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
最佳答案
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。
关于java - 如何在app中提取网站的html代码，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/60687981/