找不到记录器（log4j）的附加程序？

Question

I have put log4j to my buildpath, but I get the following message when I run my application:

log4j:WARN No appenders could be found for logger (dao.hsqlmanager).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

What do these warnings mean? Whats the appender here?

Answer 1

This Short introduction to log4j guide is a little bit old but still valid.

That guide will give you some information about how to use loggers and appenders.

---

Just to get you going you have two simple approaches you can take.

First one is to just add this line to your main method:

BasicConfigurator.configure();

Second approach is to add this standard log4j.properties (taken from the above mentioned guide) file to your classpath:

# Set root logger level to DEBUG and its only appender to A1.
log4j.rootLogger=DEBUG, A1

# A1 is set to be a ConsoleAppender.
log4j.appender.A1=org.apache.log4j.ConsoleAppender

# A1 uses PatternLayout.
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n

Answer 2

It looks like you need to add the location of your log4j.properties file to the Classpath in Eclipse.

Make sure your project is open in Eclipse, then click on the "Run" menu at the top of Eclipse and click on the following:

1. Run
2. Run Configurations
3. Classpath (tab)
4. User Entries
5. Advanced (button on the right)
6. Add Folders
7. then navigate to the folder that contains your log4j.properties file
8. Apply
9. Run

The error message should no longer appear.

Answer 3

Quick solution:

1. add code to main function :

    String log4jConfPath = "/path/to/log4j.properties"; PropertyConfigurator.configure(log4jConfPath);

2. create a file named log4j.properties at /path/to

   log4j.rootLogger=INFO, stdout log4j.appender.stdout=org.apache.log4j.ConsoleAppender log4j.appender.stdout.Target=System.out log4j.appender.stdout.layout=org.apache.log4j.PatternLayout log4j.appender.stdout.layout.ConversionPattern=%d{yy/MM/dd HH:mm:ss} %p %c{2}: %m%n

Answer 4

This is just a warning.

Fixing

This occurs when the default configuration files log4j.properties and log4j.xml can not be found and the application performs no explicit configuration.

To fix that, simply create/copy log4j.properties or log4j.xml into your a location on the classpath (usually the same as the jar files).

Optionally set java option: -Dlog4j.configuration=file:///path/to/log4j.properties .

log4j uses Thread.getContextClassLoader().getResource() to locate the default configuration files and does not directly check the file system. Knowing the appropriate location to place log4j.properties or log4j.xml requires understanding the search strategy of the class loader in use. log4j does not provide a default configuration since output to the console or to the file system may be prohibited in some environments.

Debugging

For debugging, you may try to use -Dlog4j.debug=true parameter.

Configuration of log4j.properties

Sample configuration of log4j.properties :

# Set root logger level to DEBUG and its only appender to A1.
log4j.rootLogger=DEBUG, A1

# A1 is set to be a ConsoleAppender.
log4j.appender.A1=org.apache.log4j.ConsoleAppender

# A1 uses PatternLayout.
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n

# Print only messages of level WARN or above in the package com.foo.
log4j.logger.com.foo=WARN

Here is another configuration file that uses multiple appenders:

log4j.rootLogger=debug, stdout, R

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

# Pattern to output the caller's file name and line number.
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] (%F:%L) - %m%n

log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=example.log

log4j.appender.R.MaxFileSize=100KB
# Keep one backup file
log4j.appender.R.MaxBackupIndex=1

log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%p %t %c - %m%n

Apache Solr

If using Solr , copy <solr>/example/resources/log4j.properties into a location on the classpath .

Sample configuration of log4j.properties from Solr goes like:

#  Logging level
solr.log=logs/
log4j.rootLogger=INFO, file, CONSOLE

log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender

log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=%-4r [%t] %-5p %c %x \u2013 %m%n

#- size rotation with log cleanup.
log4j.appender.file=org.apache.log4j.RollingFileAppender
log4j.appender.file.MaxFileSize=4MB
log4j.appender.file.MaxBackupIndex=9

#- File to log to and log format
log4j.appender.file.File=${solr.log}/solr.log
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%-5p - %d{yyyy-MM-dd HH:mm:ss.SSS}; %C; %m\n

log4j.logger.org.apache.zookeeper=WARN
log4j.logger.org.apache.hadoop=WARN

# set to INFO to enable infostream log messages
log4j.logger.org.apache.solr.update.LoggingInfoStream=OFF

---

See also:

• Short introduction to log4j: Default Initialization Procedure
• Why can't log4j find my properties in a J2EE or WAR application?

Answer 5

Most of the answers here suggested that log4j.properties file be placed in the right location(for maven project, it should be located in src/main/resources )

But for me, the problem is that my log4j.properties is not correctly configured. Here's a sample that works for me, you can try it out first.

# Root logger option
log4j.rootLogger=INFO, stdout

# Direct log messages to stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

Answer 6

As explained earlier there are 2 approaches

First one is to just add this line to your main method:

BasicConfigurator.configure();

Second approach is to add this standard log4j.properties file to your classpath:

While taking second approach you need to make sure you initialize the file properly, Eg.

Properties props = new Properties();
props.load(new FileInputStream("log4j property file path"));
props.setProperty("log4j.appender.File.File", "Folder where you want to store log files/" + "File Name");

Make sure you create required folder to store log files.

Answer 7

You use the Logger in your code to log a message. The Appender is a Object appended to a Logger to write the message to a specific target. There are FileAppender to write to text-files or the ConsoleAppender to write to the Console. You need to show your code of the Logger and Appender setup for more help.

please read the tutorial for a better understanding of the interaction of Logger and Appender.

Answer 8

Make sure the properties file has properly set. And again, it seems like that the compiler cannot find the properties file, you can set as follow at the pom (only when you use maven project).

<build>
       <sourceDirectory> src/main/java</sourceDirectory>
       <testSourceDirectory> src/test/java</testSourceDirectory>
        <resources>
             <resource>
                  <directory>resources</directory>
             </resource>
        </resources>           
</build >

Answer 9

I get the same error. Here the problem which leads to this error message:

I create some objects which use the Logger before I configure the log4j:

Logger.getLogger(Lang.class.getName()).debug("Loading language: " + filename);

Solution: Configure the log4j at the beginning in the main method:

PropertyConfigurator.configure(xmlLog4JConfigFile); 
// or BasicConfigurator.configure(); if you dont have a config file

Answer 10

I faced the same issue when I tried to run the JUnit test class.

The issue is resolved after I manually added the log4j.properties file in the src/test/resources folder.

Adding the below code to the log4j.properties file solved the issue:

# Root logger option
log4j.rootLogger=INFO, file, stdout

# Direct log messages to a log file
log4j.appender.file=org.apache.log4j.RollingFileAppender
log4j.appender.file.File=C:\\logging.log
log4j.appender.file.MaxFileSize=10MB
log4j.appender.file.MaxBackupIndex=10
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

# Direct log messages to stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

Answer 11

Add the following as the first code:

Properties prop = new Properties();
prop.setProperty("log4j.rootLogger", "WARN");
PropertyConfigurator.configure(prop);

Answer 12

I think you should understand where the log4j jar file or the Java code looks for the log4j configuration files.

src/main/resources/log4j.properties is Eclipse path. Place them in a proper location so that you don't have to hard code the absolute path in code.

Read my article and sample solution for that https://askyourquestions.info/how-to-see-where-the-log-is-logger-in-slf4j/

Answer 13

Another reason this may happen (in RCP4) is that you are using multiple logging frameworks in your target file. As an example, this will occur if you use a combination of slf4j, log4j and ch.qos.logback.slf4j in your target files content tab.

Answer 14

In my case, the error was the flag " additivity ". If it's "false" for you root project package, then the child packages will not have an appender and you will see the " appender not found " error.

Answer 15

如果您正在使用 Eclipse 并且在一切正常后突然出现此问题，请尝试转到Project - Clean - Clean 。

Answer 16

I ran into this issue when trying to build an executable jar with maven in intellij 12. It turned out that because the java manifest file didn't include a class path the log4j properties file couldn't be found at the root level (where the jar file was executed from.)

FYI I was getting the logger like this:

Logger log = LogManager.getLogger(MyClassIWantedToLogFrom.class);

And I was able to get it to work with a pom file that included this:

         <plugin>
            <artifactId>maven-assembly-plugin</artifactId>
            <version>2.2-beta-5</version>
            <configuration>
                <archive>
                    <manifest>
                        <addClasspath>true</addClasspath> 
                        <mainClass>com.mycompany.mainPackage.mainClass</mainClass>
                    </manifest>
                    <manifestEntries>
                        <Class-Path>.</Class-Path> <!-- need to add current directory to classpath properties files can be found -->
                    </manifestEntries>
                </archive>
                <descriptorRefs>
                    <descriptorRef>jar-with-dependencies</descriptorRef>
                </descriptorRefs>
            </configuration>
            <executions>
                <execution>
                    <id>make-assembly</id>
                    <phase>package</phase>
                    <goals>
                        <goal>single</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>

Answer 17

Make sure your project is open in Eclipse, then click on the "Run" menu at the top of Eclipse and click on the following:

1. Run

2. Run Configurations

3. Classpath (tab)

4. User Entries

5. add jar on the right

6. add log4j jar file

7. Apply

8. Run

The error message should no longer appear.

Answer 18

The reason can be lack of the word static in some:

final static Logger logging = Logger.getLogger(ProcessorTest.class);

If I make logger the instance field, I am getting exactly this very warning:

No appenders could be found for logger (org.apache.kafka.producer.Sender)

What is worse, the warning points not to ProcessorTest , where the mistake lives, but to an absolutely different class (Sender) as a source of problems. That class has correct set logger and need not any changes! We could look for the problem for ages!

Answer 19

I faced the same problem when I use log4j2. My problem is caused by using wrong dependent library:

<dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
        <scope>runtime</scope>
    </dependency>

Instead, I should use:

<dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-slf4j-impl</artifactId>
        <scope>runtime</scope>
    </dependency>

In my case, I have a log4j2.xml defined in my "resources" directory, and specified to use it by:

System.setProperty("log4j.configurationFile", "log4j2.xml");

Answer 20

Log4J display this warning message when Log4j Java code is searching to create a first log line in your program.

At this moment, Log4j make 2 things

1. it search to find log4j.properties file
2. it search to instantiate the appender define in log4j.properties

If log4J doesn't find log4j.properties file or if appender declared in log4j.rootlogger are not defined elsewhere in log4j.properties file the warning message is displayed.

CAUTION: the content of Properties file must be correct.

The following content is NOT correct

log4j.rootLogger=file

log4j.appender.FILE=org.apache.log4j.FileAppender
log4j.appender.FILE.File=c:/Trace/MsgStackLogging.log
log4j.appender.FILE.layout=org.apache.log4j.PatternLayout
log4j.appender.FILE.layout.ConversionPattern=%m%n
log4j.appender.FILE.ImmediateFlush=true
log4j.appender.FILE.Threshold=debug
log4j.appender.FILE.Append=false

because file appender is declared in LOWER-CASE in log4j.rootlogger statement and defined in log4j.appender statement using UPPER-CASE !

A correct file would be

log4j.rootLogger=FILE

log4j.appender.FILE=org.apache.log4j.FileAppender
log4j.appender.FILE.File=c:/Trace/MsgStackLogging.log
log4j.appender.FILE.layout=org.apache.log4j.PatternLayout
log4j.appender.FILE.layout.ConversionPattern=%m%n
log4j.appender.FILE.ImmediateFlush=true
log4j.appender.FILE.Threshold=debug
log4j.appender.FILE.Append=false

If MAVEN is used, you must put log4j.properties files in src/main/resources AND start a MAVEN build.

Log4j.properties file is then copied in target/classes folder.

Log4J use the log4j.properties file that it found in target/classes !

Answer 21

I had this problem too. I just forgot to mark the resources directory in IntelliJ IDEA

1. Rightclick on your directory
2. Mark directory as
3. Resources root

Answer 22

First of all: Create a log4j.properties file

# Root logger option
log4j.rootLogger=INFO, stdout

# Direct log messages to stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

Place it in src/main/resources/

After that, use this 2 dependencies:

<dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.5</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.5</version>
        </dependency>

It is necessary to add this final dependency to POM file:

<!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.1.5.RELEASE</version>
        </dependency>

Answer 23

My Eclipse installation could not find log4j.properties when running JUnit tests from Eclipse, even though the file was located at src/test/resources .

The reason was that Eclipse (or the m2e connector) did not copy content from src/test/resources to the expected output folder target/test-classes - the root cause was that in the project's properties under Java Build Path -> Source tab -> Source folders on build path -> src/test/resources , somehow there was an Excluded: ** entry. I removed that excluded entry.

Alternatively, I could have manually copied src/test/resources/log4j.properties to target/test-classes/log4j.properties .

Answer 24

If log4j.properties is indeed on the classpath, you are using Spring Boot to make a WAR file for deployment to an app server, you are omitting a web.xml file in favour of Spring Boot's autoconfigure, and you are not getting any log messages whatsoever, you need to explicitly configure Log4j. Assuming you are using Log4j 1.2.x:

public class AppConfig extends SpringBootServletInitializer {

    public static void main( String[] args ) {
        // Launch the application
        ConfigurableApplicationContext context = SpringApplication.run( AppConfig.class, args );
    }

    @Override
    protected SpringApplicationBuilder configure( SpringApplicationBuilder application ) {
        InputStream log4j = this.getClass().getClassLoader().getResourceAsStream("log4j.properties");
        PropertyConfigurator.configure(log4j);
        return application;
    }

// Other beans as required...
}

Answer 25

也许在java构建路径中添加相关项目包含log4j，当我在使用eclipse的mahout项目中遇到这个问题时，我将mahout_h2o添加到其中，它有效！

Answer 26

if you work together with a lot of projects you may face a style problem.

*you have to have one lof4j.properties file and this file is included log properties of other project.

*Beside you can try to put log4j properties files into src path when the project is worked Linux OS, libs of other project and log4.properties files can be under one folder into a location on the classpath.

Answer 27

First import:

 import org.apache.log4j.PropertyConfigurator;

Then add below code to main method:

String log4jConfPath ="path to/log4j.properties";
PropertyConfigurator.configure(log4jConfPath);

Create a file at path to and add the below code to that file.

log4j.rootLogger=INFO, stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{yy/MM/dd HH:mm:ss} %p %c{2}: %m%n

Answer 28

The solution on this site worked for me https://crunchify.com/java-how-to-configure-log4j-logger-property-correctly/ . I now see no warnings at all from log4j

I put this in a log4j.properties file that I put in src/main/resources

# This sets the global logging level and specifies the appenders
log4j.rootLogger=INFO, theConsoleAppender

# settings for the console appender
log4j.appender.theConsoleAppender=org.apache.log4j.ConsoleAppender
log4j.appender.theConsoleAppender.layout=org.apache.log4j.PatternLayout
log4j.appender.theConsoleAppender.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n

Answer 29

Consider the log4j JVM argument Dlog4j.configuration

In general:

Add the JVM argument that points out the log4j config file. The syntax is just like follows:

java [ options ] -jar file.jar [ arguments ]

A sample of a real command line is just like the following:

java -Dlog4j.configuration=conf/log4j.xml -jar myJarFile.jar myArg1 myArg2

For IntelliJ IDE users:

1.Run/Debug Configurations
2.Edit configurations...
3.VM options
4.Enter the same value also starting with "-D"

Tips:

1.Eclipse IDE users will find an equivalent approach

2.For the run/debug configuration editor, it's very likely that, at the beginning of the times, your particular executable file is not there. Depending on the size of the project you're currently working on, it can be unpleasant to navigate directories to find it. It's less of a hassle if you just run/execute the file (click play) once before proceeding to run/debug config no matter what the execution result is.

3.Pay attention to your working directory, relative paths, and classpath.

Answer 30

For me, the reason was apparently different, and the error message misleading.

With just this in my build.gradle, it would complain that slf4j was missing at the beginning of the log, but still log things, albeit in a poor format:

    compile 'log4j:log4j:1.2.17'

Adding that dependency would cause the discussed "no appenders could be found" error message for me, even though I had defined them in src/main/java/log4j.properties :

    compile 'log4j:log4j:1.2.17'
    compile 'org.slf4j:slf4j-log4j12:1.7.25'

Finally, adding the following dependency (which I only guessed at by copycatting it from another project) resolved the issue:

    compile 'log4j:log4j:1.2.17'
    compile 'org.slf4j:slf4j-log4j12:1.7.25'
    compile 'commons-logging:commons-logging:1.2'

I don't know why, but with this it works. Any insights on that?

Answer 31

在java eclipse中，将conf_ref复制到conf文件夹。