如何在Android应用中实现一个手势密码功能

package com.snda.fund.widget;  import com.snda.fund.R;  import android.content.Context; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Paint; import android.graphics.Paint.Style; import android.graphics.drawable.Drawable; import android.os.PowerManager; import android.text.TextUtils; import android.util.AttributeSet; import android.util.Log; import android.view.View;    public class LockIndicator extends View {   private int numRow = 3; // 行   private int numColum = 3; // 列   private int patternWidth = 40;   private int patternHeight = 40;   private int f = 5;   private int g = 5;   private int strokeWidth = 3;   private Paint paint = null;   private Drawable patternNoraml = null;   private Drawable patternPressed = null;   private String lockPassStr; // 手势密码     public LockIndicator(Context paramContext) {     super(paramContext);   }     public LockIndicator(Context paramContext, AttributeSet paramAttributeSet) {     super(paramContext, paramAttributeSet, 0);     paint = new Paint();     paint.setAntiAlias(true);     paint.setStrokeWidth(strokeWidth);     paint.setStyle(Paint.Style.STROKE);     patternNoraml = getResources().getDrawable(R.drawable.lock_pattern_node_normal);     patternPressed = getResources().getDrawable(R.drawable.lock_pattern_node_pressed);     if (patternPressed != null) {       patternWidth = patternPressed.getIntrinsicWidth();       patternHeight = patternPressed.getIntrinsicHeight();       this.f = (patternWidth / 4);       this.g = (patternHeight / 4);       patternPressed.setBounds(0, 0, patternWidth, patternHeight);       patternNoraml.setBounds(0, 0, patternWidth, patternHeight);     }   }     @Override   protected void onDraw(Canvas canvas) {     if ((patternPressed == null) || (patternNoraml == null)) {       return;     }     // 绘制3*3的图标     for (int i = 0; i < numRow; i++) {       for (int j = 0; j < numColum; j++) {         paint.setColor(-16777216);         int i1 = j * patternHeight + j * this.g;         int i2 = i * patternWidth + i * this.f;         canvas.save();         canvas.translate(i1, i2);         String curNum = String.valueOf(numColum * i + (j + 1));         if (!TextUtils.isEmpty(lockPassStr)) {           if (lockPassStr.indexOf(curNum) == -1) {             // 未选中             patternNoraml.draw(canvas);           } else {             // 被选中             patternPressed.draw(canvas);           }         } else {           // 重置状态           patternNoraml.draw(canvas);         }         canvas.restore();       }     }   }     @Override   protected void onMeasure(int paramInt1, int paramInt2) {     if (patternPressed != null)       setMeasuredDimension(numColum * patternHeight + this.g           * (-1 + numColum), numRow * patternWidth + this.f           * (-1 + numRow));   }        public void setPath(String paramString) {     lockPassStr = paramString;     invalidate();   }   }