minlevel="Debug" writeTo="f" /> --> <logger name="*" writeTo="f,c" /> </rules> </nlog>NLog这个配置给我怎么加注释说明

在NLog配置文件中添加注释可以使用XML的注释标记`<!-- 注释内容 -->`，例如：

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"      
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"      
      xsi:schemaLocation="http://www.nlog-project.org/schemas/NLog.xsd NLog.xsd"      
      autoReload="true"      
      throwExceptions="false"      
      internalLogLevel="Off" 
      internalLogFile="c:\temp\nlog-internal.log">

    <!-- 定义变量 -->
    <variable name="myvar" value="myvalue"/>

    <!-- 定义日志输出目标 -->
    <targets>
        <!-- 文件日志 -->
        <target xsi:type="File" name="f" fileName="logs/${shortdate}.log" 
                 archiveFileName="logs/archive.{#}.log" 
                 archiveEvery="Day" 
                 archiveNumbering="Rolling" 
                 maxArchiveFiles="30" 
                 concurrentWrites="true" 
                 keepFileOpen="false" encoding="utf-8">
            <layout xsi:type="CsvLayout" delimiter="auto" withHeader="true" >
                <column name="time" layout="${longdate:universalTime=false}" />
                <column name="threadid" layout="${threadid}"/>
                <column name="level" layout="${level:upperCase=true}"/>
                <column name="callsite" layout="${callsite:includeSourcePath=true}" />
                <column name="message" layout="${message}" />
                <column name="stacktrace" layout="${callsite:includeSourcePath=true}" />
                <column name="exception" layout="${exception:format=ToString}"/>
            </layout>
        </target>

        <!-- 控制台日志 -->
        <target xsi:type="File" name="c" layout="${threadid} ${uppercase:${level}} ${message} ${callsite} ${exception:format=tostring}" />
    </targets>

    <!-- 定义日志输出规则 -->
    <rules>
        <logger name="*" writeTo="f,c" />
    </rules>
</nlog>

在需要注释的地方添加注释即可，例如：

<!-- 定义变量 -->
<variable name="myvar" value="myvalue"/>

<!-- 定义日志输出目标 -->
<targets>
    <!-- 文件日志 -->
    <target xsi:type="File" name="f" fileName="logs/${shortdate}.log" 
             archiveFileName="logs/archive.{#}.log" 
             archiveEvery="Day" 
             archiveNumbering="Rolling" 
             maxArchiveFiles="30" 
             concurrentWrites="true" 
             keepFileOpen="false" encoding="utf-8">
        <layout xsi:type="CsvLayout" delimiter="auto" withHeader="true" >
            <column name="time" layout="${longdate:universalTime=false}" />
            <column name="threadid" layout="${threadid}"/>
            <column name="level" layout="${level:upperCase=true}"/>
            <column name="callsite" layout="${callsite:includeSourcePath=true}" />
            <column name="message" layout="${message}" />
            <column name="stacktrace" layout="${callsite:includeSourcePath=true}" />
            <column name="exception" layout="${exception:format=ToString}"/>
        </layout>
    </target>

    <!-- 控制台日志 -->
    <target xsi:type="File" name="c" layout="${threadid} ${uppercase:${level}} ${message} ${callsite} ${exception:format=tostring}" />
</targets>

<!-- 定义日志输出规则 -->
<rules>
    <logger name="*" writeTo="f,c" />
</rules>