Mocking is an essential part of unit testing, and the Mockito library makes it easy to write clean and intuitive unit tests for your Java code.
Get started with mocking and improve your application tests using our Mockito guide:
Handling concurrency in an application can be a tricky process with many potential pitfalls. A solid grasp of the fundamentals will go a long way to help minimize these issues.
Get started with understanding multi-threaded applications with our Java Concurrency guide:
Spring 5 added support for reactive programming with the Spring WebFlux module, which has been improved upon ever since. Get started with the Reactor project basics and reactive programming in Spring Boot:
Since its introduction in Java 8, the Stream API has become a staple of Java development. The basic operations like iterating, filtering, mapping sequences of elements are deceptively simple to use.
But these can also be overused and fall into some common pitfalls.
To get a better understanding on how Streams work and how to combine them with other language features, check out our guide to Java Streams:
Explore Spring Boot 3 and Spring 6 in-depth through building a full REST API with the framework:
Yes, Spring Security can be complex, from the more advanced functionality within the Core to the deep OAuth support in the framework.
I built the security material as two full courses - Core and OAuth, to get practical with these more complex scenarios. We explore when and how to use each feature and code through it on the backing project.
You can explore the course here:
Spring Data JPA is a great way to handle the complexity of JPA with the powerful simplicity of Spring Boot.
Get started with Spring Data JPA through the guided reference course:
Refactor Java code safely — and automatically — with OpenRewrite.
Refactoring big codebases by hand is slow, risky, and easy to put off. That’s where OpenRewrite comes in. The open-source framework for large-scale, automated code transformations helps teams modernize safely and consistently.
Each month, the creators and maintainers of OpenRewrite at Moderne run live, hands-on training sessions — one for newcomers and one for experienced users. You’ll see how recipes work, how to apply them across projects, and how to modernize code with confidence.
Join the next session, bring your questions, and learn how to automate the kind of work that usually eats your sprint time.
In distributed systems, managing multi-step processes (e.g., validating a driver, calculating fares, notifying users) can be difficult. We need to manage state, scattered retry logic, and maintain context when services fail.
Dapr Workflows solves this via Durable Execution which includes automatic state persistence, replaying workflows after failures and built-in resilience through retries, timeouts and error handling.
In this tutorial, we'll see how to orchestrate a multi-step flow for a ride-hailing application by integrating Dapr Workflows and Spring Boot:
1. Overview
It’s quite expensive to establish database connections. Database connection pooling is a well-established way to lower this expenditure.
In this tutorial, we’ll discuss how to use c3p0 with Hibernate to pool connections.
2. What Is c3p0?
c3p0 is a Java library that provides a convenient way for managing database connections.
In short, it achieves this by creating a pool of connections. It also effectively handles the cleanup of Statements and ResultSets after use. This cleanup is necessary to ensure that resource usage is optimized and avoidable deadlocks do not occur.
This library integrates seamlessly with various traditional JDBC drivers. Additionally, it provides a layer for adapting DriverManager-based JDBC drivers to the newer javax.sql.DataSource scheme.
And, because Hibernate supports connecting to databases over JDBC, it’s simple to use Hibernate and c3p0 together.
3. Configuring c3p0 With Hibernate
Let’s now look at how to configure an existing Hibernate application to use c3p0 as its database connection manager.
3.1. Maven Dependencies
Firstly, we’ll first need to add the hibernate-c3p0 maven dependency:
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-c3p0</artifactId>
<version>5.3.6.Final</version>
</dependency>With Hibernate 5, just adding the above dependency is enough to enable c3p0. This is true as long as no other JDBC connection pool manager is specified.
Therefore, after we add the dependency, we can run our application and check the logs:
Initializing c3p0-0.9.5.2 [built 08-December-2015 22:06:04 -0800; debug? true; trace: 10]
Initializing c3p0 pool... com.mchange.v2.c3p0.PoolBackedDataSource@34d0bdb9 [ ... default settings ... ]If another JDBC connection pool manager is being used, we can force our application to use c3p0. We just need to set the provider_class to C3P0ConnectionProvider in our properties file:
hibernate.connection.provider_class=org.hibernate.connection.C3P0ConnectionProvider3.2. Connection Pool Properties
Eventually, we will need to override the default configuration. We can add custom properties to the hibernate.cfg.xml file:
<property name="hibernate.c3p0.min_size">5</property>
<property name="hibernate.c3p0.max_size">20</property>
<property name="hibernate.c3p0.acquire_increment">5</property>
<property name="hibernate.c3p0.timeout">1800</property>Likewise, the hibernate.properties file can contain the same settings:
hibernate.c3p0.min_size=5
hibernate.c3p0.max_size=20
hibernate.c3p0.acquire_increment=5
hibernate.c3p0.timeout=1800The min_size property specifies the minimum number of connections it should maintain at any given time. By default, it will maintain at least three connections. This setting also defines the initial size of the pool.
The max_size property specifies the maximum number of connections it can maintain at any given time. By default, it will keep a maximum of 15 connections.
The acquire_increment property specifies how many connections it should try to acquire if the pool runs out of available connections. By default, it will attempt to acquire three new connections.
The timeout property specifies the number of seconds an unused connection will be kept before being discarded. By default, connections will never expire from the pool.
We can verify the new pool settings by checking the logs again:
Initializing c3p0-0.9.5.2 [built 08-December-2015 22:06:04 -0800; debug? true; trace: 10]
Initializing c3p0 pool... com.mchange.v2.c3p0.PoolBackedDataSource@b0ad7778 [ ... new settings ... ]These are the basic connection pool properties. In addition, other configuration properties can be found in the official guide.
5. Conclusion
In this article, we’ve discussed how to use c3p0 with Hibernate. We’ve looked at some common configuration properties and added c3p0 to a test application.
For most environments, we recommend using a connection pool manager such as c3p0 or HikariCP instead of traditional JDBC drivers.
