Android 开发第六弹：简易时钟（计时器）

接上篇Android 开发第五弹：简易时钟（闹钟） ，这次是一个时钟类应用，目前依旧是主要的功能，长得还是很挫。当然了，核心功能是有的……

时钟

先把简单的时钟给列出来吧，这里都写的很简单，即便要用世界各个城市的话，也只是相应的加上或减去几个小时。

新建TimeView类，并扩展自LinearLayout，然后布局文件和上一篇中那么写就好了。

<myapplication.nomasp.com.clock.TimeView
    android : id = "@+id/tabTime"
    android : layout_width = "match_parent"
    android : layout_height = "match_parent"
    android : orientation = "vertical">

    <TextView
        android : id = "@+id/tvTime"
        android : textAppearance = "?android:attr/textAppearanceLarge"
        android : layout_width = "match_parent"
        android : layout_height = "match_parent"
        android : gravity = "center" / >
</myapplication.nomasp.com.clock.TimeView>

    // 实例化TextView控件
    private TextView tvTime;

    public TimeView(Context context) {
        super(context);
    }

    public TimeView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public TimeView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    protected void onFinishInflate(){
        super.onFinishInflate();

        tvTime = (TextView)findViewById(R.id.tvTime);
        tvTime.setText("H");

        timeHandler.sendEmptyMessage(0);
    }

    private Handler timeHandler = new Handler() {

        public void handleMessage(Message msg){
            // 刷新时间
            refreshTime();

            if(getVisibility() == View.VISIBLE){
                timeHandler.sendEmptyMessageDelayed(0, 1000);
            }
        }
    };

    // 刷新时间
    private void refreshTime(){
        Calendar c = Calendar.getInstance();

        // 试着显示的时间格式
        tvTime.setText(String.format("%d:%d:%d",
                c.get(Calendar.HOUR_OF_DAY),
                c.get(Calendar.MINUTE),
                c.get(Calendar.SECOND)));
    }

    @Override
    protected void onVisibilityChanged(View changedView, int visibility) {
        super.onVisibilityChanged(changedView, visibility);

        if(visibility == View.VISIBLE){
            timeHandler.sendEmptyMessage(0);
        }else{
            timeHandler.removeMessages(0);
        }
    }

就这些了，下面正式开始计时器的部分。

TimerView

TimerView类同样是扩展自LinearLayout，并且布局的写法也是如出一辙：

<myapplication.nomasp.com.clock.TimerView
    android : id = "@+id/tabTimer"
    android : layout_width = "match_parent"
    android : layout_height = "match_parent"
    android : orientation = "vertical">

    <LinearLayout
        android : orientation = "horizontal"
        android : layout_width = "match_parent"
        android : layout_height = "wrap_content">

    <EditText
        android : id = "@+id/etHour"
        android : inputType = "number"
        android : textAppearance = "?android:attr/textAppearanceLarge"
        android : layout_width = "0dp"
        android : layout_height = "wrap_content"
        android : layout_weight = "1"
        android : singleLine = "true" / >
        android:singleLine = "true" / >

    <TextView
        android : textAppearance = "?android:attr/textAppearanceLarge"
        android : layout_width = "wrap_content"
        android : layout_height = "wrap_content"
        android : text = ":" / >

    <EditText
        android : id = "@+id/etMinute"
        android : inputType = "number"
        android : textAppearance = "?android:attr/textAppearanceLarge"
        android : layout_width = "0dp"
        android : layout_height = "wrap_content"
        android : layout_weight = "1"
        android : singleLine = "true" / >

    <TextView
        android : textAppearance = "?android:attr/textAppearanceLarge"
        android : layout_width = "wrap_content"
        android : layout_height = "wrap_content"
        android : text = ":" / >

    <EditText
        android : id = "@+id/etSecond"
        android : inputType = "number"
        android : textAppearance = "?android:attr/textAppearanceLarge"
        android : layout_width = "0dp"
        android : layout_height = "wrap_content"
        android : layout_weight = "1"
        android : singleLine = "true" / >
    < / LinearLayout>

    <LinearLayout
        android : id = "@+id/llBtnGroup"
        android : layout_width = "match_parent"
        android : layout_height = "wrap_content"
        android : orientation = "horizontal">

    <Button
        android : id = "@+id/btnStart"
        android : layout_width = "0dp"
        android : layout_height = "wrap_content"
        android : layout_weight = "1"
        android : text = "@string/start" / >

    <Button
        android : id = "@+id/btnPause"
        android : layout_width = "0dp"
        android : layout_height = "wrap_content"
        android : layout_weight = "1"
        android : text = "@string/pause" / >

    <Button
        android : id = "@+id/btnResume"
        android : layout_width = "0dp"
        android : layout_height = "wrap_content"
        android : layout_weight = "1"
        android : text = "@string/resume" / >

    <Button
        android : id = "@+id/btnReset"
        android : layout_width = "0dp"
        android : layout_height = "wrap_content"
        android : layout_weight = "1"
        android : text = "@string/reset" / >
    < / LinearLayout>

</myapplication.nomasp.com.clock.TimerView>

先把该定义的都定义好了：

    private Button btnStart, btnPause, btnResume, btnReset;
    private EditText etHour, etMinute, etSecond;

    private static final int MSG_WHAT_TIME_IS_UP = 1;
    private static final int MSG_WHAT_TIME_TICK = 2;

    // 所有时间计数
    private int allTimerCount = 0;
    private Timer timer = new Timer();
    private TimerTask timerTask = null;

    public TimerView(Context context) {
        super(context);
    }

    public TimerView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public TimerView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

核心部分，首先给各个按钮设置监听，其中的点击分别实现相应的功能，并且设置相应的可见度，还要为每个EditText设置一个动态的判断，使其值不大于59也不小于0。

@Override
    protected void onFinishInflate(){
        super.onFinishInflate();

        // 暂停
        btnPause = (Button)findViewById(R.id.btnPause);
        btnPause.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                stopTimer();

                btnPause.setVisibility(View.GONE);
                btnResume.setVisibility(View.VISIBLE);

            }
        });

        // 重置
        btnReset = (Button)findViewById(R.id.btnReset);
        btnReset.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                stopTimer();

                etHour.setText("0");
                etMinute.setText("0");
                etSecond.setText("0");

                btnReset.setVisibility(View.GONE);
                btnResume.setVisibility(View.GONE);
                btnPause.setVisibility(View.GONE);
                btnStart.setVisibility(View.VISIBLE);
            }
        });

        // 恢复
        btnResume = (Button)findViewById(R.id.btnResume);
        btnResume.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                startTime();

                btnResume.setVisibility(View.GONE);
                btnPause.setVisibility(View.VISIBLE);
            }
        });

        // 开始
        btnStart = (Button)findViewById(R.id.btnStart);
        btnStart.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                startTime();

                btnStart.setVisibility(View.GONE);
                btnPause.setVisibility(View.VISIBLE);
                btnReset.setVisibility(View.VISIBLE);
            }
        });

        etHour = (EditText)findViewById(R.id.etHour);
        etMinute = (EditText)findViewById(R.id.etMinute);
        etSecond = (EditText)findViewById(R.id.etSecond);

        // 对每一个EditText实例都作判断，值不可以大于59或小于0
        etHour.setText("00");
        etHour.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {

            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                if (!TextUtils.isEmpty(s)) {
                    int value = Integer.parseInt(s.toString());

                    if (value > 59) {
                        etHour.setText("59");
                    } else if (value < 0) {
                        etHour.setText("0");
                    }
                }
                checkToEnableBtnStart();
            }

            @Override
            public void afterTextChanged(Editable s) {

            }
        });

        etMinute.setText("00");
        etMinute.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {

            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                if (!TextUtils.isEmpty(s)) {
                    int value = Integer.parseInt(s.toString());

                    if (value > 59) {
                        etMinute.setText("59");
                    } else if (value < 0) {
                        etMinute.setText("0");
                    }
                }
                checkToEnableBtnStart();
            }

            @Override
            public void afterTextChanged(Editable s) {

            }
        });

        etSecond.setText("00");
        etSecond.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {

            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                if(!TextUtils.isEmpty(s)){
                    int value = Integer.parseInt(s.toString());

                    if(value > 59){
                        etSecond.setText("59");
                    }else if(value < 0){
                        etSecond.setText("0");
                    }
                }
                checkToEnableBtnStart();
            }

            @Override
            public void afterTextChanged(Editable s) {

            }
        });

        btnStart.setVisibility(View.VISIBLE);
        btnPause.setVisibility(View.GONE);
        btnResume.setVisibility(View.GONE);
        btnReset.setVisibility(View.GONE);
    }

判断是否可以开始计数，每个输入框都不能小于等于0更不能为空。

// 判断是否可以开始
    private void checkToEnableBtnStart(){
        btnStart.setEnabled((!TextUtils.isEmpty(etHour.getText())
                && Integer.parseInt(etHour.getText().toString()) > 0) ||
                (!TextUtils.isEmpty(etMinute.getText())
                        && Integer.parseInt(etMinute.getText().toString()) > 0) ||
                (!TextUtils.isEmpty(etSecond.getText())
                        && Integer.parseInt(etSecond.getText().toString()) > 0));
    }

接下来就可以开始计时了。

    // 开始
    private void startTime(){
        if(timerTask == null){
            // 从三个输入框中获取需要计数的总秒数
            allTimerCount = Integer.parseInt(etHour.getText().toString())*60*60
                    + Integer.parseInt(etMinute.getText().toString())*60
                    + Integer.parseInt(etSecond.getText().toString());
            timerTask = new TimerTask() {
                @Override
                // 执行计数，allTimerCount自减
                public void run() {
                    allTimerCount-- ;

                    handler.sendEmptyMessage(MSG_WHAT_TIME_TICK);

                    // 如果剩下的所有计数已经小于0，通知handler停止
                    if(allTimerCount <= 0){
                        handler.sendEmptyMessage(MSG_WHAT_TIME_IS_UP);
                        stopTimer();
                    }
                }
            };
            // 设置scedule，开始时间以及时间间隔，间隔此处为1秒
            timer.schedule(timerTask,1000,1000);
        }
    }

当然除了开始计时外，也需要能够停止计时。

    // 停止计时
    private void stopTimer(){
        if(timerTask != null){
            timerTask.cancel();
            timerTask = null;
        }
    }

接下来就是Handler了，也不算难，多写几遍就会了。

    private Handler handler = new Handler() {
        public void handleMessage(Message msg){
            switch (msg.what){
                case MSG_WHAT_TIME_TICK:

                    // 获取时间
                    int hour = allTimerCount/60/60;
                    int min = (allTimerCount/60)%60;
                    int sec = allTimerCount%60;

                    // 将时间写到对应的EditText上
                    etHour.setText(hour + "");
                    etMinute.setText(min + "");
                    etSecond.setText(sec + "");

                    break;
                case MSG_WHAT_TIME_IS_UP:

                    // 弹出对话框进行提示，包括标题、消息、返回按钮
                    new AlertDialog.Builder(getContext()).setTitle("Time is up")
                            .setMessage("Message: Time is up")
                            .setNegativeButton("Cancel",null)
                            .show();

                    // 设置相应的可见与否
                    btnReset.setVisibility(View.GONE);
                    btnResume.setVisibility(View.GONE);
                    btnPause.setVisibility(View.GONE);
                    btnStart.setVisibility(View.VISIBLE);

                    break;
                default:
                    break;
            }
        }
    };

结束

这是第二篇，还有一篇比较短的了，Android 开发第七弹：简易时钟（秒表）……

需要代码的话，直接评论留邮箱吧，我就不上传到CSDN资源了。代码会继续更新的，注释也会继续更新……

项目也上传到Github了，欢迎大家贡献代码啊——传送门 。