java DataInputStream.read() 与 DataInputStream.readFully()
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DataInputStream.read() vs DataInputStream.readFully()
提问by Krimson
Im making a simple TCP/IP Socket app
我正在制作一个简单的 TCP/IP Socket 应用程序
Whats the different between doing this:
这样做有什么不同：
DataInputStream in = new DataInputStream(clientSocket.getInputStream());
byte[] buffer = new byte[100];
in.readFully(buffer);
versus doing this:
与这样做：
DataInputStream in = new DataInputStream(clientSocket.getInputStream());
byte[] buffer = new byte[100];
in.read(buffer);
I had a look at the documentation, they have the same exact description. readFully()and read()So can I assume its the same thing?
我查看了文档，它们具有相同的确切描述。readFully()并且read()因此我可以假设它是一回事吗？
回答by Lolo
The Javadoc for DataInput.readFully(byte[] b)states:
声明的 Javadoc DataInput.readFully(byte[] b)：
Reads some bytes from an input stream and stores them into the buffer array
b. The number of bytes read is equal to the length ofb.
从输入流中读取一些字节并将它们存储到缓冲区数组中
b。读取的字节数等于 的长度b。
The Javadoc for DataInputStream.read(byte[] b)states:
声明的 Javadoc DataInputStream.read(byte[] b)：
Reads some number of bytes from the contained input stream and stores them into the buffer array
b. The number of bytes actually read is returned as an integer. This method blocks until input data is available, end of file is detected, or an exception is thrown.
从包含的输入流中读取一定数量的字节并将它们存储到缓冲区数组中
b。实际读取的字节数作为整数返回。此方法会阻塞，直到输入数据可用、检测到文件结尾或抛出异常。
Basically, readFully()will read exactlyb.lengthbytes, whereas read()will read up tob.length, maybe less, whatever is available from the input stream.
基本上，readFully()将准确读取b.length字节，而read()将读取最多b.length或更少的输入流中可用的任何内容。
回答by Lluis Felisart
Using readyou need to check return value to know how many bytes have been really read
使用read您需要检查返回值以了解实际读取了多少字节
byte[] buffer = new byte[100];
if (in.read(buffer) < 100){
// fail
}
instead with readFullya IOException will be thrown if the 100 bytes could not be read, don't need to check return value, simplify a bit.
用readFully代替，如果 100 个字节无法读取，将抛出 IOException，不需要检查返回值，简化一点。
