带有异步任务的Android启动屏幕
在我的Android应用程序的第一次活动之前,我已经引入了一个闪屏。此初始屏幕使用AsyncTask在第一个活动开始之前下载一些信息。由于这可能需要5秒钟,我有一个进度条向用户显示进度。AsyncTask按预期启动,但是我能够显示初始屏幕的唯一方法是创建一个单独的线程。如果我不使用单独的线程,splashscreen不会显示。应用程序只显示一个空白屏幕,异步任务在后台运行,然后应用程序转换到主活动 因此,它在功能上是可行的,但我希望启动AsyncTask而不产生单独的线程。我有什么选择 我要删除的代码部分如下所示带有异步任务的Android启动屏幕,android,android-asynctask,splash-screen,Android,Android Asynctask,Splash Screen,在我的Android应用程序的第一次活动之前,我已经引入了一个闪屏。此初始屏幕使用AsyncTask在第一个活动开始之前下载一些信息。由于这可能需要5秒钟,我有一个进度条向用户显示进度。AsyncTask按预期启动,但是我能够显示初始屏幕的唯一方法是创建一个单独的线程。如果我不使用单独的线程,splashscreen不会显示。应用程序只显示一个空白屏幕,异步任务在后台运行,然后应用程序转换到主活动 因此,它在功能上是可行的,但我希望启动AsyncTask而不产生单独的线程。我有什么选择 我要删除
new Thread(){
public void run()
{
startDownloadTask(); //kicks off the AsyncTask.
};
}.start();
这是我的密码
AppManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.drillexams.android"
android:versionCode="1"
android:versionName="1.0" >
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.MANAGE_ACCOUNTS" />
<uses-permission android:name="android.permission.GET_ACCOUNTS" />
<uses-permission android:name="android.permission.USE_CREDENTIALS" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="19" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_app_icon"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<uses-library android:name="android.test.runner" />
<activity
android:name="com.drillexams.android.WorkInProgressActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.drillexams.android.ExamListActivity">
<intent-filter>
<action android:name="android.intent.action.EXAMSLIST" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
<activity
android:name="com.drillexams.android.SettingsActivity"
android:parentActivityName="com.drillexams.android.ExamListActivity">
<!-- Parent activity meta-data to support API level 7+ -->
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.drillexams.android.ExamListActivity" />
</activity>
<activity
android:name="com.drillexams.android.DrillQuestionActivity"
android:parentActivityName="com.drillexams.android.ExamListActivity">
<!-- Parent activity meta-data to support API level 7+ -->
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.drillexams.android.ExamListActivity" />
</activity>
</application>
<instrumentation
android:name="android.test.InstrumentationTestRunner"
android:label="Android tests"
android:targetPackage="com.drillexams.android" />
</manifest>
<RelativeLayout 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: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=".WorkInProgressActivity" >
<ImageView
android:id="@+id/drillExamsLogoImageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:contentDescription="@string/drill_exams_logo_content_description"
android:src="@drawable/ic_drill_exams_logo" />
<ProgressBar
android:id="@+id/progressBar"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/drillExamsLogoImageView"
android:layout_centerHorizontal="true"
android:layout_marginTop="20dp" />
</RelativeLayout>
活动、工作、进行中。xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.drillexams.android"
android:versionCode="1"
android:versionName="1.0" >
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.MANAGE_ACCOUNTS" />
<uses-permission android:name="android.permission.GET_ACCOUNTS" />
<uses-permission android:name="android.permission.USE_CREDENTIALS" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="19" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_app_icon"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<uses-library android:name="android.test.runner" />
<activity
android:name="com.drillexams.android.WorkInProgressActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.drillexams.android.ExamListActivity">
<intent-filter>
<action android:name="android.intent.action.EXAMSLIST" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
<activity
android:name="com.drillexams.android.SettingsActivity"
android:parentActivityName="com.drillexams.android.ExamListActivity">
<!-- Parent activity meta-data to support API level 7+ -->
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.drillexams.android.ExamListActivity" />
</activity>
<activity
android:name="com.drillexams.android.DrillQuestionActivity"
android:parentActivityName="com.drillexams.android.ExamListActivity">
<!-- Parent activity meta-data to support API level 7+ -->
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.drillexams.android.ExamListActivity" />
</activity>
</application>
<instrumentation
android:name="android.test.InstrumentationTestRunner"
android:label="Android tests"
android:targetPackage="com.drillexams.android" />
</manifest>
<RelativeLayout 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: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=".WorkInProgressActivity" >
<ImageView
android:id="@+id/drillExamsLogoImageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:contentDescription="@string/drill_exams_logo_content_description"
android:src="@drawable/ic_drill_exams_logo" />
<ProgressBar
android:id="@+id/progressBar"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/drillExamsLogoImageView"
android:layout_centerHorizontal="true"
android:layout_marginTop="20dp" />
</RelativeLayout>
WorkInProgressActivity.java
package com.drillexams.android;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.List;
import java.util.concurrent.ExecutionException;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.SystemClock;
import android.widget.ProgressBar;
import com.actionbarsherlock.app.SherlockActivity;
import com.drillexams.android.service.DrillExamsService;
import com.drillexams.android.sync.util.DownloadExamListHelper;
import com.drillexams.android.util.DrillExamsLogger;
import com.drillexams.model.Exam;
public class WorkInProgressActivity extends SherlockActivity {
ProgressTask task = new ProgressTask();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
DrillExamsLogger.start("WorkInProgressActivity.onCreate");
setContentView(R.layout.activity_work_in_progress);
new Thread(){
public void run()
{
startDownloadTask();
};
}.start();
DrillExamsLogger.end("WorkInProgressActivity.onCreate");
}
public void startDownloadTask() {
DrillExamsLogger.start("WorkInProgressActivity.startDownloadTask");
try {
task.execute(new URL(DrillExamsService.EXAM_URL));
task.get();
} catch (MalformedURLException e) {
DrillExamsLogger.e(e);
} catch (ExecutionException e) {
DrillExamsLogger.e(e);
} catch (InterruptedException e) {
DrillExamsLogger.e(e);
}
DrillExamsLogger.end("WorkInProgressActivity.startDownloadTask");
}
public void stopProgress() {
task.cancel(true);
}
private class ProgressTask extends AsyncTask<URL, Integer, List<Exam>> {
private ProgressBar progressBar;
private String token;
@Override
protected void onPreExecute() {
super.onPreExecute();
progressBar = (ProgressBar)findViewById(R.id.progressBar);
progressBar.bringToFront();
}
protected List<Exam> doInBackground(URL... urls) {
List<Exam> examsList = null;
DrillExamsLogger.start("DownloadExamList.doInBackground");
int start=0;
for(int i=start;i<=100;i+=5){
try {
if(!isCancelled()){
publishProgress(i);
progressBar.setProgress(i);
DrillExamsLogger.v("increment " + i);
SystemClock.sleep(300);
}
} catch (Exception e) {
DrillExamsLogger.e(e);
}
}
return null;
}
protected void onPostExecute(List<Exam> params) {
super.onPostExecute(params);
DrillExamsLogger.start("WorkInProgressActivity.onPostExecute");
Intent intent = new Intent(WorkInProgressActivity.this, ExamListActivity.class);
startActivity(intent);
finish();
DrillExamsLogger.end("WorkInProgressActivity.onPostExecute");
}
}
}
package com.drillexames.android;
导入java.net.MalformedURLException;
导入java.net.URL;
导入java.util.List;
导入java.util.concurrent.ExecutionException;
导入android.content.Intent;
导入android.os.AsyncTask;
导入android.os.Bundle;
导入android.os.SystemClock;
导入android.widget.ProgressBar;
导入com.actionbarsherlock.app.SherlockActivity;
导入com.drillexamples.android.service.drillexamservice;
导入com.drillexamples.android.sync.util.DownloadExamListHelper;
导入com.drillexams.android.util.DrillExamsLogger;
导入com.drilltests.model.Exam;
公共类WorkInProgressActivity扩展了SherlockActivity{
ProgressTask任务=新的ProgressTask();
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
start(“WorkInProgressActivity.onCreate”);
setContentView(R.layout.activity\u work\u progress);
新线程(){
公开募捐
{
startDownloadTask();
};
}.start();
end(“WorkInProgressActivity.onCreate”);
}
public void startDownloadTask(){
drillExamLogger.start(“WorkInProgressActivity.startDownloadTask”);
试一试{
执行(新URL(drillExamService.EXAM_URL));
task.get();
}捕获(格式错误){
钻井测试记录器.e(e);
}捕获(执行例外){
钻井测试记录器.e(e);
}捕捉(中断异常e){
钻井测试记录器.e(e);
}
drillExamLogger.end(“WorkInProgressActivity.startDownloadTask”);
}
公共程序无效({
任务。取消(true);
}
私有类ProgressTask扩展异步任务{
私人ProgressBar ProgressBar;
私有字符串令牌;
@凌驾
受保护的void onPreExecute(){
super.onPreExecute();
progressBar=(progressBar)findViewById(R.id.progressBar);
progressBar.bringToFront();
}
受保护列表doInBackground(URL…URL){
List examsList=null;
drillexamlogger.start(“DownloadExamList.doInBackground”);
int start=0;
对于(int i=start;i这不是代理模式的典型应用程序吗?您的代理将显示初始屏幕并更新进度条,直到所有内容都加载!您正在调用progressBar.setProgress(i);
在AsyncTask后台方法中-不允许从与其创建线程不同的线程更新UI元素,这可能会引发异常
另外,您正在调用publishProgress(i)
,但是您没有重写onProgressUpdate()方法,因此它不会产生任何效果
尝试重写onProgressUpdate()方法并从中更新progressBar:
@Override
protected void onProgressUpdate(Integer... progress) {
progressBar.setProgress(progress[0]);
}
必须创建线程的原因是调用
task.get();
这将使AsyncTask在UI线程上运行,直到完成为止
因此,只需删除任务。get():
只需在setContentView()之后直接调用startDownloadTask(),就不需要从单独的线程启动它。我已经完成了您建议的更新,进度条正在正确更新。关于如何摆脱onCreate()方法中正在分叉的线程,有何想法?