Question

I want to post a text file from my desktop using Advanced Rest Client. This is my controller:

@RequestMapping(value = "/vsp/debug/compareConfig/{deviceIp:.*}", method = RequestMethod.POST, consumes = { "multipart/form-data" }, produces = { "application/json" })

public ResponseEntity<SuccessResult> compareCLIs(HttpServletRequest request, @RequestParam("file") MultipartFile file, @PathVariable("deviceIp") String device) 
{
log.info(file.getOriginalFilename());
byte[] bytearr = file.getBytes();
log.info("byte length: ", bytearr.length);
log.info("Size : ", file.getSize());

}

This does not return any value for byte length or file size. I want to read the file values to a StringBuffer. Can someone provide pointers regarding this? I am not sure if I need to save this file before parsing it to a string. If so how do I save the file in the workspace?

Answer 1

如果要将Multipart文件的内容加载到String中，最简单的解决方案是：

String content = new String(file.getBytes());

或者，如果要指定字符集：

String content = new String(file.getBytes(), "UTF-8");

但是，如果你的文件太大，这个解决方案可能不是最好的。

Answer 2

首先，这与Spring无关，其次，您不需要保存文件来解析它。

要将Multipart文件的内容读入String，您可以使用Apache Commons像这样的IOUtils类

ByteArrayInputStream stream = new   ByteArrayInputStream(file.getBytes());
String myString = IOUtils.toString(stream, "UTF-8");

Answer 3

给出的答案是正确的，但最上面的答案说这对于大文件来说效率不高，原因是它会将整个文件保留在内存中，这意味着如果您上传2gb文件，它将消耗这么多的内存。代替这样做，我们可以逐行读取文件，而Apache Commons IO为此提供了一个不错的API。

LineIterator it = FileUtils.lineIterator(theFile, "UTF-8");
try {
    while (it.hasNext()) {
        String line = it.nextLine();
        // do something with line
    }
} finally {
    LineIterator.closeQuietly(it);
}

source

How to read a Multipart file as a string in Spring?

3 个答案: