java文件读取问题

Question

In my java application, I have to read one file. The problem what I am facing, after reading the file, the results is coming as non readable format. that means some ascii characters are displayed. That means none of the letters are readable. How can I make it display that?

 // Open the file that is the first
        // command line parameter

        FileInputStream fstream = new FileInputStream("c:\\hello.txt");
        // Get the object of DataInputStream
        DataInputStream in = new DataInputStream(fstream);
        BufferedReader br = new BufferedReader(new InputStreamReader(in));
        String strLine;
        // Read File Line By Line
        while ((strLine = br.readLine()) != null) {
            // Print the content on the console
            System.out.println(strLine);
        }
        // Close the input stream
        in.close();
    } catch (Exception e) {// Catch exception if any
        System.err.println("Error: " + e.getMessage());
    }

Answer 1

Perhaps you have an encoding error. The constructor you are using for an InputStreamReader uses the default character encoding; if your file contains UTF-8 text outside the ASCII range, you will get garbage. Also, you don't need a DataInputStream, since you aren't reading any data objects from the stream. Try this code:

FileInputStream fstream = null;
try {
    fstream = new FileInputStream("c:\\hello.txt");
    // Decode data using UTF-8
    BufferedReader br = new BufferedReader(new InputStreamReader(in, "UTF-8"));
    String strLine;
    // Read File Line By Line
    while ((strLine = br.readLine()) != null) {
        // Print the content on the console
        System.out.println(strLine);
    }
} catch (Exception e) {// Catch exception if any
    System.err.println("Error: " + e.getMessage());
} finally {
    if (fstream != null) {
        try { fstream.close(); }
        catch (IOException e) {
            // log failure to close file
        }
    }
}

Answer 2

You have to implement this way to handle:-

BufferedReader br = new BufferedReader(new InputStreamReader(in, encodingformat));

.

encodingformat - change it according to which type of encoding issue you are encounter.

Examples: UTF-8 , UTF-16 , ... soon

Refer this Supported Encodings by Java SE 6 for more info.

Answer 3

Since you doesn't know the encoding the file is in, use jchardet to detect the encoding used by the file and then use that encoding to read the file as others have already suggested. This is not 100 % fool proof but works for your scenario.

Also, use of DataInputStream is unnecessary.

Answer 4

您得到的输出是一个ascii值，因此您需要在将其打印之前将其类型转换为char或string。希望这会有所帮助

Answer 5

My problem got solved. I dont know how. I copied the hello.txt contents to another file and run the java program. I could read all letters. dont know whats the problem in that.