主要活动
package com.project.mobileshoppingassistant.activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.preference.PreferenceActivity;
import android.preference.PreferenceManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ImageButton;
import com.project.mobileshoppingassistant.Environment.Constants;
import com.project.mobileshoppingassistant.MapViewActivity;
import com.project.mobileshoppingassistant.R;
import com.project.mobileshoppingassistant.model.SharedPrefs;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ImageButton bScanProduct = (ImageButton) findViewById(R.id.bScanProduct);
ImageButton blocateuser = (ImageButton) findViewById(R.id.bLocateUser);
ImageButton bAllProducts = (ImageButton) findViewById(R.id.bAllProducts);
ImageButton bSaleProducts = (ImageButton) findViewById(R.id.bSaleProducts);
ImageButton bYourCart = (ImageButton) findViewById(R.id.bYourCart);
ImageButton bYourList = (ImageButton) findViewById(R.id.bYourList);
ImageButton bLogout = (ImageButton) findViewById(R.id.bLogout);
ImageButton bTransactionHistory = (ImageButton) findViewById(R.id.bTransactionHistory);
bScanProduct.setOnClickListener(this);
bAllProducts.setOnClickListener(this);
blocateuser.setOnClickListener(this);
bSaleProducts.setOnClickListener(this);
bYourCart.setOnClickListener(this);
bYourList.setOnClickListener(this);
bLogout.setOnClickListener(this);
bTransactionHistory.setOnClickListener(this);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_settings) {
Intent i = new Intent(this, PrefsActivity.class);
startActivity(i);
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.bAllProducts:
Intent i1 = new Intent(this, ProductCategoryActivity.class);
startActivity(i1);
break;
case R.id.bLocateUser:
Intent i8 = new Intent(this, MapViewActivity.class);
startActivity(i8);
break;
case R.id.bSaleProducts:
Intent i2 = new Intent(this, SaleProductsActivity.class);
startActivity(i2);
break;
case R.id.bScanProduct:
Intent i3 = new Intent(this, ProductScanActivity.class);
startActivity(i3);
break;
case R.id.bYourCart:
Intent i4 = new Intent(this, CartActivity.class);
startActivity(i4);
break;
case R.id.bYourList:
Intent i5 = new Intent(this, YourListActivity.class);
startActivity(i5);
break;
case R.id.bTransactionHistory:
Intent i6 = new Intent(this, TransactionHistoryActivity.class);
startActivity(i6);
break;
case R.id.bLogout:
SharedPrefs.setUserEmailId(getApplicationContext(), null);
Intent i7 = new Intent(this, LoginActivity.class);
startActivity(i7);
finish();
break;
}
}
}
MapViewActivity
package com.project.mobileshoppingassistant;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.graphics.PointF;
import android.net.wifi.ScanResult;
import android.os.Bundle;
import android.os.Handler;
import android.preference.PreferenceManager;
import android.view.Menu;
import android.view.MenuItem;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;
import java.util.TreeSet;
public class MapViewActivity extends MapActivity {
public final static String EXTRA_MESSAGE_FLOOR = "com.inte.indoorpositiontracker.FLOOR";
private static final int MENU_ITEM_EDIT_MAP = 21;
public static final int SCAN_DELAY = 1000; // delay for the first scan (milliseconds)
public static final int SCAN_INTERVAL = 1000; // interval between scans (milliseconds)
public static final int MAX_SCAN_THREADS = 2; // max amount of simultaneus scans
private int mScanThreadCount = 0;
//keys to save fingerPrint to sharedPereferences--start
public static final String KEY_ID="fingerprint_id";
public static final String KEY_MAP="fingerprint_map";
public static final String KEY_POSITON_X="fingerprintX";
public static final String KEY_POSITON_Y="fingerprintY";
//end
public static final String KEY_FINGERPRINT_MADE="hasFIngerPrintBeenMade";//used to check if
// an average point has been calculated
// UI pointer to visualize user where he is on the map
private WifiPointView mLocationPointer;
// handler for callbacks to the UI thread
private static Handler sUpdateHandler = new Handler();
// runnable to refresh map (called by the handler)
private Runnable mRefreshMap = new Runnable() {
public void run() {
refreshMap();
}
};
private boolean mPaused = false; // used to detect if the application is on map edit mode
private HashMap<String, Integer> mMeasurements; // used to calculate weighted averages of signal strengths
/** INSTANCE METHODS*/
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mMeasurements = new HashMap<String, Integer>();
mLocationPointer = mMap.createNewWifiPointOnMap(new PointF(-1000, -1000));
mLocationPointer.activate();
if (PreferenceManager.getDefaultSharedPreferences(this).getBoolean(KEY_FINGERPRINT_MADE,false))
{
mLocationPointer.setFingerprint(getSavedFingerprint());
}
Timer timer = new Timer();
timer.schedule(new TimerTask() {
@Override
public void run() {
if(mPaused == false) { // start scan only when this activity is active
mWifi.startScan();
}
}
}, SCAN_DELAY, SCAN_INTERVAL);
}
@Override
public void onReceiveWifiScanResults(final List<ScanResult> results) {
IndoorPositionTracker application = (IndoorPositionTracker) getApplication();
final ArrayList<Fingerprint> fingerprints = application.getFingerprintData(mSelectedMap);
// calculating the location might take some time in case there are a lot of fingerprints (>10000),
// so it's reasonable to limit scan thread count to make sure there are not too many of these threads
// going on at the same time
if(results.size() > 0 && fingerprints.size() > 0 && mScanThreadCount <= MAX_SCAN_THREADS) {
Thread t = new Thread() {
public void run() {
mScanThreadCount++;
HashMap<String, Integer> measurements = new HashMap<String, Integer>();
for (ScanResult result : results) {
measurements.put(result.BSSID, result.level);
}
TreeSet<String> keys = new TreeSet<String>();
keys.addAll(mMeasurements.keySet());
keys.addAll(measurements.keySet());
// calculate access point signal strengths with weighted averages
// (adjust to suddent big changes in received signal strengths)
for (String key : keys) {
Integer value = measurements.get(key);
Integer oldValue = mMeasurements.get(key);
if(oldValue == null) {
mMeasurements.put(key, value);
} else if(value == null) {
mMeasurements.remove(key);
} else {
value = (int) (oldValue * 0.4f + value * 0.6f);
mMeasurements.put(key, value);
}
}
Fingerprint f = new Fingerprint(mMeasurements);
// find fingerprint closest to our location (one with the smallest euclidean distance to us)
Fingerprint closestMatch = f.getClosestMatch(fingerprints);
runOnUiThread(new Runnable() {
public void run() {
PreferenceManager.getDefaultSharedPreferences(MapViewActivity.this).edit()
.putBoolean(KEY_FINGERPRINT_MADE,true).commit();
}
});
mLocationPointer.setFingerprint(closestMatch); // translate UI pointer to new location on screen
saveFingerPrint(closestMatch);
// need to refresh map through updateHandler since only UI thread is allowed to touch its views
sUpdateHandler.post(mRefreshMap);
mScanThreadCount--;
}
};
t.start(); // start new scan thread
}
}
public void startMapEditActivity() {
Intent intent = new Intent(MapViewActivity.this, MapEditActivity.class);
intent.putExtra(EXTRA_MESSAGE_FLOOR, mSelectedMap);
startActivity(intent); // start map edit mode
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// add menu items
super.onCreateOptionsMenu(menu); // items for changing map
menu.add(Menu.NONE, MENU_ITEM_EDIT_MAP, Menu.NONE, "Edit map");
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle item selection
switch (item.getItemId()) {
case MENU_ITEM_EDIT_MAP: // start map edit mode
startMapEditActivity();
return true;
default: // change map
return super.onOptionsItemSelected(item);
}
}
private void saveMap(HashMap<String,Integer> inputMap){
SharedPreferences pSharedPref = getApplicationContext().getSharedPreferences
("MyVariables", Context.MODE_PRIVATE);
if (pSharedPref != null){
JSONObject jsonObject = new JSONObject(inputMap);
String jsonString = jsonObject.toString();
SharedPreferences.Editor editor = pSharedPref.edit();
editor.remove("My_map").commit();
editor.putString("My_map", jsonString);
editor.commit();
}
}
private HashMap<String,Integer> loadMap(){
HashMap<String,Integer> outputMap = new HashMap<String,Integer>();
SharedPreferences pSharedPref = getApplicationContext().getSharedPreferences("MyVariables", Context.MODE_PRIVATE);
try{
if (pSharedPref != null){
String jsonString = pSharedPref.getString("My_map", (new JSONObject()).toString());
JSONObject jsonObject = new JSONObject(jsonString);
Iterator<String> keysItr = jsonObject.keys();
while(keysItr.hasNext()) {
String key = keysItr.next();
Integer value = (Integer) jsonObject.get(key);
outputMap.put(key, value);
}
}
}catch(Exception e){
e.printStackTrace();
}
return outputMap;
}
private void saveFingerPrint(Fingerprint fingerprint)
{
PreferenceManager.getDefaultSharedPreferences(this).edit()
.putInt(KEY_ID,fingerprint.getId())
.putString(KEY_MAP,fingerprint.getMap())
.putFloat(KEY_POSITON_X,fingerprint.getLocation().x)
.putFloat(KEY_POSITON_Y,fingerprint.getLocation().y)
.commit();
saveMap(fingerprint.getMeasurements());
}
private Fingerprint getSavedFingerprint()
{
SharedPreferences preferences=PreferenceManager.getDefaultSharedPreferences(this);
int id=preferences.getInt(KEY_ID, -1);
String map=preferences.getString(KEY_MAP, null);
Float positionX=preferences.getFloat(KEY_POSITON_X, -1);
Float positionY=preferences.getFloat(KEY_POSITON_Y,-1);
PointF pointF=new PointF(positionX,positionY);
Fingerprint fingerprint=new Fingerprint(id,map,pointF,loadMap());
return fingerprint;
}
}
清单
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.project.mobileshoppingassistant">
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"></uses-permission>
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE"></uses-permission>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme">
<activity
android:name=".activity.SplashScreenActivity"
android:label="@string/title_activity_splash_screen"
android:screenOrientation="portrait">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".activity.ProductScanActivity"
android:label="@string/title_activity_barcode_scanner"
android:screenOrientation="portrait" />
<activity
android:name=".activity.MainActivity"
android:label="@string/title_activity_main"
android:screenOrientation="portrait" />
<activity
android:name=".activity.UserRegisterActivity"
android:label="@string/title_activity_user_register"
android:screenOrientation="portrait" />
<activity
android:name=".activity.DisplayProductActivity"
android:label="@string/title_activity_display_product"
android:screenOrientation="portrait" />
<activity
android:name=".activity.TransactionActivity"
android:label="@string/title_activity_transaction"
android:screenOrientation="portrait" />
<activity
android:name=".activity.AllProductsActivity"
android:label="@string/title_activity_all_products"
android:screenOrientation="portrait" />
<activity
android:name=".activity.LoginActivity"
android:label="@string/title_activity_login"
android:screenOrientation="portrait" />
<activity
android:name=".activity.CartActivity"
android:label="@string/title_activity_cart"
android:screenOrientation="portrait" />
<activity
android:name=".activity.OrderActivity"
android:label="@string/title_activity_order"
android:screenOrientation="portrait" />
<activity
android:name=".activity.RegisterActivity"
android:label="@string/title_activity_register"
android:screenOrientation="portrait" />
<activity
android:name=".activity.TransactionHistoryActivity"
android:label="@string/title_activity_transaction_history"
android:screenOrientation="portrait" />
<activity
android:name=".activity.PrefsActivity"
android:label="@string/title_activity_transaction_history"
android:screenOrientation="portrait" />
PrefsActivity
<activity
android:name=".activity.SaleProductsActivity"
android:label="@string/title_activity_sale_products"
android:screenOrientation="portrait" />
<activity
android:name=".activity.YourListActivity"
android:label="@string/title_activity_your_list"
android:screenOrientation="portrait" />
<activity
android:name=".activity.ProductCategoryActivity"
android:label="@string/title_activity_product_category"
android:screenOrientation="portrait" />
<activity android:name=".MapEditActivity"
android:label="Localisation">
</activity>
<activity android:name=".MapViewActivity"
android:label="Localisation"></activity>
<activity android:name=".MapActivity"
android:label="Localisation"></activity>
</application>
</manifest>
当我点击按钮定位用户（从主要到mapeditactivity）我得到一个无法启动活动组件NullException.Can有人帮忙吗？
答案 0 :(得分：0)
您尚未初始化mMap并在此处使用
mLocationPointer = mMap.createNewWifiPointOnMap(new PointF(-1000, -1000));
在使用之前初始化它。