July 4th Navy Pier

Finally, it's July 4th when everyone comes to Navy Pier, pays $20/hour parking to watch exciting fireworks, despite the fact that the exactly same fireworks happens every Wednesday and Saturday night here all summer long.

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Customize IdGenerator in JPA, gap between Hibernate and JPA annotations

JPA annotation is like a subset of Hibernate annotation, this means people will find something available in Hibernate missing in JPA. One of the important missing features in JPA is customized ID generator. JPA doesn't provide an approach for developer to plug in their own IdGenerator. For example, if you want the primary key of a table to be BigInteger coming from sequence, JPA will be out of solution. Assume you don't mind the mixture of Hibernate and JPA Annotation and your JPA provider is Hibernate, which is mostly the case, a solution before JPA starts introducing new Annotation is, to replace JPA @SequenceGenerator with Hibernate @GenericGenerator. Now, let the code talk. /** * Ordinary JPA sequence. * If the Long is changed into BigInteger, * there will be runtime error complaining about the type of primary key */ @Id @Column(name = "id", precision = 12) @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "XyzIdGenerator") @SequenceGe...

Spring, Angular and other reasons I like and hate Bazel at the same time

For several weeks I've been trying to put together an Angular application served Java Spring MVC web server in Bazel. I've seen the Java, Angular combination works well in Google, and given the popularity of Java, I want get it to work with open source. How hard can it be to run arguably the best JS framework on a server in probably the most popular server-side language with the mono-repo of planet-scale ? The rest of this post walks through the headaches and nightmares I had to get things to work but if you are just here to look for a working example, github/jiaqi/angular-on-java is all you need. https://github.com/jiaqi/angular-on-java Java web application with Appengine rule Surprisingly there isn't an official way of building Java web application in Bazel, the closest thing is the Appengine rule and Spring MVC seems to work well with it. 3 Java classes, a JSP and an appengine.xml was all I need. At this point, the server starts well but I got "No ...

1300ms to 160ms, tune Spring/Hibernate on slow MySQL

I write this article to remember the different behaviour various JDBC connection pool displays when they work with slow JDBC connection(to MySQL database, in this case). It starts with a typical Java application on Spring, Hibernate, Jetty, ApacheCXF and MySQL like following code. Version 1: without correct pooling //... service code @Transactional(isolation=Isolation.READ_COMMITTED) public void foo() { //... do something with database } //... connection pool configuration ... class = "com.mysql.jdbc.jdbc2.optional.MysqlConnectionPoolDataSource"; url = "jdbc:mysql://mysql.far-far-away.com/mysystem"; user = ... //... transaction management configuration in spring ... <tx:annotation-driven transaction-manager="transactionManager" order="100" /> <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"> <property name="sessionFactory" ref="mySessionFact...

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