Android Timer启动任务更新时间显示

来源：互联网发布：饥荒左上角数据怎么关编辑：程序博客网时间：2024/05/17 17:46

我是Android应用开发新手，今天写一个小程序，在UI每隔一秒刷新一次时间显示。

我启动了timer一秒执行一次任务，内容即setText为当前日期时间值；发现报错，才知道，关于修改UI的内容只能够在主线程中进行，timer启动的新的线程是无法刷新UI的。

所以，需要handler来处理，程序如下：

这是一个UI mainActivity:

package com.tcl.watch.ui;

import java.sql.Date;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;

import net.tsz.afinal.FinalDb;
import net.tsz.afinal.http.AjaxParams;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.RelativeLayout;
import android.widget.TextView;

import com.tcl.watch.ConfigData;
import com.tcl.watch.R;
import com.tcl.watch.bean.SensorBean;
import com.tcl.watch.data.Settings;
import com.tcl.watch.logic.DataService;
import com.tcl.watch.net.SensorTask;

public class MainActivity extends BaseActivity {

   private static final String TAG = "MainActivity";
   private TextView myTextView0, myTextView1;
   private RelativeLayout myRelativeLayout;
   private Context mContext;
   private Timer mTimer = null;
   private TimerTask mTimerTask = null;
   private long delay = 1000;   //1s
   private long period = 1000;
   private static String EncodeWeek[] = { "", "日", "一", "二", "三", "四", "五", "六" };

   private static final int MAX_SAVE_DATE = 30;

   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);
       mContext = this;
       Settings.init(this);
       myTextView0 = (TextView) findViewById(R.id.layoutTextView0);                                                //这里显示时间
       myTextView0.setText(getNowTime("hh : mm"));
       myTextView1 = (TextView) findViewById(R.id.layoutTextView1);
       myTextView1.setText(getNowTime("yyyy年MM月dd日") + " 星期" + EncodeWeek[getWeek()]);

       myRelativeLayout = (RelativeLayout) findViewById(R.id.layoutScreen);
       myRelativeLayout.setOnClickListener(new OnClickListener() {
           @Override
           public void onClick(View v) {
               Intent intent = new Intent();
               intent.setClass(MainActivity.this, SubActivity.class);
               MainActivity.this.startActivity(intent);
           }
       });

       // new SensorTask().post(new AjaxParams());
       // 查找超出时间界限的数据
       FinalDb finalDb = FinalDb.create(mContext);
       finalDb.deleteByWhere(SensorBean.class,
               "DATE(dates) = DATE('now','-1 months','localtime')");

startTimer(); //这里启动定时器

   }

   // 当前日期
   public static String getNowTime(String dateformat) {
       Date now = new Date(System.currentTimeMillis());
       SimpleDateFormat dateFormat = new SimpleDateFormat(dateformat);// 可以方便地修改日期格式
       String currentDate = dateFormat.format(now);

       return currentDate;
   }

   // 当前星期
   public static int getWeek() {
       Log.d(TAG, "lillian getWeek=" + Calendar.DAY_OF_WEEK);
       return Calendar.getInstance().get(Calendar.DAY_OF_WEEK);
   }

   /**
   * 字符串的日期格式的计算
   */
   public static int daysBetween(String oldDate) throws ParseException {
       SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
       Calendar cal = Calendar.getInstance();
       cal.setTime(sdf.parse(oldDate));
       long oldTime = cal.getTimeInMillis();
       cal.setTime(new java.util.Date());
       long newTime = cal.getTimeInMillis();
       long between_days = (newTime - oldTime) / (1000 * 60 * 60 * 24);
       return Integer.parseInt(String.valueOf(between_days));
   }

   private void startTimer() {
       if (mTimer == null) {
           mTimer = new Timer();
       }

       if (mTimerTask == null) {
           mTimerTask = new TimerTask() {
               @Override
               public void run() {
                    Message message = new Message();
                    message.what = 1;
                    timerHandler.sendMessage(message);
               }
           };
       }

       if (mTimer != null && mTimerTask != null)
           mTimer.schedule(mTimerTask, delay, period);
    }

//通过timerHandler更新UI时间显示

public Handler timerHandler = new Handler(){

       public void handleMessage(Message msg) {
           switch (msg.what) {
           case 1:
               Log.d(TAG, "lillian updateNowtime");
               updateNowTime();
               break;

           default:
               break;
           }
           super.handleMessage(msg);
       }
   };

   //update date and time on UI
   private void updateNowTime() {
       myTextView0.setText(getNowTime("hh : mm"));
       myTextView1.setText(getNowTime("yyyy年MM月dd日") + " 星期" + EncodeWeek[getWeek()]);
   }

   @SuppressWarnings("unused")
   private void stopTimer() {
       if (mTimer != null) {
           mTimer.cancel();
           mTimer = null;
       }

       if (mTimerTask != null) {
           mTimerTask.cancel();
           mTimerTask = null;
       }
   }
}

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