Android编程基于自定义控件实现时钟功能的方法

package com.example.clock;import java.util.Calendar;import java.util.Date;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.os.Handler;import android.os.Looper;import android.os.Message;import android.util.AttributeSet;import android.view.View;public class ClockView extends View {  private Paint circlePaint, dialPaint, numberPaint;  // view 的宽高  private float mWidth, mHeight;  // 圆的半径  private float circleRadius;  // 圆心X,Y坐标  private float circleX, circleY;  private int second, minute;  private double hour;  private Handler handler = new Handler(Looper.getMainLooper()) {    @Override    public void handleMessage(Message msg) {      super.handleMessage(msg);      if (msg.what == 0) {        invalidate();      }    }  };  public ClockView(Context context, AttributeSet attrs) {    super(context, attrs);    initPaint();  }  private void initPaint() {    // 刻盘圆，小时刻度，时针和分针的画笔    circlePaint = new Paint(Paint.ANTI_ALIAS_FLAG);    circlePaint.setColor(Color.BLACK);    circlePaint.setStyle(Paint.Style.STROKE);    circlePaint.setStrokeWidth(10);    // 分钟刻度的画笔    dialPaint = new Paint(Paint.ANTI_ALIAS_FLAG);    dialPaint.setColor(Color.BLACK);    dialPaint.setStrokeWidth(5);    // 数字的画笔    numberPaint = new Paint(Paint.ANTI_ALIAS_FLAG);    numberPaint.setColor(Color.BLACK);    numberPaint.setStrokeWidth(5);    numberPaint.setTextSize(30);  }  @Override  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {    super.onMeasure(widthMeasureSpec, heightMeasureSpec);    mWidth = getMeasuredWidth();    mHeight = getMeasuredHeight();    if (mWidth < mHeight) {      // 圆的半径为view的宽度的一半再减9，防止贴边      circleRadius = mWidth / 2 - 9;      circleX = mWidth / 2;      circleY = mHeight / 2;    } else {      circleRadius = mHeight / 2 - 9;      circleX = mWidth / 2;      circleY = mHeight / 2;    }  }  @Override  protected void onDraw(Canvas canvas) {    super.onDraw(canvas);    setTimes();    drawCirclePoint(canvas);    drawCircle(canvas);    drawDial(canvas);    drawPointer(canvas);  }  /**   * 圆心   *    * @param canvas   */  private void drawCirclePoint(Canvas canvas) {    canvas.drawCircle(circleX, circleY, 5, circlePaint);  }  private void drawCircle(Canvas canvas) {    canvas.drawCircle(circleX, circleY, circleRadius, circlePaint);  }  /**   * 画刻度及时间   *    * @param canvas   */  private void drawDial(Canvas canvas) {    // 时钟用长一点的刻度，画笔用画圆的画笔    Point hourStartPoint = new Point(circleX, circleY - circleRadius);    Point hourEndPoint = new Point(circleX, circleY - circleRadius + 40);    // 分钟的刻度要稍微短一些，画笔用画圆的画笔    Point startPoint2 = new Point(circleX, circleY - circleRadius);    Point endPoint2 = new Point(circleX, circleY - circleRadius + 10);    // 开始画刻度和数字，总共60个刻度，12个时钟刻度，被5整除画一个时钟刻度，被其余的为分针刻度    String clockNumber;    for (int i = 0; i < 60; i++) {      if (i % 5 == 0) {        if (i == 0) {          clockNumber = "12";        } else {          clockNumber = String.valueOf(i / 5);        }        // 时针刻度        canvas.drawLine(hourStartPoint.getX(), hourStartPoint.getY(),            hourEndPoint.getX(), hourEndPoint.getY(), circlePaint);        // 画数字，需在时针刻度末端加30        canvas.drawText(clockNumber,            circleX - numberPaint.measureText(clockNumber) / 2,            hourEndPoint.getY() + 30, numberPaint);      } else {        // 画分针刻度        canvas.drawLine(startPoint2.getX(), startPoint2.getY(),            endPoint2.getX(), endPoint2.getY(), circlePaint);      }      // 画布旋转6度      canvas.rotate(360 / 60, circleX, circleY);    }  }  /**   * 画指针 X点坐标 cos(弧度)*r Y点坐标 sin(弧度)*r toRadians将角度转成弧度   * 安卓坐标系与数学坐标系不同的地方是X轴是相反的，所以为了调整方向，需要将角度+270度   *    * @param canvas   */  private void drawPointer(Canvas canvas) {    canvas.translate(circleX, circleY);    float hourX = (float) Math.cos(Math.toRadians(hour * 30 + 270))        * circleRadius * 0.5f;    float hourY = (float) Math.sin(Math.toRadians(hour * 30 + 270))        * circleRadius * 0.5f;    float minuteX = (float) Math.cos(Math.toRadians(minute * 6 + 270))        * circleRadius * 0.8f;    float minuteY = (float) Math.sin(Math.toRadians(minute * 6 + 270))        * circleRadius * 0.8f;    float secondX = (float) Math.cos(Math.toRadians(second * 6 + 270))        * circleRadius * 0.8f;    float secondY = (float) Math.sin(Math.toRadians(second * 6 + 270))        * circleRadius * 0.8f;    canvas.drawLine(0, 0, hourX, hourY, circlePaint);    canvas.drawLine(0, 0, minuteX, minuteY, circlePaint);    canvas.drawLine(0, 0, secondX, secondY, dialPaint);    // 一秒重绘一次    handler.sendEmptyMessageDelayed(0, 1000);  }  public void startClock() {    setTimes();    invalidate();  }  private void setTimes() {    Date date = new Date();    Calendar calendar = Calendar.getInstance();    calendar.setTime(date);    second = getTimes(date, Calendar.SECOND);    minute = getTimes(date, Calendar.MINUTE);    hour = getTimes(date, Calendar.HOUR) + minute / 12 * 0.2;  }  private int getTimes(Date date, int calendarField) {    Calendar calendar = Calendar.getInstance();    calendar.setTime(date);    return calendar.get(calendarField);  }  public void stopClock() {    handler.removeMessages(0);  }}

package com.example.clock;public class Point {  private float x;  private float y;  public Point(float x, float y) {    this.x = x;    this.y = y;  }  public float getX() {    return x;  }  public void setX(float x) {    this.x = x;  }  public float getY() {    return y;  }  public void setY(float y) {    this.y = y;  }}

package com.example.clock;import android.app.Activity;import android.os.Bundle;public class ClockActivity extends Activity {  /** Called when the activity is first created. */  private ClockView clockView;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.main);    clockView = (ClockView) findViewById(R.id.clock);  }  @Override  protected void onResume() {    super.onResume();    clockView.startClock();  }  @Override  protected void onStop() {    super.onStop();    clockView.stopClock();  }}

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  android:orientation="vertical"  android:layout_width="match_parent"  android:gravity="center"  android:layout_height="match_parent">  <com.example.customview.view.ClockView    android:layout_width="match_parent"    android:id="@+id/clock"    android:layout_height="match_parent" /></LinearLayout>