Android Studio实现：按钮选Google Maps坐标并存储及回显标记

需求说明 #

• 点击按钮打开Google Maps，选择点位后将坐标返回并显示在按钮旁的TextView中
• 点击TextView中的坐标，重新打开地图并显示之前选中的标记点

依赖配置 #

在build.gradle(Module level)中添加以下依赖：

implementation 'com.google.android.gms:play-services-maps:17.0.0'
implementation 'com.google.android.gms:play-services-location:17.1.0'

权限与Manifest配置 #

在AndroidManifest.xml中添加权限和API密钥配置：

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>

<meta-data
    android:name="com.google.android.geo.API_KEY"
    android:value="你的API密钥"/>

布局文件 #

主页面布局（activity_main.xml） #

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <Button
        android:id="@+id/btn_select_location"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="选择地图点位"/>

    <TextView
        android:id="@+id/tv_selected_coords"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:text="未选择点位"
        android:textColor="@android:color/link_text"
        android:textSize="16sp"/>

</LinearLayout>

地图页面布局（activity_main2.xml） #

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <fragment
        android:id="@+id/google_map"
        android:name="com.google.android.gms.maps.SupportMapFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</FrameLayout>

代码实现 #

主Activity（MainActivity.java） #

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {
    private TextView tvSelectedCoords;
    public static final String EXTRA_LATITUDE = "extra_latitude";
    public static final String EXTRA_LONGITUDE = "extra_longitude";
    public static final int REQUEST_CODE_SELECT_LOCATION = 100;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        tvSelectedCoords = findViewById(R.id.tv_selected_coords);
        
        // 点击按钮打开地图选择点位
        findViewById(R.id.btn_select_location).setOnClickListener(v -> {
            Intent intent = new Intent(MainActivity.this, MainActivity2.class);
            startActivityForResult(intent, REQUEST_CODE_SELECT_LOCATION);
        });

        // 点击坐标文本打开地图查看已选点位
        tvSelectedCoords.setOnClickListener(v -> {
            String coords = tvSelectedCoords.getText().toString();
            if (!coords.equals("未选择点位")) {
                String[] latLng = coords.split(" : ");
                double lat = Double.parseDouble(latLng[0]);
                double lng = Double.parseDouble(latLng[1]);
                Intent intent = new Intent(MainActivity.this, MainActivity2.class);
                intent.putExtra(EXTRA_LATITUDE, lat);
                intent.putExtra(EXTRA_LONGITUDE, lng);
                startActivity(intent);
            }
        });
    }

    // 接收地图页面返回的坐标
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == REQUEST_CODE_SELECT_LOCATION && resultCode == RESULT_OK) {
            double latitude = data.getDoubleExtra(EXTRA_LATITUDE, 0);
            double longitude = data.getDoubleExtra(EXTRA_LONGITUDE, 0);
            tvSelectedCoords.setText(latitude + " : " + longitude);
        }
    }
}

地图选择Activity（MainActivity2.java） #

import android.content.Intent;
import android.os.Bundle;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

public class MainActivity2 extends AppCompatActivity implements OnMapReadyCallback {
    private GoogleMap gMap;
    private double preselectedLat = 0;
    private double preselectedLng = 0;
    private boolean isViewingExisting = false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);

        // 检查是否有传入的已选坐标
        Intent intent = getIntent();
        preselectedLat = intent.getDoubleExtra(MainActivity.EXTRA_LATITUDE, 0);
        preselectedLng = intent.getDoubleExtra(MainActivity.EXTRA_LONGITUDE, 0);
        isViewingExisting = preselectedLat != 0 || preselectedLng != 0;

        SupportMapFragment supportMapFragment = (SupportMapFragment)
                getSupportFragmentManager().findFragmentById(R.id.google_map);
        supportMapFragment.getMapAsync(this);
    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        gMap = googleMap;

        if (isViewingExisting) {
            // 显示已选择的标记点
            LatLng preselectedLoc = new LatLng(preselectedLat, preselectedLng);
            MarkerOptions markerOptions = new MarkerOptions()
                    .position(preselectedLoc)
                    .title(preselectedLat + " : " + preselectedLng);
            gMap.addMarker(markerOptions);
            gMap.animateCamera(CameraUpdateFactory.newLatLngZoom(preselectedLoc, 10));
            Toast.makeText(this, "已显示选中点位", Toast.LENGTH_SHORT).show();
        } else {
            // 允许选择新点位并返回坐标
            gMap.setOnMapClickListener(latLng -> {
                MarkerOptions markerOptions = new MarkerOptions();
                markerOptions.position(latLng);
                markerOptions.title(latLng.latitude + " : " + latLng.longitude);
                gMap.clear();
                gMap.animateCamera(CameraUpdateFactory.newLatLngZoom(latLng, 10));
                gMap.addMarker(markerOptions);

                Intent resultIntent = new Intent();
                resultIntent.putExtra(MainActivity.EXTRA_LATITUDE, latLng.latitude);
                resultIntent.putExtra(MainActivity.EXTRA_LONGITUDE, latLng.longitude);
                setResult(RESULT_OK, resultIntent);
                finish();
            });
        }
    }
}

内容的提问来源于stack exchange，提问作者Dimondikus