1.闪屏页面(Splash)

{"versionName": "2.0", "versionCode": 2, "description": "新增NB功能,赶紧体验!!!", 
"downloadUrl":  "http://www.baidu.com"}

public class SplashActivity extends Activity {
	protected static final int CODE_UPDATE_DIALOG = 0;
	protected static final int CODE_URL_ERROR = 1;
	protected static final int CODE_NET_ERROR = 2;
	protected static final int CODE_JSON_ERROR = 3;
	protected static final int CODE_ENTER_HOME = 4;// 进入主页面
	private TextView tvVersion;
	private TextView tvProgress;// 下载进度展示
	// 服务器返回的信息
	private String mVersionName;// 版本名
	private int mVersionCode;// 版本号
	private String mDesc;// 版本描述
	private String mDownloadUrl;// 下载地址
	private Handler mHandler = new Handler() {
		public void handleMessage(android.os.Message msg) {
			switch (msg.what) {
			case CODE_UPDATE_DIALOG:
				showUpdateDailog();
				break;
			case CODE_URL_ERROR:
				Toast.makeText(SplashActivity.this, "url错误", Toast.LENGTH_SHORT)
						.show();
				enterHome();
				break;
			case CODE_NET_ERROR:
				Toast.makeText(SplashActivity.this, "网络错误", Toast.LENGTH_SHORT)
						.show();
				enterHome();
				break;
			case CODE_JSON_ERROR:
				Toast.makeText(SplashActivity.this, "数据解析错误",
						Toast.LENGTH_SHORT).show();
				enterHome();
				break;
			case CODE_ENTER_HOME:
				enterHome();
				break;
			default:
				break;
			}
		};
	};
	private SharedPreferences mPref;
	private RelativeLayout rlRoot;// 根布局
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_splash);
		tvVersion = (TextView) findViewById(R.id.tv_version);
		tvVersion.setText("版本名:" + getVersionName());
		tvProgress = (TextView) findViewById(R.id.tv_progress);// 默认隐藏
		rlRoot = (RelativeLayout) findViewById(R.id.rl_root);
		mPref = getSharedPreferences("config", MODE_PRIVATE);
		// 判断是否需要自动更新
		boolean autoUpdate = mPref.getBoolean("auto_update", true);
		if (autoUpdate) {
			checkVerson();
		} else {
			mHandler.sendEmptyMessageDelayed(CODE_ENTER_HOME, 2000);// 延时2秒后发送消息
		}
		// 渐变的动画效果
		AlphaAnimation anim = new AlphaAnimation(0.3f, 1f);
		anim.setDuration(2000);
		rlRoot.startAnimation(anim);
	}
	/**
	 * 获取版本名称
	 * 
	 * @return
	 */
	private String getVersionName() {
		PackageManager packageManager = getPackageManager();
		try {
			PackageInfo packageInfo = packageManager.getPackageInfo(
					getPackageName(), 0);// 获取包的信息
			int versionCode = packageInfo.versionCode;
			String versionName = packageInfo.versionName;
			System.out.println("versionName=" + versionName + ";versionCode="
					+ versionCode);
			return versionName;
		} catch (NameNotFoundException e) {
			// 没有找到包名的时候会走此异常
			e.printStackTrace();
		}
		return "";
	}
	/**
	 * 获取本地app的版本号
	 * 
	 * @return
	 */
	private int getVersionCode() {
		PackageManager packageManager = getPackageManager();
		try {
			PackageInfo packageInfo = packageManager.getPackageInfo(
					getPackageName(), 0);// 获取包的信息
			int versionCode = packageInfo.versionCode;
			return versionCode;
		} catch (NameNotFoundException e) {
			// 没有找到包名的时候会走此异常
			e.printStackTrace();
		}
		return -1;
	}
	/**
	 * 从服务器获取版本信息进行校验
	 */
	private void checkVerson() {
		final long startTime = System.currentTimeMillis();
		// 启动子线程异步加载数据
		new Thread() {
			@Override
			public void run() {
				Message msg = Message.obtain();
				HttpURLConnection conn = null;
				try {
					// 本机地址用localhost, 但是如果用模拟器加载本机的地址时,可以用ip(10.0.2.2)来替换
					URL url = new URL("http://10.0.2.2:8080/update.json");
					conn = (HttpURLConnection) url.openConnection();
					conn.setRequestMethod("GET");// 设置请求方法
					conn.setConnectTimeout(5000);// 设置连接超时
					conn.setReadTimeout(5000);// 设置响应超时, 连接上了,但服务器迟迟不给响应
					conn.connect();// 连接服务器
					int responseCode = conn.getResponseCode();// 获取响应码
					if (responseCode == 200) {
						InputStream inputStream = conn.getInputStream();
						String result = StreamUtils.readFromStream(inputStream);
						// System.out.println("网络返回:" + result);
						// 解析json
						JSONObject jo = new JSONObject(result);
						mVersionName = jo.getString("versionName");
						mVersionCode = jo.getInt("versionCode");
						mDesc = jo.getString("description");
						mDownloadUrl = jo.getString("downloadUrl");
						// System.out.println("版本描述:" + mDesc);
						if (mVersionCode > getVersionCode()) {// 判断是否有更新
							// 服务器的VersionCode大于本地的VersionCode
							// 说明有更新, 弹出升级对话框
							msg.what = CODE_UPDATE_DIALOG;
						} else {
							// 没有版本更新
							msg.what = CODE_ENTER_HOME;
						}
					}
				} catch (MalformedURLException e) {
					// url错误的异常
					msg.what = CODE_URL_ERROR;
					e.printStackTrace();
				} catch (IOException e) {
					// 网络错误异常
					msg.what = CODE_NET_ERROR;
					e.printStackTrace();
				} catch (JSONException e) {
					// json解析失败
					msg.what = CODE_JSON_ERROR;
					e.printStackTrace();
				} finally {
					long endTime = System.currentTimeMillis();
					long timeUsed = endTime - startTime;// 访问网络花费的时间
					if (timeUsed < 2000) {
						// 强制休眠一段时间,保证闪屏页展示2秒钟
						try {
							Thread.sleep(2000 - timeUsed);
						} catch (InterruptedException e) {
							e.printStackTrace();
						}
					}
					mHandler.sendMessage(msg);
					if (conn != null) {
						conn.disconnect();// 关闭网络连接
					}
				}
			}
		}.start();
	}
	/**
	 * 升级对话框
	 */
	protected void showUpdateDailog() {
		AlertDialog.Builder builder = new AlertDialog.Builder(this);
		builder.setTitle("最新版本:" + mVersionName);
		builder.setMessage(mDesc);
		// builder.setCancelable(false);//不让用户取消对话框, 用户体验太差,尽量不要用
		builder.setPositiveButton("立即更新", new OnClickListener() {
			@Override
			public void onClick(DialogInterface dialog, int which) {
				System.out.println("立即更新");
				download();
			}
		});
		builder.setNegativeButton("以后再说", new OnClickListener() {
			@Override
			public void onClick(DialogInterface dialog, int which) {
				enterHome();
			}
		});
		// 设置取消的监听, 用户点击返回键时会触发
		builder.setOnCancelListener(new OnCancelListener() {
			@Override
			public void onCancel(DialogInterface dialog) {
				enterHome();
			}
		});
		builder.show();
	}
	/**
	 * 下载apk文件
	 */
	protected void download() {
		if (Environment.getExternalStorageState().equals(
				Environment.MEDIA_MOUNTED)) {
			tvProgress.setVisibility(View.VISIBLE);// 显示进度
			String target = Environment.getExternalStorageDirectory()
					+ "/update.apk";
			// XUtils
			HttpUtils utils = new HttpUtils();
			utils.download(mDownloadUrl, target, new RequestCallBack<File>() {
				// 下载文件的进度, 该方法在主线程运行
				@Override
				public void onLoading(long total, long current,
						boolean isUploading) {
					super.onLoading(total, current, isUploading);
					System.out.println("下载进度:" + current + "/" + total);
					tvProgress.setText("下载进度:" + current * 100 / total + "%");
				}
				// 下载成功,该方法在主线程运行
				@Override
				public void onSuccess(ResponseInfo<File> arg0) {
					System.out.println("下载成功");
					// 跳转到系统安装页面
					Intent intent = new Intent(Intent.ACTION_VIEW);
					intent.addCategory(Intent.CATEGORY_DEFAULT);
					intent.setDataAndType(Uri.fromFile(arg0.result),
							"application/vnd.android.package-archive");
					// startActivity(intent);
					startActivityForResult(intent, 0);// 如果用户取消安装的话,
														// 会返回结果,回调方法onActivityResult
				}
				// 下载失败,该方法在主线程运行
				@Override
				public void onFailure(HttpException arg0, String arg1) {
					Toast.makeText(SplashActivity.this, "下载失败!",
							Toast.LENGTH_SHORT).show();
				}
			});
		} else {
			Toast.makeText(SplashActivity.this, "没有找到sdcard!",
					Toast.LENGTH_SHORT).show();
		}
	}
	// 如果用户取消安装的话,回调此方法
	@Override
	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
		enterHome();
		super.onActivityResult(requestCode, resultCode, data);
	}
	/**
	 * 进入主页面
	 */
	private void enterHome() {
		Intent intent = new Intent(this, HomeActivity.class);
		startActivity(intent);
		finish();
	}
}