Java InputStreamReader Read readFile(String filePath)

Description

Returns the text of the specified file.

License

Open Source License

Parameter

Parameter	Description
filePath	file path

Exception

Parameter	Description
IOException	an exception

Return

text of file

Declaration

public static String readFile(String filePath) throws IOException 

Method Source Code

//package com.java2s;
//License from project: Open Source License 

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    /***//from  w ww  .j a  v a 2  s.  c  o  m
     * Returns the text of the specified file. If a Unicode Byte Order Mark (BOM) is found, the file is read with the corresponding encoding.
     * Otherwise the file is read using the default encoding.
     * @param filePath file path
     * @return text of file
     * @throws IOException
     */
    public static String readFile(String filePath) throws IOException {
        String encoding = getEncoding(filePath);
        BufferedReader bufferedReader = null;
        StringBuilder text = new StringBuilder();

        try {
            bufferedReader = new BufferedReader(
                    new InputStreamReader(new FileInputStream(filePath), "windows-1252"/*encoding*/));
            char[] buffer = new char[1024 * 16];
            int length;

            while ((length = bufferedReader.read(buffer)) != -1) {
                text.append(buffer, 0, length);
            }
        } finally {
            if (bufferedReader != null) {
                bufferedReader.close();
            }
        }

        return text.toString();
    }

    /***
     * Determines the encoding of the specified file. If a UTF16 Byte Order Mark (BOM) is found an encoding of "UTF16" is returned.
     * If a UTF8 BOM is found an encoding of "UTF8" is returned. Otherwise the default encoding is returned.
     * @param filePath file path
     * @return "UTF8", "UTF16", or default encoding.
     */
    public static String getEncoding(String filePath) {
        String encoding = System.getProperty("file.encoding");
        BufferedReader bufferedReader = null;

        try {
            // In order to read files with non-default encoding, specify an encoding in the FileInputStream constructor.
            bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream(filePath)));

            char buffer[] = new char[3];
            int length = bufferedReader.read(buffer);

            if (length >= 2) {
                if ((buffer[0] == (char) 0xff && buffer[1] == (char) 0xfe)
                        /* UTF-16, little endian */ || (buffer[0] == (char) 0xfe
                                && buffer[1] == (char) 0xff) /* UTF-16, big endian */) {
                    encoding = "UTF16";
                }
            }

            if (length >= 3) {
                if (buffer[0] == (char) 0xef && buffer[1] == (char) 0xbb && buffer[2] == (char) 0xbf) /* UTF-8 */ {
                    encoding = "UTF8";
                }
            }

        } catch (IOException ex) {
        } finally {
            if (bufferedReader != null) {
                try {
                    bufferedReader.close();
                } catch (IOException ex) {
                }
            }
        }

        return encoding;
    }
}

Related

1. readFile(String fileNm)
2. readFile(String filePath)
3. readFile(String filePath)
4. readFile(String filePath)
5. readFile(String filePath)
6. readFile(String filePath)
7. readFile(String filePath, String charsetName, long lineNow, long lineEnd)
8. readFile(String input)
9. readFile(String location)