java - Android AsyncTask 中的 Jsoup 问题

Question

总结： 我的 Jsoup 解析器可以独立运行，但是一旦复制粘贴到我的 Android 应用程序的 AsyncTask 任务类之一中，它就无法收集任何值。返回的二维数组只填充了空值。

长版： 我一直在开发一个应用程序，它通过 Jsoup 使用页面抓取来从各种博客中提取和显示内容。到目前为止，我已经编写了一些解析器，并且似乎都按预期工作。不幸的是，我最近的解析器（为 nyc-shows.brooklynvegan.com 编写）一直存在问题。

这是解析器方法本身，由添加了打印语句的 main 方法调用。自己运行这个。它有效（不完美，但有效）。

import java.io.IOException;

import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;

public class Main {

    static String TAG_EVENT = "li.ds-entry";
    static String TAG_TITLE = ".ds-entry-title";
    static String TAG_LOCATION = ".location";
    static String TAG_DATE_AND_TIME = ".ds-date";
    static String TAG_TICKET_URL = ".ds-buy-tickets";
    static String FEED_URL = "http://nyc-shows.brooklynvegan.com/";

    public static void main(String[] args) throws IOException {
    String values[][] = new String[50][6];
    values = getFeedItems();
    for (int i=0; i<values.length; i++) {
        for (int j=0; j<6; j++) {
        System.out.println(values[i][j]);
        }
    System.out.println("-----------------");
    }
    }


    public static String[][] getFeedItems() throws IOException {

    Document doc = null;
    String values[][] = new String[50][6];


    try{
        doc = Jsoup.connect(FEED_URL).timeout(0).get();
        Elements events = doc.select(TAG_EVENT);

        String delimSpace = "[ ]";
        int i = 0;
        for (Element event : events) {


        //Set event title
        Element title = event.select(TAG_TITLE).first();
        String titleString = title.text();
        if (title != null) {
            boolean isFake = checkFake(titleString);
            if (!isFake) {
            values[i][0] = titleString;
            }
            else {
            continue;
            }
        }

        //Set event date and time i guess
        Element dateAndTime = event.select(TAG_DATE_AND_TIME).first();
        if (dateAndTime != null) {
            String[] dateAndTimeTokens = dateAndTime.text().split(delimSpace);
            String date = dateAndTimeTokens[1];
            String time = dateAndTimeTokens[3];
            values[i][1] = date;
            values[i][2] = time;
        }

        //Set price (tbd)
        values[i][3] = "See Ticket";

        //Set location
        Element location = event.select(TAG_LOCATION).first();
        if (location != null) {
            values[i][4] = location.text();
        }

        //Set ticket urls
        Element ticketContainer = event.select(TAG_TICKET_URL).first();
        if (ticketContainer != null) {
            String ticket = ticketContainer.select("a").attr("href");
            values[i][5] = ticket;
        }
        else {
            values[i][3] = "Free";
        }

        i++;
        } //End of event loop
    } //End of try clause

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

    return values;
    }


    public static boolean checkFake(String s) {
    boolean isFake = false;
    String[] days = {"Today", "Tomorrow", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"};
    for (int i=0; i<days.length; i++) {
        if (s.contains(days[i])) {
        isFake = true;
        return isFake;
        }
    }
    return isFake;

     }
}

现在，这是传输到 AsyncTask 中的完全相同的方法，以便在显示加载屏幕时由我的应用程序在后台运行。

package com.example.nylist;

import java.io.IOException;
import android.app.Activity;
import android.content.Context;
import android.os.AsyncTask;
import android.util.Log;
import android.widget.Toast;

import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;

public class BVParser extends AsyncTask<Void, Void, String[][]> {
    static String TAG_EVENT = "li.ds-entry";
    static String TAG_TITLE = ".ds-entry-title";
    static String TAG_LOCATION = ".location";
    static String TAG_DATE_AND_TIME = ".ds-date";
    static String TAG_TICKET_URL = ".ds-buy-tickets";
    static String FEED_URL = "http://nyc-shows.brooklynvegan.com/";
    Context context;
    Activity activity;

    public BVParser(Activity context) {
    this.context = context.getApplicationContext();
    this.activity = context;
    } 



    @Override
    protected void onPreExecute() {
       super.onPreExecute();
       Toast.makeText(context, "Fetching...", Toast.LENGTH_LONG).show();
    }

    @Override
    protected String[][] doInBackground(Void... param) {
    String values[][] = new String[50][6];
    try {
        values = getFeedItems();
    } 
    catch (IOException e) {
        Log.d("ASSERT", "Exception occured during doInBackground", e);
        e.printStackTrace();
    }

    Log.d("ASSERT", ("values successfully returned by doInBackground, first title is: "+values[0][0]));
    return values;
    }

    protected void onPostExecute(String[][] result) {
    super.onPostExecute(result);
    int eventCount = result.length;
    Log.d("ASSERT", ("event count in onPostExecute is: "+eventCount));
    ListRow[] listrow_data = new ListRow[eventCount];
    ListRow temp;
    for (int i=0; i<eventCount; i++) {
        if (result[i] != null) {
        temp = new ListRow(context, result[i][0], result[i][1], result[i][2], 
            result[i][3], result[i][4], result[i][5], i);
        listrow_data[i] = temp;
        }
    }
    ((EventList) activity).setList(listrow_data);    
    }


    public String[][] getFeedItems() throws IOException {

    Document doc = null;
    String values[][] = new String[50][6];
    int i = 0;

    try{
        Log.d("ASSERT","Made it to try block");
        doc = Jsoup.connect(FEED_URL).timeout(0).get();
        Elements events = doc.select(TAG_EVENT);
        Log.d("ASSERT","printing events, whatever it is: "+events);

        String delimSpace = "[ ]";

        //******THIS LOOP NEVER BEGINS*****//
        for (Element event : events) {
        Log.d("ASSERT","Made it to getFeedItems's main for loop");

        //Set event title
        Element title = event.select(TAG_TITLE).first();
        String titleString = title.text();
        Log.d("ASSERT","This title is: "+titleString);
            boolean isFake = checkFake(titleString);
            if (!isFake) {
            values[i][0] = titleString;
            }
            else {
            continue;
        }

        //Set event date and time i guess
        Element dateAndTime = event.select(TAG_DATE_AND_TIME).first();
        if (dateAndTime != null) {
            String[] dateAndTimeTokens = dateAndTime.text().split(delimSpace);
            String date = dateAndTimeTokens[1];
            String time = dateAndTimeTokens[3];
            values[i][1] = date;
            values[i][2] = time;
        }

        //Set price
        values[i][3] = "See Ticket";

        //Set location
        Element location = event.select(TAG_LOCATION).first();
        if (location != null) {
            values[i][4] = location.text();
        }

        //Set ticket urls
        Element ticketContainer = event.select(TAG_TICKET_URL).first();
        if (ticketContainer != null) {
            String ticket = ticketContainer.select("a").attr("href");
            values[i][5] = ticket;
        }
        else {
            values[i][3] = "Free";
        }

        i++;
        } //End of event loop
    } //End of try clause

    catch (IOException e) {
        Log.d("ASSERT","Exception during getFeedItems");
        e.printStackTrace();
    }
    Log.d("ASSERT","The first title in getFeedItems before returning is: "+values[0][0]);
    return values;
    }


    private static boolean checkFake(String s) {
    boolean isFake = false;
    String[] days = {"Today", "Tomorrow", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"};
    for (int i=0; i<days.length; i++) {
        if (s.contains(days[i])) {
        isFake = true;
        return isFake;
        }
    }
    return isFake;

    }

}

调试尝试： 我在整个代码中添加了日志语句以调试问题。如果你运行它，你会发现问题似乎发生在 getFeedItems() 本身的某个地方，特别是在“try”块中。尽管出现了 try 语句开头的 log 语句，但运行的 for 循环events根本没有运行，因为它开头的 log 语句从不打印。

问题： 有人可以解释为什么循环events没有开始吗？是否为events空，如果是，为什么？为什么它自己运行的方法与我的 AsyncTask 中运行的方法之间存在差异？我一直在扯头发。此解析器中的逻辑几乎与我编写的（工作的）其他逻辑中的逻辑相同，但是这将返回一个只有空值的二维数组。我什至开始理解逻辑错误可能在哪里，但我似乎找不到错字。

PS： 如果将此与我的其他解析器进行比较会有所帮助，请告诉我，我会发布源代码。提前致谢。