A short guide to show you how to convert a String with commas to a long type. 1. For a normal String, you can use Long.valueOf to convert it directly. String bigNumber = "1234567899"; long result = Long.valueOf(bigNumber); 2. For a String with commas, you can use java.text.NumberFormat to convert it. String bigNumber = "1,234,567,899"; […]
In this tutorial, we will show you how to configure a Spring Batch job to read data from a CSV file into a database. Tools and libraries used : Maven 3 Eclipse 4.2 JDK 1.6 Spring Core 3.2.2.RELEASE Spring Batch 2.2.0.RELEASE MySQL Java Driver 5.1.25 1. Java Project Create a Java Project with Maven $ […]
If jobRepository is created with MapJobRepositoryFactoryBean (metadata in memory), the Spring batch jobs are running successfully. spring-config.xml <bean id="jobRepository" class="org.springframework.batch.core.repository.support.MapJobRepositoryFactoryBean"> <property name="transactionManager" ref="transactionManager" /> </bean> Problem After changing the jobRepository to store metadata into database : spring-config.xml <bean id="jobRepository" class="org.springframework.batch.core.repository.support.JobRepositoryFactoryBean"> <property name="dataSource" ref="dataSource" /> <property name="transactionManager" ref="transactionManager" /> <property name="databaseType" value="mysql" /> </bean> <bean id="jobLauncher" […]
Working with Spring Batch 2.2.0.RELEASE, and launches the job with Spring Scheduler. CustomJobLauncher.java package com.mkyong.batch; import org.springframework.batch.core.Job; import org.springframework.batch.core.JobExecution; import org.springframework.batch.core.JobParameters; import org.springframework.batch.core.launch.JobLauncher; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; @Component public class CustomJobLauncher { @Autowired JobLauncher jobLauncher; @Autowired Job job; public void run() { try { JobExecution execution = jobLauncher.run(job, new JobParameters()); System.out.println("Exit Status : " + […]
In this tutorial, we will show you how to use Java library – “Apache Commons Net” to get WHOIS data of a domain. 1. Simple Java Whois Example For domain registered under internic.net, you can get the whois data directly. WhoisTest.java package com.mkyong.whois.bo; import java.io.IOException; import java.net.SocketException; import org.apache.commons.net.whois.WhoisClient; public class WhoisTest { public static […]
This example shows how to generate a simple report using DynamicReports and JasperReports. DynamicReports is a Java reporting library that allows you to produce report documents that can be exported into many popular formats. It is based on the well-known JasperReports library. Tools used in this article : DynamicReports 3.1.3 JasperReports 5.0.4 MySQL 5.5 Maven […]
In this article, we will show you a few examples to make HTTP GET/POST requests via the following APIs Apache HttpClient 4.5.10 OkHttp 4.2.2 Java 11 HttpClient Java 1.1 HttpURLConnection (Not recommend) 1. Apache HttpClient In the old days, this Apache HttpClient is the de facto standard to send an HTTP GET/POST request in Java. […]
This article shows you how to use Apache HttpClient to send an HTTP GET/POST requests, JSON, authentication, timeout, redirection and some frequent used examples. P.S Tested with HttpClient 4.5.10 pom.xml <dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> <version>4.5.10</version> </dependency> 1. Send GET Request 1.1 Close manually. HttpClientExample1_1.java package com.mkyong.http; import org.apache.http.HttpEntity; import org.apache.http.HttpHeaders; import org.apache.http.client.methods.CloseableHttpResponse; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.CloseableHttpClient; […]
In this example, we will show you how to login a website via standard Java HttpsURLConnection. This technique should be working in most of the login form. Tools & Java Library used in this example Google Chrome Browser – Network tab to analyze HTTP request and response header fields. jsoup library – Extracts HTML form […]
Problem Developing a search form with the Spring MVC framework. /WEB-INF/pages/tools/webserver.jsp – Spring mvc + form tag <form:form method="post" commandName="searchForm" action="${pageContext.request.contextPath}/tools/webserver/" class="navbar-form pull-left" id="search-form"> Type a website : <form:input path="domainName" type="text" width="165px" placeholder="example – google.com" /> <button type="submit" class="btn btn-top-margin">Search</button> </form:form> Spring Controller @Controller @RequestMapping(value = "/tools", method = RequestMethod.GET) public class ToolsController { @RequestMapping(value […]
A funny Java example to create an ASCII art graphic. The concept is simple, get the image’s rgb color in “integer mode”, later, replace the color’s integer with ascii text. P.S This example is credited for this post ASCIIArtService.java package com.mkyong.service; import java.awt.*; import java.awt.image.BufferedImage; import java.io.IOException; public class ASCIIArtService { public static void main(String[] […]
In the DOM parser, we can use a recursive loop of the child nodes to find or count the depth of the XML document. Table of contents 1. An XML file 2. DOM Parser + Recursive Loop 3. DOM Parser + Tree Walker 4. Download Source Code 5. References P.S Tested with Java 11. Note […]
Here’s my journey to install “New Relic for PHP” to monitor my WordPress’s blog performance. Below is my server environment : Operating system CentOS 6.x 64-bit, VPS with root access cPanel 11.x Apache version 2.x PHP version 5.3.13 WordPress 3.5.1 P.S The New Relic is a web application performance tool. First, see how “New Relic […]
Using Spring Data MongoDB 1.2.1.RELEASE and Spring core 3.2.2.RELEASE, while system is starting, it hits some weird spring-asm IncompatibleClassChangeError errors : java.lang.IncompatibleClassChangeError: class org.springframework.core.type.classreading.ClassMetadataReadingVisitor has interface org.springframework.asm.ClassVisitor as super class pom.xml <properties> <spring.version>3.2.2.RELEASE</spring.version> <springdata.version>1.2.1.RELEASE</springdata.version> </properties> <dependencies> <!– Spring Core –> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>${spring.version}</version> </dependency> <!– Spring Data for MongoDB –> <dependency> <groupId>org.springframework.data</groupId> <artifactId>spring-data-mongodb</artifactId> <version>${springdata.version}</version> […]
This article shows how to read and parse a comma-separated values (CSV) file. Topics: CSV file and RFC 4180 OpenCSV – Read and Parse CSV file OpenCSV – Convert CSV file to Object Parse CSV file Challenges – Embedded commas, double quotes, and line breaks Single class to read and parse a CSV file String#split […]
In this article, we show you how to use the Locale class to play around the list of countries. P.S Tested with JDK 1.6 1. List of Countries The Locale.getISOCountries() will return a list of all 2-letter country codes defined in ISO 3166. ListCountry.java package com.webmitta.model; import java.util.Locale; public class ListCountry { public static void […]
In this tutorial, we show you how to backup and restore MongoDB with the commands : mongoexport and mongoimport. 1. Backup database with mongoexport Few examples to show you how to use the mongoexport to back up the database. Review some of the common use options. $ mongoexport Export MongoDB data to CSV, TSV or […]
In MongoDB, you can use GridFS to store binary files. In this tutorial, we show you how to use Spring Data’s GridFsTemplate to store / read image in / from MongoDB. 1. GridFS – Save example (Spring config in Annotation) Gat an image file and save it into MongoDB. SpringMongoConfig.java package com.mkyong.config; import org.springframework.context.annotation.Bean; import […]
The HttpURLConnection‘s follow redirect is just an indicator, in fact it won’t help you to do the “real” http redirection, you still need to handle it manually. URL obj = new URL(url); HttpURLConnection conn = (HttpURLConnection) obj.openConnection(); conn.setInstanceFollowRedirects(true); //you still need to handle redirect manully. HttpURLConnection.setFollowRedirects(true); 1. Java Http Redirect Example If a server is […]
The JDK source code is packaged in a src.jar, and should be in the JDK/Home folder. However, some JDK versions in Mac OSX didn’t include the source code or Javadoc. Try find it : sudo find / -name src.jar If you couldn’t find the src.jar, then get it from Apple developer website. 1. Download from […]
This example shows you how to get the Http response header values in Java. 1. Standard JDK example. URL obj = new URL("https://mkyong.com"); URLConnection conn = obj.openConnection(); //get all headers Map<String, List<String>> map = conn.getHeaderFields(); for (Map.Entry<String, List<String>> entry : map.entrySet()) { System.out.println("Key : " + entry.getKey() + " ,Value : " + entry.getValue()); } […]
This guide shows you how to enable authentication in MongoDB. The authentication is disabled by default. To configure it, you must first add a user to the “admin” database. > show dbs admin #add single user to this database testdb Note Users with normal access in “admin” database, HAVE read and write access to all […]
Starting MongoDB server, it shows error “Permission denied” on one of the database and shutdown the server automatically. $ mongod Fri Mar 8 22:54:46 [initandlisten] MongoDB starting : pid=13492 port=27017 dbpath=/data/db/ 64-bit host=Yongs-MacBook-Air.local //… Fri Mar 8 22:54:46 [initandlisten] journal dir=/data/db/journal Fri Mar 8 22:54:46 [initandlisten] recover : no journal files present, no recovery needed […]
A guide to show you how to install MongoDB on Mac OS X. MongoDB 2.2.3 Mac OS X 10.8.2 1. Download MongoDB Get MongoDB from official website, extracts it : $ cd ~/Download $ tar xzf mongodb-osx-x86_64-2.2.3.tgz $ sudo mv mongodb-osx-x86_64-2.2.3 /usr/local/mongodb 2. MongoDB Data By default, MongoDB write/store data into the /data/db folder, you […]
In Mac OS X, you can set the environment variables in one of the following files : ~/.bashrc ~/.bash_profile ~/.profile By default, Mac OS X does not has above files, you need to create it manually. $PATH example This example shows you how to set “mongodb/bin” folder to the existing $PATH environment variable. $ echo […]
This article shows how to fix the Maven error JAVA_HOME is not defined correctly. Terminal $ mvn -version Error: JAVA_HOME is not defined correctly. We cannot execute /usr/libexec/java_home/bin/java Further Reading How to set $JAVA_HOME environment variable on macOS 1. $JAVA_HOME and macOS 10.15 Catalina, macOS 11 Big Sur On macOS 10.15 Catalina and later, the […]
Problem Using Spring data and Mongodb, below is a function to find data within a date range. public List<RequestAudit> findByIpAndDate(String ip, Date startDate, Date endDate) { Query query = new Query( Criteria.where("ip").is(ip) .andOperator(Criteria.where("createdDate").gte(startDate)) .andOperator(Criteria.where("createdDate").lt(endDate)) ); return mongoOperation.find(query, RequestAudit.class); } It hits following error message : org.springframework.data.mongodb.InvalidMongoDbApiUsageException: Due to limitations of the com.mongodb.BasicDBObject, you can’t add […]
This article shows how to set the $JAVA_HOME environment variable on older Mac OS X and the latest macOS 11. Topics macOS release history What is /usr/libexec/java_home $JAVA_HOME and macOS 11 Big Sur $JAVA_HOME and Mac OS X 10.5 Leopard $JAVA_HOME and older Mac OS X Switch between different JDK versions Solution Steps to set […]
In Java, you can use HttpServletRequest.getRemoteAddr() to get the client’s IP address that’s accessing your Java web application. import javax.servlet.http.HttpServletRequest; String ipAddress = request.getRemoteAddr(); 1. Proxy Server or Cloudflare For web application which is behind a proxy server, load balancer or the popular Cloudflare solution, you should get the client IP address via the HTTP […]
Problem Downloaded a Java sample from Alexa API on Amazon service, imports it into Eclipse, but unable to compile and hits following “Access restriction” errors : Access restriction: The type BASE64Encoder is not accessible due to restriction on required library /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Classes/classes.jar P.S Using JDK 1.6 and Eclipse IDE 4.2 import sun.misc.BASE64Encoder; // Access restriction error […]
In this tutorial, we show you 2 examples to calculate date / time difference in Java : Manual time calculation. Joda time library. 1. Manual time calculation Converts Date in milliseconds (ms) and calculate the differences between two dates, with following rules : 1000 milliseconds = 1 second 60 seconds = 1 minute 60 minutes […]
Problem See following Spring REST example, if a request such as “http://localhost:8080/site/google.com” is submitted, Spring returns “google“. Look like Spring treats “.” as file extension, and extract half of the parameter value. SiteController.java package com.mkyong.web.controller; import org.springframework.stereotype.Controller; import org.springframework.ui.ModelMap; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; @Controller @RequestMapping("/site") public class SiteController { @RequestMapping(value = "/{domain}", method […]
In this example, we show you how to use Java and DOM XML parser to get the Alexa ranking from below the undocumented API : http://data.alexa.com/data?cli=10&url=domainName 1. Alexa API For example, type following URL in your browser : http://data.alexa.com/data?cli=10&url=mkyong.com Alexa will return back following XML result : <ALEXA VER="0.9" URL="mkyong.com/" HOME="0" AID="="> <DMOZ> <SITE BASE="mkyong.com/" […]
In this example, we will show you how to get Google PageRank (PR) in Java. To request a PageRank for “mkyong.com”, you just need to send following HTTP request : http://toolbarqueries.google.com/tbr?client=navclient-auto&hl=en&ch=6236440745 &ie=UTF-8&oe=UTF-8&features=Rank&q=info:mkyong.com P.S Above URL is used by Google toolbar plugin. The tricky part is following hashing value : ch=6236440745 Google is using Bob Jenkins […]
Jsoup, a HTML parser, its “jquery-like” and “regex” selector syntax is very easy to use and flexible enough to get whatever you want. Below are three examples to show you how to use Jsoup to get links, images, page title and “div” element content from a HTML page. Download jsoup The jsoup is available in […]
In this tutorial, I will show you how to run a MySQL script file using ibatis ScriptRunner class. First, download the ibatis and Mysql JDBC Driver, and add the jar files into your classpath. Now, run below code. It will execute a script.sql file. RunSqlScript.java package com.mkyong; import java.io.BufferedReader; import java.io.FileReader; import java.io.Reader; import java.sql.Connection; […]
Guide to create a web application with Maven, and add Spring MVC as web framework.
The web.xml is a configuration file to describe how a web application should be deployed. Here’re 5 web.xml examples, just for self-reference. 1. Servlet 3.1 deployment descriptor Java EE 7 XML schema, namespace is http://xmlns.jcp.org/xml/ns/javaee/ web.xml <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" version="3.1"> </web-app> 2. Servlet 3.0 deployment descriptor Java EE 6 XML schema, namespace is […]
This tutorial shows you how to convert a Java project to Java web application project in Eclipse 4.2, it should work in older version as well. 1. Java Project A simple Java project. 2. Project Facets Right click on the project properties. Select “Project Facets“, and click “convert to faceted form…” Check “Dynamic Web Module” […]
Create a simple Java project from Maven template, and also showing how to compile, run unit test, and package the project into a jar file.
