Java Client for Google Maps Services

Description

Use Java? Want to geocode something? Looking for directions? Maybe matrices of directions? This library brings the Google Maps API Web Services to your server-side Java application.

The Java Client for Google Maps Services is a Java Client library for the following Google Maps APIs:

Keep in mind that the same terms and conditions apply to usage of the APIs when they're accessed through this library.

Intended usage of this library

The Java Client for Google Maps Services is designed for use in server applications. This library is not intended for use inside of an Android app, due to the potential for loss of API keys.

If you are building a mobile application, you will need to introduce a proxy server to act as intermediary between your mobile application and the Google Maps API Web Services. The Java Client for Google Maps Services would make an excellent choice as the basis for such a proxy server.

Please see Making the most of the Google Maps Web Service APIs for more detail.

Support

This library is community supported. We're comfortable enough with the stability and features of the library that we want you to build real production applications on it. We will try to support, through Stack Overflow, the public and protected surface of the library and maintain backwards compatibility in the future; however, while the library is in version 0.x, we reserve the right to make backwards-incompatible changes. If we do remove some functionality (typically because better functionality exists or if the feature proved infeasible), our intention is to deprecate and give developers a year to update their code.

If you find a bug, or have a feature suggestion, please log an issue. If you'd like to contribute, please read How to Contribute.

Requirements

Java 1.8 or later.
A Google Maps API key.

API keys

Each Google Maps Web Service request requires an API key or client ID. API keys are freely available with a Google Account at developers.google.com/console. The type of API key you need is a Server key.

To get an API key:

Visit developers.google.com/console and log in with a Google Account.
Select one of your existing projects, or create a new project.
Enable the API(s) you want to use. The Java Client for Google Maps Services accesses the following APIs:
- Directions API
- Distance Matrix API
- Elevation API
- Geocoding API
- Maps Static API
- Places API
- Roads API
- Time Zone API
Create a new Server key.
If you'd like to restrict requests to a specific IP address, do so now.

For guided help, follow the instructions for the Directions API. You only need one API key, but remember to enable all the APIs you need. For even more information, see the guide to API keys.

Important: This key should be kept secret on your server.

Installation

You can add the library to your project via Maven or Gradle.

Note: Since 0.1.18 there is now a dependency on SLF4J. You need to add one of the adapter dependencies that makes sense for your logging setup. In the configuration samples below we are integrating slf4j-nop, but there are others like slf4j-log4j12 and slf4j-jdk14 that will make more sense in other configurations. This will stop a warning message being emitted when you start using google-maps-services.

Maven

<dependency>
  <groupId>com.google.maps</groupId>
  <artifactId>google-maps-services</artifactId>
  <version>(insert latest version)</version>
</dependency>
<dependency>
  <groupId>org.slf4j</groupId>
  <artifactId>slf4j-simple</artifactId>
  <version>1.7.25</version>
</dependency>

Gradle

repositories {
    mavenCentral()
}

dependencies {
    implementation 'com.google.maps:google-maps-services:(insert latest version)'
    implementation 'org.slf4j:slf4j-simple:1.7.25'
}

You can find the latest version at the top of this README or by searching Maven Central or Gradle, Please.

Developer Documentation

View the javadoc.

Additional documentation for the included web services is available at https://developers.google.com/maps/.

Usage

This example uses the Geocoding API with an API key:

GeoApiContext context = new GeoApiContext.Builder()
    .apiKey("AIza...")
    .build();
GeocodingResult[] results =  GeocodingApi.geocode(context,
    "1600 Amphitheatre Parkway Mountain View, CA 94043").await();
Gson gson = new GsonBuilder().setPrettyPrinting().create();
System.out.println(gson.toJson(results[0].addressComponents));

Below is the same example, using client ID and client secret (digital signature) for authentication. This code assumes you have previously loaded the clientID and clientSecret variables with appropriate values.

For a guide on how to generate the clientSecret (digital signature), see the documentation for the API you're using. For example, see the guide for the Directions API.

GeoApiContext context = new GeoApiContext.Builder()
    .enterpriseCredentials(clientID, clientSecret)
    .build();
GeocodingResult[] results =  GeocodingApi.geocode(context,
    "1600 Amphitheatre Parkway Mountain View, CA 94043").await();
Gson gson = new GsonBuilder().setPrettyPrinting().create();
System.out.println(gson.toJson(results[0].addressComponents));

The GeoApiContext is designed to be a Singleton in your application. Please instantiate one on application startup, and continue to use it for the life of your application. This will enable proper QPS enforcement across all of your requests.

For more usage examples, check out the tests.

Features

Google App Engine Support

You can use this client library on Google App Engine with a single code change.

new GeoApiContext.Builder(new GaeRequestHandler.Builder())
    .apiKey("AIza...")
    .build();

The new GaeRequestHandler.Builder() argument to GeoApiContext.Builder's requestHandlerBuilder tells the Java Client for Google Maps Services to utilise the appropriate calls for making HTTP requests from Google App Engine, instead of the default OkHttp3 based strategy.

Rate Limiting

Never sleep between requests again! By default, requests are sent at the expected rate limits for each web service, typically 50 queries per second for free users. If you want to speed up or slow down requests, you can do that too, using new GeoApiContext.Builder().queryRateLimit(qps).build(). Note that you still need to manually handle the delay between the initial request and successive pages when you're paging through multiple result sets.

Retry on Failure

Automatically retry when intermittent failures occur. That is, when any of the retriable 5xx errors are returned from the API.

To alter or disable automatic retries, see these methods in GeoApiContext:

.disableRetries()
.maxRetries()
.retryTimeout()
.setIfExceptionIsAllowedToRetry()

Client IDs

Google Maps APIs Premium Plan customers can use their client ID and secret to authenticate, instead of an API key.

POJOs

Native objects for each of the API responses.

Asynchronous or synchronous -- you choose

All requests support synchronous or asynchronous calling style.

GeocodingApiRequest req = GeocodingApi.newRequest(context).address("Sydney");

// Synchronous
try {
    req.await();
    // Handle successful request.
} catch (Exception e) {
    // Handle error
}

req.awaitIgnoreError(); // No checked exception.

// Async
req.setCallback(new PendingResult.Callback<GeocodingResult[]>() {
  @Override
  public void onResult(GeocodingResult[] result) {
    // Handle successful request.
  }

  @Override
  public void onFailure(Throwable e) {
    // Handle error.
  }
});

Building the Project

Note: You will need an API key or Client ID to run the tests.

# Compile and package the project
$ ./gradlew jar

# Run the tests
$ ./gradlew test

# Generate documentation
$ ./gradlew javadoc

# Publish documentation
$ git checkout $VERSION
$ ./gradlew javadoc
$ git checkout gh-pages
$ mkdir $VERSION
$ mv build/docs/javadoc $VERSION
$ git add $VERSION/javadoc
$ rm latest
$ ln -s $VERSION latest
$ git add latest
$ git commit -m "Javadoc for $VERSION"
$ git push origin gh-pages

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