[英]Send image via socket from android to pc
我已经在StackOverflow尝试了这些问题的代码。
发送例程在AsyncTask中。 其他代码类似于问题中的代码。
当我尝试将图像发送到PC时,在SendImageTask.java第25行和第14行出现了java.lang.NullPointerException。我无法理解该异常。 有人可以帮我吗? 这是代码:MainActivity:
public class MainActivity extends Activity {
/** Called when the activity is first created. */
private static final int SELECT_PICTURE = 1;
public static String selectedImagePath;
private ImageView img;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
System.out.println("34");
img = (ImageView) findViewById(R.id.ivPic);
System.out.println("36");
((Button) findViewById(R.id.bBrowse))
.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
System.out.println("40");
Intent intent = new Intent();
intent.setType("image/*");
intent.setAction(Intent.ACTION_GET_CONTENT);
startActivityForResult(
Intent.createChooser(intent, "Select Picture"),
SELECT_PICTURE);
System.out.println("47");
}
});
;
System.out.println("51");
Button send = (Button) findViewById(R.id.bSend);
final TextView status = (TextView) findViewById(R.id.tvStatus);
send.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
new SendImageTask().execute();
}
});
}
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (resultCode == RESULT_OK) {
if (requestCode == SELECT_PICTURE) {
Uri selectedImageUri = data.getData();
selectedImagePath = getPath(selectedImageUri);
TextView path = (TextView) findViewById(R.id.tvPath);
path.setText("Image Path : " + selectedImagePath);
img.setImageURI(selectedImageUri);
}
}
}
public String getPath(Uri uri) {
String[] projection = { MediaStore.Images.Media.DATA };
Cursor cursor = managedQuery(uri, projection, null, null, null);
int column_index = cursor
.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
cursor.moveToFirst();
return cursor.getString(column_index);
}
}
SendImageTask
class SendImageTask extends AsyncTask<Void, Void, Void> {
@Override
protected Void doInBackground(Void... voids) {
Socket sock;
try {
sock = new Socket("myip", 8000);
System.out.println("Connecting...");
// sendfile
File myFile = new File (MainActivity.selectedImagePath);
byte [] mybytearray = new byte [(int)myFile.length()];
FileInputStream fis = new FileInputStream(myFile);
BufferedInputStream bis = new BufferedInputStream(fis);
bis.read(mybytearray,0,mybytearray.length);
OutputStream os = sock.getOutputStream();
System.out.println("Sending...");
os.write(mybytearray,0,mybytearray.length);
os.flush();
sock.close();
} catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
}
取消使用getPath()
。
FileInputStream fis = new FileInputStream(myFile);
更改为
InputStream is = getContentResolver().openInputStream(data.getData());
像以前一样使用该流。
如您所见,您的应用程序在此行崩溃
FileInputStream fis = new FileInputStream(myFile);
您可以使用调试器进行测试,并尝试使用路径创建FileInputStream,您将获得“找不到文件”
这是因为您的路径不正确,您的getpath函数不正确。 如果要从图库中获取图像的路径,则需要将getPath函数更改为:
public String getPath(Uri uri) {
String[] projection = {MediaStore.Images.Media.DATA};
Cursor cursor = getContentResolver().query(uri, projection, null, null, null);
int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
cursor.moveToFirst();
int columnIndex = cursor.getColumnIndex(projection[0]);
String filePath = cursor.getString(columnIndex);
cursor.close();
return filePath;
}
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