android - 从外部存储android传输txt文件。应用程序粉碎

Question

我需要通过 WI-FI Direct 传输一个 txt 文件。问题是应用程序在传输开始后一直在崩溃（在客户端（那个，那个传输））。Wi-Fi Direct 没有问题，因为我可以毫无问题地发送字符串等。我相信，这个问题与读取文件有关。文件在空 SD 卡上。这里只有 LOST.DIR + Alice_commodities.txt（我需要传输的文件）。

这是传输类

private class Networking_files_transmit extends AsyncTask<String, Void, Void>
{

    public final int port=8888;

    @Override
    protected Void doInBackground(String... params) {

        String ServerIP=params[0];
        Socket s=null;
        OutputStream out=null;
        Context context = null;
        BufferedInputStream in=null;
        FileInputStream fis=null;


        try {

            s=new Socket(ServerIP,port);
            out= s.getOutputStream();
        } catch (UnknownHostException e) {
            Log.e("Files transmission", "Can not find host");
            e.printStackTrace();
        } catch (IOException e) {
            Log.e("Files transmission", "Problems with IO");
            e.printStackTrace();
        }

        if(s.isConnected())
        {
            int count;
            byte[] buffer=new byte [1024];
            final File myFile=new File (Environment.getExternalStorageDirectory().getAbsolutePath() + "/" + "Alice_commodities.txt");
            try {
                in=new BufferedInputStream( new FileInputStream(myFile));
                while((count=in.read(buffer)) > 0)
                {
                    out.write(buffer, 0, count);
                }
            } catch (FileNotFoundException e) {
                Log.e("Files transmission", "Can not find file");
                e.printStackTrace();
            } catch (IOException e) {
                Log.e("Files transmission", "Problems with IO, something wrong with file");
                e.printStackTrace();
            }
            try {
                out.close();
                in.close();
                s.close();
            } catch (IOException e) {
                Log.e("Files transmission", "Cannot close stream or socket");
                e.printStackTrace();
            }


        }
        else
        {
            Log.e("Files transmission", "Socket could not connect");

            try {
                out.close();
                in.close();
                s.close();
            } catch (IOException e) {
                Log.e("Files transmission", "Cannot close stream or socket");
                e.printStackTrace();
            }

        }           
        return null;
    }
    protected void onPostExecute(Void result) {           
          super.onPostExecute(result);            
          Toast toast=Toast.makeText(getApplicationContext(), "File transmited", Toast.LENGTH_SHORT);
          toast.show();                       
    }

}

和接收类

private class Networking_input_server_file_receive extends AsyncTask<Void, Void, Void>
{

    public final int port=8888;
    public long start;
    public long end;

    @Override
    protected Void doInBackground(Void... params) {

        ServerSocket ss= null;          
        Socket incoming=null;
        FileOutputStream fos=null;
        BufferedOutputStream out=null;
        InputStream in=null;

        try {
            fos = openFileOutput("new.txt", Context.MODE_PRIVATE);
        } catch (FileNotFoundException e1) {
            Log.e("FileReceiving", "Could not find a file");
            e1.printStackTrace();
        }


        try {
            ss=new ServerSocket(port);
            ss.setSoTimeout(20000);
            incoming= ss.accept();


            out = new BufferedOutputStream(fos);
        } catch (UnknownHostException e) {
            Log.e("FileReceiving", "Could not find a host");
            e.printStackTrace();
        } catch (IOException e) {
            Log.e("FileReceiving", "Problems with IO");
            e.printStackTrace();
        }
        if (incoming.isConnected())
        {
            start=System.currentTimeMillis();
            byte[] buffer = new byte[1024];
            int count;
            try {
                in = incoming.getInputStream();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            try {
                while((count=in.read(buffer)) > 0){
                    fos.write(buffer, 0, count);
                }
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            try {
                end=System.currentTimeMillis();
                fos.close();
                incoming.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }
        else
        {
            Log.e("file receiving", "Connection failed");
            try {
                fos.close();
                incoming.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }

        return null;
    }

    protected void onPostExecute(Void result) {           
          super.onPostExecute(result);            
          String s=String.valueOf(end-start);
          Toast toast=Toast.makeText(getApplicationContext(), s , Toast.LENGTH_SHORT);
          toast.show();                       
    }

}

和清单文件

<?xml version="1.0" encoding="utf-8"?>     
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.paad.wifidirect"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="14"
    android:targetSdkVersion="17" />
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission
    android:required="true"
    android:name="android.permission.ACCESS_WIFI_STATE"/>
<uses-permission
    android:required="true"
    android:name="android.permission.CHANGE_WIFI_STATE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>



<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name="com.paad.wifidirect.WiFiDirectActivity"
        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>

提前感谢您的帮助。

来自变送器的UPD错误日志

07-09 10:43:32.653 E/AndroidRuntime(12614): FATAL EXCEPTION: AsyncTask #1
07-09 10:43:32.653 E/AndroidRuntime(12614): java.lang.RuntimeException: An error occured while executing doInBackground()
07-09 10:43:32.653 E/AndroidRuntime(12614): at android.os.AsyncTask$3.done(AsyncTask.java:278)
07-09 10:43:32.653 E/AndroidRuntime(12614): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
07-09 10:43:32.653 E/AndroidRuntime(12614): at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
07-09 10:43:32.653 E/AndroidRuntime(12614): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
07-09 10:43:32.653 E/AndroidRuntime(12614): at java.util.concurrent.FutureTask.run(FutureTask.java:137)
07-09 10:43:32.653 E/AndroidRuntime(12614): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
07-09 10:43:32.653 E/AndroidRuntime(12614): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
07-09 10:43:32.653 E/AndroidRuntime(12614): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
07-09 10:43:32.653 E/AndroidRuntime(12614): at java.lang.Thread.run(Thread.java:856)
07-09 10:43:32.653 E/AndroidRuntime(12614): Caused by: java.lang.NullPointerException
07-09 10:43:32.653 E/AndroidRuntime(12614): at com.paad.wifidirect.WiFiDirectActivity$Networking_files_transmit.doInBackground(WiFiDirectActivity.java:524)
07-09 10:43:32.653 E/AndroidRuntime(12614): at com.paad.wifidirect.WiFiDirectActivity$Networking_files_transmit.doInBackground(WiFiDirectActivity.java:1)
07-09 10:43:32.653 E/AndroidRuntime(12614): at android.os.AsyncTask$2.call(AsyncTask.java:264)
07-09 10:43:32.653 E/AndroidRuntime(12614): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
07-09 10:43:32.653 E/AndroidRuntime(12614): ... 5 more

score 1 · Accepted Answer

您可以尝试评论这Toast两个类中的部分，我在尝试在 AsyncTask 中使用它们时遇到了一些问题。

protected void onPostExecute(Void result) {           
          super.onPostExecute(result);            
         // Toast toast=Toast.makeText(getApplicationContext(), "File transmited", Toast.LENGTH_SHORT);
         // toast.show();                       
    }

score 0 · Accepted Answer

取自Environment.getExternalStorageDirectory()的 API ？

我错过了检查，目录是否可用 - 如果没有，它可能为空。如果您在调试期间将外部存储安装到操作系统上，可能就是这种情况，并且可能是也可能不是您在调试之前/未调试时遇到的错误。只要您正在调试，就应该从操作系统中卸载外部存储。

如果可行，您应该使用getExternalStoragePublicDirectory进行文件传输，API 注释中提到的目录。有一个很好的例子来说明如何创建文件。

android - 从外部存储android传输txt文件。应用程序粉碎

2 回答 2

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