Android教程：在百度地图上画出轨迹

[日期：2013-04-14]

来源：Linux社区  作者：crazyxin1988

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接着上面的项目《Android访问webservice.客户端登录注册》http://www.linuxidc.com/Linux/2013-04/82747.htm，实现餐厅搜索，这个在吃客游记里就做过了，然后把餐厅显示出来，可以把该餐厅加入轨迹

关于轨迹点操作的前后台实现和之前的登录注册差不多，这里主要说一下，用户查看自己的轨迹时候，在手机

端的显示。

1.从服务器把轨迹点拿下来

2.地图上显示点

3.把点连成线

看代码吧，注释比较详细，关键的画线操作就在OverItemT这个类中。

package seu.android007.xin;

import java.util.ArrayList;
import java.util.List;

import com.baidu.mapapi.BMapManager;
import com.baidu.mapapi.GeoPoint;
import com.baidu.mapapi.ItemizedOverlay;
import com.baidu.mapapi.LocationListener;
import com.baidu.mapapi.MapActivity;
import com.baidu.mapapi.MapView;
import com.baidu.mapapi.MyLocationOverlay;
import com.baidu.mapapi.OverlayItem;
import com.baidu.mapapi.Projection;
import seu.android007.service.TraceServcie;
import seu.xin.entity.Trace;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Point;
import android.graphics.drawable.Drawable;
import android.location.Location;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.Toast;

public class MyTrace extends MapActivity {
 static MapView mMapView = null;
 LocationListener mLocationListener = null;// onResume时注册此listener，onPause时需要Remove
 MyLocationOverlay mLocationOverlay = null; // 定位图层
 static View mPopView = null; // 点击mark时弹出的气泡View
 TraceServcie traceServcie;
 private ArrayList<Trace> myTraces = new ArrayList<Trace>();
 SharedPreferences sp;

@Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.my_trace);
  traceServcie = new TraceServcie();
  sp = this.getSharedPreferences("data", MODE_WORLD_READABLE);
  int uid = sp.getInt("uid", 0);
  myTraces = traceServcie.findTracesByUid(uid);

BMapApp app = (BMapApp) this.getApplication();
  if (app.mBMapMan == null) {
   app.mBMapMan = new BMapManager(getApplication());
   app.mBMapMan.init(app.mStrKey, new BMapApp.MyGeneralListener());
  }
  app.mBMapMan.start();
  // 如果使用地图SDK，请初始化地图Activity
  super.initMapActivity(app.mBMapMan);

mMapView = (MapView) findViewById(R.id.bmapView);
  mMapView.setBuiltInZoomControls(true);
  // 设置在缩放动画过程中也显示overlay,默认为不绘制
  mMapView.setDrawOverlayWhenZooming(true);

// 添加定位图层
  mLocationOverlay = new MyLocationOverlay(this, mMapView);
  mMapView.getOverlays().add(mLocationOverlay);

// 注册定位事件
  mLocationListener = new LocationListener() {

@Override
   public void onLocationChanged(Location location) {
    if (location != null) {
     GeoPoint pt = new GeoPoint(
       (int) (location.getLatitude() * 1e6),
       (int) (location.getLongitude() * 1e6));
     mMapView.getController().animateTo(pt);
    }
   }
  };
  if (myTraces.size() == 0) {
   System.out.println("轨迹为空，调转到MyActivityGroup");
   AlertDialog.Builder builder = new AlertDialog.Builder(MyTrace.this);
   builder.setTitle("提醒");
   builder.setMessage("没有轨迹，请添加后再查看");
   builder.setPositiveButton("确定",
     new DialogInterface.OnClickListener() {

@Override
      public void onClick(DialogInterface dialog, int which) {
       // TODO Auto-generated method stub
       Intent intent = new Intent();
       intent.setClass(MyTrace.this, MyActivityGroup.class);
       startActivity(intent);
       MyTrace.this.finish();
      }
     });
   builder.create().show();
  } else {
   System.out.println("获得点后添加到图层");
   // 添加ItemizedOverlay
   Drawable marker = getResources().getDrawable(R.drawable.iconmarka); // 得到需要标在地图上的资源
   marker.setBounds(0, 0, marker.getIntrinsicWidth(),
     marker.getIntrinsicHeight()); // 为maker定义位置和边界

mMapView.getOverlays().add(new OverItemT(marker, this, myTraces)); // 添加ItemizedOverlay实例到mMapView

// 创建点击mark时的弹出泡泡
   mPopView = super.getLayoutInflater()
     .inflate(R.layout.popview, null);
   mMapView.addView(mPopView, new MapView.LayoutParams(
     LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT, null,
     MapView.LayoutParams.TOP_LEFT));
   mPopView.setVisibility(View.GONE);
  }

}

@Override
 protected void onPause() {
  BMapApp app = (BMapApp) this.getApplication();
  app.mBMapMan.getLocationManager().removeUpdates(mLocationListener);
  mLocationOverlay.disableMyLocation();
  mLocationOverlay.disableCompass(); // 关闭指南针
  app.mBMapMan.stop();
  super.onPause();
 }

@Override
 protected void onResume() {
  BMapApp app = (BMapApp) this.getApplication();
  // 注册定位事件，定位后将地图移动到定位点
  app.mBMapMan.getLocationManager().requestLocationUpdates(
    mLocationListener);
  mLocationOverlay.enableMyLocation();
  mLocationOverlay.enableCompass(); // 打开指南针
  app.mBMapMan.start();
  super.onResume();
 }

@Override
 protected boolean isRouteDisplayed() {
  // TODO Auto-generated method stub
  return false;
 }

}

class OverItemT extends ItemizedOverlay<OverlayItem> {

private List<OverlayItem> mGeoList = new ArrayList<OverlayItem>();
 private Drawable marker;
 private Context mContext;
 private ArrayList<Trace> traces = new ArrayList<Trace>();

public OverItemT(Drawable marker, Context context, ArrayList<Trace> traces) {
  super(boundCenterBottom(marker));

this.marker = marker;
  this.mContext = context;
  this.traces = traces;
  // 用给定的经纬度构造GeoPoint，单位是微度 (度 * 1E6)
  // 构造OverlayItem的三个参数依次为：item的位置，标题文本，文字片段
  for (int i = 0; i < traces.size(); i++) {
   int lat = new Integer(traces.get(i).getLatitude());
   int lon = new Integer(traces.get(i).getLongitude());
   String resName = traces.get(i).getResname();
   GeoPoint p = new GeoPoint(lat, lon);
   mGeoList.add(new OverlayItem(p, resName, i + resName));
   populate(); // createItem(int)方法构造item。一旦有了数据，在调用其它方法前，首先调用这个方法
  }

}

@Override
 public void draw(Canvas canvas, MapView mapView, boolean shadow) {

// Projection接口用于屏幕像素坐标和经纬度坐标之间的变换
  Projection projection = mapView.getProjection();
  for (int index = size() - 1; index >= 0; index--) { // 遍历mGeoList
   OverlayItem overLayItem = getItem(index); // 得到给定索引的item

String title = overLayItem.getTitle();
   // 把经纬度变换到相对于MapView左上角的屏幕像素坐标
   Point point = projection.toPixels(overLayItem.getPoint(), null);

// 可在此处添加您的绘制代码
   Paint paintText = new Paint();
   paintText.setColor(Color.BLUE);
   paintText.setTextSize(15);
   canvas.drawText(title, point.x - 30, point.y, paintText); // 绘制文本
  }

super.draw(canvas, mapView, shadow);
  // 调整一个drawable边界，使得（0，0）是这个drawable底部最后一行中心的一个像素
  // 先所有点的经度转像素
  ArrayList<Point> points = new ArrayList<Point>();
  for (int i = 0; i < this.size(); i++) {
   Point p = new Point();
   OverlayItem overLayItem = getItem(i);
   projection.toPixels(overLayItem.getPoint(), p);
   points.add(p);
  }
  // 第二个画笔 画线
  Paint paint = new Paint();
  paint.setColor(Color.BLUE);
  paint.setDither(true);
  paint.setStyle(Paint.Style.STROKE);
  paint.setStrokeJoin(Paint.Join.ROUND);
  paint.setStrokeCap(Paint.Cap.ROUND);
  paint.setStrokeWidth(4);

// 连接 所有点
  Path path = new Path();
  path.moveTo(points.get(0).x, points.get(0).y);
  for (int i = 1; i < points.size(); i++) {
   path.lineTo(points.get(i).x, points.get(i).y);
  }
  // 画出路径
  canvas.drawPath(path, paint);
  boundCenterBottom(marker);
 }

@Override
 protected OverlayItem createItem(int i) {
  // TODO Auto-generated method stub
  return mGeoList.get(i);
 }

@Override
 public int size() {
  // TODO Auto-generated method stub
  return mGeoList.size();
 }

@Override
 // 处理当点击事件
 protected boolean onTap(int i) {
  setFocus(mGeoList.get(i));
  // 更新气泡位置,并使之显示
  GeoPoint pt = mGeoList.get(i).getPoint();
  MyTrace.mMapView.updateViewLayout(MyTrace.mPopView,
    new MapView.LayoutParams(LayoutParams.WRAP_CONTENT,
      LayoutParams.WRAP_CONTENT, pt,
      MapView.LayoutParams.BOTTOM_CENTER));
  MyTrace.mPopView.setVisibility(View.VISIBLE);
  Toast.makeText(this.mContext, mGeoList.get(i).getSnippet(),
    Toast.LENGTH_SHORT).show();
  return true;
 }

@Override
 public boolean onTap(GeoPoint arg0, MapView arg1) {
  // TODO Auto-generated method stub
  // 消去弹出的气泡
  MyTrace.mPopView.setVisibility(View.GONE);
  return super.onTap(arg0, arg1);
 }
}

运行的效果图：