Added log4j support

Author: paulorb

build.gradle.kts

@@ -20,6 +20,7 @@ repositories {
     }
 }
 
+val log4jVersion = "2.12.1"
 
 dependencies {
     kapt("info.picocli:picocli-codegen:4.6.1")
@@ -30,6 +31,9 @@ dependencies {
     implementation ("com.github.paulorb:modbus-kt:1.0.12")
     implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.5.2")
     implementation("org.apache.commons:commons-csv:1.10.0")
+    implementation("org.apache.logging.log4j:log4j-core:$log4jVersion")
+    implementation("org.apache.logging.log4j:log4j-api:$log4jVersion")
+    implementation("org.apache.logging.log4j:log4j-slf4j-impl:$log4jVersion")
     testImplementation(kotlin("test"))
 }
 

src/main/kotlin/Main.kt

@@ -6,7 +6,8 @@ import picocli.CommandLine.Model.CommandSpec
 import java.util.*
 import java.util.concurrent.Callable
 import kotlin.system.exitProcess
-
+import org.apache.logging.log4j.core.config.Configurator
+import org.slf4j.LoggerFactory
 
 data class EnvParameter(
     var symbol : String,
@@ -50,6 +51,10 @@ class Checksum : Callable<Int> {
     private lateinit var modbusServer: ModbusServer
     private lateinit var environmentParameters: List<EnvParameter>
 
+    companion object {
+        val logger = LoggerFactory.getLogger("main")
+    }
+
     private fun processEnvironmentParameters(parameters: MutableList<String?>?): List<EnvParameter> {
         val envParameter = mutableListOf<EnvParameter>()
         parameters?.forEach { param ->
@@ -66,17 +71,18 @@ class Checksum : Callable<Int> {
     }
 
     override fun call(): Int {
+        Configurator.initialize(null, "log4j2.xml")
         val mainCoroutineScope = CoroutineScope(Dispatchers.Default)
         val configuration = ConfigurationParser()
 
         if(simulationRandomValues && file.isNotEmpty()){
-            println("-f and -sr cannot be mixed, one of the simulations must be chosen")
+            logger.error("-f and -sr cannot be mixed, one of the simulations must be chosen")
             return -1
         }
 
         environmentParameters = processEnvironmentParameters(parameters)
         if(environmentParameters.isNotEmpty()){
-            println("environment parameters: ${environmentParameters.toString()}")
+            logger.warn("environment parameters: ${environmentParameters.toString()}")
         }
 
         //val fileContents = Files.readAllBytes(file.toPath())

src/main/resources/log4j2.xml

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- Extra logging related to initialization of Log4j. 
+ Set to debug or trace if log4j initialization is failing. -->
+<Configuration status="warn">
+    <Appenders>
+        <!-- Console appender configuration -->
+        <Console name="console" target="SYSTEM_OUT">
+            <PatternLayout
+                    pattern="%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n" />
+        </Console>
+    </Appenders>
+    <Loggers>
+        <!-- Root logger referring to console appender -->
+        <Root level="info" additivity="false">
+            <AppenderRef ref="console" />
+        </Root>
+    </Loggers>
+</Configuration>