例如,你从服务器发送了100字节的事实并不意味着你在第一次读取时将在客户端中读取100字节。从服务器发送的字节可能在几个TCP段中到达客户端。
你需要实现一个循环,在该循环中你将阅读直到收到整个消息为止。让我提供一个示例,以DataInputStream
代替BufferedinputStream
。举一个简单的例子。
假设你事先知道服务器要发送100字节的数据。
在客户端中,你需要编写:
byte[] messageByte = new byte[1000];
boolean end = false;
String dataString = "";
try
{
DataInputStream in = new DataInputStream(clientSocket.getInputStream());
while(!end)
{
int bytesRead = in.read(messageByte);
dataString += new String(messageByte, 0, bytesRead);
if (dataString.length == 100)
{
end = true;
}
}
System.out.println("MESSAGE: " + dataString);
}
catch (Exception e)
{
e.printStackTrace();
}
现在,通常一个节点(这里的服务器)发送的数据大小通常是未知的。然后,你需要定义自己的小型协议,用于与TCP进行通信的服务器和客户端(或任何两个节点)之间的通信。
这只是可能协议的建议。你也可以摆脱“类型”。
因此,它将类似于:
byte[] messageByte = new byte[1000];
boolean end = false;
String dataString = "";
try
{
DataInputStream in = new DataInputStream(clientSocket.getInputStream());
int bytesRead = 0;
messageByte[0] = in.readByte();
messageByte[1] = in.readByte();
int bytesToRead = messageByte[1];
while(!end)
{
bytesRead = in.read(messageByte);
dataString += new String(messageByte, 0, bytesRead);
if (dataString.length == bytesToRead )
{
end = true;
}
}
System.out.println("MESSAGE: " + dataString);
}
catch (Exception e)
{
e.printStackTrace();
}
以下代码可以编译并看起来更好。假定提供长度的前两个字节以网络格式(大字节序)以二进制格式到达。对于邮件的其余部分,不关注不同的编码类型。
import java.nio.ByteBuffer;
import java.io.DataInputStream;
import java.net.ServerSocket;
import java.net.socket;
class Test
{
public static void main(String[] args)
{
byte[] messageByte = new byte[1000];
boolean end = false;
String dataString = "";
try
{
Socket clientSocket;
ServerSocket server;
server = new ServerSocket(30501, 100);
clientSocket = server.accept();
DataInputStream in = new DataInputStream(clientSocket.getInputStream());
int bytesRead = 0;
messageByte[0] = in.readByte();
messageByte[1] = in.readByte();
ByteBuffer byteBuffer = ByteBuffer.wrap(messageByte, 0, 2);
int bytesToRead = byteBuffer.getShort();
System.out.println("About to read " + bytesToRead + " octets");
//The following code shows in detail how to read from a TCP socket
while(!end)
{
bytesRead = in.read(messageByte);
dataString += new String(messageByte, 0, bytesRead);
if (dataString.length() == bytesToRead )
{
end = true;
}
}
//All the code in the loop can be replaced by these two lines
//in.readFully(messageByte, 0, bytesToRead);
//dataString = new String(messageByte, 0, bytesToRead);
System.out.println("MESSAGE: " + dataString);
}
catch (Exception e)
{
e.printStackTrace();
}
}
}