HttpURLConnection來實作檔案或圖片下載

這個範例與之前的HttpURLConnection來實作get及post動作基本原理是一樣的,一個是使用java.io.BufferedReader來取得文字的html內容,而這個範例則是使用java.io.InputStream取得binary的檔案內容。

程式的流程大概是,先建立HttpConnection,給Connection標題Header、Referer、Cookie等內容,然後建立連線,跟伺服器request要求內容,再取得http的InputStrem,要取得伺服器response的內容,把內容讀取byte[],然後寫入檔案,如此就完成下載檔案的動作了。




程式碼如下:

package com.izero.http;

import java.net.*;
import java.net.Proxy.Type;
import java.io.*;

public class WebModuleDownload {
    private org.apache.log4j.Logger logger;

    private Proxy proxy;
    private String fileName;
    private String filePath;

    public WebModuleDownload() {
        logger = org.apache.log4j.Logger.getLogger(this.getClass());
        // buff = new StringBuffer();
        proxy = null;
        fileName = null;
        filePath = null;
    }

    // 如果要使用proxy,則使用此建構值
    public WebModuleDownload(String proxyAddress, int proxyPort) {
        this();
        proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress(proxyAddress,
                proxyPort));
    }

    // 下載後可取得檔案名稱,否則為null
    public String getFileName() {
        return fileName;
    }

    // 下載後可取得檔案路徑,否則為null
    public String getFilePath() {
        return filePath;
    }

    // 下載網址,
    // 使用cookie(可為null),
    // referer(可為null),
    // 存放檔案路徑(一定要有),
    // 存放檔案名稱(如為null則使用網址的檔名)
    public boolean doGet(String sURL, String cookie, String referer,
            String filePath, String fileName) {

        boolean doSuccess = true;
        BufferedReader in = null;
        try {
            URL url = new URL(sURL);
            HttpURLConnection URLConn = null;
            // 如有使用proxy,則openConnection時傳入proxy產數
            if (proxy != null)
                URLConn = (HttpURLConnection) url.openConnection(proxy);
            else
                URLConn = (HttpURLConnection) url.openConnection();
            // 要求的標頭header
            URLConn.setRequestProperty(
                    "User-agent",
                    "Mozilla/5.0 (Windows; U; Windows NT 6.0; zh-TW; rv:1.9.1.2) "
                            + "Gecko/20090729 Firefox/3.5.2 GTB5 (.NET CLR 3.5.30729)");
            URLConn.setRequestProperty("Accept",
                    "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
            URLConn.setRequestProperty("Accept-Language",
                    "zh-tw,en-us;q=0.7,en;q=0.3");
            URLConn.setRequestProperty("Accept-Charse",
                    "Big5,utf-8;q=0.7,*;q=0.7");
            // 是否使用cookie
            if (cookie != null)
                URLConn.setRequestProperty("Cookie", cookie);
            // 是否使用referer
            if (referer != null)
                URLConn.setRequestProperty("Referer", referer);
            // URLConn.setDoInput(true);
            // URLConn.setDoOutput(true);
            // 建立連線
            URLConn.connect();
            // URLConn.getOutputStream().flush();

            // 取得下載inputstream連線
            java.io.BufferedInputStream rd = new java.io.BufferedInputStream(
                    URLConn.getInputStream());

            String saveFileName = fileName;
            // 檔名參數為null,則取下載網址的檔名為檔名
            if (fileName == null) {
                int start = sURL.lastIndexOf("/") + 1;
                int end = sURL.lastIndexOf("?", start);
                if (end == -1)
                    end = sURL.length();
                // System.out.println(start+","+end);
                saveFileName = sURL.substring(start, end);
            }

            java.io.File f = new java.io.File(filePath);
            f = new java.io.File(f.getAbsolutePath());
            if (!f.exists())
                f.mkdirs();
            f = new java.io.File(f.getAbsolutePath() + java.io.File.separator
                    + saveFileName);
            this.fileName = saveFileName;
            // 取得路徑
            this.filePath = f.getAbsolutePath();

            java.io.BufferedOutputStream fos = new java.io.BufferedOutputStream(
                    new java.io.FileOutputStream(f));

            byte[] tmp = new byte[1024];
            int len;
            // 讀取httpConection的input,寫出檔案的output
            while ((len = rd.read(tmp)) != -1) {
                // System.out.print(tmp);
                fos.write(tmp, 0, len);
            }
            fos.flush();
            fos.close();
            rd.close();

        } catch (IOException e) {
            doSuccess = false;
            logger.info(e);
            e.printStackTrace();
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (java.io.IOException ex) {
                    logger.info(ex);
                }
                in = null;

            }
        }

        return doSuccess;
    }

    public static void main(String args[]) throws IOException {
        WebModuleDownload web = new WebModuleDownload();
        web.doGet("http://l.yimg.com/f/i/tw/news/p_logo/yptw.png", null, null,
                "d:/", null);
        /*
         * java.awt.image.BufferedImage image = javax.imageio.ImageIO .read(new
         * ByteArrayInputStream(web.getContent()));
         * javax.imageio.ImageIO.write(image, "JPEG", new
         * File("d:/HEX1PA35-A.JPG"));
         */

    }
}

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