mkyong

eclipse January 2, 2015 1 min read by mkyong 14 comments

Where is Eclipse deploy web application – Tomcat

By default Eclipse deploys web application to a internal plugin folder called wtpwebapps, which is located in the following directory : {Your_Workspace}/.metadata/.plugins/org.eclipse.wst.server.core/tmp{number}/wtpwebapps #Example 1 – Windows C:\Users\mkyong\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps #Example 2 – Mac OSX /Users/mkyong/Documents/workspace/.metadata/.plugins/org.eclipse.wst.server.core/tmp0/wtpwebapps How it works In Server view, double clicks on the “Tomcat Server”, the deployment work is defined in the Server Locations To […]

ant January 1, 2015 2 min read by mkyong 0 comments

How to debug Ant Ivy project in Eclipse IDE

In this tutorial, we will show you how to debug an Ant-Ivy web project in Eclipse IDE. Technologies used : Eclipse 4.2 Eclipse Tomcat Plugin Ant 1.9.4 Apache IvyDE Spring 4.1.3.RELEASE Note Previous Ant Spring MVC web project will be reused. 1. Install Apache IvyDE Install Apache IvyDE, it integrates Ivy into Eclipse IDE. Restart […]

ant December 26, 2014 7 min read by mkyong 2 comments

Ant – Spring MVC and WAR file Example

In this tutorial, we will show you how to use Ant build script to manage a Spring MVC web application project, create a WAR file and deploy to Tomcat. Technologies used : Eclipse 4.2 JDK 1.7 Ant 1.9.4 Ant-Ivy 2.4 logback 1.1.2 jstl 1.2 Spring 4.1.3.RELEASE Tomcat 7 1. Project Directory Review the final project […]

ant December 24, 2014 3 min read by mkyong 0 comments

Ant – Create a fat jar file

In this tutorial, we will show you how to use Ant build script to create a big far / uber Jar file, which mean include the entire project external dependencies into a single jar file. Technologies used : Ant 1.9.4 Ant-Ivy 2.4 logback 1.1.2 joda-time 2.5 1. Create a Fat Jar Previous Ant + External […]

ant November 21, 2014 6 min read by mkyong 8 comments

Ant – How To Create A Jar File with external libraries

In this tutorial, we will show you how to use Ant build script to create a Jar file and working with the project’s external libraries / dependencies. Technologies used : Eclipse 4.2 JDK 1.7 Ant 1.9.4 Ant-Ivy 2.4 logback 1.1.2 joda-time 2.5 P.S Previous Ant Java project will be reused. 1. Project Structure Figure 1.1 […]

ant October 30, 2014 3 min read by mkyong 6 comments

Ant – How to create a Java Project

In this tutorial, we will show you how to use Ant build tool to manage a Java project, compile, and package it into a Jar file. Technologies used : Eclipse 4.2 Ant 1.9.4 JDK 1.7 1. Create a Java Project In Eclipse IDE, create a new Java project named “AntDateUtils”. 2. Java Source Code Create […]

maven October 21, 2014 3 min read by mkyong 18 comments

Create a fat Jar file – Maven Assembly Plugin

In this tutorial, we will show you how to create a fat/uber jar with Maven Assembly Plugin. Which means create a Jar together with its dependency Jars into a single executable Jar file. Note Maven assembly plugin is not good in producing fat/uber jar, it may cause name conflict issue, it is better to use […]

maven October 19, 2014 1 min read by mkyong 3 comments

Maven – Exclude log4j.properties in Jar file

This example shows you how to use Maven to exclude the log4j.properties file from your Jar file. Note Please, DO NOT include the log4j.properties into the final Jar file, it will cause multiple log4j.properties files in the classpath, if someone is depending on your Jar, you may accidentally override their logging configurations, depends which Jar […]

maven October 18, 2014 5 min read by mkyong 6 comments

Maven – Create a fat Jar file – One-JAR example

In this tutorial, we will show you how to use Maven build tool, One-JAR plugin to create a single Jar together with its dependency Jars into a single executable Jar file, so called fat Jar. Tools used : Maven 3.1.1 JDK 1.7 Joda-time 2.5 1. Create a simple Java project Create a Java project from […]

java October 4, 2014 1 min read by mkyong 5 comments

Java – Cron job to run a jar file

Quartz is good, but often times we just need a simple scheduler system to run a jar file periodically. On *unix system, you can use the build-in cron to schedule a scheduler job easily. In this example, we will show you how to create a cron job on *nix to run a jar file, by […]

maven September 22, 2014 3 min read by mkyong 9 comments

Create a fat Jar file – Maven Shade Plugin

In this tutorial, we will show you how to use Maven Shade Plugin to create a Jar together with its dependency Jars into a single executable Jar file, so called fat Jar or uber Jar. Note Maven Shade plugin is a better plugin to create fat/uber jar, if compare with assembly plugin, because it provides […]

gradle September 5, 2014 1 min read by mkyong 4 comments

Gradle – How to skip unit test

Be default, Gradle build is abort if any unit tests is failed. Oftentimes, we still need to build the project even the unit test is failed. To skip the entire unit tests in Gradle build, uses this option-x test gradle build -x test Review a sample output : 1. Default Gradle build : $ gradle […]

spring mvc August 29, 2014 7 min read by mkyong 4 comments

Spring MVC hello world example (Gradle and JSP)

This tutorial shows you how to create a Spring Web MVC application with the Jakarta Server Pages (JSP; formerly JavaServer Pages) template. Technologies and tools used: Java 11 Spring 5.2.22.RELEASE JSP JSTL 1.2 Servlet API 4.0.1 Bootstrap 5.2.0 (webjars) IntelliJ IDEA Gradle 7.5.1 Gradle Gretty plugin 3.0.9 for embedded servlet containers (Tomcat 9 and Jetty […]

eclipse August 28, 2014 2 min read by mkyong 24 comments

How to configure hot deploy in Eclipse

In this tutorial, we will show you how to configure Eclipse debugger to support hot deploy, hot swap or hot code replace without restarting the Server, this speed development a lot. Environment : Eclipse 4.4 (Supported in older version as well) Eclipse Tomcat Plugin 1. Hot deploy example Review a simple hot deploy example, code […]

gradle August 27, 2014 3 min read by mkyong 31 comments

Gradle – Create a Jar file with dependencies

In this tutorial, we will show you how to use Gradle build tool to create a single Jar file with dependencies. Tools used : Gradle 2.0 JDK 1.7 Logback 1.1.2 1. Project Directory Create following project folder structure : By default, Gradle is using the standard Maven project structure. ${Project}/src/main/java/ ${Project}/src/main/resources/ ${Project}/src/test/java/ 2. Java Files […]

gradle August 25, 2014 1 min read by mkyong 1 comment

Gradle – bootstrap class path not set in conjunction with -source 1.5

My environment : JDK 1.7 Eclipse 4.4 Gradle 2.0 While gradle builld the project, I get following compile warning message : :compileJavawarning: [options] bootstrap class path not set in conjunction with -source 1.5 1 warning Figure : Eclipse console view. Solution The warning is saying you are using JDK 1.7, but try to compile the […]

gradle August 24, 2014 1 min read by mkyong 1 comment

Gradle : Add Eclipse project nature

Eclipse project natures are configured in the .project file. For example : .project <?xml version="1.0" encoding="UTF-8"?> <projectDescription> <name>hello</name> <comment></comment> <projects> </projects> <buildSpec> <buildCommand> <name>org.eclipse.jdt.core.javabuilder</name> <arguments> </arguments> </buildCommand> </buildSpec> <natures> <nature>org.springsource.ide.eclipse.gradle.core.nature</nature> <nature>org.eclipse.jdt.core.javanature</nature> </natures> </projectDescription> To add a nature, just modify the nature tag, and add whatever nature you want. In Gradle, you can add the Eclipse […]

maven August 19, 2014 1 min read by mkyong 3 comments

Maven – Exclude logback.xml in Jar file

This example shows you how to use Maven to exclude the logback.xml file from the final Jar file. Note Please, DO NOT include the logback.xml into the final Jar file, it will cause multiple logback.xml files in the classpath, if someone is using your Jar, you may override other’s logging configurations accidentally. pom.xml <project> <build> […]

nginx August 7, 2014 1 min read by mkyong 2 comments

Nginx : Block Referrer Spam

In this article, we will show you how to block referrer spam in one of our Nginx web server. 1. Find the Patterns Check the Nginx access.log file, and identify the “referrer spam” patterns. $ sudo tail -f /var/log/nginx/access.log Some patterns : 200 http://???.ru/engine/redirect.php?url=http://mywebsite.com/site/blogspot.com.au 200 http://???.com/tp/out.php?link=alternatevideo&url=http%3A//mywebsite.com/site/readyliftproshop.com 200 http://???.edu/online/redirect.asp?url=http://mywebsite/site/wheretoshophongkong.com We are going to block following patterns […]

nginx August 6, 2014 1 min read by mkyong 14 comments

Nginx + Apache Tomcat configuration example

This tutorial shows you how to configure Nginx as a reverse proxy to redirect the traffics from port 80 to Apache Tomcat on port 8080. Here is the environment in my Linode server : Debian 7.5 Nginx 1.2.1 Tomcat 7.0.28 P.S Both Nginx and Tomcat are installed via apt-get install. 1. Tomcat Configuration Edit server.xml, […]

java August 5, 2014 4 min read by mkyong 9 comments

Java : Return a random item from a List

Normally, we are using the following ways to generate a random number in Java. 1. ThreadLocalRandom (JDK 1.7) //Generate number between 0-9 int index = ThreadLocalRandom.current().nextInt(10); 2. Random() //Generate number between 0-9 Random random = new Random(); int index = random.nextInt(10); 3. Math.random() //Generate number between 0-9 int index = (int)(Math.random()*10); Note 1. For single […]

nginx August 1, 2014 1 min read by mkyong 0 comments

Nginx : Block User Agent

In Nginx, you can block certain user agents (normally it is crawler) like this : /etc/nginx/sites-enabled/default server { listen 80; server_name mysite.com; root /etc/tomcat7/webapps/mysite; if ($http_user_agent ~* (ahrefs|wget|crawler|majestic) ) { return 403; } location / { <!– xxx –> } } In above example, for “user agent” that contains one of this pattern : ahrefs|wget|crawler|majestic, […]

nginx July 31, 2014 1 min read by mkyong 6 comments

Count IP address in Nginx access logs

Recently, many referer spam hit on my server, below is the command I used to find and count the IP Address from a Nginx access log file. $ sudo awk ‘{print $1}’ /var/log/nginx/access.log | sort | uniq -c | sort -nr Full example. $ sudo awk ‘{print $1}’ /var/log/nginx/access.log | sort | uniq -c | […]

java July 30, 2014 2 min read by mkyong 15 comments

jsoup : Send search query to Google

This example shows you how to use jsoup to send a search query to Google. Document doc = Jsoup .connect("https://www.google.com/search?q=mario"); .userAgent("Mozilla/5.0") .timeout(5000).get(); Unusual traffic from your computer network Don’t use this example to spam Google, you will get above message from Google, read this Google answer. 1. jsoup example Example to send a “mario” search […]

java July 30, 2014 11 min read by mkyong 58 comments

Java – Read a file from resources folder

In Java, we can use getResourceAsStream or getResource to read a file or multiple files from a resources folder or root of the classpath. The getResourceAsStream method returns an InputStream. // the stream holding the file content InputStream is = getClass().getClassLoader().getResourceAsStream("file.txt"); // for static access, uses the class name directly InputStream is = JavaClassName.class.getClassLoader().getResourceAsStream("file.txt"); The […]

tomcat July 29, 2014 1 min read by mkyong 2 comments

How to change Tomcat manager default path ?

By default, Tomcat’s manager webapp is able to access via yourapp:8080/manager. It is a good practice to change the default /manager to something else, to avoid potential brute force attack. Environment Tomcat 7 (apt-get install) Debian 7.5 1. Solution This article show you how to change / rename the default manager webapp path from “/manager” […]

tomcat July 27, 2014 1 min read by mkyong 3 comments

How to change Tomcat to use JDK 7

The current environment is using Tomcat 7 + JDK 6. How to configure Tomcat to use JDK 7? Environment Tomcat 7 (apt-get install) Debian 7.5 JDK 6 and JDK 7 P.S Tomcat 7 is installed via apt-get Note You may interest at this tutorial – Apache Tomcat 8 + JDK 8 on Debian 1. Solution […]

tomcat July 26, 2014 2 min read by mkyong 1 comment

Find out Tomcat is using which JDK or JAVA_HOME

In this article, we will show you how to find out which JRE / JDK or JAVA_HOME is used by the Tomcat container. Environment : Debian 7.5 Tomcat 7, installed via apt-get JDK 6 and JDK 7 Note To understand how Tomcat pick up which JDK to run, refer to the Tomcat startup script – […]

tutorials July 25, 2014 1 min read by mkyong 3 comments

Log4j Tutorial

Apache log4j, a classic logging tool in Java. Here are a series of Log4j 1.2 tutorials.

eclipse July 25, 2014 1 min read by mkyong 0 comments

Eclipse – red-x icon didn’t display on project explorer

In Eclipse IDE, If a project contains errors, a small “red-x” icon will be displayed in the files that are causing the error. This useful feature is supported in Java related perspectives only, for example, “Package Explorer”. 1. Problem Personally, I prefer to use the “Project Explorer” perspective (pure folder structure), but the “red-x” icon […]

mongodb July 24, 2014 2 min read by mkyong 0 comments

MongoDB : write Aggregation result into a new collection

This article shows you 2 ways to export a MongoDB “aggregation” result into another new collection. 1. $out Example This $out operator is New in version 2.6. 1.1 Review a simple grouping example, it writes the result to a new variable “result”. > var result = db.hc_hosting.aggregate( { $group : { _id : "$hosting", total […]

unix / linux July 23, 2014 1 min read by mkyong 19 comments

Ubuntu : Status 14: The disk contains an unclean file system

Dual boot Windows and Ubuntu, but Ubuntu is unable to access the Windows partition /dev/sdb3, shows the following error message : Error mounting /dev/sdb3 … status 14: The disk contains an unclean file system (0, 0). Metadata kept in Windows cache, refused to mount. Failed to mount ‘/dev/sdb3’: Operation not permitted The NTFS partition is […]

unix / linux July 20, 2014 1 min read by mkyong 2 comments

Linux : How to gzip a folder

On Linux, gzip is unable to compress a folder, it used to compress a single file only. To compress a folder, you should use tar + gzip, which is tar -z. Note $ tar –help -z, -j, -J, –lzma Compress archive with gzip/bzip2/xz/lzma For example, tar -zcvf outputFileName folderToCompress 1. Tar + Gzip a folder […]

mongodb July 18, 2014 2 min read by mkyong 1 comment

mongoimport unable to import $numberLong

A collection with NumberLong type data as follows : > db.hc_whois.findOne(); { "_id" : NumberLong(3000001), "startIpInLong" : NumberLong(1543503872), "endIpInLong" : NumberLong(1544552447), "name" : "ap-net-1", //… } Export it with mongoexport : server1 $ mongoexport -d mydb -c hc_whois -o whois.json whois.json { "_id" : { "$numberLong" : "3000001" }, "startIpInLong" : { "$numberLong" : "1543503872" […]

java July 13, 2014 3 min read by mkyong 5 comments

How to Fix “Unsupported major.minor version 51.0” on Java

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java July 5, 2014 1 min read by mkyong 7 comments

servlet-api-2.5.jar – jar not loaded

Deployed a “war” file on Tomcat, and hits following error messages : Jul 17, 2014 7:59:55 PM org.apache.catalina.loader.WebappClassLoader validateJarFile INFO: validateJarFile(D:\apache-tomcat-7.0.53\webapps\hc\WEB-INF\lib\servlet-api-2.5.jar) – jar not loaded. See Servlet Spec 3.0, section 10.7.2. Offending class: javax/servlet/Servlet.class Tools used : JDK1.7 Maven 3 Tomcat 7 1. Reason The Tomcat’s container comes with own version of servlet-api.jar, and the […]

jsf2 July 5, 2014 6 min read by mkyong 2 comments

JSF 2 + Log4j Integration Example

In this tutorial, we will show you how to integrate the log4j framework with the JSF 2.x web application. JSF is using java.util.logging, you need extra works to redirect the logging from JSF’s java.util.logging to log4j, with a serious penalty of performance, make sure use this trick only during local development or debugging environment. Review […]

logging July 2, 2014 4 min read by mkyong 54 comments

Log4j hello world example

In this tutorial, we will show you how to use the classic log4j 1.2.x to log a debug or error message in a Java application. 1. Project Directory Review the final project structure, a standard Maven style Java project. 2. Get Log4j Declares the following dependencies : pom.xml <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.17</version> </dependency> For non-Maven […]

unix / linux June 23, 2014 1 min read by mkyong 0 comments

Download file from server using SSH

Normally, you use Secure copy or SCP to download a file from another server via SSH connection. For example, scp username@remotehost:remoteFileToDownload localFolderNameToSaveTheFile 1. SCP Examples 1.1 Download File From Server Example to download a log file (hc.audit.log) from server (198.58.x.x), into your current local folder. scp [email protected]:/var/log/tomcat7/hc.audit.log . 1.2 Upload File To Server Example to […]

unix / linux June 13, 2014 1 min read by mkyong 6 comments

Debian : Change default Java version

Deployed a Debian 7.5 on Linode server, the default is using OpenJDK 1.6. How to upgrade to OpenJDK 1.7? $ java -version java version "1.6.0_31" OpenJDK Runtime Environment (IcedTea6 1.13.3) (6b31-1.13.3-1~deb7u1) OpenJDK 64-Bit Server VM (build 23.25-b01, mixed mode) Tracing the java, it’s using the Debian’s alternative settings : $ ls -lsa /usr/bin/ | grep […]

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