java - Android 自定义 map fragment 属性

Question

我正在尝试将标记添加到我的一项 Activity 的谷歌地图 fragment 中。 map 已显示，但没有标记。这可能与 Activity 类型有关。源代码如下。

content_checkin_info.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.example.martin.ivebeenthere.CheckinInfo"
    tools:showIn="@layout/app_bar_checkin_info">

    <ImageView
        android:layout_width="80dp"
        android:layout_height="80dp"
        android:id="@+id/imageView3"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:src="@drawable/craig"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text=""
        android:id="@+id/textView7"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text=""
        android:id="@+id/textView8"
        android:layout_below="@+id/textView7"
        android:layout_alignLeft="@+id/textView7"
        android:layout_alignStart="@+id/textView7" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text=""
        android:id="@+id/textView9"
        android:layout_marginTop="30dp"
        android:layout_below="@+id/fragment"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />

    <fragment
        android:layout_width="wrap_content"
        android:layout_height="250dp"
        android:name="com.google.android.gms.maps.MapFragment"
        android:id="@+id/fragment"
        android:layout_below="@+id/imageView3"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:layout_marginTop="31dp"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />

</RelativeLayout>

CheckinInfo.java

package com.example.martin.ivebeenthere;

import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.view.View;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;
import android.widget.Toast;


import com.google.android.gms.common.GooglePlayServicesUtil;
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;

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.DefaultHttpClient;
import org.apache.http.protocol.BasicHttpContext;
import org.apache.http.protocol.HttpContext;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;
import java.io.InputStream;

public class CheckinInfo extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {

    private TextView txtInfo;
    private TextView txtUser;
    private TextView txtVisit;

    private SupportMapFragment mapFragment;
    private GoogleMap mMap;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_checkin_info);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        new LongRunningGetIO().execute();

        mapFragment = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.fragment));
        if (mapFragment != null) {
            mapFragment.getMapAsync(new OnMapReadyCallback() {
                @Override
                public void onMapReady(GoogleMap googleMap) {
                    mMap = googleMap;
                    LatLng mayo = new LatLng(53.9345, -9.3516);
                    mMap.addMarker(new MarkerOptions().position(mayo).title("Jack White - Mayo"));
                }
            });
        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.setDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);
    }

    private class LongRunningGetIO extends AsyncTask<Void, Void, String> {

        protected String getASCIIContentFromEntity(HttpEntity entity) throws IllegalStateException, IOException {
            InputStream in = entity.getContent();
            StringBuffer out = new StringBuffer();
            int n = 1;
            while (n > 0) {
                byte[] b = new byte[4096];
                n = in.read(b);
                if (n > 0) out.append(new String(b, 0, n));
            }
            return out.toString();
        }

        @Override
        protected String doInBackground(Void... params) {
            HttpClient httpClient = new DefaultHttpClient();
            HttpContext localContext = new BasicHttpContext();
            HttpGet httpGet = new HttpGet("https://api.myjson.com/bins/20xew");
            String text = null;
            try {
                HttpResponse response = httpClient.execute(httpGet, localContext);
                HttpEntity entity = response.getEntity();
                text = getASCIIContentFromEntity(entity);
            } catch (Exception e) {
                return e.getLocalizedMessage();
            }
            return text;
        }

        protected void onPostExecute(String results) {
            if (results != null) {

                JSONArray myJSONArray;
                try {
                    myJSONArray = new JSONArray(results);

                    for (int i = 0; i < myJSONArray.length(); i++) {
                        JSONObject obj = (JSONObject) myJSONArray.get(i);

                        String info = obj.getString("Info");
                        String user = obj.getString("User");
                        String visit = obj.getString("Visit");
                        txtInfo = (TextView) findViewById(R.id.textView9);
                        txtUser = (TextView) findViewById(R.id.textView7);
                        txtVisit = (TextView) findViewById(R.id.textView8);
                        txtInfo.setText(info);
                        txtUser.setText(user);
                        txtVisit.setText(visit);
                    }
                } catch (JSONException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

            }
        }
    }

    @Override
    public void onBackPressed() {
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.checkin_info, menu);
        return true;
    }

    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        int id = item.getItemId();

        if (id == R.id.nav_feed) {
            startActivity(new Intent(getApplicationContext(), Feed.class));
        } else if (id == R.id.nav_map) {
            startActivity(new Intent(getApplicationContext(), Map.class));
        } else if (id == R.id.nav_account) {
            startActivity(new Intent(getApplicationContext(), Account.class));
        } else if (id == R.id.nav_logout) {
            startActivity(new Intent(getApplicationContext(), Home.class));
            Toast.makeText(getApplicationContext(), "Logged Out",
                    Toast.LENGTH_LONG).show();
        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }
}

Answer 1

因为下面的代码返回null

mapFragment = ((SupportMapFragment) getSupportFragmentManager()
    .findFragmentById(R.id.fragment));

使用时也应该在xml中使用SupportMapFragment

  <fragment
        android:layout_width="wrap_content"
        android:layout_height="250dp"
        android:name="com.google.android.gms.maps.SupportMapFragment"
        android:id="@+id/fragment"
        android:layout_below="@+id/imageView3"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:layout_marginTop="31dp"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />