在工作和生活中，遇見新的同事或者合作伙伴，交換名片是一個常見的使用者需求，紙質名片常忘帶、易丟失，是客戶的一個痛點。因此，市場上出現了很多交換電子名片的APP和小程式。那麼，如何給自己的APP開發一個名片交換功能呢？

![](https://oscimg.oschina.net/oscnet/up-e1b1a0140feac53aa6646a6f9445a9a8619.JPEG)

我們可以接入[華為近距離通訊服務](https://developer.huawei.com/consumer/cn/hms/huawei-nearbyservice?ha_source=hms1)，透過近距離裝置間訊息訂閱（Nearby Message），快速實現一對一或一對多名片交換。下圖是功能演示：

![](https://oscimg.oschina.net/oscnet/up-e759788f93864e848986824b74a468ec41c.gif)

開發具體步驟如下：

#### 1\. 開發準備

如果您已經是華為的開發者，可以省略此步驟。如果您以前沒有整合華為移動服務的經驗，那麼需要先配置AppGallery Connect，開通近距離通訊服務並整合HMS SDK。相關步驟請參考[官方文件](https://developer.huawei.com/consumer/cn/doc/development/system-Guides/enabling-service-0000001050042529?ha_source=hms1)。

#### 2\. 新增許可權

在使用Nearby Message之前，需要新增網路許可權、藍芽許可權、位置許可權。在工程的AndroidManifest.xml檔案中新增如下許可權：

```java
<uses-permission android:name="android.permission.INTERNET "></uses-permission>
 <uses-permission android:name="android.permission.BLUETOOTH"></uses-permission>
 <uses-permission android:name="android.permission.BLUETOOTH_ADMIN"></uses-permission>
 
 <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"></uses-permission>
 <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"></uses-permission>
```

#### 3\. 程式碼開發

**3.1 動態許可權申請**

檢查藍芽開關、位置開關是否開啟、網路是否可用，並對位置許可權進行動態許可權申請

```java
@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 封裝名片釋出介面和名片訂閱介面**

訂閱到的名片訊息（onFound），把名片新增到查詢名片對話方塊中顯示；名片訊息丟失時（onLost），從查詢名片對話方塊中刪除該名片

```java
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  名片交換選單處理**

面對面交換名片交換碼，釋出個人名片成功後，訂閱名片訊息

```java
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  收藏名片處理**

收藏名片時把名片加入收藏列表，名片取消收藏時把名片從引數列表中刪除，並把資料儲存到本地儲存中。

```java
@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();
 }
```

本次給大家演示的demo用到了華為HMS Nearby service的近距離裝置間訊息訂閱功能。基於Nearby Message能力不僅僅可以用來做面對面交換名片，還可以幫助開發者實現很多有趣的功能，例如：

-   競技類手遊中的面對面組隊功能
-   牌類手遊中的面對面約局功能
-   近場AA收款功能
-   音樂曲目共享功能

**欲瞭解更多詳情**
[訪問華為近距離通訊服務官網](https://developer.huawei.com/consumer/cn/hms/huawei-nearbyservice?ha_source=hms1)  
[獲取華為近距離通訊服務開發指導文件](https://developer.huawei.com/consumer/cn/doc/development/system-Guides/introduction-nearby-0000001060363166?ha_source=hms1)  
**華為近距離通訊服務開源倉庫地址：**[GitHub](https://github.com/HMS-Core/hms-nearby-demo)、[Gitee](https://gitee.com/hms-core/hms-nearby-demo)  
[華為HMS Core官方論壇 ](https://developer.huawei.com/consumer/cn/forum/block/hms-core?ha_source=hms1)  
解決整合問題請到[Stack Overflow](https://stackoverflow.com/questions/tagged/huawei-mobile-services?tab=Newest)
**關注我們，第一時間瞭解HMS Core最新技術~**</string></void></void>

這麼遞名片才高效！教你給應用開發個交換名片功能

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