ObjectInputStream


描述

该java.io.ObjectInputStream.readFields()方法从流中读取持久字段并使其可用的名字。

声明

以下是java.io.ObjectInputStream.readFields()方法的声明。

public ObjectInputStream.GetField readFields()

参数

NA

返回值

google.gr

此方法返回表示要反序列化的对象的持久字段的GetField对象。

异常

ClassNotFoundException - 如果找不到序列化对象的类。

IOException - 如果发生I / O错误。

NotActiveException - 如果流当前未读取对象。

实例

以下示例显示了java.io.ObjectInputStream.readFields()方法的用法。

package com.tutorialspoint;

import java.io.*;

public class ObjectInputStreamDemo {
   public static void main(String[] args) {
      try {
         // create a new file with an ObjectOutputStream
         FileOutputStream out = new FileOutputStream("test.txt");
         ObjectOutputStream oout = new ObjectOutputStream(out);

         // write something in the file
         oout.writeObject(new Example());
         oout.flush();

         // create an ObjectInputStream for the file we created before
         ObjectInputStream ois = new ObjectInputStream(new FileInputStream("test.txt"));

         // read the object and print the string
         Example a = (Example) ois.readObject();

         // print the string that is in Example class
         System.out.println("" + a.s);

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

   static class Example implements Serializable {
      String s = "Hello World!";

      private String readObject(ObjectInputStream in)
         throws IOException, ClassNotFoundException {

         // call readFields in readObject
         ObjectInputStream.GetField gf = in.readFields();

         // save the string and return it
         return (String) gf.get("s", null);
      }
   }
}

让我们编译并运行上面的程序,这将产生以下结果

Hello World!