在Java中将文件读入byte []数组的优雅方式 [英] Elegant way to read file into byte[] array in Java

问题描述

可能重复：

Java中的文件到字节[]

我想从文件读取数据并将其解组成宗地。
在文档中不清楚，该FileInputStream有方法来读取其所有的内容。为了实现这个，我做了以下工作：

I want to read data from file and unmarshal it to Parcel. In documentation it is not clear, that FileInputStream has method to read all its content. To implement this, I do folowing:

FileInputStream filein = context.openFileInput(FILENAME);


int read = 0;
int offset = 0;
int chunk_size = 1024;
int total_size = 0;

ArrayList<byte[]> chunks = new ArrayList<byte[]>();
chunks.add(new byte[chunk_size]);
//first I read data from file chunk by chunk
while ( (read = filein.read(chunks.get(chunks.size()-1), offset, buffer_size)) != -1) {
    total_size+=read;
    if (read == buffer_size) {
         chunks.add(new byte[buffer_size]);
    }
}
int index = 0;

// then I create big buffer        
byte[] rawdata = new byte[total_size];

// then I copy data from every chunk in this buffer
for (byte [] chunk: chunks) {
    for (byte bt : chunk) {
         index += 0;
         rawdata[index] = bt;
         if (index >= total_size) break;
    }
    if (index>= total_size) break;
}

// and clear chunks array
chunks.clear();

// finally I can unmarshall this data to Parcel
Parcel parcel = Parcel.obtain();
parcel.unmarshall(rawdata,0,rawdata.length);

我认为这段代码看起来很丑陋，我的问题是：
如何读取数据从文件到字节[]精美？ ：

I think this code looks ugly, and my question is: How to do read data from file into byte[] beautifully? :)

推荐答案

很久以前：

这些

A long time ago:

Call any of these

byte[] org.apache.commons.io.FileUtils.readFileToByteArray(File file)
byte[] org.apache.commons.io.IOUtils.toByteArray(InputStream input) 

从

http://commons.apache.org/io/

如果图书馆的足迹对于您的Android应用来说太大，您只需使用commons-io库中的相关课程

If the library footprint is too big for your Android app, you can just use relevant classes from the commons-io library

幸运的是，我们现在在nio包中有几个方便的方法。例如：

Luckily, we now have a couple of convenience methods in the nio packages. For instance:

byte[] java.nio.file.Files.readAllBytes(Path path)

Javadoc here

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