downloadutil.java

来自「用Java开发的多线程下载工具」· Java 代码 · 共 118 行

package download;

/**
 *功能：测试URL有效性，获取URL资源信息
 */
import java.io.*;
import java.net.*;
import java.util.HashMap;

public class DownLoadUtil
{
	/**
	 * 功能：建立URL连接，将连接结果写入TestResult类型的类对象中 返回类型：TestResult(自定义类)
	 */
	public static TestResult TestURL(String tmp)
	{
		TestResult r = new TestResult();
		URL tmp_URL;
		try
		{
			System.out.println("正在连接URL[" + tmp + "]");
			tmp_URL = new URL(tmp);
			HttpURLConnection http = (HttpURLConnection) tmp_URL
					.openConnection();
			if (http.getResponseCode() >= 400)
			{
				System.out.println("资源[" + tmp_URL + "]服务器响应错误！");
				r.myUrl = null;
				r.myResult = -1;
				return r;
			}
			else
			{
				System.out.println("资源[" + tmp_URL + "]连接成功！");
				r.myUrl = tmp_URL;
				r.myResult = 1;
				// 获取文件长度
				r.fileLength = http.getContentLength();
				if (r.fileLength == -1)
				{
					System.out.println("资源[" + tmp + "]无法获知的文件长度！");
				}
				else
				{
					System.out.println("资源[" + tmp + "]文件大小为"
							+ Math.round(r.fileLength / 1024 * 100) / 100.0
							+ "k。");
				}
				// 获取文件名
				r.fileName = getFileName(http);
				System.out.println("资源[" + tmp + "]文件名为" + r.fileName);
				// 获取MIME列表
				r.http_MIME = getMIME(http);
				return r;
			}
		}
		catch (MalformedURLException e1)
		{
			System.out.println("资源[" + tmp + "]格式错误！");
			r.myUrl = null;
			r.myResult = -2;
			return r;
		}
		catch (IOException e2)
		{
			System.out.println("资源[" + tmp + "]连接错误！");
			r.myUrl = null;
			r.myResult = -3;
			return r;
		}
	}

	/**
	 * 功能：获取下载文件名长度 返回值：String
	 */
	private static String getFileName(HttpURLConnection http)
	{
		String filename = http.getURL().getFile();
		return filename;// .substring(filename.lastIndexOf("/")+1);
	}

	/**
	 * 功能：获取URL连接时的MIME信息 返回值：HashMap<String,String>
	 */
	private static HashMap<String, String> getMIME(HttpURLConnection http)
	{
		HashMap<String, String> http_MIME = new HashMap<String, String>();
		System.out.println("资源[" + http.getURL() + "]MIME信息！");
		System.out.println("=====================信息开始=======================");
		for (int i = 0;; i++)
		{
			String mine = http.getHeaderField(i);
			if (mine == null)
				break;
			System.out.println(http.getHeaderFieldKey(i) + ":" + mine);
			http_MIME.put(http.getHeaderFieldKey(i), http.getHeaderField(i));
		}
		System.out.println("=====================信息结束=======================");
		return http_MIME;
	}
}

/**
 * 功能：记录URL连接测试结果信息
 */
class TestResult implements Serializable
{
	public URL myUrl;

	public int myResult;

	public int fileLength;

	public String fileName;

	public HashMap<String, String> http_MIME;
}