安卓如何在Java中从DataInputStream获取字符串？

Question

我正在开发一个由socket组成的应用程序。它需要将一个字符串值从客户端（安卓设备）传输到服务器（运行Ubuntu的PC）。 在服务器端代码中，我需要将通过socket传输的值存储在字符串变量中

下面是我用来将字符串值发送到服务器的代码

//instantiating the socket object for the client
Socket client = new Socket("192.168.0.103", port);

OutputStream outToServer = client.getOutputStream();

DataOutputStream out = new DataOutputStream(outToServer);

String msg = "My String Value";

//Message to be send to server
out.writeUTF(msg);

//Closing the client's socket. No connections after this.
client.close();  

下面是我用来在服务器上获取字符串值的代码

//Server object. Stores the reference to the socket object returned by the accept()
//The returned socket object contains established connection to the client.
Socket server = serverSocket.accept();

DataInputStream in = new DataInputStream(server.getInputStream());
System.out.println(in.readUTF());
//This prints "My String Message"

//Something like this i want to do.
String msg = in.readUTF();

//closing the server socket. No connection now.
server.close();

现在发生的事情是服务器端的程序被卡在了线路上：

String msg = in.readUTF();

将DataInputStream中的字符串值存储到字符串变量中的正确方法是什么

Answer 1

正如@david conrad所解释的，当您第一次读取时，输入缓冲区在下一次读取时变为空，因此解决方案仍然是首先将内容缓冲到字符串中，然后您可以将该字符串用于任何内容（例如println）

DataInputStream in = new DataInputStream(server.getInputStream());
String msg = in.readUTF();
System.out.println(msg);

Answer 2

您只写一次数据，而在另一端您尝试读取两次，但只有一个数据副本需要读取

DataInputStream in = new DataInputStream(server.getInputStream());
System.out.println(in.readUTF());
//This prints "My String Message"

这还将使用流中存在的字符串的唯一副本

Right now what is happening is the program at server side is getting stuck at line:

String msg = in.readUTF();

当您第二次调用in.readUTF()时，它会等待客户端发送更多数据（另一个字符串），但由于客户端从不发送更多数据，它将永远等待（或者直到您终止它，或者连接超时）