Android 輸入法設定文章

　　Android 9.0 預設輸入法的設定流程分析

　　Android 9.0 新增預置第三方輸入法/設定預設輸入法(軟鍵盤)

前言

在上一篇文章  Android 9.0 新增預置第三方輸入法/設定預設輸入法(軟鍵盤)    中我們可以通過設定enabled_input_methods和default_input_method兩個key-value的值來顯示的指定可選的輸入法及預設輸入法。

但是，檢視Android原生程式碼，並沒任何地方顯示的設定這兩個值，但是當開機後，我們去console先檢視，這兩個值卻被設定為了google原生輸入法，那這兩個值是在哪裡設定的呢？本篇將簡單介紹

設定流程分析

1.  Android系統開機後，當ActivityManagerService及PackageManagerService都ready後，systemserver會回撥到InputMethodManagerService::systemRunning()方法http://aosp.opersys.com/xref/android-9.0.0_r61/xref/frameworks/base/services/core/java/com/android/server/InputMethodManagerService.java#1508

2. systemRunning()方法中會去設定一些初始引數，並依次呼叫buildInputMethodListLocked和resetDefaultImeLocked

  1. public void systemRunning(StatusBarManagerService statusBar) {
  2.     synchronized (mMethodMap) {
  3.         ....
  4.         final String defaultImiId = mSettings.getSelectedInputMethod(); // 獲取預設輸入法，第一次開機時應該是空
  5.         final boolean imeSelectedOnBoot = !TextUtils.isEmpty(defaultImiId);
  6.         buildInputMethodListLocked(!imeSelectedOnBoot /* resetDefaultEnabledIme */);// 傳遞引數resetDefaultEnabledIme=true
  7.         resetDefaultImeLocked(mContext);
  8.         updateFromSettingsLocked(true);
  9.         ....
  10.     }
  11. }

3. 接下來我們來看一下buildInputMethodListLocked方法，部分原始碼如下：

http://aosp.opersys.com/xref/android-9.0.0_r61/xref/frameworks/base/services/core/java/com/android/server/InputMethodManagerService.java#3616

點選檢視程式碼

  1. void buildInputMethodListLocked(boolean resetDefaultEnabledIme) {
  2.     if (DEBUG) {
  3.         Slog.d(TAG, "--- re-buildInputMethodList reset = " + resetDefaultEnabledIme
  4.                 + " \n ------ caller=" + Debug.getCallers(10));
  5.     }
  6.     if (!mSystemReady) {
  7.         Slog.e(TAG, "buildInputMethodListLocked is not allowed until system is ready");
  8.         return;
  9.     }
  10.     mMethodList.clear();
  11.     mMethodMap.clear();
  12.     mMethodMapUpdateCount++;
  13.     mMyPackageMonitor.clearKnownImePackageNamesLocked();
  15.     // 第一階段
  16.     // Use for queryIntentServicesAsUser
  17.     final PackageManager pm = mContext.getPackageManager();
  19.     // Note: We do not specify PackageManager.MATCH_ENCRYPTION_* flags here because the default
  20.     // behavior of PackageManager is exactly what we want.  It by default picks up appropriate
  21.     // services depending on the unlock state for the specified user.
  22.     final List<ResolveInfo> services = pm.queryIntentServicesAsUser(
  23.             new Intent(InputMethod.SERVICE_INTERFACE),
  24.             getComponentMatchingFlags(PackageManager.GET_META_DATA
  25.                     | PackageManager.MATCH_DISABLED_UNTIL_USED_COMPONENTS),
  26.             mSettings.getCurrentUserId());
  28.     final HashMap<String, List<InputMethodSubtype>> additionalSubtypeMap =
  29.             mFileManager.getAllAdditionalInputMethodSubtypes();
  30.     for (int i = 0; i < services.size(); ++i) {
  31.         ResolveInfo ri = services.get(i);
  32.         ServiceInfo si = ri.serviceInfo;
  33.         final String imeId = InputMethodInfo.computeId(ri);
  34.         if (!android.Manifest.permission.BIND_INPUT_METHOD.equals(si.permission)) {
  35.             Slog.w(TAG, "Skipping input method " + imeId
  36.                     + ": it does not require the permission "
  37.                     + android.Manifest.permission.BIND_INPUT_METHOD);
  38.             continue;
  39.         }
  41.         if (DEBUG) Slog.d(TAG, "Checking " + imeId);
  43.         final List<InputMethodSubtype> additionalSubtypes = additionalSubtypeMap.get(imeId);
  44.         try {
  45.             InputMethodInfo p = new InputMethodInfo(mContext, ri, additionalSubtypes);
  46.             mMethodList.add(p);
  47.             final String id = p.getId();
  48.             mMethodMap.put(id, p);
  50.             if (DEBUG) {
  51.                 Slog.d(TAG, "Found an input method " + p);
  52.             }
  53.         } catch (Exception e) {
  54.             Slog.wtf(TAG, "Unable to load input method " + imeId, e);
  55.         }
  56.     }
  57.     // Construct the set of possible IME packages for onPackageChanged() to avoid false
  58.     // negatives when the package state remains to be the same but only the component state is
  59.     // changed.
  60.     {
  61.         // Here we intentionally use PackageManager.MATCH_DISABLED_COMPONENTS since the purpose
  62.         // of this query is to avoid false negatives.  PackageManager.MATCH_ALL could be more
  63.         // conservative, but it seems we cannot use it for now (Issue 35176630).
  64.         final List<ResolveInfo> allInputMethodServices = pm.queryIntentServicesAsUser(
  65.                 new Intent(InputMethod.SERVICE_INTERFACE),
  66.                 getComponentMatchingFlags(PackageManager.MATCH_DISABLED_COMPONENTS),
  67.                 mSettings.getCurrentUserId());
  68.         final int N = allInputMethodServices.size();
  69.         for (int i = 0; i < N; ++i) {
  70.             final ServiceInfo si = allInputMethodServices.get(i).serviceInfo;
  71.             if (android.Manifest.permission.BIND_INPUT_METHOD.equals(si.permission)) {
  72.                 mMyPackageMonitor.addKnownImePackageNameLocked(si.packageName);
  73.             }
  74.         }
  75.     }
  77.     //第二階段
  78.     boolean reenableMinimumNonAuxSystemImes = false;
  79.     if (resetDefaultEnabledIme || reenableMinimumNonAuxSystemImes) {
  80.         final ArrayList<InputMethodInfo> defaultEnabledIme =
  81.                 InputMethodUtils.getDefaultEnabledImes(mContext, mMethodList,
  82.                         reenableMinimumNonAuxSystemImes);
  83.         final int N = defaultEnabledIme.size();
  84.         for (int i = 0; i < N; ++i) {
  85.             final InputMethodInfo imi =  defaultEnabledIme.get(i);
  86.             if (DEBUG) {
  87.                 Slog.d(TAG, "--- enable ime = " + imi);
  88.             }
  89.             setInputMethodEnabledLocked(imi.getId(), true);
  90.         }
  91.     }
  93. }

把程式碼處理流程大概分兩個階段：

第一階段：透過PackageManager去檢索已安裝的輸入法app，構建一個List：mMethodList

第二階段：將上一步驟中檢索的的輸入法做enable ime處理，此時呼叫到了setInputMethodEnabledLocked(imi.getId(), true)

4.  再來看看setInputMethodEnabledLocked的內容：這個方法比較簡單，呼叫mSettings.appendAndPutEnabledInputMethodLocked(id, false)去做設定

http://aosp.opersys.com/xref/android-9.0.0_r61/xref/frameworks/base/services/core/java/com/android/server/InputMethodManagerService.java#3987

點選檢視程式碼

  1.     boolean setInputMethodEnabledLocked(String id, boolean enabled) {
  2.         // Make sure this is a valid input method.
  3.         InputMethodInfo imm = mMethodMap.get(id);
  4.         if (imm == null) {
  5.             throw new IllegalArgumentException("Unknown id: " + mCurMethodId);
  6.         }
  8.         List<Pair<String, ArrayList<String>>> enabledInputMethodsList = mSettings
  9.                 .getEnabledInputMethodsAndSubtypeListLocked();
  11.         if (enabled) {
  12.             for (Pair<String, ArrayList<String>> pair: enabledInputMethodsList) {
  13.                 if (pair.first.equals(id)) {
  14.                     // We are enabling this input method, but it is already enabled.
  15.                     // Nothing to do. The previous state was enabled.
  16.                     return true;
  17.                 }
  18.             }
  19.             mSettings.appendAndPutEnabledInputMethodLocked(id, false);
  20.             // Previous state was disabled.
  21.             return false;
  22.         } else {
  23.             StringBuilder builder = new StringBuilder();
  24.             if (mSettings.buildAndPutEnabledInputMethodsStrRemovingIdLocked(
  25.                     builder, enabledInputMethodsList, id)) {
  26.                 // Disabled input method is currently selected, switch to another one.
  27.                 final String selId = mSettings.getSelectedInputMethod();
  28.                 if (id.equals(selId) && !chooseNewDefaultIMELocked()) {
  29.                     Slog.i(TAG, "Can't find new IME, unsetting the current input method.");
  30.                     resetSelectedInputMethodAndSubtypeLocked("");
  31.                 }
  32.                 // Previous state was enabled.
  33.                 return true;
  34.             } else {
  35.                 // We are disabling the input method but it is already disabled.
  36.                 // Nothing to do.  The previous state was disabled.
  37.                 return false;
  38.             }
  39.         }
  40.     }

5. 流程就走到了InputMethodUtils::putEnabledInputMethodStr，將值寫入Settings資料庫 putString(Settings.Secure.ENABLED_INPUT_METHODS, str);

http://aosp.opersys.com/xref/android-9.0.0_r61/xref/frameworks/base/core/java/com/android/internal/inputmethod/InputMethodUtils.java#1052

http://aosp.opersys.com/xref/android-9.0.0_r61/xref/frameworks/base/core/java/com/android/internal/inputmethod/InputMethodUtils.java#1108

分析到這裡Settings資料庫中enabled_input_methods這個key-value就有了預設值了，一般是“com.android.inputmethod.latin/.LatinIME”

6. 接著分析，buildInputMethodListLocked()完成後，返回到systemRunning()中繼續呼叫到resetDefaultImeLocked()

  1.     private void resetDefaultImeLocked(Context context) {
  2.         // Do not reset the default (current) IME when it is a 3rd-party IME
  3.         if (mCurMethodId != null && !InputMethodUtils.isSystemIme(mMethodMap.get(mCurMethodId))) {
  4.             return;
  5.         }
  6.         final List<InputMethodInfo> suitableImes = InputMethodUtils.getDefaultEnabledImes(
  7.                 context, mSettings.getEnabledInputMethodListLocked());
  8.         if (suitableImes.isEmpty()) {
  9.             Slog.i(TAG, "No default found");
  10.             return;
  11.         }
  12.         final InputMethodInfo defIm = suitableImes.get(0);
  13.         if (DEBUG) {
  14.             Slog.i(TAG, "Default found, using " + defIm.getId());
  15.         }
  16.         setSelectedInputMethodAndSubtypeLocked(defIm, NOT_A_SUBTYPE_ID, false);
  17.     }

7. 繼續走到setSelectedInputMethodAndSubtypeLocked方法中

點選檢視程式碼

  1.     private void setSelectedInputMethodAndSubtypeLocked(InputMethodInfo imi, int subtypeId,
  2.             boolean setSubtypeOnly) {
  3.         // Updates to InputMethod are transient in VR mode. Its not included in history.
  4.         final boolean isVrInput = imi != null && imi.isVrOnly();
  5.         if (!isVrInput) {
  6.             // Update the history of InputMethod and Subtype
  7.             mSettings.saveCurrentInputMethodAndSubtypeToHistory(mCurMethodId, mCurrentSubtype);
  8.         }
  10.         mCurUserActionNotificationSequenceNumber =
  11.                 Math.max(mCurUserActionNotificationSequenceNumber + 1, 1);
  12.         if (DEBUG) {
  13.             Slog.d(TAG, "Bump mCurUserActionNotificationSequenceNumber:"
  14.                     + mCurUserActionNotificationSequenceNumber);
  15.         }
  17.         if (mCurClient != null && mCurClient.client != null) {
  18.             executeOrSendMessage(mCurClient.client, mCaller.obtainMessageIO(
  19.                     MSG_SET_USER_ACTION_NOTIFICATION_SEQUENCE_NUMBER,
  20.                     mCurUserActionNotificationSequenceNumber, mCurClient));
  21.         }
  23.         if (isVrInput) {
  24.             // Updates to InputMethod are transient in VR mode. Any changes to Settings are skipped.
  25.             return;
  26.         }
  28.         // Set Subtype here
  29.         if (imi == null || subtypeId < 0) {
  30.             mSettings.putSelectedSubtype(NOT_A_SUBTYPE_ID);
  31.             mCurrentSubtype = null;
  32.         } else {
  33.             if (subtypeId < imi.getSubtypeCount()) {
  34.                 InputMethodSubtype subtype = imi.getSubtypeAt(subtypeId);
  35.                 mSettings.putSelectedSubtype(subtype.hashCode());
  36.                 mCurrentSubtype = subtype;
  37.             } else {
  38.                 mSettings.putSelectedSubtype(NOT_A_SUBTYPE_ID);
  39.                 // If the subtype is not specified, choose the most applicable one
  40.                 mCurrentSubtype = getCurrentInputMethodSubtypeLocked();
  41.             }
  42.         }
  44.         if (!setSubtypeOnly) {
  45.             // Set InputMethod here
  46.             mSettings.putSelectedInputMethod(imi != null ? imi.getId() : "");
  47.         }
  48.     }

8. mSettings.putSelectedInputMethod(imi != null ? imi.getId() : "") ==> putSelectedInputMethod==>putString(Settings.Secure.DEFAULT_INPUT_METHOD, imeId)
最終將值寫入Settings資料庫中的default_input_method

http://aosp.opersys.com/xref/android-9.0.0_r61/xref/frameworks/base/core/java/com/android/internal/inputmethod/InputMethodUtils.java#1315

至此default_input_method這個key-value也有了預設值