import android.app.job.JobParameters;
import android.app.job.JobService;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.util.Log;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.HttpURLConnection;
import java.net.URL;
public class JobSchedulerService extends JobService {
private static final String LOG_TAG = "MyJobService";
@Override
public void onCreate() {
super.onCreate();
Log.i(LOG_TAG, "MyJobService created");
}
@Override
public void onDestroy() {
super.onDestroy();
Log.i(LOG_TAG, "MyJobService destroyed");
}
// 当任务开始时会执行onStartJob(JobParameters params)方法，因为这是系统用来触发已经被执行的任务。
// 正如你所看到的，这个方法返回一个boolean值。如果返回值是false,系统假设这个方法返回时任务已经执行完毕。
// 如果返回值是true,那么系统假定这个任务正要被执行，执行任务的重担就落在了你的肩上。
// 当任务执行完毕时你需要调用jobFinished(JobParameters params, boolean needsRescheduled)来通知系统。
@Override
public boolean onStartJob(JobParameters params) {
// This is where you would implement all of the logic for your job. Note that this runs
// on the main thread, so you will want to use a separate thread for asynchronous work
// (as we demonstrate below to establish a network connection).
// If you use a separate thread, return true to indicate that you need a "reschedule" to
// return to the job at some point in the future to finish processing the work. Otherwise,
// return false when finished.
//在这里可以写你所需要的所有逻辑。因为它是运行在主线程中的，所以你可能需要使用一个单独的线程作一些异步的
//任务。如果你使用一个单独的线程，返回true来表明你这个工作可能需要在以后某个时间点才能完成，如果你知道它
//现在就完成了，就直接返回false就行了。
Log.i(LOG_TAG, "Totally and completely working on job " + params.getJobId());
// First, check the network, and then attempt to connect.
if (isNetworkConnected()) {
new SimpleDownloadTask() .execute(params);
return true;
} else {
Log.i(LOG_TAG, "No connection on job " + params.getJobId() + "; sad face");
}
return false;
}
@Override
public boolean onStopJob(JobParameters params) {
// Called if the job must be stopped before jobFinished() has been called. This may
// happen if the requirements are no longer being met, such as the user no longer
// connecting to WiFi, or the device no longer being idle. Use this callback to resolve
// anything that may cause your application to misbehave from the job being halted.
// Return true if the job should be rescheduled based on the retry criteria specified
// when the job was created or return false to drop the job. Regardless of the value
// returned, your job must stop executing.
Log.i(LOG_TAG, "Whelp, something changed, so I'm calling it on job " + params.getJobId());
return false;
}
/**
* Determines if the device is currently online.
*/
private boolean isNetworkConnected() {
ConnectivityManager connectivityManager =
(ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
return (networkInfo != null && networkInfo.isConnected());
}
/**
* Uses AsyncTask to create a task away from the main UI thread. This task creates a
* HTTPUrlConnection, and then downloads the contents of the webpage as an InputStream.
* The InputStream is then converted to a String, which is logged by the
* onPostExecute() method.
*/
private class SimpleDownloadTask extends AsyncTask<JobParameters, Void, String> {
protected JobParameters mJobParam;
@Override
protected String doInBackground(JobParameters... params) {
// cache system provided job requirements
mJobParam = params[0];
try {
InputStream is = null;
// Only display the first 50 characters of the retrieved web page content.
int len = 50;
URL url = new URL("https://www.baidu.com");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(10000); //10sec
conn.setConnectTimeout(15000); //15sec
conn.setRequestMethod("GET");
//Starts the query
conn.connect();
int response = conn.getResponseCode();
Log.d(LOG_TAG, "The response is: " + response);
is = conn.getInputStream();
// Convert the input stream to a string
Reader reader = null;
reader = new InputStreamReader(is, "UTF-8");
char[] buffer = new char[len];
reader.read(buffer);
return new String(buffer);
} catch (IOException e) {
return "Unable to retrieve web page.";
}
}
@Override
protected void onPostExecute(String result) {
jobFinished(mJobParam, false);
Log.i(LOG_TAG, result);
}
}
}