InputStream.read(array)未返回array.length时到达流的末尾

Question

我有以下几行代码：

final int packetLength = 64 //just some constant
InputStream in = socket.getInputStream();
byte[] packet = new byte[packetLength];
int read = in.read(packet, 0, packetLength)
if(read != packetLength) {
    //End of stream=
}

我能确定如果read(byte[], int, int)没有返回与它应该读取的长度相同的值，那么流已经到达流的末尾吗？

因为下一个read()调用应该返回-1，不是吗？

Answer 1

不，你不能确定。InputStream在读取您请求的所有数据之前不会进行阻塞——在读取一些数据之前会进行阻塞。（InputStream的默认实现将读取，直到它能读取所有内容，但不能保证子类实现会这样做。）

您应该读取直到read调用返回-1，或者如果您只想读取packetLength字节：

byte[] packet = new byte[packetLength];
int offset = 0;
while (offset < packetLength) {
    int bytesRead = in.read(packet, offset, packetLength - offset);
    if (bytesRead == -1) { 
        // Incomplete packet - handle however you want to
    }
    offset += bytesRead;
}
// Hooray - read the complete packet.