输入法学习笔记

输入法学习1前言输入法学习的例子是基于sdk下samples\android-8\SoftKeyboard例子学习，同时参考源码中的packages\inputmethods下的三个输入法软件：LatinIME，OpenWnn，PinyinIME。

2输入法整体输入法整体结构由四个部分组成（四个类），分别是：SoftKeyboard，LatinKeyboardView，LatinKeyboard，CandidateView。

还有其他的一些xml格式配置文件（后文讨论）1.SoftKeyboard：继承于InputMethodService，包括输入法内部逻辑，键盘布局，选词等，最终把选出的字符通过commitText提交出来tinKeyboard：实现词语匹配，负责解析并保存键盘布局，并提供选词算法，供程序运行当中使用tinKeyboardView：专门用于绘制键盘外观，它与CandidateView合起来，组成了InputView，就是我们看到的软键盘4.CandidateView：候选词框，在中文输入时体现的尤为明显。

3SoftKeyboard3.1概述SoftKeyboard类继承于InputMethodService，是一种特殊的service，安装到系统中后由android 系统在管理输入法的时候统一调用，所有的输入法都继承于InputMethodService类以满足被系统识别的需要。

InputMethodService作为一种service也有类似onCreat()，onStart()，onFinish()，onDestory()等回调函数，只是形式上发生了变化。

不同于一般的service，InputMethodService有一些对于输入法来说独一无二的方法：1.onInitializeInterface()：这里是进行UI初始化的地方，创建以后和配置修改以后，都会调用这个方法。

源码中这个函数函数体为空，是需要继承类来实现的。

2.onStartInput()：根据源码的提示，这个函数在text开始被编辑的时候调用，我们可以在这里做一下初始化的工作来匹配产生编辑动作editor。

3.onCreateInputView()：返回一个层次性的输入视图，而且只是在第一次这个视图显示的时候被调用。

4.onCreateCandidatesView()：创建候选框的视图5.onCreateExtractTextView()：在全屏模式下的一个视图（正常不会调用）6.onStartInputView()：它是在输入视图被显示并且在一个新的输入框中输入已经开始的时候调用，正是在这个方法中，将inputview和当前keyboard重新关联起来。

7.onFinishInput()：用户停止编辑时调用SoftKeyboard的生命周期如下图：3.2源码解析3.2.1onCreateprivate String mWordSeparators; //默认的使得输入中断的字符@Overridepublic void onCreate() {super.onCreate();mWordSeparators = getResources().getString(R.string.word_separators);//对resource这个东西有了一些了解：getResources是contextWrapper类的函数，//contextWrapper而是inputmethodservice的间接基类，这里的意思是把}在这里仅仅是把使得输入中断的字符提取出来，字符的设置在strings.xml文件里。

3.2.2onInitializeInterfaceprivate int mLastDisplayWidth; //记录键盘宽度@Overridepublic void onInitializeInterface() {//这只加载键盘，类似于findViewById，离真正生成界面还早if (mQwertyKeyboard != null) { //如果键盘已经加载了就进入这里// Configuration changes can happen after the keyboard gets recreated, so we need to be able to //re-build the keyboards if the available space has changed.int displayWidth = getMaxWidth();//获取屏幕的宽度以检查配置是否被更改if (displayWidth == mLastDisplayWidth)//说明配置没有被更改return;//没有被更改则没有动作mLastDisplayWidth = displayWidth; //配置被更改了执行这里，记录下目前的宽度}//然后重新new各个键盘mQwertyKeyboard = new LatinKeyboard(this, R.xml.qwerty);mSymbolsKeyboard = new LatinKeyboard(this, R.xml.symbols);mSymbolsShiftedKeyboard = new LatinKeyboard(this, R.xml.symbols_shift);}注意，在源码中getMaxWidth()函数被如下诠释：/*** Return the maximum width, in pixels, available the input method.* Input methods are positioned at the bottom of the screen and, unless* running in fullscreen, will generally want to be as short as possible* so should compute their height based on their contents. However, they* can stretch as much as needed horizontally. The function returns to* you the maximum amount of space available horizontally, which you can* use if needed for UI placement.** <p>In many cases this is not needed, you can just rely on the normal* view layout mechanisms to position your views within the full horizontal* space given to the input method.** <p>Note that this value can change dynamically, in particular when the* screen orientation changes.*/public int getMaxWidth() {WindowManager wm = (WindowManager) getSystemService(Context.WINDOW_SERVICE);return wm.getDefaultDisplay().getWidth();}3.2.3onCreateInputView@Overridepublic View onCreateInputView() {//mInputView = (KeyboardView)findViewById(yout.input);//上边的函数findViewById对于keyboardView是不能用的只对TextView等可以用mInputView = (KeyboardView) getLayoutInflater().inflate(yout.input, null);//加载keyboardview的资源xml文件mInputView.setOnKeyboardActionListener(this);//加载监听函数，建类的时候已经加载了监听函数mInputView.setKeyboard(mQwertyKeyboard);//默认加载字母键盘return mInputView; //通过这个return,自己定义的keyboardview类对象就与这个类绑定了}3.2.4onCreateCandidatesViewprivate CompletionInfo[] mCompletions; //候选串之串private StringBuilder mComposing = new StringBuilder(); //一个字符串private boolean mPredictionOn; //这东西是决定能不能有候选条private boolean mCompletionOn; //决定auto是否需要显示在候选栏@Overridepublic View onCreateCandidatesView() {mCandidateView = new CandidateView(this); //这里的构造函数为什么是new而不是像//inputview一样在资源里绑定呢？return mCandidateView; //通过这个return,自己定义的CandidatesView就与这个类绑定了}3.2.5onStartInput/*** Called to inform the input method that text input has started in an* editor. You should use this callback to initialize the state of your* input to match the state of the editor given to it.** @param attribute The attributes of the editor that input is starting* in.* @param restarting Set to true if input is restarting in the same* editor such as because the application has changed the text in* the editor. Otherwise will be false, indicating this is a new* session with the editor.*/@Overridepublic void onStartInput(EditorInfo attribute, boolean restarting) {super.onStartInput(attribute, restarting);//父类方法里这个函数是空的，因此这句应该没用// Reset our state. We want to do this even if restarting, because the underlying state of the text //editor could have changed in any way.mComposing.setLength(0); //候选栏置空updateCandidates();if (!restarting) {// Clear shift states.mMetaState = 0;//如果是重启的键盘，则功能组合键没有被启用}mPredictionOn = false; //不显示候选词mCompletionOn = false; //允许auto的内容显示在后选栏中mCompletions = null; //候选串字串清空// We are now going to initialize our state based on the type of text being edited.//一个靠谱的猜测：inputtype的给定值里面有那么几个掩码，但是从参数传来的具体inputtype 值里面包含了所有的信息，不同的掩码能够得出不同的信息//例如TYPE_MASK_CLASS就能得出下面四种，这四种属于同一类期望信息，这个信息叫做CLASS,下面一个掩码TYPE_MASK_V ARIATION按位与出来的是一类//叫做VARIATION的信息switch (attribute.inputType&EditorInfo.TYPE_MASK_CLASS) {//按位与的两者是同一类型的，attribute是EditorInfo类型的参数case EditorInfo.TYPE_CLASS_NUMBER:case EditorInfo.TYPE_CLASS_DA TETIME:// Numbers and dates default to the symbols keyboard, with no extra features.mCurKeyboard = mSymbolsKeyboard;//选择数字键盘break;case EditorInfo.TYPE_CLASS_PHONE:// Phones will also default to the symbols keyboard, though often you will want to have a dedicated phone keyboard. Symbols keyboard就是数字键盘mCurKeyboard = mSymbolsKeyboard;break;case EditorInfo.TYPE_CLASS_TEXT:// This is general text editing. We will default to the// normal alphabetic keyboard, and assume that we should// be doing predictive text (showing candidates as the// user types).mCurKeyboard = mQwertyKeyboard; //选择字幕键盘mPredictionOn = true; //设置需要候选词条// We now look for a few special variations of text that will// modify our behavior.int variation = attribute.inputType & EditorInfo.TYPE_MASK_V ARIATION;if (variation == EditorInfo.TYPE_TEXT_V ARIATION_PASSWORD ||variation == EditorInfo.TYPE_TEXT_V ARIATION_VISIBLE_PASSWORD) {// Do not display predictions what the user is typing when they are entering a password.mPredictionOn = false; //密码框的输入是不需要候选词条的}if (variation == EditorInfo.TYPE_TEXT_V ARIATION_EMAIL_ADDRESS|| variation == EditorInfo.TYPE_TEXT_V ARIATION_URI|| variation == EditorInfo.TYPE_TEXT_V ARIATION_FILTER) {// Our predictions are not useful for e-mail addresses or URIs.mPredictionOn = false; //如果是网站或者是邮箱地址，不用候选词条}if ((attribute.inputType&EditorInfo.TYPE_TEXT_FLAG_AUTO_COMPLETE) != 0) {// If this is an auto-complete text view, then our predictions// will not be shown and instead we will allow the editor// to supply their own. We only show the editor's// candidates when in fullscreen mode, otherwise relying// own it displaying its own UI.mPredictionOn = false; //不用候选词条mCompletionOn = isFullscreenMode(); //判断是否是全屏//经过测试，当输入法处在全屏模式的时候，原本auto的候选词会显示在输入法的候选栏中//这是mCompletiOn的作用，这个值初始化设为false.//如果把这里的两个值都设置为true则可以发现再输入任意auto的时候都会在候选栏中显示auto的词语}// We also want to look at the current state of the editor// to decide whether our alphabetic keyboard should start out// shifted.updateShiftKeyState(attribute); //这个函数在后面分析break;default:// For all unknown input types, default to the alphabetic// keyboard with no special features.mCurKeyboard = mQwertyKeyboard;updateShiftKeyState(attribute); //决定是否需要初始大写状态}// Update the label on the enter key, depending on what the application// says it will do.mCurKeyboard.setImeOptions(getResources(), attribute.imeOptions); //这个函数的定义在keyboard文件中，稍后分析。