java - MalformedStreamException : Stream ended unexpectedly

Question

给定:
byteString 是

-----------------------------149742642616556
Content-Disposition: form-data; name="file"; filename="test.txt"
Content-Type: text/plain

test
-----------------------------149742642616556--

然后这段代码(未优化):

Pattern pattern = Pattern.compile(BOUNDARY_PATTERN); // "(?m)\\A-+\\d+$"
Matcher matcher = pattern.matcher(byteString);
String boundary = null;
while (matcher.find()) {
    boundary = matcher.group();
    contentType = "multipart/form-data; boundary=" + boundary;
}
LOG.info("Content Type = " + contentType);

@SuppressWarnings("deprecation")
org.apache.commons.fileupload.MultipartStream multipartStream =
        new org.apache.commons.fileupload.MultipartStream(new ByteArrayInputStream(byteString.getBytes()), boundary.getBytes());
ByteArrayOutputStream bos = new ByteArrayOutputStream();
multipartStream.readBodyData(bos); // throw error
byte[] byteBody = bos.toByteArray();

抛出这个错误:

org.apache.commons.fileupload.MultipartStream$MalformedStreamException: Stream ended unexpectedly
    at org.apache.commons.fileupload.MultipartStream$ItemInputStream.makeAvailable(MultipartStream.java:1005)
    at org.apache.commons.fileupload.MultipartStream$ItemInputStream.read(MultipartStream.java:903)
    at java.io.InputStream.read(InputStream.java:101)
    at org.apache.commons.fileupload.util.Streams.copy(Streams.java:100)
    at org.apache.commons.fileupload.util.Streams.copy(Streams.java:70)
    at org.apache.commons.fileupload.MultipartStream.readBodyData(MultipartStream.java:593)

这里可能有什么问题？我很感激这里的帮助。

Answer 1

该问题似乎是由于行尾错误和检索边界的方式造成的。 根据来自 RFC2046 的 SO answer 引用:

The Content-Type field for multipart entities requires one parameter, "boundary". The boundary delimiter line is then defined as a line consisting entirely of two hyphen characters ("-", decimal value 45) followed by the boundary parameter value from the Content-Type header field, optional linear whitespace, and a terminating CRLF.

问题恰恰在于两点: 行尾类型 和 边界参数值前面的两个连字符 。

行尾

由于您的代码没有准确显示 byteString 的值，我尝试了 LF ( \n ) 和 CRLF ( \r\n ) 行尾，看看会发生什么。

当 坏的 行尾(即不是 CRLF)是 时，该问题似乎重现了 最后一个边界 ，如下所示:

String byteString=
    "-----------------------------149742642616556\r\n" +
    "Content-Disposition: form-data; name=\"file\"; filename=\"test.txt\"\r\n" +
    "Content-Type: text/plain; charset=UTF-8\r\n" +
    "\r\n" +
    "test\r\n" + // <-- only \n here lead to a MalformedStreamException
    "-----------------------------149742642616556--\r\n";

听起来 MultipartStream 无法解析边界的开头，因为它没有在上一行中捕获行的右端 (CRLF)。 因此，我使用了 LF 终止符，您应该将它们替换为 CRLF 终止符。

边界格式

RFC 告诉我们边界定界符是两个连字符 + 边界参数 + CRLF。您的正则表达式不仅捕获边界参数值，还包括两个连字符。所以我替换了这部分:

// capturing group = boundary parameter value
String regexp="(?m)\\A--(-*\\d+)$";
// [...]
while (matcher.find()) {
    boundary = matcher.group(1);
    // [...]
}

工作代码

可作为 MCVE 运行

您将在下面找到的代码可以在没有 Tomcat 的控制台中运行。只需要 commons-fileupload-1.3.3-bin.tar.gz 和 commons-io-2.6-bin.tar.gz。

要查看 MultipartStream 解析的内容，我在 bos 调用中暂时将 System.out 替换为 readBodyData() (如评论中所述)。

编译:

javac Test.java -classpath ./commons-fileupload-1.3.3-bin/commons-fileupload-1.3.3.jar 

运行:

java -classpath ./commons-fileupload-1.3.3-bin/commons-fileupload-1.3.3.jar:./commons-io-2.6/commons-io-2.6.jar:. Test

代码本身

import java.util.regex.*;
import java.io.*;
import org.apache.commons.fileupload.*;

public class Test {
    public final static void main(String[] argv) {
    String byteString=
        "-----------------------------149742642616556\r\n" +
        "Content-Disposition: form-data; name=\"file\"; filename=\"test.txt\"\r\n" +
        "Content-Type: text/plain; charset=UTF-8\r\n" +
        "\r\n" +
        "test\r\n" + // <-- only \n here lead to a MalformedStreamException
        "-----------------------------149742642616556--\r\n";

    String regexp="(?m)\\A--(-*\\d+)$"; // edited regexp to catch the right boundary

    Pattern pattern = Pattern.compile(regexp);
    Matcher matcher = pattern.matcher(byteString);
    String boundary = null;
    String contentType=null;
    while (matcher.find()) {
        boundary = matcher.group(1);
        contentType = "multipart/form-data; boundary=\"" + boundary + "\"";
    }

    System.out.println("boundary = \"" + boundary + "\"");

    @SuppressWarnings("deprecation")
        org.apache.commons.fileupload.MultipartStream multipartStream =
        new org.apache.commons.fileupload.MultipartStream
        (new ByteArrayInputStream(byteString.getBytes()), boundary.getBytes());
     ByteArrayOutputStream bos = new ByteArrayOutputStream();

    try {
        // Use the commented line instead the following one
        // To see what the multipartStream is reading (for debug)
        // multipartStream.readBodyData(System.out);
        multipartStream.readBodyData(bos);
    } catch (MultipartStream.MalformedStreamException e) {
        System.out.println("Malformed Exception " + e.getMessage());
    } catch (IOException e) {
        System.out.println(e.getMessage());
    }
    byte[] byteBody = bos.toByteArray();

    // Displaying the body read
    for(byte c : byteBody) {
        System.out.format("%c", c);
    }
    System.out.println();
    }
}

输出:

boundary = "---------------------------149742642616556"
-----------------------------149742642616556
Content-Disposition: form-data; name="file"; filename="test.txt"
Content-Type: text/plain; charset=UTF-8

test