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》，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