该项目实现了一个完整的输入法程序，该输入法包含了小写字母软键盘和数字软键盘，会根据EditText控件相应属性值自动切换到小写字母或数字软键盘。
通过小写字母软键盘也可手动切换到数字软键盘和大写字母软键盘。
1.输入法的初始化工作
输入法程序必须有一个服务类，该类必须继承自InputMethodService,该类的配置代码如下：
<service
android:name="net.csdn.leigo.input.method.SoftKeyboard"
android:permission="android.permission.BIND_INPUT_METHOD" >
<intent-filter >
<action android:name="android.view.InputMethod"/>
</intent-filter>
<meta-data android:name="android.view.im" android:resource="@xml/method"/>
</service>
在res目录下新建xml/method.xml:
<?xml version="1.0" encoding="UTF-8"?> <input-method xmlns:android="http://schemas.android.com/apk/res/android" />
输入法服务类的核心方法是onCreateInputView,该方法返回一个View对象，该对象实际上就是软键盘的界面。
package net.csdn.leigo.input.method;
import net.csdn.leigo.input.R;
import android.inputmethodservice.InputMethodService;
import android.inputmethodservice.KeyboardView;
import android.view.View;
public class SoftKeyboard extends InputMethodService {
private KeyboardView mInputView;
@Override
public View onCreateInputView() {
// 装载软键盘布局文件
mInputView = (KeyboardView) getLayoutInflater().inflate(R.layout.input,
null);
return mInputView;
}
}
在onCreateInputView方法中通过装载一个布局文件(input.xml)来创建一个View对象，这个布局文件就是软键盘的界面。
<?xml version="1.0" encoding="utf-8"?>
<net.csdn.leigo.input.method.LatinKeyboardView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/keyboard"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true" />
上面的代码只定义了一个控件：LatinKeyboardView,该控件用于显示软键盘的界面，
package net.csdn.leigo.input.method;
import android.content.Context;
import android.inputmethodservice.KeyboardView;
import android.util.AttributeSet;
public class LatinKeyboardView extends KeyboardView {
static final int KEYCODE_OPTIONS = -100;
public LatinKeyboardView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public LatinKeyboardView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
}
LatinKeyboardView类并没有实际的代码，只是一个继承自KeyboardView的类。KeyboardView是一个拥有标准键盘的类，如果只想显示标准的软键盘，直接从KeyboardView
类继承即可。
2.响应键盘操作
软键盘有两种类型的按键：输入按键(用于输入数字、符号和字母)和功能按键，要想处理这两种按键的动作，输入法服务类需要实现KeyboardView.OnKeyboardActionListener接口。处理按键的方法是onKey,
public void onKey(int primaryCode, int[] keyCodes) {
if (isWordSeparator(primaryCode)) { // 处理符号键盘
if (mComposing.length() > 0) {
commitTyped(getCurrentInputConnection());
}
sendKey(primaryCode);
updateShiftKeyState(getCurrentInputEditorInfo());
} else if (primaryCode == Keyboard.KEYCODE_DELETE) { // 处理删除按键
handleBackspace();
} else if (primaryCode == Keyboard.KEYCODE_SHIFT) {//处理Shift按键
handleShift();
} else if (primaryCode == Keyboard.KEYCODE_CANCEL) { //处理Cancel按键
handleClose();
return;
} else if (primaryCode == LatinKeyboardView.KEYCODE_OPTIONS) {
} else if (primaryCode == Keyboard.KEYCODE_MODE_CHANGE
&& mInputView != null) {
Keyboard current = mInputView.getKeyboard();
if (current == mSymbolsKeyboard
|| current == mSymbolsShiftedKeyboard) {
current = mQwertyKeyboard;
} else {
current = mSymbolsKeyboard;
}
mInputView.setKeyboard(current);
if (current == mSymbolsKeyboard) {
current.setShifted(false);
}
} else {
handleCharacter(primaryCode, keyCodes);
}
}
上面代码中涉及到一些处理功能按键的方法，例如，handleBackspace(处理退格动作)，handleShift(处理Shift键)，handleClose(用于关闭软键盘)
private void handleBackspace() {
final int length = mComposing.length();
if (length > 1) {
mComposing.delete(length - 1, length);
getCurrentInputConnection().setComposingText(mComposing, 1);
updateCandidates();
} else if (length > 0) {
mComposing.setLength(0);
getCurrentInputConnection().commitText("", 0);
updateCandidates();
} else {
keyDownUp(KeyEvent.KEYCODE_DEL);
}
updateShiftKeyState(getCurrentInputEditorInfo());
}
private void handleShift() {
if (mInputView == null) {
return;
}
Keyboard currentKeyboard = mInputView.getKeyboard();
if (mQwertyKeyboard == currentKeyboard) {
//切换到字母键盘
checkToggleCapsLock();
mInputView.setShifted(mCapsLock || !mInputView.isShifted());
} else if (currentKeyboard == mSymbolsKeyboard) {
//切换到符号键盘
mSymbolsKeyboard.setShifted(true);
mInputView.setKeyboard(mSymbolsShiftedKeyboard);
mSymbolsShiftedKeyboard.setShifted(true);
} else if (currentKeyboard == mSymbolsShiftedKeyboard) {
mSymbolsShiftedKeyboard.setShifted(false);
mInputView.setKeyboard(mSymbolsKeyboard);
mSymbolsKeyboard.setShifted(false);
}
}
private void handleCharacter(int primaryCode, int[] keyCodes) {
if (isInputViewShown()) {
if (mInputView.isShifted()) {
primaryCode = Character.toUpperCase(primaryCode);
}
}
if (isAlphabet(primaryCode) && mPredictionOn) {
mComposing.append((char) primaryCode);
getCurrentInputConnection().setComposingText(mComposing, 1);
updateShiftKeyState(getCurrentInputEditorInfo());
updateCandidates();
} else {
getCurrentInputConnection().commitText(
String.valueOf((char) primaryCode), 1);
}
}
private void handleClose() {
commitTyped(getCurrentInputConnection());
requestHideSelf(0);
//关闭软键盘
mInputView.closing();
}
3.根据EditText控件的属性显示不同的软键盘
如果将<EditText>标签的android:inputType属性设为'number",当EditText控件处于焦点时，会显示数字键盘；否则会显示输入字母的键盘。当EditText控件获得焦点时，会调用
输入法服务类的onStartInput方法，在该方法中会根据当前文本输入框的输入条件显示不同的软键盘。
@Override
public void onStartInput(EditorInfo attribute, boolean restarting) {
super.onStartInput(attribute, restarting);
//清空输入缓冲区
mComposing.setLength(0);
updateCandidates();
if (!restarting) {
//清空Shift状态
mMetaState = 0;
}
mPredictionOn = false;
mCompletionOn = false;
mCompletions = null;
switch (attribute.inputType & EditorInfo.TYPE_MASK_CLASS) {
case EditorInfo.TYPE_CLASS_NUMBER:
case EditorInfo.TYPE_CLASS_DATETIME:
//当文本输入框要求输入数字或日期时，显示数字软键盘
mCurKeyboard = mSymbolsKeyboard;
break;
case EditorInfo.TYPE_CLASS_PHONE:
//显示符号软键盘
mCurKeyboard = mSymbolsKeyboard;
break;
case EditorInfo.TYPE_CLASS_TEXT:
//显示输入字母的软键盘
mCurKeyboard = mQwertyKeyboard;
mPredictionOn = true;
int variation = attribute.inputType
& EditorInfo.TYPE_MASK_VARIATION;
if (variation == EditorInfo.TYPE_TEXT_VARIATION_PASSWORD
|| variation == EditorInfo.TYPE_TEXT_VARIATION_VISIBLE_PASSWORD) {
mPredictionOn = false;
}
if (variation == EditorInfo.TYPE_TEXT_VARIATION_EMAIL_ADDRESS
|| variation == EditorInfo.TYPE_TEXT_VARIATION_URI
|| variation == EditorInfo.TYPE_TEXT_VARIATION_FILTER) {
mPredictionOn = false;
}
if ((attribute.inputType & EditorInfo.TYPE_TEXT_FLAG_AUTO_COMPLETE) != 0) {
mPredictionOn = false;
mCompletionOn = isFullscreenMode();
}
//更新Shift状态
updateShiftKeyState(attribute);
break;
default:
//对于所有未知类型，显示字母输入键盘
mCurKeyboard = mQwertyKeyboard;
updateShiftKeyState(attribute);
}
mCurKeyboard.setImeOptions(getResources(), attribute.imeOptions);
}