This example shows you how to get the HTTP request headers in Java. To get the HTTP request headers, you need this class HttpServletRequest : 1. HttpServletRequest Examples 1.1 Loop over the request header’s name and print out its value. WebUtils.java package com.mkyong.web.utils; import javax.servlet.http.HttpServletRequest; import java.util.Enumeration; import java.util.HashMap; import java.util.Map; public class WebUtils { […]
If you like my works and tutorials on “mkyong.com”, please consider making a donation of $10 or whatever you can to protect and sustain the following charities : Thanks. 1. Doctors Without Borders The Doctors Without Borders works in nearly 70 countries providing medical aid to those most in need regardless of their race, religion, […]
In this tutorial, we will show you how to use @Test attributes invocationCount and threadPoolSize to perform a load test or stress test on a website. Tools used : TestNG 6.8.7 Selenium 2.39.0 Maven 3 P.S We are using the Selenium library to automate browsers to access a website. 1. Project Dependency Get TestNG and […]
In this tutorial, we will show you how to create two custom annotations – @Test and @TestInfo, to simulate a simple unit test framework. P.S This unit test example is inspired by this official Java annotation article. 1. @Test Annotation This @interface tells Java this is a custom annotation. Later, you can annotate it on […]
A classic example, show you how to get started with TestNG unit test framework. Tools used : TestNG 6.8.7 Maven 3 Eclipse IDE 1. TestNG Dependency Add TestNG library in the pom.xml. pom.xml <dependency> <groupId>org.testng</groupId> <artifactId>testng</artifactId> <version>6.8.7</version> <scope>test</scope> </dependency> 2. TestNG Example Review a simple class, has a method to return a fixed email “[email protected]”. […]
In this tutorial, we show you how to convert an IP address to its decimal equivalent in Java, and vice versa. For examples : 255.255.255.255 <-> 4294967295 192.168.1.2 <-> 3232235778 1. IP Address to Decimal We show you two ways to convert an IP address to a decimal number Normal power of 256 Bit shifting […]
Before you understand what is & 0xFF, make sure you know following stuffs : Bitwise AND operator, link. Converts hex to/from binary, and decimal to/from binary. In short, & 0xFF is used to make sure you always get the last 8 bits. Let’s see an example to convert an IP address to/from decimal number. 1. […]
In this tutorial, we will show you how to include static resources like JavaScript or CSS in a JSP page. Summary steps : Put static resources like cs, js or images into this folder webapp\resources Create a Spring mvc:resources mapping Include in JSP page via JSTL tag c:url or Spring tag spring:url P.S This project […]
This article shows how to solve the java.lang.OutOfMemoryError: Java heap space in Eclipse IDE. Table of contents 1. Eclipse – OutOfMemoryError: Java heap space 2. Temporary fix – Increase the heap size 3. eclipse.ini 4. The solution, find the reason behind the heap size error. 5. References 1. Eclipse – OutOfMemoryError: Java heap space In […]
Review following documents : Collection : domain { "_id" : 1001, "domainName" : "google.com" "tag" : [ "search engine", "search", "find anything", "giant" ] }, { "_id" : 1002, "domainName" : "yahoo.com" "tag" : [ "search engine", "online portal", ] }, { "_id" : 1003, "domainName" : "mkyong.com" } 1. Question How to find all […]
In this tutorial, we show you how to integrate jQuery autocomplete plugin with Spring MVC. Tools and Libraries used : Spring MVC 3.2 jQuery autocomplete plugin – github Maven 3 Eclipse IDE Review the tutorial’s flows : An HTML page, with a textbox. If the user is tying on the textbox, it will fire an […]
This tutorial shows you how to work with java.util.Date and java.util.Calendar. 1. Java Date Examples Few examples to work with Date APIs. Example 1.1 – Convert Date to String. SimpleDateFormat sdf = new SimpleDateFormat("dd/M/yyyy"); String date = sdf.format(new Date()); System.out.println(date); //15/10/2013 Example 1.2 – Convert String to Date. SimpleDateFormat sdf = new SimpleDateFormat("dd-M-yyyy hh:mm:ss"); String […]
This article shows you how to attach the JDK source code in Eclipse IDE. In Eclipse, select Windows -> Preferences -> Java -> Installed JREs , expands rt.jar, select “Source attachment” and find the src.zip from your disk drive. P.S JDK source code is inside the src.zip. Note You may interest at this article – […]
The JDK source code is inside the src.zip, this article shows you how to get it on Windows, Ubuntu (Linux) and Mac OSX. 1. Windows In Windows, visit the Oracle website and download the JDK (not JRE). Install the JDK and the src.zip is inside the JDK installed folder, for example : C:\Program Files\Java\jdk1.7.0_40\src.zip 2. […]
A leap year is a year containing one additional day (366 days a year). Review the leap year algorithm : if year is divisible by 400 then is_leap_year else if year is divisible by 100 then not_leap_year else if year is divisible by 4 then is_leap_year else not_leap_year P.S Algorithm from wikipedia leap year. 1. […]
Two Java examples show you how to print the elapsed time in days, hours, minutes and seconds format. 1. Standard JDK Date APIs You need to calculate the elapsed time manually. DateTimeUtils.java package com.mkyong.dateUtils; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Date; public class DateTimeUtils { public static void main(String[] args) { DateTimeUtils obj = new DateTimeUtils(); […]
In Mongodb, you can use sort()to do the date sorting. 1. MongoDB Sorting Examples In Mongodb, to sort a “date” field, issues : //The ‘1’ = sort ascending (oldest to newest) db.domain.find().sort({lastModifiedDate:1}) { "_id" : 1, "lastModifiedDate" : ISODate("2013-08-13T07:18:04.774Z") } { "_id" : 2, "lastModifiedDate" : ISODate("2013-09-03T08:12:16.309Z") } { "_id" : 3, "lastModifiedDate" : ISODate("2013-10-03T08:12:16.309Z") […]
In SQL, the ‘like’ query is looks like this : select * from tags where tagName like ‘%apple%’ In MongoDB console, it looks like this : db.tags.find({"tagName": /apple/}) In Spring data mongodb, it implements with Criteria or BasicQuery : String tagName = "apple"; Query query = new Query(); query.limit(10); query.addCriteria(Criteria.where("tagName").regex(tagName)); mongoOperation.find(query, Tags.class); String tagName = […]
Review a simple jQuery example to loop over a JavaScript array object. var json = [ {"id":"1","tagName":"apple"}, {"id":"2","tagName":"orange"}, {"id":"3","tagName":"banana"}, {"id":"4","tagName":"watermelon"}, {"id":"5","tagName":"pineapple"} ]; $.each(json, function(idx, obj) { alert(obj.tagName); }); Above code snippet is working fine, prompts the “apple”, “orange” … as expected. Problem : JSON string Review below example, declares a JSON string (enclosed with single […]
There is no direct way to iterate over a Java List with jQuery, see the following case study : Spring controller @RequestMapping(value = "/", method = RequestMethod.GET) public ModelAndView getPages() { List<String> list = new ArrayList<String>(); list.add("List A"); list.add("List B"); list.add("List C"); list.add("List D"); list.add("List E"); ModelAndView model = new ModelAndView("somepage"); model.addObject("list", list); return model; […]
Below is a JSON string. JSON String { "name": "mkyong", "age": 30, "address": { "streetAddress": "88 8nd Street", "city": "New York" }, "phoneNumber": [ { "type": "home", "number": "111 111-1111" }, { "type": "fax", "number": "222 222-2222" } ] } To access the JSON object in JavaScript, parse it with JSON.parse(), and access it via […]
In this tutorial, we show you how to find a location using an IP address, with the following technologies : Spring MVC frameworks. jQuery (Ajax Request). GeoLite database. Google Map. Review the tutorial’s flows A page with a text input and button. Type an IP address, and clicks on the button. jQuery fires an Ajax […]
In this example, we show you how to find a location (country, city, latitude, longitude) using an IP address. 1. GeoLite Database The MaxMind provides a free GeoLite database (IP Address to Location). Get a free GeoLite free Databases – here Get a GeoIP client Java APIs – here Start code it. 2. GeoLite Java […]
There are many ways the favicon can be recognized by the web browser : Example 1 <head> <link rel="icon" href="http://example.com/image.ico" /> </head> Example 2 <head> <link rel="icon" href="http://example.com/image.png" /> </head> Example 3 – weird, but Google use it. <head> <meta content="/images/google_favicon_128.png" itemprop="image" /> </head> 1. Jsoup Example Code snippets to get above favicon with Jsoup. […]
In this tutorial, we show you how to do exception handling in Spring MVC frameworks. Normally, we use @ExceptionHandler to decide which “view” should be returned back if certain exception is raised. P.S This @ExceptionHandler class is available since Spring 3.0 1. Project Structure Review the project directory structure, a standard Maven project. 2. Custom […]
In this tutorial, we show you how to print the List values via JSTL c:forEach tag. P.S This web project is using Spring MVC frameworks v3.2 1. Project Structure Review the project directory structure, a standard Maven project. 2. Project Dependencies Add Spring and JSTL libraries. pom.xml <properties> <spring.version>3.2.2.RELEASE</spring.version> <jstl.version>1.2</jstl.version> </properties> <dependencies> <!– jstl –> […]
In this article, we show you 2 examples to join two lists in Java. JDK – List.addAll() Apache Common – ListUtils.union() 1. List.addAll() example Just combine two lists with List.addAll(). JoinListsExample.java package com.mkyong.example; import java.util.ArrayList; import java.util.List; public class JoinListsExample { public static void main(String[] args) { List<String> listA = new ArrayList<String>(); listA.add("A"); List<String> listB […]
Below code snippet shows you how to execute a JavaScript in Selenium WebDriver. WebDriver driver = new ChromeDriver(); if (driver instanceof JavascriptExecutor) { ((JavascriptExecutor) driver).executeScript("alert(‘hello world’);"); } 1. WebDriver Example In this example, it uses WebDriver to load “google.com”, and executes a simple alert () later. JavaScriptExample.java package com.mkyong.test; import org.openqa.selenium.JavascriptExecutor; import org.openqa.selenium.WebDriver; import org.openqa.selenium.chrome.ChromeDriver; […]
By default, the “.” doesn’t match line breaks. To match multiple lines, add (?s) prefix or enable the Pattern.DOTALL flag. 1. Example A address sample, we need to extract the “Address 1” only. Starting… Address 1: 88 app 2/8 superman taman, puchong 36100, Malaysia Address 2: abc End Failed : To extract “Address 1”, this […]
The Selenium WebDriver is closed, but the “chromedriver.exe” process is left hanging in the system. See figure : Problem Here is the code, a simple WebDriver example to load a URL and exists, but the chromedriver.exe never get killed. LoadWebPageExample.java package com.mkyong.test; import org.openqa.selenium.WebDriver; import org.openqa.selenium.chrome.ChromeDriver; import org.openqa.selenium.chrome.ChromeOptions; import org.openqa.selenium.remote.DesiredCapabilities; public class LoadWebPageExample { public […]
In Java, by default, the regular expression (regex) matching is case sensitive. To enable the regex case insensitive matching, add (?) prefix or enable the case insensitive flag directly in the Pattern.compile(). A regex pattern example. Pattern = Registrar:\\s(.*) Case Insensitive, add (?) prefix. Pattern = (?)Registrar:\\s(.*) Case Insensitive, add Pattern.CASE_INSENSITIVE flag. Pattern.compile("Registrar:\\s(.*)", Pattern.CASE_INSENSITIVE); 1. […]
A simple example to use Jackson to convert a JSON string to a Map. String json = "{name:\"mkyong\"}"; Map<String,String> map = new HashMap<String,String>(); ObjectMapper mapper = new ObjectMapper(); map = mapper.readValue(json, new TypeReference<HashMap<String,String>>(){}); Problem When the program is executed, it hits following error message org.codehaus.jackson.JsonParseException: Unexpected character (‘n’ (code 110)): was expecting double-quote to start […]
A desktop computer, Windows 8 is installed, connect to a nearby router via a wireless USB adapter. D-Link DWA-132 – Wireless N USB Adapter D-Link Wireless N300 Router DIR-615 Fiber optic internet If the computer is idle sometime, it will interval drops the wifi connection, and reconnect it again. The desktop computer was installed Windows […]
Developing a simple Java program to write a file in the C drive root directory (where Windows is installed), but the program prompts an “access is denied” error. Try to create an empty file in the C drive root directory manually, but no options to create any files, only new folder is allowed. P.S The […]
Spring Batch tutorials with full example, including itemReader, itemProcessor, itemWriter, Tasklet, Listener, unit test, scheduler, partitioning and etc.
In this tutorial, we will show you how to use the Quartz scheduler framework to schedule a Spring batch job to run every 10 seconds. Tools and libraries used Maven 3 Eclipse 4.2 JDK 1.6 Spring Core 3.2.2.RELEASE Spring Batch 2.2.0.RELEASE Quartz 1.8.6 The relationship looks like the following : Spring Batch <–> Spring QuartzJobBean […]
Spring Batch is a framework for batch processing – execution of a series of jobs. In Spring Batch, A job consists of many steps and each step consists of a READ-PROCESS-WRITE task or single operation task (tasklet). For “READ-PROCESS-WRITE” process, it means “read” data from the resources (csv, xml or database), “process” it and “write” […]
In this tutorial, we will show you how to use Spring TaskScheduler to schedule a batch job to run every 5 seconds. Tools and libraries used Maven 3 Eclipse 4.2 JDK 1.6 Spring Core 3.2.2.RELEASE Spring Batch 2.2.0.RELEASE 1. Project Directory Structure A standard Maven project. 2. Spring TaskScheduler Spring 3.0 introduces a TaskScheduler for […]
Photo Credit : Spring Source In Spring Batch, “Partitioning” is “multiple threads to process a range of data each”. For example, assume you have 100 records in a table, which has “primary id” assigned from 1 to 100, and you want to process the entire 100 records. Normally, the process starts from 1 to 100, […]
In this tutorial, we will show you how to read data from a MySQL database, with JdbcCursorItemReader and JdbcPagingItemReader, and write it into an XML file. Tools and libraries used Maven 3 Eclipse 4.2 JDK 1.6 Spring Core 3.2.2.RELEASE Spring OXM 3.2.2.RELEASE Spring Batch 2.2.0.RELEASE MySQL Java Driver 5.1.25 P.S This example – MySQL jdbc […]
