Wednesday, March 30, 2016

Load something from Internet using URLConnection and ReadableByteChannel, in Thread

Last example show "Load something from Internet using URLConnection and BufferedReader, in Thread". Here is another example using java.nio.channels.ReadableByteChannel.

Read operations are synchronous on a ReadableByteChannel, that is, if a read is already in progress on the channel then subsequent reads will block until the first read completes. It is undefined whether non-read operations will block.


MainActivity.java
package com.blogspot.android_er.androidinternet;

import android.os.Bundle;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.widget.TextView;
import android.widget.Toast;

import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.nio.ByteBuffer;
import java.nio.channels.Channels;
import java.nio.channels.ReadableByteChannel;

public class MainActivity extends AppCompatActivity {

    TextView textResult;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textResult = (TextView)findViewById(R.id.tresult);

        MyThread myThread = new MyThread("http://android-er.blogspot.com", textResult);
        myThread.start();
    }

    class MyThread extends Thread{
        String target;
        TextView textviewResult;

        private Handler handler = new Handler();

        public MyThread(String target, TextView textviewResult) {
            super();
            this.target = target;
            this.textviewResult = textviewResult;
        }

        @Override
        public void run() {
            String result = "";

            URL url = null;
            try {
                url = new URL(target);
                URLConnection urlConnection = url.openConnection();
                InputStream inputStream = urlConnection.getInputStream();

                ReadableByteChannel readableByteChannel = Channels.newChannel(inputStream);
                ByteBuffer buffer = ByteBuffer.allocate(1024);

                while (readableByteChannel.read(buffer) > 0)
                {
                    result += new String(buffer.array());
                    buffer.clear();
                }

            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }

            final String finalResult = result;
            handler.post(new Runnable() {
                @Override
                public void run() {
                    textviewResult.setText(finalResult);
                    Toast.makeText(MainActivity.this,
                            "finished", Toast.LENGTH_LONG).show();
                }
            });
        }
    }
}


For layout and AndroidManifest.xml, refer to the previous post "Load something from Internet using URLConnection and BufferedReader, in AsyncTask".


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