Android开发:自定义验证码输入View

设计给的验证码输入效果是这样的： 校验码固定为6位数字，未输入位用一条横线占位，注意，这不是-,而是一条横线，中间的间隔比其他地方的间隔大。这显然不是简单的EditText能实现的。参考了TextView源码后，自定义了一个View实现这个效果。 实现原理，自定义View继承自View,点击时弹出键盘接收用户输入，在onDraw时绘画。代码如下：

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.text.InputType;
import android.util.AttributeSet;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;
import android.view.inputmethod.EditorInfo;
import android.view.inputmethod.InputConnection;
import android.view.inputmethod.InputMethodManager;

import com.pocketdigi.plib.core.PLog;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import me.mailang.secretary.R;

/**
* 验证码输入View
* Created by fhp on 14/12/18.
*/
public class VerifyCodeView extends View {
StringBuilder verifyCodeBuilder;
//一个字符或横线占用的宽度
private int characterWidth;
//一个数字后中间的间隔
private int centerSpacing;
//两字符间隔
private int characterSpacing;
private int textSize;
Paint textPaint;
float textBaseY;
public VerifyCodeView(Context context, AttributeSet attrs) {
super(context, attrs);
//能获取焦点才能弹出软键盘
setFocusableInTouchMode(true);
verifyCodeBuilder = new StringBuilder(6);
textPaint=new Paint(Paint.ANTI_ALIAS_FLAG);
centerSpacing=getResources().getDimensionPixelSize(R.dimen.reg_verifycode_center_spacing);
characterSpacing=getResources().getDimensionPixelSize(R.dimen.reg_verifycode_character_spacing);
textSize=getResources().getDimensionPixelSize(R.dimen.reg_verifycode_textsize);
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    //在View上点击时弹出软键盘
    InputMethodManager imm = (InputMethodManager) getContext().getSystemService(Context.INPUT\_METHOD\_SERVICE);
    //反射调隐藏的focusIn方法，如果不调，在VerifyCodeView之前有EditText等可输入控件时，不会弹出输入法
    //可能有其他google提供的方法，但我没找到
    Class immClass = imm.getClass();
    try {
        Method focusIn = immClass.getDeclaredMethod("focusIn", View.class);
        focusIn.invoke(imm,this);
    } catch (NoSuchMethodException | InvocationTargetException | IllegalAccessException e) {
        e.printStackTrace();
    }
    imm.viewClicked(this);
    imm.showSoftInput(this, 0);
    return super.onTouchEvent(event);
}

@Override
public InputConnection onCreateInputConnection(EditorInfo outAttrs) {
    //定义软键盘样式为数字键盘
    outAttrs.inputType = InputType.TYPE\_CLASS\_NUMBER;
    return super.onCreateInputConnection(outAttrs);
}

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    //接收按键事件，67是删除键(backspace),7-16就是0-9
    if (keyCode == 67 && verifyCodeBuilder.length() > 0) {
        verifyCodeBuilder.deleteCharAt(verifyCodeBuilder.length() - 1);
        //重新绘图
        invalidate();
    } else if (keyCode >= 7 && keyCode <= 16 && verifyCodeBuilder.length() < 6) {
        verifyCodeBuilder.append(keyCode - 7);
        invalidate();
    }
    //到了6位自动隐藏软键盘
    if (verifyCodeBuilder.length() >= 6) {
        InputMethodManager imm = (InputMethodManager) getContext().getSystemService(Context.INPUT\_METHOD\_SERVICE);
        imm.hideSoftInputFromWindow(getWindowToken(), 0);
    }
    return super.onKeyDown(keyCode, event);
}

/\*\*
 \* 获取输入的校验码
 \* @return
 */
public String getVerifyCodeStr() {
    return verifyCodeBuilder.toString();
}

/\*\*
 \* 设置显示的校验码
 \* @param verifyCode
 */
public void setVerifyCode(String verifyCode) {
    if(verifyCodeBuilder.length()>0) {
        verifyCodeBuilder.delete(0, verifyCodeBuilder.length());
    }
    verifyCodeBuilder.append(verifyCode);
    invalidate();
}

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    //计算一个字符的宽度
    if(characterWidth==0) {
        int w = getWidth() - getPaddingLeft() - getPaddingRight();
        characterWidth=(w-centerSpacing-4*characterSpacing)/6;
    }
    textPaint.setTextSize(textSize);
    textPaint.setTextAlign(Paint.Align.CENTER);
    Paint.FontMetrics fontMetrics = textPaint.getFontMetrics();
    float fontHeight = fontMetrics.bottom - fontMetrics.top;
    if(textBaseY==0)
        textBaseY = getHeight() - (getHeight() - fontHeight) / 2 - fontMetrics.bottom;
    //写已输入的验证码
    if(verifyCodeBuilder.length()>0) {
        textPaint.setColor(getResources().getColor(R.color.white));
        String verifyCodeStr = getVerifyCodeStr();
        char\[\] chars = verifyCodeStr.toCharArray();
        int x,y=(int)textBaseY;
        for(int i=0;i