Amap API document analysis: Java implements map coordinate conversion function

Amap API document analysis: Java implements map coordinate conversion function

Introduction:
With the development of the Internet, map services have become an indispensable part of people's lives. As a leading domestic map service provider, Amap's API documentation provides a wealth of functions to facilitate developers to use map-related services in their own applications. This article will introduce the coordinate conversion service of Amap API in detail and give Java sample code.

1. Amap API coordinate conversion service

1.1 What is coordinate conversion?
In map applications, different map service providers usually use different coordinate systems. For example, Amap uses the Mars coordinate system (GCJ-02), while Google Maps uses the WGS84 coordinate system. Coordinate conversion is to convert the coordinate system of one map service provider to the coordinate system of another map service provider so that the same location information can be displayed on different maps.

1.2 Gaode Map Coordinate Conversion API
Gaode Map API provides the CoordinateConvert class to implement the coordinate conversion function. This class contains the convert method, which can convert between various coordinate systems.

The sample code is as follows:

import com.amap.api.maps.CoordinateConverter;
import com.amap.api.maps.model.LatLng;

public class CoordinateConvertExample {

    public static void main(String[] args) {
        // 创建一个坐标转换对象
        CoordinateConverter converter = new CoordinateConverter();

        // 设置原坐标类型为火星坐标系
        converter.from(CoordinateConverter.CoordType.GPS);

        // 设置目标坐标类型为百度坐标系
        converter.coord(new LatLng(39.913935, 116.397063));

        // 开始转换
        LatLng result = converter.convert();

        // 输出转换结果
        System.out.println("转换后的坐标：" + result.latitude + ", " + result.longitude);
    }
}

2. Use Amap API for coordinate conversion

2.1 Import Amap SDK
First, in your Java project Import the Amap SDK. You can download the SDK from the official website (https://lbs.amap.com/dev/) and configure it according to the SDK documentation.

2.2 Create a coordinate conversion object
Create a coordinate conversion object by instantiating the CoordinateConverter object. Next, you need to set the type of the original coordinates and set the original coordinates through the coord method.

2.3 Set the coordinate conversion type
Use the from method to set the coordinate system type that needs to be converted, such as converting GPS coordinates to Baidu coordinates.

2.4 Start conversion
Call the convert method to perform coordinate conversion.

2.5 Get the conversion result
The converted longitude and latitude can be obtained through the LatLng object.

2.6 Output conversion results
Use System.out.println to print the converted coordinates.

Summary:
This article introduces the coordinate conversion service of Amap API and gives Java sample code. By using the coordinate conversion function of the Amap API, coordinate conversion between different map service providers can be achieved, making it easy to display the same location information on different maps.

FAQ:
1. What other commonly used coordinate transformation types are there in the coordinate transformation service of Amap API?
Answer: In addition to the commonly used coordinate conversion between GCJ-02 and WGS84, the Amap API also supports other coordinate conversion types, such as the National Survey Bureau GCJ-02 coordinates to Baidu BD-09 coordinates, etc. For specific coordinate conversion types and usage methods, please refer to the Amap API documentation.

2. How to convert batch coordinates?
Answer: The CoordinateConvert class provided by Amap API also supports batch coordinate conversion. Set the original type of coordinates through the from method, then call the coord method to pass in multiple coordinates, and finally call the convert method to convert. The conversion result returns a List<LatLng> object, which can be traversed to obtain the conversion result of each coordinate.

References:
Gaode Map API Documentation: https://lbs.amap.com/api/webservice/guide/api/convert

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