java - 如何在app中提取网站的html代码

Question

我正在学习有关 Android Studio 的类(class)，我的任务是使用 DownloadTask 类提取此网站的 HTML 代码 http://www.posh24.se/kandisar

但即使当我几乎复制老师的代码时，它对我也不起作用(同时，如果我下载他的整个项目并启动它，它会完美地工作)，但对于提取的这个特定部分，它不起作用工作，我不知道为什么......

请注意，我确实在 AndroidManifest.xml 文件中写入了 Internet 权限: <uses-permission android:name="android.permission.INTERNET" />

我得到的是“失败”语句，这意味着 DownloadTask 中存在问题，但我不知道是什么问题!

这是我的 java 代码，我尝试在其中测试是否可以在日志中显示 HTML 代码:

package com.example.guesstheceleb;

import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.Button;
import android.widget.ImageView;

import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.concurrent.ExecutionException;

public class MainActivity extends AppCompatActivity {

    ImageView celebrityImageView;
    Button button0;
    Button button1;
    Button button2;
    Button button3;

    public class DownloadTask extends AsyncTask<String, Void, String> {


        @Override
        protected String doInBackground(String... urls) {

            String result = "";
            URL url;
            HttpURLConnection urlConnection = null;

            try {

                url = new URL(urls[0]);

                urlConnection = (HttpURLConnection)url.openConnection();

                InputStream in = urlConnection.getInputStream();

                InputStreamReader reader = new InputStreamReader(in);

                int data = reader.read();

                while (data != -1) {

                    char current = (char) data;

                    result += current;

                    data = reader.read();
                }

                return result;

            }
            catch (Exception e) {

                e.printStackTrace();

            }

            return "failed";
        }
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        celebrityImageView = (ImageView) findViewById(R.id.celebrityImageView);
        button0 = (Button) findViewById(R.id.button0);
        button1 = (Button) findViewById(R.id.button1);
        button2 = (Button) findViewById(R.id.button2);
        button3 = (Button) findViewById(R.id.button3);

        DownloadTask taskURL = new DownloadTask();
        String code = "";
        try {
            code = taskURL.execute("http://www.posh24.se/kandisar").get();
        } catch (ExecutionException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        Log.i("prout",code);

    }
}

现在这是老师的代码。但真正重要的是 DownloadTask 类以及它在 onCreate 方法中的使用，但我将把它们全部放在以防万一

package com.example.robpercival.guessthecelebrity;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Random;
import java.util.concurrent.ExecutionException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;


public class MainActivity extends Activity {

    ArrayList<String> celebURLs = new ArrayList<String>();
    ArrayList<String> celebNames = new ArrayList<String>();
    int chosenCeleb = 0;
    int locationOfCorrectAnswer = 0;
    String[] answers = new String[4];

    ImageView imageView;
    Button button0;
    Button button1;
    Button button2;
    Button button3;

    public void celebChosen(View view) {

        if (view.getTag().toString().equals(Integer.toString(locationOfCorrectAnswer))) {

            Toast.makeText(getApplicationContext(), "Correct!", Toast.LENGTH_LONG).show();

        } else {

            Toast.makeText(getApplicationContext(), "Wrong! It was " + celebNames.get(chosenCeleb), Toast.LENGTH_LONG).show();

        }

        createNewQuestion();

    }

    public class ImageDownloader extends AsyncTask<String, Void, Bitmap> {


        @Override
        protected Bitmap doInBackground(String... urls) {

            try {

                URL url = new URL(urls[0]);

                HttpURLConnection connection = (HttpURLConnection) url.openConnection();

                connection.connect();

                InputStream inputStream = connection.getInputStream();

                Bitmap myBitmap = BitmapFactory.decodeStream(inputStream);

                return myBitmap;


            } catch (MalformedURLException e) {

                e.printStackTrace();

            } catch (IOException e) {

                e.printStackTrace();

            }

            return null;
        }
    }


    public class DownloadTask extends AsyncTask<String, Void, String> {


        @Override
        protected String doInBackground(String... urls) {

            String result = "";
            URL url;
            HttpURLConnection urlConnection = null;

            try {

                url = new URL(urls[0]);

                urlConnection = (HttpURLConnection)url.openConnection();

                InputStream in = urlConnection.getInputStream();

                InputStreamReader reader = new InputStreamReader(in);

                int data = reader.read();

                while (data != -1) {

                    char current = (char) data;

                    result += current;

                    data = reader.read();
                }

                return result;

            }
            catch (Exception e) {

                e.printStackTrace();

            }

            return null;
        }
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        imageView = (ImageView) findViewById(R.id.imageView);
        button0 = (Button) findViewById(R.id.button);
        button1 = (Button) findViewById(R.id.button2);
        button2 = (Button) findViewById(R.id.button3);
        button3 = (Button) findViewById(R.id.button4);

        DownloadTask task = new DownloadTask();
        String result = null;

        try {

            result = task.execute("http://www.posh24.se/kandisar").get();

            String[] splitResult = result.split("<div class=\"sidebarContainer\">");

            Pattern p = Pattern.compile("<img src=\"(.*?)\"");
            Matcher m = p.matcher(splitResult[0]);

            while (m.find()) {

                celebURLs.add(m.group(1));

            }

            p = Pattern.compile("alt=\"(.*?)\"");
            m = p.matcher(splitResult[0]);

            while (m.find()) {

                celebNames.add(m.group(1));

            }


        } catch (InterruptedException e) {

            e.printStackTrace();

        } catch (ExecutionException e) {

            e.printStackTrace();

        }

        createNewQuestion();

    }

    public void createNewQuestion() {

        Random random = new Random();
        chosenCeleb = random.nextInt(celebURLs.size());

        ImageDownloader imageTask = new ImageDownloader();

        Bitmap celebImage;

        try {

            celebImage = imageTask.execute(celebURLs.get(chosenCeleb)).get();

            imageView.setImageBitmap(celebImage);

            locationOfCorrectAnswer = random.nextInt(4);

            int incorrectAnswerLocation;

            for (int i=0; i<4; i++) {

                if (i == locationOfCorrectAnswer) {

                    answers[i] = celebNames.get(chosenCeleb);

                } else {

                    incorrectAnswerLocation = random.nextInt(celebURLs.size());

                    while (incorrectAnswerLocation == chosenCeleb) {

                        incorrectAnswerLocation = random.nextInt(celebURLs.size());

                    }

                    answers[i] = celebNames.get(incorrectAnswerLocation);


                }


            }

            button0.setText(answers[0]);
            button1.setText(answers[1]);
            button2.setText(answers[2]);
            button3.setText(answers[3]);


        } catch (Exception e) {
            e.printStackTrace();
        }




    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.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();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

感谢您的耐心等待

Answer 1

我检查了你的代码并发现了问题。如果你想获取http://www.posh24.se/kandisar的Html，你应该使用代理网址。您的代码是正确的，您可以通过以下 URL 进行检查:http://info.cern.ch并查看结果。