使用js从本地存储读取文件

Question

hi i'm using java script to read txt file from my pc. i try to do it in 3 ways like that:

function readTextFile(file) {
            var rawFile = new XMLHttpRequest();
            rawFile.open("GET", file, false);
            rawFile.onreadystatechange = function() {
                if (rawFile.readyState === 4) {
                    if (rawFile.status === 200 || rawFile.status == 0) {
                        var allText = rawFile.responseText;
                        console.log(allText);
                    }
                }
            }
            rawFile.send(null);
        }
        console.log("1");
        readTextFile("text.txt"); //GOOD
        console.log("2");
        readTextFile("D:/Documents/Documents/Aptana Studio 3 Workspace/Yonit_web_services/test/text.txt"); //BAD
        console.log("3");
        readTextFile("file:///D:/Documents/Documents/Aptana Studio 3 Workspace/Yonit_web_services/test/text.txt"); //BAD

all of them are pointing at the same file i got an error like that:

XMLHttpRequest cannot load file:///D:/Documents/Documents/Aptana%20Studio%203%20Workspace/Yonit_web_services/test/text.txt. Cross origin requests are only supported for HTTP. test.html:21readTextFile test.html:21(anonymous function) test.html:26

whay is that ? thanks.

Answer 1

I had the same problem a while back. I fixed it by opening Chrome through Windows command prompt with this parameter: --disable-web-security

Please note that this has security vulnerabilities.

Answer 2

Browser does not allow to file access through javascript due to security reasons, find the link below.

Security

But in HTML5 its possible via using File Upload/ Download, link File Uplaod/Download

Answer 3

The first method of reading the file:

readTextFile("text.txt"); //GOOD

is working because "text.txt" is a relative path in the same respect that if you had the file system:

\index.html
\img\img.png

img.png would be accessible to index.html in this respect you might be able to access files and folders in parent and parrent's parent directories by using relative path-ing.

from a windows command prompt you can test these relative paths with dir as follows:

REM Dir will show contents of current directory
Dir
REM Dir .. will show contents of parent directory
Dir ..
REM Dir ../.. will show contents of parent's parent directory
Dir ../..

the same path-ing should work in JavaScript

This being said, the restrictions on d:/ and file://D:/ are most likely for security reason. You might want to check out http://en.wikipedia.org/wiki/Samba_%28software%29 for more details.

Answer 4

您总是可以做一件事，并将其放在应用程序从其访问的某个URL上（仅当它不包含任何安全信息时）。