Java client library for Google Maps API Web Services
Java
Latest commit 3412f40 Jan 10, 2017 @domesticmouse domesticmouse committed on GitHub Merge pull request #223 from domesticmouse/master
Fixing tests

README.md

Java Client for Google Maps Services

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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. Analytics

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.

Note: The Java Client for Google Maps Services is for use in server applications. If you're 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.

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 1.7 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 https://developers.google.com/console. The type of API key you need is a Server key.

To get an API key:

  1. Visit https://developers.google.com/console and log in with a Google Account.
  2. Select one of your existing projects, or create a new project.
  3. 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
    • Places API
    • Roads API
    • Time Zone API
  4. Create a new Server key.
  5. 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.

Maven

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

Gradle

repositories {
    mavenCentral()
}

dependencies {
    compile 'com.google.maps:google-maps-services:(insert latest version)'
    ...
}

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().setApiKey("AIza...");
GeocodingResult[] results =  GeocodingApi.geocode(context,
    "1600 Amphitheatre Parkway Mountain View, CA 94043").await();
System.out.println(results[0].formattedAddress);

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().setEnterpriseCredentials(clientID, clientSecret);
GeocodingResult[] results =  GeocodingApi.geocode(context,
    "1600 Amphitheatre Parkway Mountain View, CA 94043").await();
System.out.println(results[0].formattedAddress);

In real world scenarios, it's important to instantiate GeoApiContext as a static variable or inside a singleton, since it must have only one instance alive, despite the number of calls to GeocodingApi. Instantiating GeoApiContext once per request could cause too many threads alive at JVM (see here).

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 line code change.

GeoApiContext context = new GeoApiContext(new GaeRequestHandler()).setApiKey(API_KEY);

The new GaeRequestHandler() argument to the GeoApiContext constructor tells the Java Client for Google Maps Services to utilise the apropriate calls for making HTTP requests from Google App Engine, instead of the default OkHttp based strategy.

Rate Limiting

Never sleep between requests again! By default, requests are sent at the expected rate limits for each web service, typically 10 queries per second for free users. If you want to speed up or slow down requests, you can do that too, using new GeoApiContext().setQueryRateLimit(qps).

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()
  • .setMaxRetries()
  • .setRetryTimeout()
  • .toggleifExceptionIsAllowedToRetry()

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
$ API_KEY=AIza.... ./gradlew test

# Run the tests with enterprise credentials.
$ CLIENT_ID=... CLIENT_SECRET=... ./gradlew test

# Generate documentation
$ ./gradlew javadoc

# Publish documentation
$ ./gradlew javadoc
$ git checkout gh-pages
$ rm -rf javadoc
$ mkdir $VERSION
$ mv build/docs/javadoc $VERSION
$ git add $VERSION/javadoc
$ git add latest
$ git commit
$ git push origin gh-pages