Java Android：从http获取文件并存储在SD卡中

我已经关注了许多类似问题中的内容，但仍然存在一个问题

从jsp我得到一个pdf，如果我转到URL，浏览器会自动打开pdf，jsp页面会执行以下操作：

//Gets the pdf from the database
BufferedInputStream bis = new BufferedInputStream(file.getBinaryStream(), buffer);
ByteArrayOutputStream baos=new ByteArrayOutputStream();
int readed=0;
while ((readed=bis.read())!=-1) baos.write(readed);
bis.close();
byte[] pdf=baos.toByteArray();
response.setContentType("application/pdf");
response.setContentLength(pdf.length);              
response.getOutputStream().write(pdf, 0, pdf.length);

这段代码之所以有效，是因为如果我们浏览到URL，就会将PDF文件输入到浏览器中

然后在Android中，我在异步任务中执行以下操作：

InputStream is = null;
try {
URL url = new URL(myurl); // <-- this is the same URL tested into browser
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
urlConnection.connect();
FileOutputStream fos = new FileOutputStream(getWorkingDir()+fileName);
InputStream inputStream = urlConnection.getInputStream();
int totalSize = urlConnection.getContentLength(); //<- this seems to be incorrect,     totalSize value is 22 but file is more than 50Kb length
int downloadedSize = 0;
byte[] buffer = new byte[1024];
int bufferLength = 0; //used to store a temporary size of the buffer
while ( (bufferLength = inputStream.read(buffer)) >=0) {
  fos.write(buffer, 0, bufferLength);
  downloadedSize += bufferLength;
  // at this point downloadedSize is only 2, and next iteration in while exists so a file os size 2bytes is created...
}
fos.close();

你知道当它试图获取二进制pdf文件时为什么不工作吗

失败在哪里

---

感谢您的专业知识…

这对我很有用。请尝试修改以下内容：

private void savePrivateExternalFile(String fileURL, String fName) {
   HttpURLConnection connection = null;
    URL url = null;
    try {

        url = new URL(fileURL);
        connection = (HttpURLConnection) url.openConnection();
        connection.addRequestProperty(BConstant.WEB_SERVICES_COOKIES,
                cookie);
             connection.setDoOutput(true);
        connection.connect();
    } catch (IOException e1) {
        e1.printStackTrace();
    }
    File folderDir = null;
        folderDir = new File(getExternalFilesDir("Directory Name") + "/Files");

    File file = new File(folderDir, fName);

    if (file.exists()) {
        file.delete();
    }

    if ((folderDir.mkdirs() || folderDir.isDirectory())) {
        try {
            InputStream inputStream = connection.getInputStream();
            BufferedInputStream bufferedInputStream = null;

                bufferedInputStream = new BufferedInputStream(inputStream,
                        1024 * 5);

            FileOutputStream fileOutputStream = new FileOutputStream(
                    folderDir + "/" + fName);
            byte[] buffer = new byte[1024];
                int len1 = 0;
                while ((len1 = inputStream.read(buffer)) != -1) {
                    fileOutputStream.write(buffer, 0, len1);
                }

                bufferedInputStream.close();

            fileOutputStream.close();
            inputStream.close();
            connection.disconnect();
            } catch (Exception e) {
            e.printStackTrace();
        }
      }

如果要打开下载的文件，请使用此选项：

File file = new File(getExternalFilesDir("Directory Name")+ "/Files/" + fileName);
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(Uri.fromFile(file),"application/pdf");
intent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
startActivity(intent);

在清单文件中添加此行：

是的，已测试且存在相同的问题，如果我在while中放入一个日志，写入len1，它只有2个字节，while没有更多的迭代（下一个tiem len1==-1）。我尝试过的每件事都应该是有效的，但有些地方我错过了，奇怪的。。。（仅更改注释行连接。addRequestProperty（BConstant.WEB\u SERVICES\u COOKIES，cookie））使用我的代码您只需更改url和fname。fname可以是文件的任何字符串名称。它会像黄油一样起作用。只需尝试硬编码url，然后运行代码。您的代码在java应用程序中工作，但在应用程序中不工作，尝试使用harcoded字符串也会出现相同的错误，但发现了问题，代码正常（您的代码和我的前一个代码），因此问题在于通信，因为url已从外部服务器重定向到内部服务器，似乎有一些问题在那里或在服务器，将检查，代码正在工作，谢谢。啊，我不能投票给你的答案好，因为我没有声誉，但谢谢！！！

private void savePrivateExternalFile(String fileURL, String fName) {
   HttpURLConnection connection = null;
    URL url = null;
    try {

        url = new URL(fileURL);
        connection = (HttpURLConnection) url.openConnection();
        connection.addRequestProperty(BConstant.WEB_SERVICES_COOKIES,
                cookie);
             connection.setDoOutput(true);
        connection.connect();
    } catch (IOException e1) {
        e1.printStackTrace();
    }
    File folderDir = null;
        folderDir = new File(getExternalFilesDir("Directory Name") + "/Files");

    File file = new File(folderDir, fName);

    if (file.exists()) {
        file.delete();
    }

    if ((folderDir.mkdirs() || folderDir.isDirectory())) {
        try {
            InputStream inputStream = connection.getInputStream();
            BufferedInputStream bufferedInputStream = null;

                bufferedInputStream = new BufferedInputStream(inputStream,
                        1024 * 5);

            FileOutputStream fileOutputStream = new FileOutputStream(
                    folderDir + "/" + fName);
            byte[] buffer = new byte[1024];
                int len1 = 0;
                while ((len1 = inputStream.read(buffer)) != -1) {
                    fileOutputStream.write(buffer, 0, len1);
                }

                bufferedInputStream.close();

            fileOutputStream.close();
            inputStream.close();
            connection.disconnect();
            } catch (Exception e) {
            e.printStackTrace();
        }
      }

File file = new File(getExternalFilesDir("Directory Name")+ "/Files/" + fileName);
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(Uri.fromFile(file),"application/pdf");
intent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
startActivity(intent);

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />