声明后InputStream对象关闭

Question

该代码在XStream的帮助下读写对象。

在从中的XML文件读取对象的块in ，在声明后关闭InputStream对象。 这导致异常java.io.IOException: Stream Closed

ObjectInputStream objectIn = stream.createObjectInputStream(in)

编译时。

import java.io.*;
import java.util.*;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.xml.DomDriver;

public class PlayersXStreamIO
{
    public static void main(String... args) throws IOException, ClassNotFoundException
    {
        XStream stream = new XStream(new DomDriver());
        stream.setMode(XStream.ID_REFERENCES);

        if(args.length == 1)
        {
            try(OutputStream out = new FileOutputStream(args[0]);
                    ObjectOutputStream objectOut = stream.createObjectOutputStream(out))
            {
                Player max = new Player("max");
                max.setScore(5);
                Player moritz = new Player("moritz");
                moritz.setScore(3);
                objectOut.writeObject(max);
                objectOut.writeObject(moritz);
            }
        }
        else
        {
            try(InputStream in = new FileInputStream(args[0]);
                    ObjectInputStream objectIn = stream.createObjectInputStream(in))
            { // in.closed = true;
                List<Player> players = new ArrayList<>();
                while(in.available() > 0)
                {
                    players.add((Player) objectIn.readObject());
                }
                System.out.println(Arrays.toString(players.toArray()));
            }
        }
    }
}

堆栈跟踪为：

 Exception in thread "main" java.io.IOException: Stream Closed at java.io.FileInputStream.available(Native Method) at capitel02.PlayersXStreamIO.main(PlayersXStreamIO.java:39) 

Answer 1

我猜想在包装FileInputStream来创建ObjectInputStream ，实现已经解析了完整的文件并关闭了它。 因此，您将收到一个流结束异常。 解决方案是不访问文件输入流本身，而仅访问由objectIn变量引用的创建的ObjectInputStream 。

Answer 2

正如Arie所提出的，该问题是由于

while（in.available（）> 0）

应该使用readObject（）：

try{  

   List<Player> players = new ArrayList<>();
   while(trye){  
   {
         players.add((Player) objectIn.readObject());
   }  
} catch (EOFException e){};