Android仿支付宝自定义密码输入框及安全键盘(密码键盘)

 0、前言

 之前做过的项目里有运用到一个支付场景：用户办理业务时需要输入交易密码，并且可根据平台下发的支付方式进行选择。这与支付宝的密码输入方式十分相似，如果使用Android系统或者第三方软件的键盘，会有密码泄露的风险。因此，大多数的应用软件使用的是自定义的密码输入框及安全键盘。

 由于密码输入方式需要实现一个从底部弹出的效果，因此总体上决定采用BottomSheetDialog来进行封装，同时为了提高安全性，还应该随机生成键盘上的数字，界面如下图所示：

 首先新建一个PasswordInputView类，将需要使用到的Context对象、支付金额、可支持的支付方式等数据，作为该类构造方法的参数进行传递。下文还将提到该类有一个回调方法，当用户输入的密码满足六位时，可以在回调方法中获取密码并显示出来。PasswordInputView类的构造方法如下所示：

public PasswordInputView(Context context, String payMoney, List<String> payWayList) { 
 this.context = context; 
 this.payMoney = payMoney; 
 this.payWayList = payWayList; 
 payPwdDialog = new BottomSheetDialog(context); 
 View view = LayoutInflater.from(context).inflate(R.layout.dialog_pay_pwd, null, false); 
 initStep1(view); 
 initStep2(view); 
 llyPwdInputView = (LinearLayout) view.findViewById(R.id.lly_pwd_input_view); 
 llyPayWaySelect = (LinearLayout) view.findViewById(R.id.lly_pay_way_select); 
 showStep1(); // 显示第一页 
} 

1、自定义密码输入框

 因为不能明文显示输入的密码，所以使用“●”来代替每位密码。自定义密码输入框涉及到的自定义属性，主要包括：输入框的大小、颜色、圆角半径以及密码圆点的大小、颜色、半径。因此，自定义属性attrs.xml文件如下所示：

<?xml version="1.0" encoding="utf-8"?> 
<resources> 
 <declare-styleable name="PasswordEditText"> 
  <attr name="borderWidth" format="dimension"/> 
  <attr name="borderColor" format="color"/> 
  <attr name="borderRadius" format="dimension"/> 
  <attr name="passwordLength" format="integer"/> 
  <attr name="passwordWidth" format="dimension"/> 
  <attr name="passwordColor" format="color"/> 
  <attr name="passwordRadius" format="dimension"/> 
 </declare-styleable> 
</resources> 

 接下来就需要去绘制自定义控件了。首先获取自定义属性，然后在onDraw()中进行绘制，代码如下所示：

package com.syd.paypwddialogdemo; 
import static android.graphics.Paint.ANTI_ALIAS_FLAG; 
import android.content.Context; 
import android.content.res.Resources; 
import android.content.res.TypedArray; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Paint; 
import android.graphics.RectF; 
import android.support.v7.widget.AppCompatEditText; 
import android.util.AttributeSet; 
/** 
 * 自定义密码输入框 
 */ 
public class PasswordEditText extends AppCompatEditText { 
 private int textLength; 
 private int borderColor; 
 private float borderWidth; 
 private float borderRadius; 
 private int passwordLength; 
 private int passwordColor; 
 private float passwordWidth; 
 private float passwordRadius; 
 private Paint passwordPaint = new Paint(ANTI_ALIAS_FLAG); 
 private Paint borderPaint = new Paint(ANTI_ALIAS_FLAG); 
 private final int defaultContMargin = 5; 
 private final int defaultSplitLineWidth = 3; 
 public PasswordEditText(Context context, AttributeSet attrs) { 
  super(context, attrs); 
  final Resources res = getResources(); 
  final int defaultBorderColor = res.getColor(R.color.colorGray); 
  final float defaultBorderWidth = res.getDimension(R.dimen.default_ev_border_width); 
  final float defaultBorderRadius = res.getDimension(R.dimen.default_ev_border_radius); 
  final int defaultPasswordLength = res.getInteger(R.integer.default_ev_password_length); 
  final int defaultPasswordColor = res.getColor(R.color.colorBlack); 
  final float defaultPasswordWidth = res.getDimension(R.dimen.default_ev_password_width); 
  final float defaultPasswordRadius = res.getDimension(R.dimen.default_ev_password_radius); 
  TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.PasswordEditText, 0, 0); 
  try { 
   borderColor = a.getColor(R.styleable.PasswordEditText_borderColor, defaultBorderColor); 
   borderWidth = a.getDimension(R.styleable.PasswordEditText_borderWidth, defaultBorderWidth); 
   borderRadius = a.getDimension(R.styleable.PasswordEditText_borderRadius, defaultBorderRadius); 
   passwordLength = a.getInt(R.styleable.PasswordEditText_passwordLength, defaultPasswordLength); 
   passwordColor = a.getColor(R.styleable.PasswordEditText_passwordColor, defaultPasswordColor); 
   passwordWidth = a.getDimension(R.styleable.PasswordEditText_passwordWidth, defaultPasswordWidth); 
   passwordRadius = a.getDimension(R.styleable.PasswordEditText_passwordRadius, defaultPasswordRadius); 
  } finally { 
   a.recycle(); 
  } 
  borderPaint.setStrokeWidth(borderWidth); 
  borderPaint.setColor(borderColor); 
  passwordPaint.setStrokeWidth(passwordWidth); 
  passwordPaint.setStyle(Paint.Style.FILL); 
  passwordPaint.setColor(passwordColor); 
 } 
 @Override 
 protected void onDraw(Canvas canvas) { 
  int width = getWidth(); 
  int height = getHeight(); 
  RectF rect = new RectF(0, 0, width, height); 
  borderPaint.setColor(borderColor); 
  canvas.drawRoundRect(rect, borderRadius, borderRadius, borderPaint); 
  RectF rectIn = new RectF(rect.left + defaultContMargin, rect.top + defaultContMargin, 
    rect.right - defaultContMargin, rect.bottom - defaultContMargin); 
  borderPaint.setColor(Color.WHITE); 
  canvas.drawRoundRect(rectIn, borderRadius, borderRadius, borderPaint); 
  borderPaint.setColor(borderColor); 
  borderPaint.setStrokeWidth(defaultSplitLineWidth); 
  for (int i = 1; i < passwordLength; i++) { 
   float x = width * i / passwordLength; 
   canvas.drawLine(x, 0, x, height, borderPaint); 
  } 
  float cx, cy = height / 2; 
  float half = width / passwordLength / 2; 
  for (int i = 0; i < textLength; i++) { 
   cx = width * i / passwordLength + half; 
   canvas.drawCircle(cx, cy, passwordWidth, passwordPaint); 
  } 
 } 
 @Override 
 protected void onTextChanged(CharSequence text, int start, int lengthBefore, int lengthAfter) { 
  super.onTextChanged(text, start, lengthBefore, lengthAfter); 
  this.textLength = text.toString().length(); 
  invalidate(); 
 } 
 public int getBorderColor() { 
  return borderColor; 
 } 
 public void setBorderColor(int borderColor) { 
  this.borderColor = borderColor; 
  borderPaint.setColor(borderColor); 
  invalidate(); 
 } 
 public float getBorderWidth() { 
  return borderWidth; 
 } 
 public void setBorderWidth(float borderWidth) { 
  this.borderWidth = borderWidth; 
  borderPaint.setStrokeWidth(borderWidth); 
  invalidate(); 
 } 
 public float getBorderRadius() { 
  return borderRadius; 
 } 
 public void setBorderRadius(float borderRadius) { 
  this.borderRadius = borderRadius; 
  invalidate(); 
 } 
 public int getPasswordLength() { 
  return passwordLength; 
 } 
 public void setPasswordLength(int passwordLength) { 
  this.passwordLength = passwordLength; 
  invalidate(); 
 } 
 public int getPasswordColor() { 
  return passwordColor; 
 } 
 public void setPasswordColor(int passwordColor) { 
  this.passwordColor = passwordColor; 
  passwordPaint.setColor(passwordColor); 
  invalidate(); 
 } 
 public float getPasswordWidth() { 
  return passwordWidth; 
 } 
 public void setPasswordWidth(float passwordWidth) { 
  this.passwordWidth = passwordWidth; 
  passwordPaint.setStrokeWidth(passwordWidth); 
  invalidate(); 
 } 
 public float getPasswordRadius() { 
  return passwordRadius; 
 } 
 public void setPasswordRadius(float passwordRadius) { 
  this.passwordRadius = passwordRadius; 
  invalidate(); 
 } 
} 

2、安全键盘的实现

 安全键盘主要是通过GridView来实现，上文提到为了保证安全性，在安全键盘初始化的时候，应该随机生成键盘上的数字，代码如下所示：

/** 
 * 初始化密码键盘 
 */ 
private void initKeyboard() { 
 final int number = 10; 
 int[] keys = new int[number]; 
 for (int i = 0; i < 10; i++) { 
  keys[i] = i; 
 } 
 // 随机生成键盘数字 
 Random random = new Random(); 
 for (int i = 0; i < number; i++) { 
  int p = random.nextInt(number); 
  int tmp = keys[i]; 
  keys[i] = keys[p]; 
  keys[p] = tmp; 
 } 
 numList = new ArrayList<>(); 
 for (int i = 0; i < 12; i++) { 
  Map<String, String> map = new HashMap<>(); 
  if (i < 9) { 
   map.put("num", String.valueOf(keys[i])); 
  } else if (i == 9) { 
   map.put("num", ""); 
  } else if (i == 10) { 
   map.put("num", String.valueOf(keys[9])); 
  } else if (i == 11) { 
   map.put("num", ""); 
  } 
  numList.add(map); 
 } 
 KeyAdapter keyAdapter = new KeyAdapter(context, numList, handler); 
 gvKeyboard.setAdapter(keyAdapter); 
} 

 安全键盘点击事件的处理，是在适配器KeyAdapter的构造方法中传入Handler对象，通过收发消息的方式在PasswordInputView类中处理的，代码如下所示：

holder.btnKey.setOnClickListener(new View.OnClickListener() { 
 @Override 
 public void onClick(View v) { 
  Message msg = new Message(); 
  msg.what = Constants.KEYBOARD_INPUT; 
  msg.obj = position; 
  handler.sendMessage(msg); 
 } 
}); 

 Handler对象在PasswordInputView类中定义，主要用于处理安全键盘的点击事件，代码如下所示：

Handler handler = new Handler() { 
 @Override 
 public void dispatchMessage(Message msg) { 
  switch (msg.what) { 
   case Constants.KEYBOARD_INPUT: 
    int position = (int) msg.obj; 
    if (position < 11 && position != 9) { 
     // 点击0-9按键 
     password = etPwd.getText().append(numList.get(position).get("num")).toString(); 
     etPwd.setText(password); 
    } else { 
     if (position == 11) { 
      // 点击退格键 
      if (!TextUtils.isEmpty(password) && !password.equals("")) { 
       password = etPwd.getText().delete(password.length() - 1, password.length()).toString(); 
       etPwd.setText(password); 
      } 
     } 
    } 
    break; 
  } 
 } 
}; 

 为了方便外部获取到用户输入的密码，设计一个回调接口OnPwdInputListener，并在PasswordInputView类中为回调接口创建一个set方法，代码如下所示：

package com.syd.paypwddialogdemo; 
public interface OnPwdInputListener { 
 void onPwdInput(String password); 
} 

 当PasswordEditText控件的TextWatcher对象监听到输入的密码满足六位时，调用回调方法，将密码作为参数进行传递，代码如下所示：

textWatcher = new TextWatcher() { 
 @Override 
 public void afterTextChanged(Editable s) { 
  if (etPwd.getText().length() == 6) { 
   onPwdInputListener.onPwdInput(etPwd.getText().toString()); 
  } 
 } 
}; 
etPwd.addTextChangedListener(textWatcher); 

在外部调用set方法，创建OnPwdInputListener对象，重写回调方法，即可获取到用户输入的密码，代码如下所示：

pwdInputView.setOnPwdInputListener(new OnPwdInputListener() { 
 @Override 
 public void onPwdInput(String password) { 
  Toast.makeText(MainActivity.this, password, Toast.LENGTH_SHORT).show(); 
 } 
}); 

3、结语

 以上介绍了自定义密码输入框及安全键盘的大致实现思路，对源码感兴趣的小伙伴可以点击下载Demo，查看具体的实现过程及演示效果。