Home | History | Annotate | Download | only in util 
      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.dexgen.util;
     18 
     19 import java.io.File;
     20 import java.io.FileInputStream;
     21 import java.io.IOException;
     22 
     23 /**
     24  * File I/O utilities.
     25  */
     26 public final class FileUtils {
     27     /**
     28      * This class is uninstantiable.
     29      */
     30     private FileUtils() {
     31         // This space intentionally left blank.
     32     }
     33 
     34     /**
     35      * Reads the named file, translating {@link IOException} to a
     36      * {@link RuntimeException} of some sort.
     37      *
     38      * @param fileName {@code non-null;} name of the file to read
     39      * @return {@code non-null;} contents of the file
     40      */
     41     public static byte[] readFile(String fileName) {
     42         File file = new File(fileName);
     43         return readFile(file);
     44     }
     45 
     46     /**
     47      * Reads the given file, translating {@link IOException} to a
     48      * {@link RuntimeException} of some sort.
     49      *
     50      * @param file {@code non-null;} the file to read
     51      * @return {@code non-null;} contents of the file
     52      */
     53     public static byte[] readFile(File file) {
     54         if (!file.exists()) {
     55             throw new RuntimeException(file + ": file not found");
     56         }
     57 
     58         if (!file.isFile()) {
     59             throw new RuntimeException(file + ": not a file");
     60         }
     61 
     62         if (!file.canRead()) {
     63             throw new RuntimeException(file + ": file not readable");
     64         }
     65 
     66         long longLength = file.length();
     67         int length = (int) longLength;
     68         if (length != longLength) {
     69             throw new RuntimeException(file + ": file too long");
     70         }
     71 
     72         byte[] result = new byte[length];
     73 
     74         try {
     75             // convert to try-with-resources once dexgen uses an Android API 19+ which supports it
     76             FileInputStream in = new FileInputStream(file);
     77             try {
     78                 int at = 0;
     79                 while (length > 0) {
     80                     int amt = in.read(result, at, length);
     81                     if (amt == -1) {
     82                         throw new RuntimeException(file + ": unexpected EOF");
     83                     }
     84                     at += amt;
     85                     length -= amt;
     86                 }
     87             } finally {
     88                 in.close();
     89             }
     90         } catch (IOException ex) {
     91             throw new RuntimeException(file + ": trouble reading", ex);
     92         }
     93 
     94         return result;
     95     }
     96 }
     97