Java URLConnection不允许我访问有关Http错误的数据（404500等）

我正在制作一个爬虫程序，需要从流中获取数据，不管它是否为200。CURL正在做这件事，就像任何标准浏览器一样

以下内容实际上不会获取请求的内容，即使存在一些异常，也会抛出一个包含http错误状态代码的异常。我想要输出，不管怎样，有办法吗？我更喜欢使用这个库，因为它实际上会进行持久连接，这非常适合我正在进行的爬行类型

package test;

import java.net.*;
import java.io.*;

public class Test {

    public static void main(String[] args) {

         try {

            URL url = new URL("http://github.com/XXXXXXXXXXXXXX");
            URLConnection connection = url.openConnection();

            DataInputStream inStream = new DataInputStream(connection.getInputStream());
            String inputLine;

            while ((inputLine = inStream.readLine()) != null) {
                System.out.println(inputLine);
            }
            inStream.close();
        } catch (MalformedURLException me) {
            System.err.println("MalformedURLException: " + me);
        } catch (IOException ioe) {
            System.err.println("IOException: " + ioe);
        }
    }
}

工作了，谢谢：以下是我的想法——只是一个粗略的概念证明：

import java.net.*;
import java.io.*;

public class Test {

    public static void main(String[] args) {
//InputStream error = ((HttpURLConnection) connection).getErrorStream();

        URL url = null;
        URLConnection connection = null;
        String inputLine = "";

        try {

            url = new URL("http://verelo.com/asdfrwdfgdg");
            connection = url.openConnection();

            DataInputStream inStream = new DataInputStream(connection.getInputStream());

            while ((inputLine = inStream.readLine()) != null) {
                System.out.println(inputLine);
            }
            inStream.close();
        } catch (MalformedURLException me) {
            System.err.println("MalformedURLException: " + me);
        } catch (IOException ioe) {
            System.err.println("IOException: " + ioe);

            InputStream error = ((HttpURLConnection) connection).getErrorStream();

            try {
                int data = error.read();
                while (data != -1) {
                    //do something with data...
                    //System.out.println(data);
                    inputLine = inputLine + (char)data;
                    data = error.read();
                    //inputLine = inputLine + (char)data;
                }
                error.close();
            } catch (Exception ex) {
                try {
                    if (error != null) {
                        error.close();
                    }
                } catch (Exception e) {

                }
            }
        }

        System.out.println(inputLine);
    }
}

简单：

URLConnection connection = url.openConnection();
InputStream is = connection.getInputStream();
if (connection instanceof HttpURLConnection) {
   HttpURLConnection httpConn = (HttpURLConnection) connection;
   int statusCode = httpConn.getResponseCode();
   if (statusCode != 200 /* or statusCode >= 200 && statusCode < 300 */) {
     is = httpConn.getErrorStream();
   }
}

---

调用

openConnection

后，需要执行以下操作

将URLConnection强制转换为HttpURLConnection

调用getResponseCode

如果响应成功，则使用getInputStream，否则使用getErrorStream

---

（成功测试应该是

200“InputStream is=connection.getResponseMessage（）；”我在URLConnection类中没有看到getResponseMessage方法，它是HttpUrlConnection的一部分，所以我们不应该对它进行类型转换吗？或者我们可以用getInputStream替换getResponseMessage，或者它会引发异常吗？这是一个输入错误，它是
连接。getInputStream（）
。回答得非常好而且简短
URLConnection connection = url.openConnection();
InputStream is = null;
try {
    is = connection.getInputStream();
} catch (IOException ioe) {
    if (connection instanceof HttpURLConnection) {
        HttpURLConnection httpConn = (HttpURLConnection) connection;
        int statusCode = httpConn.getResponseCode();
        if (statusCode != 200) {
            is = httpConn.getErrorStream();
        }
    }
}