我正在尝试在Android Studio中创建一个应用程序，它要求您将文件下载到用户设备上的sdcard / Download /文件夹。问题是，当我输入要下载的URL并单击下载时，该应用程序显示“不幸的是，*已停止”。我有很多文件，所以在这里。
首先，继承清单......
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.NautGames.xecta.app" >
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.NautGames.xecta.app.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.INTERNET" />
<!-- Permission: Writing to SDCard -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_PHONE_STATE"/>
</manifest>
继承MainActivity类......
package com.NautGames.xecta.app;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
//Chat bot library
import org.alicebot.ab.Chat;
import org.alicebot.ab.Bot;
import android.view.View;
import android.widget.Button;
import android.os.Environment;
import android.widget.TextView;
public class MainActivity extends ActionBarActivity {
TextView input;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
//EditText mEdit = (EditText)findViewById(R.id.editText1);
public void buttonOnClick(View v)
{
input = (TextView) findViewById(R.id.editText1);
String dbPath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/Download/Ab";
Button button=(Button) v;
//Creating bot
String botname="xecta";
String path= dbPath;
Bot xecta = new Bot(botname, path);
Chat chatSession = new Chat(xecta);
String request = input.getText().toString();
String response = chatSession.multisentenceRespond(request);
((Button) v).setText(response);
}
public void buttonDownload(View v)
{
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
DownloaderThread（下载文件）......
package com.NautGames.xecta.app;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import android.os.Environment;
import android.os.Message;
/**
* Downloads a file in a thread. Will send messages to the
* AndroidFileDownloader activity to update the progress bar.
*/
public class DownloaderThread extends Thread
{
// constants
private static final int DOWNLOAD_BUFFER_SIZE = 4096;
// instance variables
private AndroidFileDownloader parentActivity;
private String downloadUrl;
/**
//Instantiates a new DownloaderThread object.
// @param parentActivity Reference to AndroidFileDownloader activity.
// @param inUrl String representing the URL of the file to be downloaded.
*/
public DownloaderThread(AndroidFileDownloader inParentActivity, String inUrl)
{
downloadUrl = "";
if(inUrl != null)
{
downloadUrl = inUrl;
}
parentActivity = inParentActivity;
}
/**
* Connects to the URL of the file, begins the download, and notifies the
* AndroidFileDownloader activity of changes in state. Writes the file to
* the root of the SD card.
*/
@Override
public void run()
{
URL url;
URLConnection conn;
int fileSize, lastSlash;
String fileName;
BufferedInputStream inStream;
BufferedOutputStream outStream;
File outFile;
FileOutputStream fileStream;
Message msg;
// we're going to connect now
msg = Message.obtain(parentActivity.activityHandler,
AndroidFileDownloader.MESSAGE_CONNECTING_STARTED,
0, 0, downloadUrl);
parentActivity.activityHandler.sendMessage(msg);
try
{
url = new URL(downloadUrl);
conn = url.openConnection();
conn.setUseCaches(false);
fileSize = conn.getContentLength();
// get the filename
lastSlash = url.toString().lastIndexOf('/');
fileName = "file.bin";
if(lastSlash >=0)
{
fileName = url.toString().substring(lastSlash + 1);
}
if(fileName.equals(""))
{
fileName = "file.bin";
}
// notify download start
int fileSizeInKB = fileSize / 1024;
msg = Message.obtain(parentActivity.activityHandler,
AndroidFileDownloader.MESSAGE_DOWNLOAD_STARTED,
fileSizeInKB, 0, fileName);
parentActivity.activityHandler.sendMessage(msg);
// start download
inStream = new BufferedInputStream(conn.getInputStream());
outFile = new File(Environment.getExternalStorageDirectory() + "/" + fileName);
fileStream = new FileOutputStream(outFile);
outStream = new BufferedOutputStream(fileStream, DOWNLOAD_BUFFER_SIZE);
byte[] data = new byte[DOWNLOAD_BUFFER_SIZE];
int bytesRead = 0, totalRead = 0;
while(!isInterrupted() && (bytesRead = inStream.read(data, 0, data.length)) >= 0)
{
outStream.write(data, 0, bytesRead);
// update progress bar
totalRead += bytesRead;
int totalReadInKB = totalRead / 1024;
msg = Message.obtain(parentActivity.activityHandler,
AndroidFileDownloader.MESSAGE_UPDATE_PROGRESS_BAR,
totalReadInKB, 0);
parentActivity.activityHandler.sendMessage(msg);
}
outStream.close();
fileStream.close();
inStream.close();
if(isInterrupted())
{
// the download was canceled, so let's delete the partially downloaded file
outFile.delete();
}
else
{
// notify completion
msg = Message.obtain(parentActivity.activityHandler,
AndroidFileDownloader.MESSAGE_DOWNLOAD_COMPLETE);
parentActivity.activityHandler.sendMessage(msg);
}
}
catch(MalformedURLException e)
{
String errMsg = parentActivity.getString(R.string.error_message_bad_url);
msg = Message.obtain(parentActivity.activityHandler,
AndroidFileDownloader.MESSAGE_ENCOUNTERED_ERROR,
0, 0, errMsg);
parentActivity.activityHandler.sendMessage(msg);
}
catch(FileNotFoundException e)
{
String errMsg = parentActivity.getString(R.string.error_message_file_not_found);
msg = Message.obtain(parentActivity.activityHandler,
AndroidFileDownloader.MESSAGE_ENCOUNTERED_ERROR,
0, 0, errMsg);
parentActivity.activityHandler.sendMessage(msg);
}
catch(Exception e)
{
String errMsg = parentActivity.getString(R.string.error_message_general);
msg = Message.obtain(parentActivity.activityHandler,
AndroidFileDownloader.MESSAGE_ENCOUNTERED_ERROR,
0, 0, errMsg);
parentActivity.activityHandler.sendMessage(msg);
}
}
}
最后，AndroidFileDownload（也是下载文件）......
package com.NautGames.xecta.app;
import android.app.Activity;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class AndroidFileDownloader extends Activity implements OnClickListener
{
// Used to communicate state changes in the DownloaderThread
public static final int MESSAGE_DOWNLOAD_STARTED = 1000;
public static final int MESSAGE_DOWNLOAD_COMPLETE = 1001;
public static final int MESSAGE_UPDATE_PROGRESS_BAR = 1002;
public static final int MESSAGE_DOWNLOAD_CANCELED = 1003;
public static final int MESSAGE_CONNECTING_STARTED = 1004;
public static final int MESSAGE_ENCOUNTERED_ERROR = 1005;
// instance variables
private AndroidFileDownloader thisActivity;
private Thread downloaderThread;
private ProgressDialog progressDialog;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
thisActivity = this;
downloaderThread = null;
progressDialog = null;
setContentView(R.layout.activity_main);
Button button = (Button) this.findViewById(R.id.download_button);
button.setOnClickListener(this);
}
/** Called when the user clicks on something. */
@Override
public void onClick(View view)
{
EditText urlInputField = (EditText) this.findViewById(R.id.url_input);
String urlInput = urlInputField.getText().toString();
downloaderThread = new DownloaderThread(thisActivity, urlInput);
downloaderThread.start();
}
/**
* This is the Handler for this activity. It will receive messages from the
* DownloaderThread and make the necessary updates to the UI.
*/
public Handler activityHandler = new Handler()
{
public void handleMessage(Message msg)
{
switch(msg.what)
{
/*
* Handling MESSAGE_UPDATE_PROGRESS_BAR:
* 1. Get the current progress, as indicated in the arg1 field
* of the Message.
* 2. Update the progress bar.
*/
case MESSAGE_UPDATE_PROGRESS_BAR:
if(progressDialog != null)
{
int currentProgress = msg.arg1;
progressDialog.setProgress(currentProgress);
}
break;
/*
* Handling MESSAGE_CONNECTING_STARTED:
* 1. Get the URL of the file being downloaded. This is stored
* in the obj field of the Message.
* 2. Create an indeterminate progress bar.
* 3. Set the message that should be sent if user cancels.
* 4. Show the progress bar.
*/
case MESSAGE_CONNECTING_STARTED:
if(msg.obj != null && msg.obj instanceof String)
{
String url = (String) msg.obj;
// truncate the url
if(url.length() > 16)
{
String tUrl = url.substring(0, 15);
tUrl += "...";
url = tUrl;
}
String pdTitle = thisActivity.getString(R.string.progress_dialog_title_connecting);
String pdMsg = thisActivity.getString(R.string.progress_dialog_message_prefix_connecting);
pdMsg += " " + url;
dismissCurrentProgressDialog();
progressDialog = new ProgressDialog(thisActivity);
progressDialog.setTitle(pdTitle);
progressDialog.setMessage(pdMsg);
progressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
progressDialog.setIndeterminate(true);
// set the message to be sent when this dialog is canceled
Message newMsg = Message.obtain(this, MESSAGE_DOWNLOAD_CANCELED);
progressDialog.setCancelMessage(newMsg);
progressDialog.show();
}
break;
/*
* Handling MESSAGE_DOWNLOAD_STARTED:
* 1. Create a progress bar with specified max value and current
* value 0; assign it to progressDialog. The arg1 field will
* contain the max value.
* 2. Set the title and text for the progress bar. The obj
* field of the Message will contain a String that
* represents the name of the file being downloaded.
* 3. Set the message that should be sent if dialog is canceled.
* 4. Make the progress bar visible.
*/
case MESSAGE_DOWNLOAD_STARTED:
// obj will contain a String representing the file name
if(msg.obj != null && msg.obj instanceof String)
{
int maxValue = msg.arg1;
String fileName = (String) msg.obj;
String pdTitle = thisActivity.getString(R.string.progress_dialog_title_downloading);
String pdMsg = thisActivity.getString(R.string.progress_dialog_message_prefix_downloading);
pdMsg += " " + fileName;
dismissCurrentProgressDialog();
progressDialog = new ProgressDialog(thisActivity);
progressDialog.setTitle(pdTitle);
progressDialog.setMessage(pdMsg);
progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
progressDialog.setProgress(0);
progressDialog.setMax(maxValue);
// set the message to be sent when this dialog is canceled
Message newMsg = Message.obtain(this, MESSAGE_DOWNLOAD_CANCELED);
progressDialog.setCancelMessage(newMsg);
progressDialog.setCancelable(true);
progressDialog.show();
}
break;
/*
* Handling MESSAGE_DOWNLOAD_COMPLETE:
* 1. Remove the progress bar from the screen.
* 2. Display Toast that says download is complete.
*/
case MESSAGE_DOWNLOAD_COMPLETE:
dismissCurrentProgressDialog();
displayMessage(getString(R.string.user_message_download_complete));
break;
/*
* Handling MESSAGE_DOWNLOAD_CANCELLED:
* 1. Interrupt the downloader thread.
* 2. Remove the progress bar from the screen.
* 3. Display Toast that says download is complete.
*/
case MESSAGE_DOWNLOAD_CANCELED:
if(downloaderThread != null)
{
downloaderThread.interrupt();
}
dismissCurrentProgressDialog();
displayMessage(getString(R.string.user_message_download_canceled));
break;
/*
* Handling MESSAGE_ENCOUNTERED_ERROR:
* 1. Check the obj field of the message for the actual error
* message that will be displayed to the user.
* 2. Remove any progress bars from the screen.
* 3. Display a Toast with the error message.
*/
case MESSAGE_ENCOUNTERED_ERROR:
// obj will contain a string representing the error message
if(msg.obj != null && msg.obj instanceof String)
{
String errorMessage = (String) msg.obj;
dismissCurrentProgressDialog();
displayMessage(errorMessage);
}
break;
default:
// nothing to do here
break;
}
}
};
/**
* If there is a progress dialog, dismiss it and set progressDialog to
* null.
*/
public void dismissCurrentProgressDialog()
{
if(progressDialog != null)
{
progressDialog.hide();
progressDialog.dismiss();
progressDialog = null;
}
}
/**
* Displays a message to the user, in the form of a Toast.
* @param message Message to be displayed.
*/
public void displayMessage(String message)
{
if(message != null)
{
Toast.makeText(thisActivity, message, Toast.LENGTH_SHORT).show();
}
}
}
继续记录：
Process: com.NautGames.xecta.app, PID: 3032
java.lang.IllegalStateException: Could not find a method onClick(View) in the activity class com.NautGames.xecta.app.MainActivity for onClick handler on view class android.widget.Button with id 'download_button'
at android.view.View$1.onClick(View.java:3810)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.om.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NoSuchMethodException: onClick [class android.view.View]
at java.lang.Class.getConstructorOrMethod(Class.java:472)
at java.lang.Class.getMethod(Class.java:857)
at android.view.View$1.onClick(View.java:3803)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
有人能告诉我这是什么问题吗？ 提前谢谢。
答案 0 :(得分：1)
既然你在AndroidFileDownload中说过，我建议你这样做：
@Override
public void onClick(View view)
// you need to get the id of the clicked view:
if(view.getId() == R.id.download_button) {
EditText urlInputField = (EditText) thisActivity.findViewById(R.id.url_input);
String urlInput = urlInputField.getText().toString();
downloaderThread = new DownloaderThread(thisActivity, urlInput);
downloaderThread.start();
}
}
原因如下：NoSuchMethodException: onClick [class android.view.View]。这意味着您的onClick方法无法找到您设置id方法的按钮（onClickListener）。
然后，在将来，我认为问题将是您的清单文件中未声明AndroidFileDownload。您应该按如下方式添加它：
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.NautGames.xecta.app.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
// add every activity in your app like this below
<activity
android:name="com.NautGames.xecta.app.AndroidFileDownloader"
android:label="@string/app_name" />
</application>