java - 以字节为单位的字符串无法转换为等效的字符串

Question

这个问题已经有答案了:

equals vs Arrays.equals in Java (9 个回答)

已关闭 5 年前。

public class MyClass{
static final String BROADCAST = "Broadcasting";
public static final int PORT = 12344;
public static String host = "localhost";
public static void main(String[] args) {
    // TODO Auto-generated method stub
    DatagramSocket serverSocket;
    try {
        serverSocket = new DatagramSocket(PORT);
        InetAddress addr = InetAddress.getByName(host);

        byte[] sendData = BROADCAST.getBytes();

        DatagramPacket sendPacket = new DatagramPacket(
                sendData, //data byte array
                sendData.length, //number of bytes
                addr, //destination host address
                PORT); //destination port
        serverSocket.send(sendPacket);
        byte[] rcvData = new byte[1024];

        DatagramPacket rcvPacket = new DatagramPacket(
                rcvData, rcvData.length);

        //packet gets filled in by receive
        serverSocket.receive(rcvPacket);

        //Why the two Strings are not the same?
        //Why the bytes derived from the same string different?
        byte[] a = rcvData;
        byte[] b= BROADCAST.getBytes();
        System.out.println(a.equals(b));
        System.out.println(new String(a));
        System.out.println(new String(b));
        System.out.println((new String(a).equals(new String(b))));


    } catch (SocketException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (UnknownHostException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}
}

我注意到

1)我使用getByte()方法得到的字节数组是不同的。

2) 尽管a和b的字符串(从代码来看)完全相同，但它们并不相等。

这是我从四个 print 语句得到的输出:

false

Broadcasting

Broadcasting

false

Answer 1

您的接收代码不正确，因为传入数据包的大小并不总是与您的接收缓冲区的大小相同。所以你在将数据转换为String时需要限制数据的长度，否则，你也会转换垃圾。

byte[] a = rcvData;
byte[] b = BROADCAST.getBytes();
String recStr = new String(rcvData, 0, rcvPacket.getLength());
System.out.println(recStr.equals(new String(b)));

那么您实际上是在准确比较发送和接收的数据包内容。