In Java standalone application, you can use -D option to pass in the system properties : $ java -Dgeoip.file="/home/mkyong/geoip/test.db" test.jar In Java web application, you can pass the system properties via context-param in web.xml : web.xml <web-app> <context-param> <param-name>geoip.file</param-name> <param-value>/home/mkyong/geoip/test.db</param-value> </context-param> </web-app>
In this tutorial, we will show you how to import a “List” from a properties file, via Spring EL @Value Tested with : Spring 4.0.6 JDK 1.7 Spring @Value and List In Spring @Value, you can use the split() method to inject the ‘List” in one line. config.properties server.name=hydra,zeus server.id=100,102,103 AppConfigTest.java package com.mkyong.analyzer.test; import java.util.List; […]
Spring default loads application.properties into the application’s environment, and we can use @PropertySource to load custom .properties files. file.properties file.path=/server1/file/path Application.java @Configuration @PropertySource("classpath:file.properties") public class Application { @Value("${file.path}") private String path; //… } Table of contents: 1. Project Structure 2. Properties Files 3. @PropertySource and @Value 4. Loads property files from multiple sources 5. Placeholder […]
This article shows how to provide a default value for the @Value annotation. In the below code, if the property.name doesn’t exist in the application properties or environment, defaultValue will be assigned to the propertyName field. SimpleComponent.java import org.springframework.beans.factory.annotation.Value; import org.springframework.stereotype.Component; @Component public class SimpleComponent { @Value("${property.name:defaultValue}") private String propertyName; // getters, setters, etc } […]
To allow multiple private keys connect to different servers, edit ~/.ssh/config : ~/.ssh/config Host 10.10.10.1 IdentityFile ~/.ssh/linode_rsa Host 200.20.20.2 IdentityFile ~/.ssh/id_rsa If you SSH to 10.10.10.1, private key ~/.ssh/linode_rsa will be used. If you SSH to 200.20.20.2, private key ~/.ssh/id_rsa will be used. 1. Single Private Key for Multiple Servers 1.1 You have following public […]
In this tutorial, we will show you how to enable remote access to a MongoDB server. Here is the tested environment : 1. MongoDB Server Private IP – 192.168.161.100 Public IP – 45.56.65.100 MongoDB 2.6.3, port 27017 IpTables Firewall 2. Application Server (Same LAN network) Private IP – 192.168.161.200 Public IP – irrelevant 3. Developers […]
In this tutorial, we will show you how to use Logback Mapped Diagnostic Context (MDC) and SiftingAppender to create a separate log file for each thread. P.S Tested with Logback 1.1.2, should work in earlier version. Note More info, refer to this Logback MDC documentation 1. logback.xml example A logback.xml file to show you how […]
A simple Spring @PropertySource example to read a properties file. db.properties db.driver=oracle.jdbc.driver.OracleDriver AppConfig.java @Configuration @PropertySource("classpath:db.properties") public class AppConfig { @Value("${db.driver}") private String driver; But the property placeholder ${} is unable to resolve in @Value, if print out the driver variable, it will display string ${db.driver} directly, instead of “oracle.jdbc.driver.OracleDriver”. Solution To resolve ${} in Spring […]
A code snippet to show you how to get the number of available processors / cores / CPUs in your environment. int processors = Runtime.getRuntime().availableProcessors(); System.out.println(processors); Output 8 P.S Tested with Intel(R) Core(TM) i7-4770 CPU @3.40GHz
In this tutorial, we will show you how to change the Eclipse Theme. Tools used : Eclipse 4.4 Luna, works on earlier version. Eclipse Color Theme Plugin Figure : This is how your final Eclipse IDE looks like 1. Install Eclipse Color Theme Plugin Install the theme plugin and restart Eclipse. Eclipse menu -> Help […]
For self-reference, this article shows you how to create a Abstract class for Spring Controller, or a template method design pattern. 1. Abstract Controller In Abstract class, the @Controller annotation is optional, your implemented class will apply it. AbstractResultController.java package com.mkyong.web.controller; import java.util.Map; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.servlet.ModelAndView; […]
Here are a few logback.xml examples that are used in my projects, just for sharing. P.S Tested with Logback 1.2.3 1. Send logs to Console All logging will be redirected to console. logback.xml <configuration> <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender"> <layout class="ch.qos.logback.classic.PatternLayout"> <Pattern> %d{HH:mm:ss.SSS} [%t] %-5level %logger{36} – %msg%n </Pattern> </layout> </appender> <logger name="com.mkyong" level="debug" additivity="false"> <appender-ref ref="CONSOLE"/> […]
In this article, we will show you how to use Jsoup to check if an URL is going to redirect. 1. URL Redirection Normally, a redirect URL will return an HTTP code of 301 or 307, and the target URL will be existed in the response header “location” field. Review a sample of HTTP Response […]
This MongoDB article shows you how to remove a field from document and array. 1. Remove a field from Documents Sample of document, and you want to remove the field “affLink”. domain.json { “_id” : 1, “domain” : “mkyong.com”, “affLink” : “abc” } To remove a field from all documents, set {multi: true}, else only […]
Review a Javascript code snippet to call a function which declared inside jQuery code : <script> //javascript function submitSearchForm() { updateErrorMessage("Please enter a website url"); } //jquery jQuery(document).ready(function($) { function updateErrorMessage(msg) { $(‘#error’).html(msg).hide().fadeIn(500); } } ); </script> But, browser console shows the updateErrorMessage function is not defined. Uncaught ReferenceError: updateErrorMessage is not defined Solution To […]
Spring @Profile allow developers to register beans by condition. For example, register beans based on what operating system (Windows, *nix) your application is running, or load a database properties file based on the application running in development, test, staging or production environment. In this tutorial, we will show you a Spring @Profile application, which does […]
This is common to mix XML configuration into Spring @Configuration, because developers are used to the XML namespaces. In Spring, you can use @ImportResource to import Spring XML configuration files into @Configuration : AppConfig.java import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.ImportResource; @Configuration @ImportResource("classpath:/config/spring.xml") public class AppConfig { } Another example AppConfig.java import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.ImportResource; import org.springframework.context.annotation.Import; @Configuration […]
A document, and you want to update all the ‘source’ values to UPPERCASE. whois.json { “_id” : NumberLong(1), “country” : “au”, “source” : “apnic” } { “_id” : NumberLong(2), “country” : “cn”, “source” : “apnic” } { “_id” : NumberLong(3), “country” : “us”, “source” : “arin” } Solution No sure if there is any ready […]
In this tutorial, we will show you few examples (ZonedDateTime (Java 8), Date, Calendar and Joda Time) to convert a date and time between different time zones. All examples will be converting the date and time from (UTC+8:00) Asia/Singapore – Singapore Time Date : 22-1-2015 10:15:55 AM to (UTC-5:00) America/New_York – Eastern Standard Time Date […]
This Java example shows you how to display a list of TimeZone with GMT in front. P.S Tested with JDK 1.7 Java 8 You may interest at this example – Display all ZoneId and its UTC offset TimeZoneExample.java package com.mkyong.test; import java.util.TimeZone; import java.util.concurrent.TimeUnit; public class TimeZoneExample { public static void main(String[] args) { String[] […]
In this tutorial, we will show you how to enable data caching in a Spring application, and integrate with the popular Ehcache framework. Tools used Ehcache 2.9 Spring 4.1.4.RELEASE Logback 1.0.13 Maven 3 / Gradle 2 JDK 1.7 Eclipse 4.4 Note Spring supports caching since version 3.1 Spring cache has been significantly improved since version […]
Prior to MongoDB 2.6, there is no official function to $unset a field from array document. Note $unset is not working with arrays $pull is used to remove the entire record, not a particular field. 1. Arrays Documents In this article, we will show you how to remove the field “countryName” from below array. > […]
In this tutorial, we will show you two examples to help you getting started with Ehcache. Tools used : Ehcache 2.9 Maven 3 Gradle 2 JDK 1.7 P.S Ehcache required JDK 1.5 or above. 1. Project Directory Structure 2. Hello World Assume this is a Maven project : pom.xml <dependency> <groupId>net.sf.ehcache</groupId> <artifactId>ehcache</artifactId> <version>2.9.0</version> </dependency> Read […]
Review a simple Java application and log a message via Logback. App.java package com.mkyong.test; import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class App { private static final Logger log = LoggerFactory.getLogger(App.class); public static void main(String[] args) { log.debug("Testing"); } } P.S Tested with Logback 1.1.2 1. Problem A simple logback.xml to log a message to console. logback.xml […]
Ehcache is using SLF4j logging, to log stuff, put a slf4j implementation in the project classpath, in this example, we use logback. Tools used : Ehcache 2.9 Maven 3 logback 1.0.13 1. Project Directory Structure 2. Project Dependencies pom.xml <dependency> <groupId>net.sf.ehcache</groupId> <artifactId>ehcache</artifactId> <version>2.9.0</version> </dependency> <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-classic</artifactId> <version>1.0.13</version> </dependency> 3. Logback.xml Create a logback.xml file […]
Apache Ant tutorial with full example, including Ant installation, create JAR file, WAR file, working with dependency with Ivy tools , running jUnit and TestNG test and etc
In Java, you can use calendar.setTime(date) to convert a Date object to a Calendar object. Calendar calendar = Calendar.getInstance(); Date newDate = calendar.setTime(date); A Full example DateAndCalendar.java import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Date; public class DateAndCalendar { public static void main(String[] argv) throws ParseException { //1. Create a Date from String SimpleDateFormat sdf […]
In this tutorial, we will show you how to run a TestNG test in Ant build. 1. Run by Classes build.xml <taskdef name="testng" classname="org.testng.TestNGAntTask"> <classpath location="lib/testng-6.8.14.jar" /> </taskdef> <target name="testng" depends="compile"> <!– Assume test.path contains the project library dependencies –> <testng classpathref="test.path" outputDir="${report.dir}" haltOnFailure="true"> <!– Extra project classpath, which is not included in above "test.path" […]
In Maven, you can get source code for project dependencies in most IDEs like this : $ mvn dependency:sources $ mvn dependency:resolve -Dclassifier=javadoc Get source code for Jar Get javadoc for Jar, normally, developers don’t provide this. 1. Eclipse IDE In Eclipse IDE, it’s better to use the maven eclipse plugin: $ mvn eclipse:eclipse -DdownloadSources=true […]
In this tutorial, we will show you how to run a junit test in Ant build. 1. Run a unit test build.xml <target name="junit" depends="compile"> <junit printsummary="yes" haltonfailure="no"> <!– Project classpath, must include junit.jar –> <classpath refid="test.path" /> <!– test class –> <classpath location="${test.classes.dir}" /> <test name="com.mkyong.test.TestMessage" haltonfailure="no" todir="${report.dir}"> <formatter type="plain" /> <formatter type="xml" /> […]
Declares a junit task in Ant like this build.xml <!– Run jUnit –> <target name="junit" depends="resolve"> <junit printsummary="yes" haltonfailure="no"> <classpath refid="test.path" /> <classpath location="${build.dir}" /> <test name="com.mkyong.test.TestMessage" haltonfailure="no" todir="${report.dir}" outfile="result"> <formatter type="plain" /> <formatter type="xml" /> </test> </junit> </target> Run ant junit, but hits the following error message : BUILD FAILED build.xml:86: The <classpath> for […]
A code snippet to use Joda Time to convert a java.util.Date to different timezone : //java.util.Date : 22-1-2015 10:15:55 AM //System TimeZone : Asia/Singapore //Convert java.util.Date to America/New_York TimeZone DateTime dt = new DateTime(date); DateTimeZone dtZone = DateTimeZone.forID("America/New_York"); DateTime dtus = dt.withZone(dtZone); //21-1-2015 09:15:55 PM – Correct! //Convert Joda DateTime back to java.util.Date, and print […]
To install Apache Ant on Windows, you just need to download the Ant’s zip file, and Unzip it, and configure the ANT_HOME Windows environment variables. Tools Used : JDK 1.7 Apache Ant 1.9.4 Windows 8.1 1. JAVA_HOME Make sure JDK is installed, and JAVA_HOME is configured as Windows environment variable. 2. Download Apache Ant Visit […]
In this tutorial, we will show you how to install Apache Ant on Mac OSX. Tools : Apache Ant 1.9.4 Mac OSX Yosemite 10.10 Preinstalled Apache Ant? In older version of Mac, Apache Ant may be already installed by default, check if Apache Ant is installed : $ ant -v 1. Get Apache Ant Visit […]
Here’s the scenario, morning wake up and find out my Windows 8.1 is displaying a black screen upon boot, no login screen, but a movable white cursor, random clicks will display the small loading icons? Problem : Black screen upon boot, movable cursor. Unable to display the Windows login screen. Detail : Windows 8.1 64 […]
In Ant, you can use pathconvert task to print out the classpath from path : build.xml <path id="project.web.classpath"> <pathelement location="test/lib/junit-4.11.jar"/> <pathelement location="test/lib/hamcrest-core-1.3.jar"/> <fileset dir="${lib.web.dir}"> <include name="**/*.jar" /> </fileset> </path> <target name="print-classpath"> <pathconvert property="classpathInName" refid="project.web.classpath" /> <echo>Classpath is ${classpathInName}</echo> </target> Test : $ ant print-classpath Buildfile: /Users/mkyong/Documents/workspace/AntSpringMVC/build.xml print-classpath: [echo] Classpath is /Users/mkyong/Documents/workspace/AntSpringMVC/test/lib/junit-4.11.jar: /Users/mkyong/Documents/workspace/AntSpringMVC/testlib/hamcrest-core-1.3.jar: …… BUILD SUCCESSFUL […]
In Java, you can use Enum valueOf() to convert a String to an Enum object, review the following case study : 1. Java Enum example WhoisRIR.java package com.mkyong.whois.utils; public enum WhoisRIR { ARIN("whois.arin.net"), RIPE("whois.ripe.net"), APNIC("whois.apnic.net"), AFRINIC("whois.afrinic.net"), LACNIC("whois.lacnic.net"), JPNIC("whois.nic.ad.jp"), KRNIC("whois.nic.or.kr"), CNNIC("ipwhois.cnnic.cn"), UNKNOWN(""); private String url; WhoisRIR(String url) { this.url = url; } public String url() { […]
In this tutorial, we will show you how to extract a tar.gz file : tar vxf filename.tar.gz Example For example, apache-ant-1.9.4-bin.tar.gz in your ~/Download folder. $ cd ~ $ pwd /Users/mkyong # Optionally, create a new folder for the archived file. $ mkdir tools $ cd tools $ pwd /Users/mkyong/tools # Copy archived file to […]
By default, most Java web application servers are listening on port 8080, and it can easily cause the popular 8080 port conflict error. In Mac OSX, you can use sudo lsof -i :8080 | grep LISTEN to find out what program is listening on port 8080 : In terminal $ lsof -i :8080 | grep […]
In Mac OSX, you can use sudo lsof -i :80 to find out what program is using or listening on port 80 : In terminal $ sudo lsof -i :80 Password: COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME httpd 12649 root 5u IPv6 0xede4ca21f607010b 0t0 TCP *:http (LISTEN) httpd 12650 _www 5u IPv6 […]
