In this tutorial, we will show you a few examples to configure the embedded database engines like HSQL, H2 and Derby in Spring framework. Technologies used : Spring 4.1.6.RELEASE jUnit 4.1.2 Maven 3 Embedded databases tested : HSQLDB 2.3.2 H2 1.4.187 Derby 10.11.1.1 The embedded database concept is very helpful during the development phase, because […]
In Spring, you can use MethodInvokingFactoryBean to run a method, get the result and inject the result into another bean. This method invoker is very useful in XML configuration, but less use now in favor of annotation and Spring expression. 1. MethodInvokingFactoryBean 1.1 Example to get the current Java version. Spring XML Configuration <!– 1. […]
In this example, we will show you how to set active @Profile in a Spring MVC web application. @Profile Examples @Configuration public class AppConfig { @Profile("dev") @Bean public CacheManager cacheManager() { //… } @Profile("live") @Bean public EhCacheManagerFactoryBean ehCacheCacheManager() { //… } @Profile("testdb") @Bean public DataSource dataSource() { //… } } To set active @Profile in […]
A Spring @Configuration example to start an HSQLDB embedded database or in-memory database. DataSourceConfig.java package com.mkyong.config.db; import javax.sql.DataSource; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.jdbc.datasource.embedded.EmbeddedDatabase; import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseBuilder; import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseType; @Configuration public class DataSourceConfig { @Bean public DataSource dataSource(){ //jdbc:hsqldb:mem:testdb EmbeddedDatabaseBuilder builder = new EmbeddedDatabaseBuilder(); EmbeddedDatabase db = builder.setType(EmbeddedDatabaseType.HSQL) .addScript("db/hsqldb/db.sql") .build(); return db; } } Review the […]
In this tutorial, we will show you how to setup slf4j and logback in a Spring MVC web application. Technologies used : Spring 4.1.6.RELEASE Logback 1.1.3 Maven 3 or Gradle 2.0 Tomcat 7 Eclipse 4.4 Note By default, Spring is using the Jakarta Commons Logging API (JCL), read this. To setup logback framework you need […]
The source code is attached to the JAR, but Eclipse is keep showing “Source not found” while I jumped to the source via “F3 – Open Declaration”. Tools tested : Gradle 2.4 Eclipse 4.4 1. Gradle Eclipse Project 1.1 A web project build with Gradle and development in Eclipse IDE. build.gradle apply plugin: ‘java’ apply […]
In this tutorial, we will show you how to display project dependencies with the Gradle build tool. Review a simple Spring MVC project dependencies. build.gradle dependencies { compile ‘org.slf4j:jcl-over-slf4j:1.7.12’ compile ‘ch.qos.logback:logback-classic:1.1.3’ compile(‘org.springframework:spring-webmvc:4.1.6.RELEASE’){ exclude group: ‘commons-logging’, module: ‘commons-logging’ } compile ‘org.hsqldb:hsqldb:2.3.2’ providedCompile ‘javax.servlet:servlet-api:2.5’ } P.S Tested with Gradle 2.4 1. gradle dependencies Display project dependencies (direct […]
If you run or debug a web project in Eclipse, the project name will be the default context root. For example, a project named “springmvc”, the default context root will be http://localhost:8080/springmvc Technologies tested : Eclipse 4.4 Eclipse Tomcat server plugin Maven 3 Gradle 2.0 Note The context root tell you the URL of a […]
Few Maven Jetty 8.x and 9.x plugin examples, just for quick reference. 1. Maven Jetty Plugin 9.x Note You need to use Maven 3 and Java 1.7 for Maven Jetty 9.x plugin. 1.1 The ‘groupId’ is org.eclipse.jetty, by default, it runs on port 8080, in root context ‘/’. pom.xml <plugin> <groupId>org.eclipse.jetty</groupId> <artifactId>jetty-maven-plugin</artifactId> <version>9.2.11.v20150529</version> </plugin> To […]
Code snippets to show you how to convert string to bytes and vice versa. 1. To convert a string to bytes. data = "" #string data = "".encode() #bytes data = b"" #bytes 2. To convert bytes to a String. data = b"" #bytes data = b"".decode() #string data = str(b"") #string P.S Tested with […]
In Java, we can use Integer.parseInt(String) to convert a String to an int; For unparsable String, it throws NumberFormatException. Integer.parseInt("1"); // ok Integer.parseInt("+1"); // ok, result = 1 Integer.parseInt("-1"); // ok, result = -1 Integer.parseInt("100"); // ok Integer.parseInt(" 1"); // NumberFormatException (contains space) Integer.parseInt("1 "); // NumberFormatException (contains space) Integer.parseInt("2147483648"); // NumberFormatException (Integer max 2,147,483,647) […]
In Maven, you can use mvn dependency:tree to display the project dependencies in tree format. 1. Maven Project Review a simple Maven project, declared Spring and logback dependencies. pom.xml <properties> <spring.version>4.1.6.RELEASE</spring.version> <logback.version>1.1.3</logback.version> <jcl.slf4j.version>1.7.12</jcl.slf4j.version> </properties> <dependencies> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>${spring.version}</version> <exclusions> <exclusion> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>jcl-over-slf4j</artifactId> <version>${jcl.slf4j.version}</version> […]
In this tutorial, we will show you how to associate a NameCheap domain name to an Amazon EC2 instance. In AWS Create an Elastic IP and point to the Amazon EC2 instance. Go to service Route 53, create a ‘A’ record and point to the Elastic IP. In Route 53, copy the Amazon NS (name […]
In Java, there are few ways to display double in 2 decimal places. Table of contents. 1. DecimalFormat("0.00") 2. String.format("%.2f") 3. BigDecimal 4. References Possible Duplicate How to round double / float value to 2 decimal places 1. DecimalFormat(“0.00”) We can use DecimalFormat("0.00") to ensure the number is round to 2 decimal places. DecimalExample.java package […]
A simple Math.pow example, display 2 to the power of 8. In Math 2^8 = 2x2x2x2x2x2x2x2 =256 In Java Math.pow(2, 8) Note In Java, the symbol ^ is a XOR operator, DON’T use this for the power calculation. TestPower.java package com.mkyong.test; import java.text.DecimalFormat; public class TestPower { static DecimalFormat df = new DecimalFormat(".00"); public static […]
To quick start a new Gradle Java project, type gradle init –type java-library $ gradle init –type java-library :wrapper :init BUILD SUCCESSFUL Total time: 4.866 secs The following files and folders will be created automatically. P.S Tested with Gradle 2.0 1. Java Project Structure Both src/main/java and src/test/java folders are created. The Library*.java is a […]
In this tutorial, we will show you how to do the data grouping with Spring Data + MongoDB aggregation framework. 1. Test Data domain.json { "_id" : 1, "domainName" : "test1.com", "hosting" : "hostgator.com" } { "_id" : 2, "domainName" : "test2.com", "hosting" : "aws.amazon.com"} { "_id" : 3, "domainName" : "test3.com", "hosting" : "aws.amazon.com" […]
In Gardle, the application plugin, you can pass the system properties via applicationDefaultJvmArgs : gradle.build apply plugin:’application’ mainClassName = "com.mkyong.analyzer.engine.hydra.entryPointForJar" applicationName = ‘analyzer’ distZip { archiveName ‘analyzer-‘ + version + ‘.zip’ } applicationDefaultJvmArgs = ["-Dlogback.configurationFile=logback.xml"] The problem is how to get the APP_HOME for logback.xml? gradle.build applicationDefaultJvmArgs = ["-Dlogback.configurationFile=APP_HOME/logback.xml"] You can hard code the APP_HOME, […]
A Spring MVC web application, noticed all the Spring’s beans are loaded twice!? package com.mkyong.config.db; @Configuration public class MongoDevConfig { private final static Logger logger = LoggerFactory.getLogger(MongoDevConfig.class); @Bean MongoDbFactory mongoDbFactory() throws Exception { logger.debug("Init…… MongoDbFactory() in production mode!"); //… return new new SimpleMongoDbFactory(mongo, "db");; } } During Application startup : 2015-03-05 17:52:32 DEBUG c.m.config.MongoLiveConfig – […]
In MongoDB console, you can use field:1 to select the fields to return from a query : > db.hosting.find({},{domain:1, count:1}); In Spring Data for MongoDB, you use query.fields().include : HostingDaoImpl.java package com.mkyong.core.hosting.dao; import java.util.List; import org.springframework.data.domain.Sort; import org.springframework.data.mongodb.core.query.Criteria; import org.springframework.data.mongodb.core.query.Query; import org.springframework.data.mongodb.core.query.Update; import org.springframework.stereotype.Repository; import com.hostingcompass.core.db.dao.MongoDaoImpl; @Repository public class HostingDaoImpl extends MongoDaoImpl<Hosting> implements HostingDao { […]
In Gradle, the WAR plugin will generate the final WAR file with the following pattern: ${baseName}-${appendix}-${version}-${classifier}.${extension} Example : hello.1.0.war To change the default WAR filename, update war.archiveName. For example : build.gradle project(‘:web’) { apply plugin: ‘war’ war { archiveName ‘hello-gradle.war’ } dependencies { compile project(‘:core’) providedCompile ‘javax.servlet:servlet-api:2.5’ providedCompile ‘org.apache.tomcat:tomcat-jsp-api:7.0.55’ //… } } Build it… $ […]
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 […]
