Question

我正在尝试使用以下代码下载超过100mb的视频mp4文件。但我得到＆＃34; java.lang.OutOfMemoryError：Java堆空间＆＃34;在下载时。

使用jdk1.7＆amp; Spring MVC。

我在SO链接下面提到但是没有一个对我有效。

how to download large files without memory issues in java

java.lang.OutOfMemoryError: Java heap space while downloading a large file from an URL

请帮我解决这个问题。

OutputStream outStream = null;
FileInputStream inputStream = null;
try {
    ServletContext context =  request.getSession().getServletContext();     
    String fileName = Integer.toString(fileId);     
    filePath = fileName+".mp4";

    File downloadFile = new File(filePath);
    inputStream = new FileInputStream(new File(filePath));
    // get MIME type of the file
    String mimeType = context.getMimeType(filePath);
    if (mimeType == null) {
        mimeType = "application/octet-stream";
    }
    response.setContentType(mimeType);
    response.setContentLength((int) downloadFile.length());
    String headerKey = "Content-Disposition";
    String headerValue = String.format("attachment; filename=\"%s\"",downloadFile.getName());
    response.setHeader(headerKey, headerValue);
    outStream = response.getOutputStream();
    byte[] buffer = new byte[1024];
    int bytesRead = 0, bytesBuffered = 0;
    while((bytesRead = inputStream.read(buffer)) > -1) {
        outStream.write(buffer, 0, bytesRead);
        bytesBuffered += bytesRead;
        if (bytesBuffered > 1024 * 1024) { //flush after 1MB
            bytesBuffered = 0;
            outStream.flush();
        }
    }
} catch(Exception e) {
    e.printStackTrace();
} finally {
    if (inputStream != null) {
        inputStream.close();
    }
    if (outStream != null) {
        outStream.flush();
        outStream.close();
    }
}

Answer 1

我尝试使用500 MB文件下面的代码并没有收到内存不足错误

OutputStream outStream = response.getOutputStream();

String mimeType = "application/zip";
String headerKey = "Content-Disposition";
String headerValue = String.format("attachment; filename=\"%s\"",
            "abc.zip");
response.setHeader(headerKey, headerValue);
response.setContentType(mimeType);
response.setStatus(HttpServletResponse.SC_OK);

File downloadFile = new File("file path");
InputStream inputStream = new FileInputStream(downloadFile);

int n = 0;
byte[] buf = new byte[1024];

while ((n = inputStream.read(buf)) != -1) {
        outStream.write(buf, 0, n);
}

inputStream.close();
outStream.flush();
outStream.close();

和JVM设置为：

-XX:PermSize=256m
-XX:MaxPermSize=512m
-Xms1024m
-Xmx2048m
-Dosgi.requiredJavaVersion=1.8
-XX:+UseG1GC
-XX:+UseStringDeduplication

Answer 2

您需要致电HttpServletResponse.flushBuffer()，而不仅仅是OutputStream.flush()，而且更频繁。

java.lang.OutOfMemoryError：下载巨大文件时的Java堆空间

2 个答案: