AndroidPickerView滚动选择器的使用方法

package com.jingchen.timerpicker; 
 
import java.util.ArrayList; 
import java.util.List; 
import java.util.Timer; 
import java.util.TimerTask; 
 
import android.content.Context; 
import android.graphics.Canvas; 
import android.graphics.Paint; 
import android.graphics.Paint.Align; 
import android.graphics.Paint.FontMetricsInt; 
import android.graphics.Paint.Style; 
import android.os.Handler; 
import android.os.Message; 
import android.util.AttributeSet; 
import android.view.MotionEvent; 
import android.view.View; 
 
/** 
 * 滚动选择器 
 * 
 * @author chenjing 
 * 
 */ 
public class PickerView extends View 
{ 
 
  public static final String TAG = "PickerView"; 
  /** 
   * text之间间距和minTextSize之比 
   */ 
  public static final float MARGIN_ALPHA = 2.8f; 
  /** 
   * 自动回滚到中间的速度 
   */ 
  public static final float SPEED = 2; 
 
  private List mDataList; 
  /** 
   * 选中的位置，这个位置是mDataList的中心位置，一直不变 
   */ 
  private int mCurrentSelected; 
  private Paint mPaint; 
 
  private float mMaxTextSize = 80; 
  private float mMinTextSize = 40; 
 
  private float mMaxTextAlpha = 255; 
  private float mMinTextAlpha = 120; 
 
  private int mColorText = 0x333333; 
 
  private int mViewHeight; 
  private int mViewWidth; 
 
  private float mLastDownY; 
  /** 
   * 滑动的距离 
   */ 
  private float mMoveLen = 0; 
  private boolean isInit = false; 
  private onSelectListener mSelectListener; 
  private Timer timer; 
  private MyTimerTask mTask; 
 
  Handler updateHandler = new Handler() 
  { 
 
    @Override 
    public void handleMessage(Message msg) 
    { 
      if (Math.abs(mMoveLen)  datas) 
  { 
    mDataList = datas; 
    mCurrentSelected = datas.size() / 2; 
    invalidate(); 
  } 
 
  public void setSelected(int selected) 
  { 
    mCurrentSelected = selected; 
  } 
 
  private void moveHeadToTail() 
  { 
    String head = mDataList.get(0); 
    mDataList.remove(0); 
    mDataList.add(head); 
  } 
 
  private void moveTailToHead() 
  { 
    String tail = mDataList.get(mDataList.size() - 1); 
    mDataList.remove(mDataList.size() - 1); 
    mDataList.add(0, tail); 
  } 
 
  @Override 
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) 
  { 
    super.onMeasure(widthMeasureSpec, heightMeasureSpec); 
    mViewHeight = getMeasuredHeight(); 
    mViewWidth = getMeasuredWidth(); 
    // 按照View的高度计算字体大小 
    mMaxTextSize = mViewHeight / 4.0f; 
    mMinTextSize = mMaxTextSize / 2f; 
    isInit = true; 
    invalidate(); 
  } 
 
  private void init() 
  { 
    timer = new Timer(); 
    mDataList = new ArrayList(); 
    mPaint = new Paint(Paint.ANTI_ALIAS_FLAG); 
    mPaint.setStyle(Style.FILL); 
    mPaint.setTextAlign(Align.CENTER); 
    mPaint.setColor(mColorText); 
  } 
 
  @Override 
  protected void onDraw(Canvas canvas) 
  { 
    super.onDraw(canvas); 
    // 根据index绘制view 
    if (isInit) 
      drawData(canvas); 
  } 
 
  private void drawData(Canvas canvas) 
  { 
    // 先绘制选中的text再往上往下绘制其余的text 
    float scale = parabola(mViewHeight / 4.0f, mMoveLen); 
    float size = (mMaxTextSize - mMinTextSize) * scale + mMinTextSize; 
    mPaint.setTextSize(size); 
    mPaint.setAlpha((int) ((mMaxTextAlpha - mMinTextAlpha) * scale + mMinTextAlpha)); 
    // text居中绘制，注意baseline的计算才能达到居中，y值是text中心坐标 
    float x = (float) (mViewWidth / 2.0); 
    float y = (float) (mViewHeight / 2.0 + mMoveLen); 
    FontMetricsInt fmi = mPaint.getFontMetricsInt(); 
    float baseline = (float) (y - (fmi.bottom / 2.0 + fmi.top / 2.0)); 
 
    canvas.drawText(mDataList.get(mCurrentSelected), x, baseline, mPaint); 
    // 绘制上方data 
    for (int i = 1; (mCurrentSelected - i) >= 0; i++) 
    { 
      drawOtherText(canvas, i, -1); 
    } 
    // 绘制下方data 
    for (int i = 1; (mCurrentSelected + i)  MARGIN_ALPHA * mMinTextSize / 2) 
    { 
      // 往下滑超过离开距离 
      moveTailToHead(); 
      mMoveLen = mMoveLen - MARGIN_ALPHA * mMinTextSize; 
    } else if (mMoveLen <-MARGIN_ALPHA * mMinTextSize / 2) 
    { 
      // 往上滑超过离开距离 
      moveHeadToTail(); 
      mMoveLen = mMoveLen + MARGIN_ALPHA * mMinTextSize; 
    } 
 
    mLastDownY = event.getY(); 
    invalidate(); 
  } 
 
  private void doUp(MotionEvent event) 
  { 
    // 抬起手后mCurrentSelected的位置由当前位置move到中间选中位置 
    if (Math.abs(mMoveLen) <0.0001) 
    { 
      mMoveLen = 0; 
      return; 
    } 
    if (mTask != null) 
    { 
      mTask.cancel(); 
      mTask = null; 
    } 
    mTask = new MyTimerTask(updateHandler); 
    timer.schedule(mTask, 0, 10); 
  } 
 
  class MyTimerTask extends TimerTask 
  { 
    Handler handler; 
 
    public MyTimerTask(Handler handler) 
    { 
      this.handler = handler; 
    } 
 
    @Override 
    public void run() 
    { 
      handler.sendMessage(handler.obtainMessage()); 
    } 
 
  } 
 
  public interface onSelectListener 
  { 
    void onSelect(String text); 
  } 
} 

package com.jingchen.timerpicker; 
 
import java.util.ArrayList; 
import java.util.List; 
 
import com.jingchen.timerpicker.PickerView.onSelectListener; 
 
import android.app.Activity; 
import android.os.Bundle; 
import android.view.Menu; 
import android.widget.TextView; 
import android.widget.Toast; 
 
public class MainActivity extends Activity 
{ 
 
  PickerView minute_pv; 
  PickerView second_pv; 
 
  @Override 
  protected void onCreate(Bundle savedInstanceState) 
  { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    minute_pv = (PickerView) findViewById(R.id.minute_pv); 
    second_pv = (PickerView) findViewById(R.id.second_pv); 
    List data = new ArrayList(); 
    List secOnds= new ArrayList(); 
    for (int i = 0; i <10; i++) 
    { 
      data.add("0" + i); 
    } 
    for (int i = 0; i <60; i++) 
    { 
      seconds.add(i <10 &＃63; "0" + i : "" + i); 
    } 
    minute_pv.setData(data); 
    minute_pv.setOnSelectListener(new onSelectListener() 
    { 
 
      @Override 
      public void onSelect(String text) 
      { 
        Toast.makeText(MainActivity.this, "选择了 " + text + " 分", 
            Toast.LENGTH_SHORT).show(); 
      } 
    }); 
    second_pv.setData(seconds); 
    second_pv.setOnSelectListener(new onSelectListener() 
    { 
 
      @Override 
      public void onSelect(String text) 
      { 
        Toast.makeText(MainActivity.this, "选择了 " + text + " 秒", 
            Toast.LENGTH_SHORT).show(); 
      } 
    }); 
  } 
 
  @Override 
  public boolean onCreateOptionsMenu(Menu menu) 
  { 
    getMenuInflater().inflate(R.menu.main, menu); 
    return true; 
  } 
 
}