org.apache.commons.fileupload.disk.DiskFileItem是否正确创建? [英] org.apache.commons.fileupload.disk.DiskFileItem is not created properly?

问题描述

我正在尝试使用以下示例中显示的代码:

I am trying to use the code shown in the following example:

java.lang.NullPointerException

我的测试方法包含以下代码:

My Test method contains the following code:

final File TEST_FILE = new File("C:/my_text.txt");
final DiskFileItem diskFileItem = new DiskFileItem("fileData", "text/plain", true, TEST_FILE.getName(), 100000000, TEST_FILE.getParentFile());
diskFileItem.getOutputStream();

System.out.println("diskFileItem.getString() = " + diskFileItem.getString());

该位置存在文本文件，但以上代码中的最后一行不输出文件内容.

The text file exists in this location but the last line in the above code does not output the file content.

知道为什么吗?

N.B.

以下内容会打印文件内容:

The following does print the file content:

BufferedReader input =  new BufferedReader(new FileReader(TEST_FILE));
String line = null;
while (( line = input.readLine()) != null){
    System.out.println(line);
}

推荐答案

在您的第一个代码片段中，您使用OutputStream，但它不起作用.在第二部分中，您将使用InputStream(或它的任何暗示)，它会起作用:)您可能想尝试使用getInputStream()代替... OutputStream将写入未读取的字节.

In your first code snip you use an OutputStream and it doesn't work. In the second part you use an InputStream (or whatever impl of this) and it works :) You might want to try with getInputStream() instead... OutputStream is to write bytes not reading.

http://commons.apache.org/fileupload/apidocs /org/apache/commons/fileupload/disk/DiskFileItem.html

尝试这个，很简单，从头开始只是为了提供帮助:

try this one, it's simple and from scratch just to help :

final File TEST_FILE = new File("D:/my_text.txt");
    //final DiskFileItem diskFileItem = new DiskFileItem("fileData", "text/plain", true, TEST_FILE.getName(), 100000000, TEST_FILE);
    try
    {
        DiskFileItem fileItem = (DiskFileItem) new DiskFileItemFactory().createItem("fileData", "text/plain", true, TEST_FILE.getName());
        InputStream input =  new FileInputStream(TEST_FILE);
        OutputStream os = fileItem.getOutputStream();
        int ret = input.read();
        while ( ret != -1 )
        {
            os.write(ret);
            ret = input.read();
        }
        os.flush();
        System.out.println("diskFileItem.getString() = " + fileItem.getString());
    }
    catch (Exception e)
    {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

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