Java doesn’t allow multi-value method returning. To return 2 values for a method, you can create a "pair" object which contains two values. /** * a pair of objects. like other containers, you’d rather return an empty * container than a null one * * * */ public class MyDuplet<L,R> { public L left; public …
The Problem When a bean is inserted or updated, its "createdAt" or "updatedAt" should be set as the current time. MyBatis won’t do that for you by default. You can manually set them before inserting them. But you may forget it. Solution The solution is to have a MyBatis interceptor which does the job before …
MyBatis: Automatically set timestamps for beans saved Read More »
You may find it useful where you can’t use Spring MVC’s StringTrimEditor the trim method /** * trim string fields to null. * Note: only the root string fields are trimmed. string fields of the * bean’s composite fields are let alone. * All reflection related security exceptions are ignored. * * @param bean */ …
Add bean validation dependency Hibernate provides an implementation of bean-validation. So we will dependent on it. But it has nothing to do with Hiberante ORM. org.hibernate hibernate-validator 5.1.3.Final Create a validator class as a spring bean @Component public class MyBeanValidator { @Resource private Validator validator; public <T> List<String> validateBean(T bean) { List<string> errors = new …
There are many situations that multi-table data consistency can limit your work. For example, unit tests on single table , batch data migration and so on.
Don’t let your user input a "username" while registering. It’s totally unnecessary. And it can be awkward when user logins with an Open ID, such as Google or Facebook. What will be the user name in this case? If a user registers on your site, just use their email as username. It will make …
restClient.property(ClientProperties.CONNECT_TIMEOUT, 5000); restClient.property(ClientProperties.READ_TIMEOUT, 5000);
Just put a log4j.xml on test’s class path and log4j will be activated. However, you may hate to have 2 "log4j.xml" in your eclipse. You want the log4j config for testing to be called log4j-test.xml. In that case, do the following: //create your own runner, withen which load log4j public class MySpringJunit4ClassRunner extends SpringJUnit4ClassRunner { …
How to enable log4j when doing spring-based integration test? Read More »
Your server says it will return JSON string as response, but the ContentType header it sends is not "application/json" but "text/html". What will happen? Your client will see an exception saying "A message body reader for … was not found" . What you need to do is to have your own "provider" and let …
The server side should send error code and error message. Is that all? Yes, basically it will work, but not perfect yet. What you need to do: 1. Differentiate known, user-readable errors from unknown, developer-readable errors. 2. Send an error ID to client side when there is an unknown error, with which the client …