我创建了这个用于下载Web内容的代码,我使用了Asynctask,但是DownloadTask
类没有返回结果。但是,当我在这个课程中登录时,它会显示网站的内容。因此DownloadTask
课程会下载内容,但不会返回内容!
这是我的代码:
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.concurrent.ExecutionException;
public class MainActivity extends AppCompatActivity {
public class DownloadTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... urls) {
String result = "";
URL url;
HttpURLConnection urlConnection = null;
try {
url = new URL(urls[0]);
urlConnection = (HttpURLConnection)url.openConnection();
InputStream in = urlConnection.getInputStream();
InputStreamReader reader = new InputStreamReader(in);
int data = reader.read();
while (data != -1) {
char current = (char) data;
result += current;
data = reader.read();
}
return result;
}
catch (Exception e) {
e.printStackTrace();
}
return result;
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
DownloadTask task = new DownloadTask();
String result = null;
try {
result = task.execute("http://www.stackoverflow.com").get();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
Log.i("Log", "Result ...>>>>>>>" + result);
}
}
答案 0 :(得分:1)
您的代码正确,但是您必须添加连接互联网的权限
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.waleed.downloadtask">
<uses-permission android:name="android.permission.INTERNET"/>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
答案 1 :(得分:1)
//此替代方法对我有用。尝试以下代码
BufferedReader br = new BufferedReader(reader);
String inputLine;
while ((inputLine = br.readLine()) != null)
result += inputLine;
in.close();
//而不是
int data = reader.read();
while (data != -1) {
char current = (char) data;
result += current;
data = reader.read();}
答案 2 :(得分:0)
您是否在“清单”中添加了访问Internet的权限?
while (data != -1) {
char current = (char) data;
result += current;
data = reader.read();
}
return result;
}
catch (Exception e) {
e.printStackTrace();
}
return Null; // This one should return null or something else if you
didnt get a proper url
}
}
答案 3 :(得分:0)
首先确保设备已连接到互联网。否则,日志将显示错误 未知主机异常由于您的设备未连接到Internet。并且无法从Internet下载内容。您的设备应连接到Internet。 然后尝试以下代码 `
});
oktaSignIn.renderEl(
{ el: '#okta-login-container' },
function (res) {
if (res.status == 'SUCCESS') {
alert("User successfully authenticated");
console.log(res);*/
$location.path("https://www.google.com/");
}
);