Question

import java.net.URL;
import java.net.URLConnection;
import java.util.Scanner;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

/ ** *此简短程序通过以下示例演示了URL和URLConnection类 *尝试打开与URL的连接并从中读取文本。网址可以 *在命令行上指定。如果未提供命令行参数， *提示用户输入。它可以是完整的网址，包括 *以“ protocol”开头（“ http：//”，“ ftp：//”或“ file：//”）。如果有 *不是以这些协议之一开头，而是将“ http：//”添加到 *输入行。如果尝试获取数据时发生错误，则会显示一条消息 *输出。否则，URL中的文本将复制到屏幕上。 * /

public class FetchURL {

public static void main(String[] args) {
    String url; // The url from the command line or from user input.
    url = "http://sites.google.com/site/stephenkofflercodingprojects/"
            + "files-to-download/CBS 20181223 PAGEVIEWS.TXT";
    System.out.println();
    try {
        readTextFromURL(url);
    } catch (IOException e) {
        System.out.println("\n*** Sorry, an error has occurred ***\n");
        System.out.println(e);
        System.out.println();
    }
}

/**
 * This subroutine attempts to copy text from the specified URL onto the 
screen.
 * Any error must be handled by the caller of this subroutine.
 * 
 * @param urlString contains the URL in text form
 */
static void readTextFromURL(String urlString) throws IOException {

    /*
     * Open a connection to the URL, and get an input stream for reading 
data from
     * the URL.
     */

    URL url = new URL(urlString);
    URLConnection connection = url.openConnection();
    InputStream urlData = connection.getInputStream();

    /*
     * Check that the content is some type of text. Note: If 
getContentType() method
     * were called before getting the input stream, it is possible for 
 contentType
     * to be null only because no connection can be made. The 
getInputStream()
     * method will throw an error if no connection can be made.
     */

    String contentType = connection.getContentType();
    System.out.println("Stream opened with content type: " + contentType);
    System.out.println();
    if (contentType == null || contentType.startsWith("text") == false)
        throw new IOException("URL does not seem to refer to a text file.");
    System.out.println("Fetching context from " + urlString + " ...");
    System.out.println();

    /*
     * Copy lines of text from the input stream to the screen, until end-of- 
 file is
     * encountered (or an error occurs).
     */

    BufferedReader in; // For reading from the connection's input stream.
    in = new BufferedReader(new InputStreamReader(urlData));

    while (true) {
        String line = in.readLine();
        if (line == null)
            break;
        System.out.println(line);
    }
    in.close();

} // end readTextFromURL()

} // end class FetchURL

服务器返回的HTTP响应代码：URL的400：我的URL是否有问题？

0 个答案: