mkyong

mkyong

Software Engineer • Writer • Dad

20+ years hands-on, writing about Java, Spring, and AI. Every code example here is tested.

1,960 posts

Posts by mkyong

logging 2 min read 24 comments

Here’s an XML version of log4j properties file, just for sharing. 1. Output to Console Redirect the logging to console. log4j.xml <?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE log4j:configuration SYSTEM "log4j.dtd"> <log4j:configuration debug="true" xmlns:log4j=’http://jakarta.apache.org/log4j/’> <appender name="console" class="org.apache.log4j.ConsoleAppender"> <layout class="org.apache.log4j.PatternLayout"> <param name="ConversionPattern" value="%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L – %m%n" /> </layout> </appender> <root> <level value="DEBUG" /> <appender-ref ref="console" /> […]

Read more log4j.xml Example
spring security 6 min read 52 comments

In this tutorial, previous Spring Security + Hibernate4 XML example will be reused, and convert it to a annotation-based example. Technologies used : Spring 3.2.8.RELEASE Spring Security 3.2.3.RELEASE Hibernate 4.2.11.Final MySQL Server 5.6 Tomcat 7 (Servlet 3.x container) Quick Note : Create a session factory with LocalSessionFactoryBuilder Inject session factory into a UserDao Integrate UserDao […]

Read more Spring Security + Hibernate Annotation Example
spring security 8 min read 42 comments

In this tutorial, we will show you how to integrate Hibernate 4 in Spring Security, XML configuration example. Note For annotation version, please read this Spring Security + Hibernate Annotation Example. Technologies used : Spring 3.2.8.RELEASE Spring Security 3.2.3.RELEASE Hibernate 4.2.11.Final MySQL Server 5.6 JDK 1.6 Maven 3 Eclipse 4.3 Quick Notes Create a session […]

Read more Spring Security + Hibernate XML Example
hibernate 1 min read 3 comments

Spring 3.2.x + Hibernate 4.3.x integration, hits JtaPlatform ClassNotFoundException, search the project classpath, find out that JtaPlatform is at different package? hibernate-core.4.3.5.Final.jar org.hibernate.engine.transaction.jta.platform.spi.JtaPlatform Error message shows org.hibernate.service.jta.platform.spi.JtaPlatform Caused by: java.lang.NoClassDefFoundError: org/hibernate/service/jta/platform/spi/JtaPlatform at org.springframework.orm.hibernate4.SpringSessionContext.<init>(SpringSessionContext.java:56) ~[spring-orm-3.2.8.RELEASE.jar:3.2.8.RELEASE] … 40 common frames omitted Caused by: java.lang.ClassNotFoundException: org.hibernate.service.jta.platform.spi.JtaPlatform //… pom.xml <!– Hibernate ORM –> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-core</artifactId> <version>4.3.5.Final</version> </dependency> <!– […]

Read more java.lang.ClassNotFoundException: org.hibernate.service.jta.platform.spi.JtaPlatform
spring security 1 min read 10 comments

In Spring Security, database authentication with bcrypt password hashing. import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder; import org.springframework.security.crypto.password.PasswordEncoder; //… String password = “123456”; PasswordEncoder passwordEncoder = new BCryptPasswordEncoder(); String hashedPassword = passwordEncoder.encode(password); spring-security.xml <authentication-manager> <authentication-provider> <password-encoder hash="bcrypt" /> //… </authentication-provider> </authentication-manager> CREATE TABLE users ( username VARCHAR(45) NOT NULL , password VARCHAR(45) NOT NULL , enabled TINYINT NOT NULL DEFAULT […]

Read more Spring Security : Encoded password does not look like BCrypt
computer tips 1 min read 4 comments

Problem After upgrading from Windows 8 Enterprise to Windows 8.1, Google Chrome displays pink color screen like this : Windows Environment Chrome 34.0.1847.137 m Windows 8.1 NVIDIA 331.58 Chrome GPU : NVIDIA 9.18.13.3158 To get the Chrome GPU, type chrome://gpu in the browser URL, refer to the driver version. Driver vendor NVIDIA Driver version 9.18.13.3523 […]

Read more Google Chrome displays pink color screen
spring 2 min read 10 comments

Spring + Hibernate4 integration, and transaction are managed by Spring AOP, example : spring-hibernate.xml <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd"> <bean id="txManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager"> <property name="sessionFactory" ref="sessionFactory"></property> </bean> <tx:advice id="txAdvice" transaction-manager="txManager"> <tx:attributes> <tx:method name="get*" read-only="true" /> <tx:method name="*" /> </tx:attributes> </tx:advice> <aop:config> <aop:pointcut id="userDaoPointCut" expression="execution(* com.mkyong.users.service.*Dao.*(..))" /> <aop:advisor advice-ref="txAdvice" pointcut-ref="userDaoPointCut" /> […]

Read more ClassNotFoundException: org.aspectj.weaver.reflect.ReflectionWorld$ReflectionWorldException
spring security 1 min read 1 comment

This Spring Security example shows you how to check if a user is login from a “remember me” cookie. private boolean isRememberMeAuthenticated() { Authentication authentication = SecurityContextHolder.getContext().getAuthentication(); if (authentication == null) { return false; } return RememberMeAuthenticationToken.class.isAssignableFrom(authentication.getClass()); } @RequestMapping(value = "/admin/update**", method = RequestMethod.GET) public ModelAndView updatePage() { ModelAndView model = new ModelAndView(); if (isRememberMeAuthenticated()) […]

Read more Spring Security : Check if user is from remember me cookie
spring 2 min read 0 comments

Integrates Spring 3 and Hibernate 4, the system shows the following message while performing database operation : org.hibernate.HibernateException: No Session found for current thread The sessionFactory is injected like this : spring-hibernate4.xml <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"> <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close"> <property name="driverClassName" value="com.mysql.jdbc.Driver" /> <property name="url" value="jdbc:mysql://localhost:3306/test" /> <property name="username" value="root" /> <property name="password" […]

Read more Spring + Hibernate : No Session found for current thread
spring 1 min read 5 comments

A Simple DAO class extends JdbcDaoSupport, but, unable to inject or @autowired a “dataSource”, the method setDataSource is final, can’t override. UserDetailsDaoImpl.java package com.mkyong.users.dao; import javax.sql.DataSource; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.jdbc.core.support.JdbcDaoSupport; import org.springframework.stereotype.Repository; @Repository public class UserDetailsDaoImpl extends JdbcDaoSupport implements UserDetailsDao { //Error, cannot override the final method from JdbcDaoSupport @Autowired public void setDataSource(DataSource dataSource) { […]

Read more How to autowire DataSource in JdbcDaoSupport
spring 1 min read 5 comments

Upgrading Spring version and noticed that queryForInt() is deprecated, what should be replaced by? private boolean isUserExists(String username) { String sql = "SELECT count(*) FROM USERS WHERE username = ?"; boolean result = false; //The method queryForInt(String, Object…) from the type JdbcTemplate is deprecated int count = getJdbcTemplate().queryForInt(sql, new Object[] { username }); if (count […]

Read more JdbcTemplate queryForInt() is Deprecated
python 2 min read 6 comments

In this example, we will show you how to read an XML file and print out its values, via Python xml.dom.minidom. 1. XML File A simple XML file, later parse it with Python minidom. staff.xml <?xml version="1.0"?> <company> <name>Mkyong Enterprise</name> <staff id="1001"> <nickname>mkyong</nickname> <salary>100,000</salary> </staff> <staff id="1002"> <nickname>yflow</nickname> <salary>200,000</salary> </staff> <staff id="1003"> <nickname>alex</nickname> <salary>20,000</salary> </staff> […]

Read more Python – Read XML file (DOM Example)
spring 2 min read 16 comments

Reviewing a legacy project, and found this Spring JDBC code snippets : public User getUser(String username) { String sql = "SELECT * FROM USER WHERE username = ?"; return getJdbcTemplate().queryForObject( sql, new Object[] { username }, new RowMapper<UserAttempts>() { public UserAttempts mapRow(ResultSet rs, int rowNum) throws SQLException { User user = new User(); user.setId(rs.getInt("id")); user.setUsername(rs.getString("username")); […]

Read more queryForObject() throws EmptyResultDataAccessException when record not found
spring mvc 1 min read 8 comments

Developing a Spring MVC, using a JSP file as a View resource. example.jsp <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> <html> <body> <h1>Spring MVC web application</h1> </body> </html> Above is a simple JSP page, but hits the following jstl error? SEVERE: Servlet.service() for servlet mvc-dispatcher threw exception org.apache.jasper.JasperException: The absolute uri: http://java.sun.com/jsp/jstl/core cannot be resolved in either […]

Read more The absolute uri: http://java.sun.com/jsp/jstl/core cannot be resolved
spring security 7 min read 51 comments

In preview post, we are using XML files to configure the Spring Security in a Spring MVC environment. In this tutorial, we are going to show you how to convert the previous XML-base Spring Security project into a pure Spring annotation project. Technologies used : Spring 3.2.8.RELEASE Spring Security 3.2.3.RELEASE Eclipse 4.2 JDK 1.6 Maven […]

Read more Spring Security Hello World Annotation Example
eclipse 1 min read 8 comments

Here is the development environment Eclipse 4.3 Kepler Java 1.7 Spring 3.2, a MVC project using JSP view. 1. Problem Recently, Eclipse IDE is prompting following error message on top of all of the .tag file. The superclass "javax.servlet.jsp.tagext.SimpleTagSupport" was not found on the Java Build Path. See figure : P.S The SimpleTagSupport class is […]

Read more Eclipse – SimpleTagSupport was not found on the Java Build Path
eclipse 1 min read 7 comments

In Eclipse IDE, run a Java web application with Tomcat server plugin, but the console prompts Exception in thread "x" java.lang.OutOfMemoryError: Java heap space 1. Solution – Increase Heap Size in Tomcat By default, Tomcat allocated a small amount of heap size. To solve it, you need to increase the Tomcat’s heap size manually. 1.1 […]

Read more Eclipse + Tomcat – java.lang.OutOfMemoryError: Java heap space
mongodb 5 min read 15 comments

In this tutorial, we will show you how to generate an auto-incrementing sequence id in MongoDB + Spring Data environment. Tools used in this project : Spring Data MongoDB 1.2.1.RELEASE MongoDB 2.4.5 Eclipse 4.2 Maven 3 At the end of this tutorial, if the collection name “hosting” is saved, a new auto-incrementing sequence id will […]

Read more Spring Data MongoDB – Auto Sequence ID example
spring mvc 2 min read 2 comments

In Spring MVC + JSP view page environment. index.jsp <html> <head> <title>Welcome!</title> <c:url var="assets" value="/resources/abc" /> <link href="${assets}/css/style.min.css" rel="stylesheet"> <script src="<c:url value="/resources/js/jquery.1.10.2.min.js" />"> </script> </head> … </html> In the Spring config file, mapped a resource path, mvc-dispatcher-servlet.xml <beans … <context:component-scan base-package="com.mkyong.test" /> <mvc:resources mapping="/resources/**" location="/resources/" /> </beans> 1. Problem After deployed, Spring MVC can’t get […]

Read more JSP – jsessionid appear in CSS and JS link
java 2 min read 6 comments

In this example, we will show you how to append values in Object[] and int[] array. Object[] obj = new Object[] { "a", "b", "c" }; ArrayList<Object> newObj = new ArrayList<Object>(Arrays.asList(obj)); newObj.add("new value"); newObj.add("new value 2"); 1. Object[] Array Example Example to append values with ArrayList : TestApp.java package com.mkyong.test; import java.util.ArrayList; import java.util.Arrays; public […]

Read more Java – Append values into an Object[] array
java 2 min read 2 comments

Examples show you how to convert between int[] and its’ wrapper class Integer[]. 1. Convert int[] to Integer[] public static Integer[] toObject(int[] intArray) { Integer[] result = new Integer[intArray.length]; for (int i = 0; i < intArray.length; i++) { result[i] = Integer.valueOf(intArray[i]); } return result; } 2. Convert Integer[] to int[] public static int[] toPrimitive(Integer[] […]

Read more Java – Convert int[] to Integer[] example
unit test 3 min read 13 comments

In this tutorial, we will show you how to test Spring’s components with TestNG. Tools used : TestNG 6.8.7 Spring 3.2.2.RELEASE Maven 3 Eclipse IDE 1. Project Dependencies To integrate Spring with TestNG, you need spring-test.jar, add the following : pom.xml <properties> <spring.version>3.2.2.RELEASE</spring.version> <testng.version>6.8.7</testng.version> </properties> <dependencies> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> <version>${spring.version}</version> […]

Read more TestNG + Spring Integration Example
unit test 3 min read 3 comments

In this tutorial, we will show you how to do the group testing in TestNG. 1. Groups on Methods Review a test group example. runSelenium() and runSelenium1() are belong to group selenium-test. testConnectOracle() and testConnectMsSQL() are belong to group database. runFinal() will be executed if groups selenium-test and database are passed. TestGroup.java package com.mkyong.testng.examples.group; import […]

Read more TestNG – Groups Test
mongodb 4 min read 10 comments

In this tutorial, we will show you how to use MongoDB aggregate function to group documents (data). 1. Test Data Data in JSON format, shows the hosting provider for website. website.json { “_id” : 1, “domainName” : “test1.com”, “hosting” : “hostgator.com” } { “_id” : 2, “domainName” : “test2.com”, “hosting” : “aws.amazon.com”} { “_id” : […]

Read more MongoDB – Aggregate and Group example
maven 2 min read 2 comments

Creating a Maven site, but the build is very slow to generate the dependency report. C:\mkyong_projects\>mvn site [INFO] Scanning for projects… [INFO] [INFO] ————————————– [INFO] Building Maven Webapp 1.0-SNAPSHOT [INFO] ————————————– [INFO] //… [INFO] Generating "Project License" report [INFO] Generating "Project Team" report [INFO] Generating "Project Summary" report [INFO] Generating "Dependencies" report //…… Hanging here… […]

Read more Maven site build is very slow – dependency report
qa 2 min read 2 comments

Review the “maven-emma-plugin” in pom.xml : pom.xml <project> //… <build> <plugins> <plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>emma-maven-plugin</artifactId> <version>1.0-alpha-3</version> <inherited>true</inherited> <executions> <execution> <phase>process-classes</phase> <goals> <goal>instrument</goal> </goals> </execution> </executions> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <inherited>true</inherited> <configuration> <forkMode>once</forkMode> <reportFormat>xml</reportFormat> <classesDirectory> ${project.build.directory}/generated-classes/emma/classes </classesDirectory> </configuration> </plugin> </plugins> </build> </project> 1. Problem When I run the command mvn emma:emma to generate the code coverage report, […]

Read more Emma – Class x appears to be instrumented already
java 1 min read 8 comments

Eclipse IDE prompts warning on new DefaultHttpClient, mark this class as deprecated. package com.mkyong.web.controller; import org.apache.http.Header; import org.apache.http.HttpResponse; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.DefaultHttpClient; public class WebCrawler { public static void main(String[] args) throws Exception { HttpClient client = new DefaultHttpClient(); HttpGet request = new HttpGet("https://mkyong.com"); HttpResponse response = client.execute(request); //… } } Solution Dive […]

Read more The type DefaultHttpClient is deprecated
java 3 min read 9 comments

If a web request is coming from Google crawler or Google bot, the requested “user agent” should look similar like this : Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html) or (rarely used): Googlebot/2.1 (+http://www.google.com/bot.html) Source : Google crawlers 1. Java Example In Java, you can get the “user agent” from HttpServletRequest. Example : Service hosted at abcdefg.com @Autowired […]

Read more Java – Check if web request is from Google crawler