下載

 1.調用

URL url = new URL(DownStatic.murlsString); // 尋找資源服務器

connection = (HttpURLConnection) url.openConnection();  與服務器建立連接

InputStream is = connection.getInputStream();   建立資源流

randomAccessFile = new RandomAccessFile(DownStatic.mpathString, "rwd"); 建立本地文件

public class DownStatic {

    public static String murlsString;
    public static String mpathString;
    private static int compeleteSize; // 完成大小

    public static native void displayProgress(String numString);

    public static native void setFileSize(int pSize);

    public static native void downloadFail();

    public static String downloadAndroid(String pPathString, String pUrlsString) {
        System.out.println("sendWeibo  :  " + pUrlsString);
        System.out.println("sendWeibo  :  " + pPathString);

        File fileM = new File(pPathString);
        if (fileM.exists()) {// 如果存在刪除從新下載
            fileM.delete();
        }
        DownStatic.murlsString = pUrlsString;
        DownStatic.mpathString = pPathString;
        DownStatic.down();

        return "";
    }

    public static void down() {
        HttpURLConnection connection = null;
        RandomAccessFile randomAccessFile = null;
        InputStream is = null;

        try {
            URL url = new URL(DownStatic.murlsString);
            connection = (HttpURLConnection) url.openConnection();
            connection.setConnectTimeout(5000); // 5秒
            connection.setRequestMethod("GET");
            DownStatic.setFileSize(connection.getContentLength());

            // 設置範圍，格式爲Range：bytes x-y;
            // connection.setRequestProperty("Range", "bytes="
            // + (0 + 0) + "-" + endPos);
            // randomAccessFile = new RandomAccessFile(localfile, "rwd"); // rwd

            randomAccessFile = new RandomAccessFile(DownStatic.mpathString,
                    "rwd");

            // 數據同步讀寫
            // randomAccessFile.seek(startPos + compeleteSize);
            // 將要下載的文件寫到保存在保存路徑下的文件中

            is = connection.getInputStream();

            byte[] buffer = new byte[4096]; // 每次寫入字節數
            int length = -1;
            String string;

            // 不斷下載
            while ((length = is.read(buffer)) != -1) {
                randomAccessFile.write(buffer, 0, length);
                DownStatic.compeleteSize += length;
                string = String.valueOf(DownStatic.compeleteSize);
                DownStatic.displayProgress(string);
            }

        } catch (Exception e) {// 下載失敗
            System.out.println("Exception e  Exception e");
            DownStatic.downloadFail();
            e.printStackTrace();
        } finally {
            try {
                is.close();
                randomAccessFile.close();
                connection.disconnect();
            } catch (Exception e) {
                System.out.println("finally finally e  Exception e");
                e.printStackTrace();
            }
        }

    }

}