Java代碼實現下載網絡上的pdf文件

一、需求

下載網絡上的PDF文件保存到本地 

 二、URL分析

 1.http://www.chinatax.gov.cn/download/pdf/bszn/11.pdf

2.http://www.chinatax.gov.cn/download/pdf/bszn/12.pdf

URL具有規律性都是以數字.pdf結尾，可以使用for循環遍歷下載 

三、代碼實現 

 

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class DownloadPdf {
	/**
	 * 從網絡Url中下載文件
	 * 
	 * @param urlStr
	 * @param fileName
	 * @param savePath
	 * @throws IOException
	 */
	public static void downLoadByUrl(String urlStr, String fileName,
			String savePath) throws IOException {
		URL url = new URL(urlStr);
		HttpURLConnection conn = (HttpURLConnection) url.openConnection();
		// 設置超時間爲3秒
		conn.setConnectTimeout(5 * 1000);
		// 防止屏蔽程序抓取而返回403錯誤
		conn.setRequestProperty("User-Agent",
				"Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");
		// 得到輸入流
		InputStream inputStream = conn.getInputStream();
		// 獲取自己數組
		byte[] getData = readInputStream(inputStream);
		// 文件保存位置
		File saveDir = new File(savePath);
		if (!saveDir.exists()) {
			saveDir.mkdir();
		}
		File file = new File(saveDir + File.separator + fileName);
		FileOutputStream fos = new FileOutputStream(file);
		fos.write(getData);
		if (fos != null) {
			fos.close();
		}
		if (inputStream != null) {
			inputStream.close();
		}
		System.out.println("info:" + url + " download success");

	}

	/**
	 * 從輸入流中獲取字節數組
	 * 
	 * @param inputStream
	 * @return
	 * @throws IOException
	 */
	public static byte[] readInputStream(InputStream inputStream)
			throws IOException {
		byte[] buffer = new byte[1024];
		int len = 0;
		ByteArrayOutputStream bos = new ByteArrayOutputStream();
		while ((len = inputStream.read(buffer)) != -1) {
			bos.write(buffer, 0, len);
		}
		bos.close();
		return bos.toByteArray();
	}

	/**
	 * 
	 * @Title: main
	 * @Description:直接運行即可下載
	 * @param args
	 * 
	 */
	public static void main(String[] args) {
		for (int i = 111; i <= 113; i++) {
			try {
				downLoadByUrl("http://www.chinatax.gov.cn/download/pdf/bszn/"
						+ i + ".pdf", "" + i + ".pdf", "E:/pdf");
			} catch (Exception e) {
				System.out.println("下載出現異常：" + e);
			}

		}
	}
}

四、下載結果