Starting from Spark Framework Tutorials, my first step was to follow Setting up Spark with Maven.
I use Eclipse as my favorite IDE and when I was at the end of the tutorial I run the app.
This is the first error I came across:
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SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
that I solved thanks to this Stackoverflow answer adding to pom.xml the following:
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<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>
Then there was this warning:
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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.
that I solved following this post: Fix for log4j WARN No appenders could be found for logger, Please initialize the log4j system properly:
adding log4j.xml to the project:
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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/" debug="false">
<!-- console appender -->
<appender name="console" class="org.apache.log4j.ConsoleAppender">
<param name="Target" value="System.out" />
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="%-5p %c{1} - %m%n" />
</layout>
</appender>
<!-- rolling file appender -->
<appender name="file" class="org.apache.log4j.RollingFileAppender">
<param name="File" value="logs/main.log" />
<param name="Append" value="true" />
<param name="ImmediateFlush" value="true" />
<param name="MaxFileSize" value="10MB" />
<param name="MaxBackupIndex" value="5" />
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="%d %d{Z} [%t] %-5p (%F:%L) - %m%n" />
</layout>
</appender>
<root>
<priority value="DEBUG" />
<appender-ref ref="file" />
<appender-ref ref="console" />
</root>
</log4j:configuration>
and thanks to this post: Log4j Tutorial addin the init() method to the MainApp.java file:
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package com.example.web.app;
import static spark.Spark.get;
import java.text.SimpleDateFormat;
import java.util.Date;
import org.apache.log4j.xml.DOMConfigurator;
public class MainApp {
static {
init();
}
public static void main(String[] args) {
get("/hello", (req, res) -> {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
String message = String.format("Hello World [%s]", sdf.format(new Date()));
return message;
});
}
/**
* method to init log4j configurations
*/
private static void init() {
DOMConfigurator.configure("log4j.xml");
}
}
Finally I was able to call my basic endpoint http://localhost:4567/hello from Postman.
Thanks to Chiu-Ki Chan for her advices about blogging in her video How to be an Android Expert from Android Summit 2015