Android教程：在百度地图上画出轨迹

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：