[Android] Android 定时任务实现的三种方法(以SeekBar的进度自动实现为例)
一、采用Handler与线程的sleep(long)方法
二、采用Handler与timer及TimerTask结合的方法
三、采用Handler的postDelayed(Runnable, long)方法
布局文件: activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".activity.MainActivity">
<SeekBar
android:id="@+id/seek_bar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:maxHeight="5.0dp"
android:minHeight="5.0dp"
android:progressDrawable="@drawable/sb_bar"
android:thumb="@drawable/sb_thumb"
/>
<TextView
android:id="@+id/txt_cur"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center" />
<Button
android:id="@+id/btn_start1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="start1"
android:text="第一种方法启动"/>
<Button
android:id="@+id/btn_start2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="start2"
android:text="第二种方法启动"/>
<Button
android:id="@+id/btn_start3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="start3"
android:text="第三种方法启动"/>
</LinearLayout>
MainActivity.java 响应代码：
package com.jack.testprogress.activity;
import android.content.Context;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.SeekBar;
import android.widget.TextView;
import com.jack.testprogress.R;
import java.util.Timer;
import java.util.TimerTask;
/**
* Android 定时任务实现的三种方法 ,推荐方法3
* 以SeekBar的进度自动实现，为例
*
*/
public class MainActivity extends AppCompatActivity {
private final String TAG = "seek_bar";
private Context mContext;
private SeekBar seek_bar;
private TextView txt_cur;
private int progressStart = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mContext = MainActivity.this;
txt_cur = (TextView) findViewById(R.id.txt_cur);
seek_bar = (SeekBar) findViewById(R.id.seek_bar);
seek_bar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
txt_cur.setText("当前进度值:" + progress + " / 100 ");
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
}
});
}
//发送方法1, 新建handleMessage接收消息，然后再新建Thread发送（java方法）
protected void start1(View v) {
progressStart = 0; //每次操作前 先重置 progressStart
//接收消息，并更新
final Handler handler = new Handler() {
@Override
public void handleMessage(Message msg) {
if (msg.what == 123) {
seek_bar.setProgress(progressStart);
}
}
};
new Thread() {
@Override
public void run() {
while (progressStart < 100) {
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
progressStart++;
Log.i(TAG, "int:" + progressStart);
handler.sendEmptyMessage(123);
}
}
}.start();
}
//发送方法2, 新建handleMessage接收消息，Timer+TimerTask定时器发送
protected void start2(View v) {
progressStart = 0; //每次操作前 先重置 progressStart
final Handler handler = new Handler() {
@Override
public void handleMessage(Message msg) {
if (msg.what == 123) {
seek_bar.setProgress(progressStart);
}
}
};
Timer timer = new Timer();
TimerTask timerTask = new TimerTask() {
@Override
public void run() {
if (progressStart < 100) { //注意此处是if,而不是死循环while
progressStart++;
Log.i(TAG, "int:" + progressStart);
handler.sendEmptyMessage(123);
}
}
};
timer.schedule(timerTask, 100, 100);
}
//方法3,Handler + Runnable,推荐多使用此方法
protected void start3(View v) {
progressStart = 0; //每次操作前 先重置 progressStart
final int interval_time = 100;//间隔时间 100毫秒
final Handler handler = new Handler();
handler.postDelayed(
new Runnable() {
@Override
public void run() {
//要做的事情
if (progressStart < 100) { //进度小于100
progressStart++;
Log.i(TAG, "int:" + progressStart);
seek_bar.setProgress(progressStart);
handler.postDelayed(this, interval_time);
} else {
Log.i(TAG, "cancel int:" + progressStart);
handler.removeCallbacks(this); //完成任务后,取消定时器
}
}
}
, interval_time); //启动发送
}
}
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本文原文地址：https://www.cnblogs.com/wukong1688/p/10657659.html
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