Scaling an image with default Java API loses quality (horribly!): public static BufferedImage resizeImage(Buffer... The imgscalr library does the job beautifully. And its' very easy to do: // import org.imgscalr.Scalr; public static... To import the library in Maven: <dependency> <groupId>org.imgscalr</groupId> ...

Validation groups can be used to control which rules validation rules to run. A validation group can be identified by any Java interface (not class!). Multiple validation groups may be specified when validating. In this example, I added a validation group named MyValidationGroup ( src/main/java/com/example/MyValidationGroup.java in Maven project): package com.example; public interface MyVal... and added a @Size rule for a person's name, because my database can only store up to 15 characters for a person's name: package com.example; import javax.validatio... Now validate Person with a JUnit test ( src/test/java/com/example/TestPersonWithGroup.java in Maven project): package com.example; import java.util.Set; ... Test with " mvn clean test ". The rules where groups is not specified, which belong to the javax.validation.groups.Default group, are not executed with these tests.

The landing page after login can be configured with the default-target-url attribute of form-login . If a user was redirected to the login form after requesting a restricted URL, she's redirected to the original requested page after successful login. An easy configuration looks like this: <beans:beans xmlns="http://www.springframework.org... But there are times that you want to do more initialization after login (such as loading user data), or apply more complex logic before redirecting. This is where the authentication-success-handler-ref attribute comes into play. You create a class that implements org.springframework.security.web.authentication.AuthenticationSuccessHandler and use that as the authentication-success-handler-ref : <http entry-point-ref="authProcessFilterEn... This is a skeleton implementation: public class MyAuthenticationSuccessHandler implem...

By default, Java uses $JAVA_HOME/jre/lib/security/cacerts to very an SSL certificate. You can add a certificate to this file: $ keytool -importcert -alias VeriSignClass3Interna... The default password for cacerts is: "changeit".

This code snippet gets the default keystore used by the Java keytool and displays the list of aliases along with the key type (certificate or private key). import java.io.File; import java.io.FileInputSt... The default keystore used by the above code is: $HOME/.keystore .

You can customize Tomcat error page with error code: <error-page> <error-code>404</error-code> ... or Java exception type: <error-page> <exception-type>java.lang.Throwab... Either error-code or exception-type is required, but not both. There's no way to aggregate error codes, such as: <!-- This does not work! --> <error-page> ... Customizing error pages is about the only way to suppress the default stack trace in Tomcat in case of an unhandled exception.

The annotation @org.hibernate.annotations.Type overrides the default hibernate mapping type used for a column. This can usually be omitted since Hibernate normaly infers the correct type to use. But @Type is required in ambiguous scenarios such as a java.util.Date attribute, which can map to SQL DATE , TIME or TIMESTAMP . You use the @Type("timestamp") annotation to tell Hibernate that a timestamp converter should be used, which identifies an instance of org.hibernate.type.TimestampType . @Type can also be used to identify custom type converters, which can be defined with @TypeDef at the class level: @TypeDefs( { @TypeDef( na... or with an xml file: <?xml version="1.0"?> <!DOCTYPE hibernate-mappi...

This is a simple Hello World application with Spring 3 MVC. Like the default Apache HTTPd welcome page, it displays " It works! " when successfully deployed. The sole purpose is to show the minimum elements needed to setup Spring 3 MVC. I use Maven since it's so much easier than downloading the dependencies manually. Directory layout: ./src ./src/main ./src/main/webapp ./src/... pom.xml : <?xml version="1.0" encoding="UTF-8"?> <project... WEB-INF/web.xml : <?xml version="1.0" encoding="UTF-8"?> <web-app... WEB-INF/applicationContext.xml (empty, but needed): <?xml version="1.0" encoding="UTF-8"?> <beans x... WEB-INF/spring-servlet.xml : <?xml version="1.0" encoding="UTF-8"?> <beans x... WEB-INF/jsp/home.jsp : <!DOCTYPE html> <html> <head> <title>H... Build with: mvn clean package The resulting webapp is target/springmvc.war .

These are the minimum steps to configure Spring MVC in web.xml : Bootstrap Spring MVC by registering ContextLoaderListener : <listener> <listener-class> org.springfra... Register the DispatcherServlet : <servlet> <servlet-name>spring</servlet-name> ... Add servlet-mapping : <servlet-mapping> <servlet-name>spring</servle... Configure DispatcherServlet with WEB-INF/spring-servlet.xml , which configures WebApplicationContext specific to this servlet. <?xml version="1.0" encoding="UTF-8"?> <beans x... Optionally, use context-param in web.xml to configure the global WebApplicationContext : <!-- XmlWebApplicationContext is the default, so t... If you omit this section, you have to create file WEB-INF/applicationContext.xml , even if it's empty. This is the full web.xml : <?xml version="1.0" encoding="UTF-8"?> <web-app...

By default, tomcat uses an enhanced java.util.logging implementation called JULI, which can be configured at two different levels: Globally, with the ${catalina.base}/conf/logging.properties file. Per web application, with WEB-INF/classes/logging.properties . The configuration file is a normal Java properties file: Logging handlers are specified with the handlers property. handlers = 1catalina.org.apache.juli.FileHandler, ... The root logger can define its set of handlers using the .handlers property. .handlers = 1catalina.org.apache.juli.FileHandler,... A prefix may be added to handler names. The prefix starts with a digit and ends with a dot ( . ), for example: # 1catalina. is a prefix 1catalina.org.apache.j... System property replacement is performed for property values which contain ${systemPropertyName} . Each handler can have its own specific properties: 3manager.org.apache.juli.FileHandler.level = FINE ... Loggers can define their own...