Introduction to the administrative division query function of developing Amap API using Java

Using Java to develop the administrative division query function of Amap API

Introduction:
With the rapid development of the mobile Internet, map applications have become an irreplaceable part of people's lives. As one of the leading map applications in China, Amap provides a rich API interface that can easily obtain various map-related data. The administrative division query function can help us quickly obtain detailed information about a designated area. This article will introduce how to use Java to develop the administrative division query function of the Amap API, and attach a code example.

1. Preparation
   First, we need to apply for a developer account for the Amap API and obtain the corresponding API Key. Before using the Amap API, you need to activate the corresponding service permissions and ensure that the administrative division query service permissions have been activated.
2. Import dependency packages
   In the Java development environment, we need to import the relevant dependency packages to use the Amap API. You can use build tools such as Maven to add the following dependencies to the project:

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.75</version>
</dependency>
<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.12</version>
</dependency>

Fastjson is used here to parse the JSON data returned by the API, and httpclient is used to send HTTP requests.

3. Write query code
   Next, we can write Java code as needed to complete the administrative division query. The following is a simple example:

import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

import java.io.IOException;

public class DistrictQuery {

    public static void main(String[] args) throws IOException {
        String key = "your-api-key";
        String keywords = "上海市";
        String url = "https://restapi.amap.com/v3/config/district?keywords=" + keywords + "&key=" + key;

        HttpClient httpClient = HttpClients.createDefault();
        HttpGet httpGet = new HttpGet(url);
        HttpResponse response = httpClient.execute(httpGet);
        HttpEntity entity = response.getEntity();
        String result = EntityUtils.toString(entity, "UTF-8");

        JSONObject jsonObject = JSONObject.parseObject(result);
        JSONArray districts = jsonObject.getJSONArray("districts");
        for (int i = 0; i < districts.size(); i++) {
            JSONObject district = districts.getJSONObject(i);
            String name = district.getString("name");
            String level = district.getString("level");
            String center = district.getString("center");

            System.out.println("名称：" + name);
            System.out.println("级别：" + level);
            System.out.println("中心点坐标：" + center);
        }
    }
}

In the above code, we first specify the API Key and query keywords, and then construct the query URL. Next, send the HTTP request through HttpClient and parse the returned JSON data. Finally, we can obtain the name, level and center point coordinates of each administrative division in the query results, and process or display them.

4. Run the code
   After completing the above steps, we can run the code to obtain detailed information of the specified area. In this example, we will obtain the administrative division information of Shanghai and print out the name, level and center point coordinates.

After running the code, you can see the following output:

名称：上海市
级别：province
中心点坐标：121.4737,31.2304
名称：上海市
级别：city
中心点坐标：121.4737,31.2304
名称：黄浦区
级别：district
中心点坐标：121.4846,31.2316
...

5. Summary
   Through the above steps, we have successfully used Amap in the Java development environment Administrative division query function of Map API. We first prepared the certification information required for development and imported the relevant dependency packages. Next, I wrote query code, used the API to send HTTP requests and parsed the returned JSON data. Finally, we obtain the detailed information in the query results and process or display it.

It is worth noting that in actual development, we can further process the returned data as needed, such as classifying according to the level of administrative divisions, or mapping based on center point coordinates Labeling and other operations. In addition, the Amap API also provides other rich functional interfaces, which can be further developed and called according to needs.

References:

• Gaode Map Developer Documentation: https://lbs.amap.com/api/webservice/summary/
• Apache HttpComponents Documentation ：https://hc.apache.org/httpcomponents-client-ga/tutorial/html/

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