strawberry

A lightweight Java utility library that utilizes Google Guice to inject data-structures from a Redis database into object instance fields. The name of the library was roughly constructed as follows: Red(is) + Guice = Strawberry(-juice). This library should not be seen as an alternative to Johm (a very powerful Object-Hash Mapping library) but rather a compliment. Johm is designed for storing (and retrieving) Java objects in Redis, whereas strawberry's main focus is on reading (and caching) configuration values from Redis and injecting these values (which could be list or map structures) into object instance fields.

Installing with Maven

To use strawberry with Maven 2/3, you must add the following repository to your project's pom.xml file:

<repository>
  <id>strawberry-repo</id>
  <name>strawberry repository on GitHub</name>
  <url>http://wcmatthysen.github.com/strawberry/repository/</url>
</repository>

Then, you can add the following dependency:

<dependency>
  <groupId>com.github</groupId>
  <artifactId>strawberry</artifactId>
  <version>1.0.0</version>
</dependency>

Getting Started

The following section assumes that you have access to Redis on your own machine (or another machine on your LAN). For Linux users the installation instructions are listed on the Redis website, whereas Windows users will need to put in some additional effort in getting Redis to run natively.

To start off we are going to populate Redis with a couple of configuration values. Let's assume that you have a string, double, integer and boolean configuration value stored at keys config:string, config:double, config:int, config:boolean respectively. You can use redi-cli to set these values by executing the following commands:

redis 127.0.0.1:6379> set config:string "test value"
OK
redis 127.0.0.1:6379> set config:double "0.123456"
OK
redis 127.0.0.1:6379> set config:int "123456"
OK
redis 127.0.0.1:6379> set config:boolean "True"
OK

Next, we assume that you have a class named ConfigStore. Suppose that this class serves as storage mechanism for all configuration values in your application. The first step in populating ConfigStore's fields with values from the Redis database would be to make use of the @Redis-annotation as the following code-snippet shows:

import com.github.strawberry.guice.Redis;

public class ConfigStore {

    @Redis("config:string")
    private String stringValue;

    @Redis("config:double")
    private double doubleValue;

    @Redis("config:int")
    private int intValue;

    @Redis("config:boolean")
    private boolean booleanValue;

    public String getStringValue() {
        return this.stringValue;
    }
 
    public double getDoubleValue() {
        return this.doubleValue;
    }
    
    public int getIntValue() {
        return this.intValue;
    }
 
    public boolean getBooleanValue() {
        return this.booleanValue;
    }
}

Then, we need to install RedisModule in one of our Google Guice modules (or use it as our main module). The RedisModule class that ships with strawberry is responsible for setting up the custom injections that need to occur for the @Redis-annotated fields in ConfigStore (or any other class that have @Redis-annotated fields). RedisModule expects a JedisPool (pool of Jedis connections to a Redis database) as constructor argument.

Thus, assuming that we have our main module MyCustomModule containing bindings for our application, we can install RedisModule as follows:

import com.github.strawberry.guice.RedisModule;
import com.google.inject.AbstractModule;
import redis.clients.jedis.JedisPool;

public class MyCustomModule extends AbstractModule {

    private final JedisPool pool = new JedisPool("localhost", 6379);

    @Override
    protected void configure() {
        install(new RedisModule(this.pool));
        // set up the rest of your bindings here.
    }
}

Finally, we can provide this module to our main Injector and let Guice inject the field values for our ConfigStore instance as the following code-snippet shows:

import com.google.inject.Guice;
import com.google.inject.Injector;

public class MyApplication {
    
    public static void main(String[] args) {
        Injector injector = Guice.createInjector(new MyCustomModule());
        ConfigStore config = injector.getInstance(ConfigStore.class);
        
        System.out.println(config.getStringValue());
        System.out.println(config.getDoubleValue());
        System.out.println(config.getIntValue());
        System.out.println(config.getBooleanValue());
    }
}

If you run this application you should see the following output:

test value
0.123456
123456
true

Where to go from here?

For more complex examples (such as aggregate field or complex data-structure injection) you can consult the Wiki-pages. The test cases also provides for usage examples.

License

Strawberry Library Copyright (C) 2011 - 2012

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, see http://www.gnu.org/licenses/.