本文實例講述了Android編程基于自定義控件實現時鐘功能的方法。分享給大家供大家參考，具體如下：

在學習安卓群英傳自定義控件章節的時候，有一個例子是繪制時鐘，在實現了書上的例子后就想看這個時鐘能不能動起來。

這里選擇延遲一秒發送消息重繪view來實現的動畫，對外提供了開啟時鐘，關閉時鐘的方法，當activity執行onResume方法的時候，執行startClock()方法，當移除view或activity執行onStop方法的時候可以執行stopClock()方法。

首先根據view的寬高來確定圓心的位置，并畫出一個圓。再通過view高度的一半減去圓的半徑，確定刻度的起始位置，選擇刻度的長度并繪制出來。然后再刻度下方繪制出數字。最終將畫布進行旋轉，時鐘總共有60個刻度，循環旋轉，每次旋轉6度即可。

最后是繪制指針，通過計算算出指針對應每個刻度的X,Y坐標并繪制直線。

代碼實現

自定義控件的代碼(ClockView.java)：

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 的寬高

private float mWidth, mHeight;

// 圓的半徑

private float circleRadius;

// 圓心X,Y坐標

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() {

// 刻盤圓，小時刻度，時針和分針的畫筆

circlePaint = new Paint(Paint.ANTI_ALIAS_FLAG);

circlePaint.setColor(Color.BLACK);

circlePaint.setStyle(Paint.Style.STROKE);

circlePaint.setStrokeWidth(10);

// 分鐘刻度的畫筆

dialPaint = new Paint(Paint.ANTI_ALIAS_FLAG);

dialPaint.setColor(Color.BLACK);

dialPaint.setStrokeWidth(5);

// 數字的畫筆

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) {

// 圓的半徑為view的寬度的一半再減9，防止貼邊

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);

}

/**

* 圓心

*

* @param canvas

*/

private void drawCirclePoint(Canvas canvas) {

canvas.drawCircle(circleX, circleY, 5, circlePaint);

}

private void drawCircle(Canvas canvas) {

canvas.drawCircle(circleX, circleY, circleRadius, circlePaint);

}

/**

* 畫刻度及時間

*

* @param canvas

*/

private void drawDial(Canvas canvas) {

// 時鐘用長一點的刻度，畫筆用畫圓的畫筆

Point hourStartPoint = new Point(circleX, circleY - circleRadius);

Point hourEndPoint = new Point(circleX, circleY - circleRadius + 40);

// 分鐘的刻度要稍微短一些，畫筆用畫圓的畫筆

Point startPoint2 = new Point(circleX, circleY - circleRadius);

Point endPoint2 = new Point(circleX, circleY - circleRadius + 10);

// 開始畫刻度和數字，總共60個刻度，12個時鐘刻度，被5整除畫一個時鐘刻度，被其余的為分針刻度

String clockNumber;

for (int i = 0; i < 60; i++) {

if (i % 5 == 0) {

if (i == 0) {

clockNumber = "12";

} else {

clockNumber = String.valueOf(i / 5);

}

// 時針刻度

canvas.drawLine(hourStartPoint.getX(), hourStartPoint.getY(),

hourEndPoint.getX(), hourEndPoint.getY(), circlePaint);

// 畫數字，需在時針刻度末端加30

canvas.drawText(clockNumber,

circleX - numberPaint.measureText(clockNumber) / 2,

hourEndPoint.getY() + 30, numberPaint);

} else {

// 畫分針刻度

canvas.drawLine(startPoint2.getX(), startPoint2.getY(),

endPoint2.getX(), endPoint2.getY(), circlePaint);

}

// 畫布旋轉6度

canvas.rotate(360 / 60, circleX, circleY);

}

}

/**

* 畫指針 X點坐標 cos(弧度)*r Y點坐標 sin(弧度)*r toRadians將角度轉成弧度

* 安卓坐標系與數學坐標系不同的地方是X軸是相反的，所以為了調整方向，需要將角度+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);

// 一秒重繪一次

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);

}

}

Point.java：

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;

}

}

Acitivity(ClockActivity.java)：

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布局(main.xml)：

android:orientation="vertical"

android:layout_width="match_parent"

android:gravity="center"

android:layout_height="match_parent">

android:layout_width="match_parent"

android:id="@+id/clock"

android:layout_height="match_parent" />

希望本文所述對大家Android程序設計有所幫助。

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