Java InputStreamReader Read readFile(String fileName)

Description

Reads contents of file fully and returns as string.

License

Apache License

Parameter

Parameter	Description
fileName	file name.

Return

contents of entire file.

Declaration

public static String readFile(String fileName) 

Method Source Code

//package com.java2s;
/*//from  w  ww. ja  v  a2s .c om
Copyright 2009-2014 Igor Polevoy
    
Licensed under the Apache License, Version 2.0 (the "License"); 
you may not use this file except in compliance with the License. 
You may obtain a copy of the License at 
    
http://www.apache.org/licenses/LICENSE-2.0 
    
Unless required by applicable law or agreed to in writing, software 
distributed under the License is distributed on an "AS IS" BASIS, 
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
See the License for the specific language governing permissions and 
limitations under the License. 
*/

import java.io.*;

public class Main {
    /**
     * Reads contents of file fully and returns as string.
     *
     * @param fileName file name.
     * @return contents of entire file.
     */
    public static String readFile(String fileName) {
        FileInputStream in = null;
        try {
            in = new FileInputStream(fileName);
            return read(in);
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            close(in);
        }
    }

    /**
     * Reads contents of file fully and returns as string.
     *
     * @param fileName file name.
     * @return contents of entire file.
     */
    public static String readFile(String fileName, String charset) {
        FileInputStream in = null;
        try {
            in = new FileInputStream(fileName);
            return read(in, charset);
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            close(in);
        }
    }

    /**
     * Reads contents of the input stream fully and returns it as String. Sets UTF-8 encoding internally.
     *
     * @param in InputStream to read from.
     * @return contents of the input stream fully as String.
     * @throws IOException in case of IO error
     */
    public static String read(InputStream in) throws IOException {
        return read(in, "UTF-8");
    }

    /**
     * Reads contents of the input stream fully and returns it as String.
     *
     * @param in InputStream to read from.
     * @param charset name of supported charset to use
     * @return contents of the input stream fully as String.
     * @throws IOException in case of IO error
     */
    public static String read(InputStream in, String charset) throws IOException {
        if (in == null)
            throw new IllegalArgumentException("input stream cannot be null");

        InputStreamReader reader = new InputStreamReader(in, charset);
        char[] buffer = new char[1024];
        StringBuilder sb = new StringBuilder();

        for (int x = reader.read(buffer); x != -1; x = reader.read(buffer)) {
            sb.append(buffer, 0, x);
        }
        return sb.toString();
    }

    /**
     * Reads file into a byte array.
     *
     * @param file file to read.
     * @return content of file.
     * @throws java.io.IOException
     */
    public static byte[] read(File file) throws IOException {
        FileInputStream is = new FileInputStream(file);
        try {
            return bytes(is);
        } finally {
            close(is);
        }
    }

    public static void close(Closeable c) {
        try {
            if (c != null)
                c.close();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * Reads contents of the input stream fully and returns it as byte array.
     *
     * @param in InputStream to read from.
     * @return contents of the input stream fully as byte array
     * @throws IOException in case of IO error
     */
    public static byte[] bytes(InputStream in) throws IOException {
        if (in == null)
            throw new IllegalArgumentException("input stream cannot be null");

        ByteArrayOutputStream bout = new ByteArrayOutputStream(1024);
        byte[] bytes = new byte[1024];

        for (int x = in.read(bytes); x != -1; x = in.read(bytes))
            bout.write(bytes, 0, x);

        return bout.toByteArray();
    }
}

Related

1. readFile(String file)
2. readFile(String file)
3. readFile(String file, String charset)
4. readFile(String file, String lineBreak)
5. readFile(String fileFullPath)
6. readFile(String filename)
7. readFile(String fileName)
8. readFile(String filename)
9. readFile(String filename)