从 URL 连接读取 Java

Question

我正在尝试从 URL 连接读取 html 代码。在一种情况下，我尝试读取的 html 文件在实际文档类型声明之前包含 5 个换行符。在这种情况下，输入阅读器会抛出 EOF 异常。

URL pageUrl = 
    new URL(
        "http://www.nytimes.com/2011/03/15/sports/basketball/15nbaround.html"
    );

URLConnection getConn = pageUrl.openConnection();
getConn.connect();
DataInputStream dis = new DataInputStream(getConn.getInputStream());
//some read method here

有人遇到过这样的问题吗？

URL pageUrl = new URL("http://www.nytimes.com/2011/03/15/sports/basketball/15nbaround.html");
URLConnection getConn = pageUrl.openConnection();
getConn.connect();
DataInputStream dis = new DataInputStream(getConn.getInputStream());
String urlData = "";
while ((urlData = dis.readUTF()) != null)
    System.out.println(urlData);

//抛出异常

java.io.EOFException 在 java.io.DataInputStream.readUnsignedShort(DataInputStream.java:323) 在 java.io.DataInputStream.readUTF(DataInputStream.java:572) 在 java.io.DataInputStream.readUTF(DataInputStream.java:547)

对于bufferedreader，它只是响应null并且不继续

pageUrl = new URL("http://www.nytimes.com/2011/03/15/sports/basketball/15nbaround.html");
URLConnection getConn = pageUrl.openConnection();
getConn.connect();
BufferedReader br = new BufferedReader(new InputStreamReader(getConn.getInputStream()));
String urlData = "";
while(true)
     urlData = br.readLine();
     System.out.println(urlData);

输出为空

Answer 1

您正在使用DataInputStream 读取未使用DataOutputStream 编码的数据。检查您致电DataInputStream#readUtf() 的记录行为； it first reads two bytes 形成一个 16 位整数，表示后面包含 UTF 编码字符串的字节数。您从 HTTP 服务器读取的数据不是以这种格式编码的。

相反，根据RFC 2616 第 6.1 和 2.2 节，HTTP 服务器发送以 ASCII 编码的标头。您需要将标头作为文本读取，然后确定消息正文（“实体”）的编码方式。

Answer 2

这很好用：

package url;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URL;

/**
 * UrlReader
 * @author Michael
 * @since 3/20/11
 */
public class UrlReader
{

    public static void main(String[] args)
    {
        UrlReader urlReader = new UrlReader();

        for (String url : args)
        {
            try
            {
                String contents = urlReader.readContents(url);
                System.out.printf("url: %s contents: %s\n", url, contents);
            }
            catch (Exception e)
            {
                e.printStackTrace();
            }
        }
    }


    public String readContents(String address) throws IOException
    {
        StringBuilder contents = new StringBuilder(2048);
        BufferedReader br = null;

        try
        {
            URL url = new URL(address);
            br = new BufferedReader(new InputStreamReader(url.openStream()));
            String line = "";
            while (line != null)
            {
                line = br.readLine();
                contents.append(line);
            }
        }
        finally
        {
            close(br);
        }

        return contents.toString();
    }

    private static void close(Reader br)
    {
        try
        {
            if (br != null)
            {
                br.close();
            }
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }
}

Answer 3

这个：

public class Main {
    public static void main(String[] args) 
        throws MalformedURLException, IOException 
    {
        URL pageUrl = new URL("http://www.google.com");
        URLConnection getConn = pageUrl.openConnection();
        getConn.connect();
        BufferedReader dis = new BufferedReader( 
                                 new InputStreamReader(
                                     getConn.getInputStream()));
        String myString;
        while ((myString = dis.readLine()) != null)
        {
            System.out.println(myString);
        }
    }
}

完美运行。但是，您提供的 URL 没有返回任何内容。