Build a Sample Java API Client App

Follow the instructions below to generate a sample Java API client application that you can build with Apache Maven and include as a dependency in your own project.

Prerequisites

Before you start, make sure that you have installed the following:

Generate the Client App

To run all the commands in the procedure below, all you need is your favorite command-line tool like Linux console or Windows Command Prompt.

To generate the client app:

  1. Use the commands below to create an empty folder:

    Linux
    Windows
    mkdir /tmp/example-client
    mkdir C:\tmp\example-client
    and move to the new folder:
    Linux
    Windows
    cd /tmp/example-client
    cd C:\tmp\example-client

  2. Use the OLP CLI command below to get your access token:

    olp api token get

    An output similar to the one below is generated if your credentials have been configured properly:

    Token: eyJhbGciOiJSUzUxMiIsImN0eSI6IkpX...qrMg5Nj1woORNHaigA
Token Expires at: 2019-08-01T14:03:48.100Z

  3. Use the OLP CLI command below to list all the location services that you have access to:

    olp service list

    The output looks similar to the one below:

    name                            version      HRN
Location Service Demo           1.0.0        hrn:here:service::olp-here:location-service-demo-1
Rendering - Vector Tiles        2.0.0        hrn:here:service::olp-here:rendering-vector-tiles-2
Routing - Intermodal            1.0.0        hrn:here:service::olp-here:routing-intermodal-1
Routing                         1.0.0        hrn:here:service::olp-here:routing-1

    From the above list, you need the HRN of the HERE Location Service Demo service to get its OpenAPI specification. HERE provides this location service for demonstration purposes only.

  4. Use the access token and the service HRN obtained from the previous steps to download the OpenAPI specification of the HERE Location Service Demo service:

    Linux
    Windows
    curl https://registry.services.api.platform.here.com/v1/services/hrn:here:service::olp-here:location-service-demo-1/openApi \
      -H "Authorization: Bearer <your access token>" \g
      -o /tmp/example-client/openapi.yaml
    curl https://registry.services.api.platform.here.com/v1/services/hrn:here:service::olp-here:location-service-demo-1/openApi ^
      -H "Authorization: Bearer <your access token>" ^
      -o C:\tmp\example-client\openapi.yaml

  5. Use the OpenAPI generator command below to generate the client application based on the service's specification:

    Linux
    Windows
    openapi-generator generate \
       --generator-name java \
       --output /tmp/example-client \
       --input-spec /tmp/example-client/openapi.yaml \
       --api-package com.here.ols.example.client.api \
       --model-package com.here.ols.example.client.model \
       --invoker-package com.here.ols.example.invoker \
       --group-id com.here.ols.example \
       --artifact-id example-client
    openapi-generator generate ^
       --generator-name java ^
       --output C:\tmp\example-client ^
       --input-spec C:\tmp\example-client\openapi.yaml ^
       --api-package com.here.ols.example.client.api ^
       --model-package com.here.ols.example.client.model ^
       --invoker-package com.here.ols.example.invoker ^
       --group-id com.here.ols.example ^
       --artifact-id example-client

    The resulting file structure looks like the one below:

    Linux
    Windows
    ls
   build.gradle  git_push.sh*       gradlew*      pom.xml          src/
   build.sbt     gradle/            gradlew.bat   README.md
   docs/         gradle.properties  openapi.yaml  settings.gradle
    dir
   build.gradle  git_push.sh        gradlew       pom.xml          src
   build.sbt     gradle             gradlew.bat   README.md
   docs          gradle.properties  openapi.yaml  settings.gradle

    For a full description of all the parameters that you can pass to the generate command, use the openapi-generator help generate command or see the OpenAPI Generator documentation.

  6. From your command-line tool, create a simple main class that calls the /v1/pedestrianroutes endpoint and writes the result to the standard output:

    Linux
    Windows
    cat >> /tmp/example-client/src/main/java/com/here/ols/example/Example.java << EOF
package com.here.ols.example;

import com.here.ols.example.client.api.ServiceApi;
import com.here.ols.example.invoker.ApiClient;
import com.here.ols.example.invoker.ApiException;

public class Example {

   public static void main(String... args) throws ApiException {
      ServiceApi serviceApi = new ServiceApi();
      ApiClient apiClient = new ApiClient();
      apiClient.setBasePath(args[0]);
      apiClient.addDefaultHeader("Authorization", "Bearer " + args[1]);
      serviceApi.setApiClient(apiClient);
      System.out.println(serviceApi.getPedestrianRoutes());
   }
}
EOF
    copy con C:\tmp\example-client\src\main\java\com\here\ols\example\Example.java
package com.here.ols.example;

import com.here.ols.example.client.api.ServiceApi;
import com.here.ols.example.invoker.ApiClient;
import com.here.ols.example.invoker.ApiException;

public class Example {

   public static void main(String... args) throws ApiException {
      ServiceApi serviceApi = new ServiceApi();
      ApiClient apiClient = new ApiClient();
      apiClient.setBasePath(args[0]);
      apiClient.addDefaultHeader("Authorization", "Bearer " + args[1]);
      serviceApi.setApiClient(apiClient);
      System.out.println(serviceApi.getPedestrianRoutes());
   }
}

    This main class consumes two parameters:

    • The service base URL
    • Your access token

  7. Build your client application with Maven in your project:

    mvn clean package

    As a result, you end up with the sample client .jar file.

  8. Use the command below to run the example client app:

Linux
Windows
java -classpath "target/example-client-1.0.0.jar;target/lib/*" com.here.ols.example.Example \
      https://location-service-demo.services.api.platform.here.com \
      <your access token>
java -classpath "C:\tmp\example-client\target\example-client-1.0.0.jar;target\lib\*" com.here.ols.example.Example ^
      https://location-service-demo.services.api.platform.here.com ^
      <your access token>

The command displays the following output:

   {"type":"FeatureCollection","features":[{"type":"Feature","properties":null,"geometry":{"type":"LineString","coordinates":[[30.50373315811157,50.4742767962409],[30.50529956817627,50.47310234931454],[30.503690242767334,50.47196884379929],[30.506608486175537,50.470248048543745],[30.50472021102905,50.468977897586086],[30.506522655487057,50.46829500662366],[30.506179332733154,50.4681037953868]]}}]}

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