Android 运行AsyncTask时获取运行时异常
使用Android 运行AsyncTask时获取运行时异常,android,android-studio,exception,Android,Android Studio,Exception,使用AsyncTask类,我在Runtime时得到一个异常。但我无法准确地指出发生这种情况时,BufferReader中的确切位置。我可以在调试器中看到,在我的设备上读取文件的第一行和第二行,但我认为此时创建节点对象或更新进度是在抛出异常时。感谢您的帮助 package com.example.george.droidscanner; import android.os.AsyncTask; import android.os.Bundle; import android.support.v7
AsyncTask
类,我在Runtime
时得到一个异常。但我无法准确地指出发生这种情况时,BufferReader
中的确切位置。我可以在调试器中看到,在我的设备上读取文件的第一行和第二行,但我认为此时创建节点对象或更新进度是在抛出异常时。感谢您的帮助
package com.example.george.droidscanner;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
Button btnRead;
TextView textResult;
ListView listViewNode;
ArrayList<Node> listNote;
ArrayAdapter<Node> adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnRead = (Button)findViewById(R.id.readclient);
textResult = (TextView)findViewById(R.id.result);
listViewNode = (ListView)findViewById(R.id.nodelist);
listNote = new ArrayList<>();
ArrayAdapter<Node> adapter = new ArrayAdapter<Node>(
MainActivity.this,
android.R.layout.simple_list_item_1,
listNote);
listViewNode.setAdapter(adapter);
btnRead.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
new TaskReadAddresses(listNote, listViewNode).execute();
}
});
}
private class TaskReadAddresses extends AsyncTask<Void, Node, Void> {
ArrayList<Node> array;
ListView listView;
TaskReadAddresses(ArrayList<Node> array, ListView v){
listView = v;
this.array = array;
array.clear();
textResult.setText("querying...");
}
@Override
protected Void doInBackground(Void... params) {
readAddresses();
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
textResult.setText("Done");
}
@Override
protected void onProgressUpdate(Node... values) {
listNote.add(values[0]);
((ArrayAdapter)(listView.getAdapter())).notifyDataSetChanged();
}
private void readAddresses() {
BufferedReader bufferedReader = null;
try {
bufferedReader = new BufferedReader(new FileReader("/proc/net/arp"));
String line;
while ((line = bufferedReader.readLine()) != null) {
String[] splitted = line.split(" +");
if (splitted != null && splitted.length >= 4) {
String ip = splitted[0];
String mac = splitted[3];
if (mac.matches("..:..:..:..:..:..")) {
Node thisNode = new Node(ip, mac);
publishProgress(thisNode);
}
}
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally{
try {
bufferedReader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
XML文件
<?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:padding="16dp"
android:orientation="vertical"
tools:context="com.example.george.droidscanner.MainActivity">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:autoLink="web"
android:text="http://android-er.blogspot.com/"
android:textStyle="bold" />
<Button
android:id="@+id/readclient"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAllCaps="false"
android:text="Read Ip/MAC addresses"/>
<TextView
android:id="@+id/result"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:typeface="monospace"
android:textSize="24sp"/>
<ListView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/nodelist">
</ListView>
</LinearLayout>
运行时异常错误
E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #1
Process: com.example.george.droidscanner, PID: 18522
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:304)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
at java.util.concurrent.FutureTask.run(FutureTask.java:242)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:818)
Caused by: java.lang.SecurityException: Permission denied (missing INTERNET permission?)
at java.net.InetAddress.lookupHostByName(InetAddress.java:451)
at java.net.InetAddress.getLocalHost(InetAddress.java:396)
at com.example.george.droidscanner.Node.queryHost(Node.java:44)
at com.example.george.droidscanner.Node.<init>(Node.java:24)
at com.example.george.droidscanner.MainActivity$TaskReadAddresses.readAddresses(MainActivity.java:95)
at com.example.george.droidscanner.MainActivity$TaskReadAddresses.doInBackground(MainActivity.java:67)
at com.example.george.droidscanner.MainActivity$TaskReadAddresses.doInBackground(MainActivity.java:53)
at android.os.AsyncTask$2.call(AsyncTask.java:292)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:818)
Caused by: android.system.GaiException: android_getaddrinfo failed: EAI_NODATA (No address associated with hostname)
at libcore.io.Posix.android_getaddrinfo(Native Method)
at libcore.io.ForwardingOs.android_getaddrinfo(ForwardingOs.java:55)
at java.net.InetAddress.lookupHostByName(InetAddress.java:438)
at java.net.InetAddress.getLocalHost(InetAddress.java:396)
at com.example.george.droidscanner.Node.queryHost(Node.java:44)
at com.example.george.droidscanner.Node.<init>(Node.java:24)
at com.example.george.droidscanner.MainActivity$TaskReadAddresses.readAddresses(MainActivity.java:95)
at com.example.george.droidscanner.MainActivity$TaskReadAddresses.doInBackground(MainActivity.java:67)
at com.example.george.droidscanner.MainActivity$TaskReadAddresses.doInBackground(MainActivity.java:53)
at android.os.AsyncTask$2.call(AsyncTask.java:292)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:818)
E/AndroidRuntime:致命异常:异步任务#1
进程:com.example.george.droidscanner,PID:18522
java.lang.RuntimeException:执行doInBackground()时出错
在android.os.AsyncTask$3.done处(AsyncTask.java:304)
位于java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
位于java.util.concurrent.FutureTask.setException(FutureTask.java:222)
位于java.util.concurrent.FutureTask.run(FutureTask.java:242)
在android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
位于java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
位于java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
运行(Thread.java:818)
原因:java.lang.SecurityException:权限被拒绝(缺少INTERNET权限?)
位于java.net.InetAddress.lookupHostByName(InetAddress.java:451)
位于java.net.InetAddress.getLocalHost(InetAddress.java:396)
位于com.example.george.droidscanner.Node.queryHost(Node.java:44)
位于com.example.george.droidscanner.Node.(Node.java:24)
位于com.example.george.droidscanner.MainActivity$TaskReadAddresses.readAddresses(MainActivity.java:95)
位于com.example.george.droidscanner.MainActivity$taskreaddresses.doInBackground(MainActivity.java:67)
位于com.example.george.droidscanner.MainActivity$taskreaddresses.doInBackground(MainActivity.java:53)
在android.os.AsyncTask$2.call(AsyncTask.java:292)
位于java.util.concurrent.FutureTask.run(FutureTask.java:237)
在android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
位于java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
位于java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
运行(Thread.java:818)
原因:android.system.gai异常:android\u getaddrinfo失败:EAI\u NODATA(没有与主机名关联的地址)
位于libcore.io.Posix.android_getaddrinfo(本机方法)
位于libcore.io.ForwardingOs.android_getaddrinfo(ForwardingOs.java:55)
位于java.net.InetAddress.lookupHostByName(InetAddress.java:438)
位于java.net.InetAddress.getLocalHost(InetAddress.java:396)
位于com.example.george.droidscanner.Node.queryHost(Node.java:44)
位于com.example.george.droidscanner.Node.(Node.java:24)
位于com.example.george.droidscanner.MainActivity$TaskReadAddresses.readAddresses(MainActivity.java:95)
位于com.example.george.droidscanner.MainActivity$taskreaddresses.doInBackground(MainActivity.java:67)
位于com.example.george.droidscanner.MainActivity$taskreaddresses.doInBackground(MainActivity.java:53)
在android.os.AsyncTask$2.call(AsyncTask.java:292)
位于java.util.concurrent.FutureTask.run(FutureTask.java:237)
在android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
位于java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
位于java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
运行(Thread.java:818)
在清单中添加此行:
<uses-permission android:name="android.permission.INTERNET"/>
如您在日志中所见。这是由于
原因:java.lang.SecurityException:权限被拒绝(缺少INTERNET权限?)
将以下权限添加到AndroidManifest
<uses-permission android:name="android.permission.INTERNET" />
这是问题之一,但不是主要问题。注意,在这之前有一个例外。你运行它并工作了吗?。。。因为我刚刚添加了权限,但仍然有例外我很糟糕,我在错误的地方添加了权限。。。谢天谢地,我在错误的地方添加了权限。。。谢谢
<uses-permission android:name="android.permission.INTERNET" />