无法创建ObjectInputStream

Question

为什么不能创建ObjectInputStream对象？每次我尝试创建一个时，我都会得到EOFException，但我不知道为什么。有人能帮我吗？下面是我遇到问题的代码和从执行中获得的堆栈跟踪。文件为空。

public void loadFromFileStudent() throws IOException, ClassNotFoundException {
    try{
        InputStream inputStream = new FileInputStream("student.txt");
        System.out.println(inputStream.toString());
        ObjectInputStream objectInputStream;
        objectInputStream = new ObjectInputStream(inputStream);
        System.out.println(objectInputStream.toString());
        this.repo=(Dictionary<Integer, Student>)   objectInputStream.readObject();

        objectInputStream.close();
        inputStream.close();
    }catch (EOFException e){
        e.printStackTrace();;
        //System.out.println(e.getMessage());
    }
}

。

java.io.FileInputStream@65ddcac5
java.io.EOFException
    at java.io.ObjectInputStream$PeekInputStream.readFully(ObjectInputStream.java:2324)
    at java.io.ObjectInputStream$BlockDataInputStream.readShort(ObjectInputStream.java:2793)
    at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:799)
    at java.io.ObjectInputStream.<init>(ObjectInputStream.java:299)
    at repository.Repository.loadFromFileStudent(Repository.java:94)
    at repository.Repository.<init>(Repository.java:112)
    at utils.DataStructure.createRepository(DataStructure.java:16)
    at controller.Controller.<init>(Controller.java:9)
    at utils.DataStructure.createController(DataStructure.java:20)
    at application.RunMenu.<init>(RunMenu.java:15)
    at application.App.main(App.java:5)

Answer 1

当到达文件末尾时抛出EOFException。也就是说，您已经阅读了整个文件。因此，不应该在try语句中关闭流，而应该使用try-with-resources自动关闭它们。

试试像这样简单的东西：

public void loadFromFileStudent() throws IOException, ClassNotFoundException {
    try (InputStream inputStream = new FileInputStream("student.txt");
        ObjectInputStream objectInputStream = new ObjectInputStream(inputStream)) {
        this.repo = (Dictionary<Integer, Student>) objectInputStream.readObject();
    } catch (FileNotFoundException e) {
        System.out.println ("File not found");
    } catch (IOException e) {
        System.out.println ("Error while reading");
    } catch (ClassNotFoundException e) {
        System.out.println ("No class");
    } catch (ClassCastException e) {
        System.out.println ("Could not cast to class");
    }
}

编写也同样简单：

public void writeObject ( Object o ) {
    try (FileOutputStream fos = new FileOutputStream ( this.filename );
        ObjectOutputStream oos = new ObjectOutputStream(fos)) {
        oos.writeObject(o);
        oos.flush();
    } catch (NotSerializableException e) {
        System.out.println ("Object wont be serialized");
        e.printStackTrace();
    } catch (IOException e) {
        System.out.println ("Error while writing to file");
        e.printStackTrace();
    }
}

Answer 2

根据我对这个问题的理解，我假设OP正在做一些类似下面的事情，这应该是可行的。可能是OP在写入/读取过程中遗漏了一些东西。希望这能帮你弄清楚。

public class Test2 {
    public static void main(String[] args) {
        Test2 t = new Test2();
        t.create();
        t.read();
    }

    public void create(){
        try{
            ObjectOutputStream os = new ObjectOutputStream(new FileOutputStream("D:\\test\\ab.txt"));
            Student st = new Student("chevs");
            Dictionary<Integer, Student> dict = new Hashtable<Integer, Student>();
            dict.put(1, st);
            os.writeObject(dict);
        }catch(Exception e){
            e.printStackTrace();
        }
    }
    public void read()
    {
        try{
            InputStream inputStream = new FileInputStream("D:\\test\\a.txt");
            System.out.println(inputStream.toString());
            ObjectInputStream objectInputStream;
            objectInputStream = new ObjectInputStream(inputStream);
            System.out.println(objectInputStream.toString());
            private Dictionary<Integer, Student> repo=(Dictionary<Integer, Student>)   objectInputStream.readObject();
            System.out.println(repo.get(1));
            objectInputStream.close();
            inputStream.close();

        }catch (Exception e){
            e.printStackTrace();;
        }
    }

    public class Student  implements Serializable{
        public String name=null;
            public Student(String name){
               this.name=name;
            }
        public String toString() {
            return name.toString();
        }
    }

}