Java FileInputStream Read readFile(String fileName)

Description

Reads the named file, translating IOException to a RuntimeException of some sort.

License

Apache License

Parameter

Parameter	Description
fileName	non-null; name of the file to read

Return

non-null; contents of the file

Declaration

public static byte[] readFile(String fileName) 

Method Source Code

//package com.java2s;
/*/*from www.  ja v a 2s  . c  om*/
 * Copyright (C) 2007 The Android Open Source Project
 *
 * 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.File;
import java.io.FileInputStream;
import java.io.IOException;

public class Main {
    /**
     * Reads the named file, translating {@link IOException} to a
     * {@link RuntimeException} of some sort.
     * 
     * @param fileName non-null; name of the file to read
     * @return non-null; contents of the file
     */
    public static byte[] readFile(String fileName) {
        File file = new File(fileName);
        return readFile(file);
    }

    /**
     * Reads the given file, translating {@link IOException} to a
     * {@link RuntimeException} of some sort.
     * 
     * @param file non-null; the file to read
     * @return non-null; contents of the file
     */
    public static byte[] readFile(File file) {
        if (!file.exists()) {
            throw new RuntimeException(file + ": file not found");
        }

        if (!file.isFile()) {
            throw new RuntimeException(file + ": not a file");
        }

        if (!file.canRead()) {
            throw new RuntimeException(file + ": file not readable");
        }

        long longLength = file.length();
        int length = (int) longLength;
        if (length != longLength) {
            throw new RuntimeException(file + ": file too long");
        }

        byte[] result = new byte[length];

        try {
            FileInputStream in = new FileInputStream(file);
            int at = 0;
            while (length > 0) {
                int amt = in.read(result, at, length);
                if (amt == -1) {
                    throw new RuntimeException(file + ": unexpected EOF");
                }
                at += amt;
                length -= amt;
            }
            in.close();
        } catch (IOException ex) {
            throw new RuntimeException(file + ": trouble reading", ex);
        }

        return result;
    }
}

Related

1. readFile(String filename)
2. readFile(String fileName)
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