在工作和生存中，遇见新的共事或者合作伙伴，替换名片是一个常见的用户需要，纸质名片常忘带、易失落，是客户的一个痛点。因而，市场上呈现了很多替换电子名片的APP和小程序。那么，如何给本人的APP开发一个名片替换性能呢？
咱们能够接入华为近距离通信服务，通过近距离设施间音讯订阅（Nearby Message），疾速实现一对一或一对多名片替换。下图是性能演示：
开发具体步骤如下：
1. 开发筹备
如果您曾经是华为的开发者，能够省略此步骤。如果您以前没有集成华为挪动服务的教训，那么须要先配置AppGallery Connect，开明近距离通信服务并集成HMS SDK。相干步骤请参考官网文档。
2. 增加权限
在应用Nearby Message之前，须要增加网络权限、蓝牙权限、地位权限。在工程的AndroidManifest.xml文件中增加如下权限：
<uses-permission android:name="android.permission.INTERNET " /> <uses-permission android:name="android.permission.BLUETOOTH" /> <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" /> <!-- The location permission is also required in Android 6.0 or later. --> <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /> <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />3. 代码开发
3.1 动静权限申请
查看蓝牙开关、地位开关是否关上、网络是否可用，并对地位权限进行动静权限申请
@Override public void onStart() { super.onStart(); getActivity().getApplication().registerActivityLifecycleCallbacks(this); checkPermission(); } @Override public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) { for (int i = 0; i < permissions.length; ++i) { if (grantResults[i] != 0) { showWarnDialog(Constants.LOCATION_ERROR); } } } private void checkPermission() { if (!BluetoothCheckUtil.isBlueEnabled()) { showWarnDialog(Constants.BLUETOOTH_ERROR); return; } if (!LocationCheckUtil.isLocationEnabled(this.getActivity())) { showWarnDialog(Constants.LOCATION_SWITCH_ERROR); return; } if (!NetCheckUtil.isNetworkAvailable(this.getActivity())) { showWarnDialog(Constants.NETWORK_ERROR); return; } String[] deniedPermission = PermissionUtil.getDeniedPermissions(this.getActivity(), new String[] { Manifest.permission.ACCESS_COARSE_LOCATION, Manifest.permission.ACCESS_FINE_LOCATION }); if (deniedPermission.length > 0) { PermissionUtil.requestPermissions(this.getActivity(), deniedPermission, 10); } }3.2 封装名片公布接口和名片订阅接口
订阅到的名片音讯（onFound），把名片增加到查找名片对话框中显示；名片音讯失落时（onLost），从查找名片对话框中删除该名片
private MessageHandler mMessageHandler = new MessageHandler() { @Override public void onFound(Message message) { CardInfo cardInfo = JsonUtils.json2Object(new String(message.getContent(), Charset.forName("UTF-8")), CardInfo.class); if (cardInfo == null) { return; } mSearchCardDialogFragment.addCardInfo(cardInfo); } @Override public void onLost(Message message) { CardInfo cardInfo = JsonUtils.json2Object(new String(message.getContent(), Charset.forName("UTF-8")), CardInfo.class); if (cardInfo == null) { return; } mSearchCardDialogFragment.removeCardInfo(cardInfo); } }; private void publish(String namespace, String type, int ttlSeconds, OnCompleteListener<Void> listener) { Message message = new Message(JsonUtils.object2Json(mCardInfo).getBytes(Charset.forName("UTF-8")), type, namespace); Policy policy = new Policy.Builder().setTtlSeconds(ttlSeconds).build(); PutOption option = new PutOption.Builder().setPolicy(policy).build(); Nearby.getMessageEngine(getActivity()).put(message, option).addOnCompleteListener(listener); } private void subscribe(String namespace, String type, int ttlSeconds, OnCompleteListener<Void> listener, GetCallback callback) { Policy policy = new Policy.Builder().setTtlSeconds(ttlSeconds).build(); MessagePicker picker = new MessagePicker.Builder().includeNamespaceType(namespace, type).build(); GetOption.Builder builder = new GetOption.Builder().setPolicy(policy).setPicker(picker); if (callback != null) { builder.setCallback(callback); } Nearby.getMessageEngine(getActivity()).get(mMessageHandler, builder.build()).addOnCompleteListener(listener); }3.3 名片替换菜单解决
面对面替换名片替换码，公布集体名片胜利后，订阅名片音讯
private boolean onExchangeItemSelected() { PinCodeDialogFragment dialogFragment = new PinCodeDialogFragment(passwrod -> { MyCardFragment.this.publish(passwrod, passwrod, Policy.POLICY_TTL_SECONDS_MAX, result -> { if (!result.isSuccessful()) { String str = "Exchange card fail, because publish my card fail. exception: " + result.getException().getMessage(); Log.e(TAG, str); Toast.makeText(getActivity(), str, Toast.LENGTH_LONG).show(); return; } MyCardFragment.this.subscribe(passwrod, passwrod, Policy.POLICY_TTL_SECONDS_INFINITE, ret -> { if (!ret.isSuccessful()) { MyCardFragment.this.unpublish(passwrod, passwrod, task -> { String str = "Exchange card fail, because subscribe is fail, exception(" + ret.getException().getMessage() + ")"; if (!task.isSuccessful()) { str = str + " and unpublish fail, exception(" + task.getException().getMessage() + ")"; } Log.e(TAG, str); Toast.makeText(getActivity(), str, Toast.LENGTH_LONG).show(); }); return; } mSearchCardDialogFragment.setOnCloseListener(() -> { MyCardFragment.this.unpublish(passwrod, passwrod, task -> { if (!task.isSuccessful()) { Toast.makeText(getActivity(), "Unpublish my card fail, exception: " + task.getException().getMessage(), Toast.LENGTH_LONG).show(); } }); MyCardFragment.this.unsubscribe(task -> { if (!task.isSuccessful()) { Toast.makeText(getActivity(), "Unsubscribe fail, exception: " + task.getException().getMessage(), Toast.LENGTH_LONG).show(); } }); }); mSearchCardDialogFragment.show(getParentFragmentManager(), "Search Card"); }, null); }); }); dialogFragment.show(getParentFragmentManager(), "pin code"); return true; }3.4 珍藏名片解决
珍藏名片时把名片加入收藏列表，名片勾销珍藏时把名片从参数列表中删除，并把数据保留到本地存储中。
@Override public void onFavorite(CardInfo cardInfo, boolean isFavorite) { if (isFavorite) { mFavoriteMap.put(cardInfo.getId(), cardInfo); } else { mFavoriteMap.remove(cardInfo.getId()); } Set<String> set = new HashSet<>(mFavoriteMap.size()); for (CardInfo card : mFavoriteMap.values()) { set.add(JsonUtils.object2Json(card)); } SharedPreferences sharedPreferences = getContext().getSharedPreferences("data", Context.MODE_PRIVATE); sharedPreferences.edit().putStringSet(Constants.MY_FAVORITES_KEY, set).apply(); }本次给大家演示的demo用到了华为HMS Nearby service的近距离设施间音讯订阅性能。基于Nearby Message能力不仅仅能够用来做面对面替换名片，还能够帮忙开发者实现很多乏味的性能，例如：
- 竞技类手游中的面对面组队性能
- 棋牌类手游中的面对面约局性能
- 近场AA收款性能
- 音乐曲目共享性能
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