Java Java.io.ObjectOutputStream.writeFields()用法及代码示例

描述

这个java.io.ObjectOutputStream.writeFields()方法将缓冲的字段传递给流。

声明

以下是声明java.io.ObjectOutputStream.writeFields()方法。

public void writeFields()

参数

NA

返回值

此方法不返回值。

异常

• IOException− 如果在写入底层流时发生 I/O 错误。

• NotActiveException− 当未调用类 writeObject 方法来写入对象的状态时调用。

示例

下面的例子展示了使用java.io.ObjectOutputStream.writeFields()方法。

package com.tutorialspoint;

import java.io.*;

public class ObjectOutputStreamDemo {
   public static void main(String[] args) {
      double d = 1.59875d;
      
      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();
         oout.close();

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

         // read an object from the stream and cast it to Example
         Example a = (Example) ois.readObject();

         // print var of a
         System.out.println("" + a.var);
      } catch (Exception ex) {
         ex.printStackTrace();
      }
   }

   static public class Example implements Serializable {
      static int var = 76458;
      
      // assign a new serialPersistentFields 
      private static final ObjectStreamField[] serialPersistentFields = {
         new ObjectStreamField("var", Integer.TYPE)
      };

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

         // get the field and assign it at var
         ObjectInputStream.GetField fields = in.readFields();

         // get var
         var = fields.get("var", 0);
      }

      private void writeObject(ObjectOutputStream out) throws IOException {

         // write into the ObjectStreamField array the variable string
         ObjectOutputStream.PutField fields = out.putFields();
         fields.put("var", var);
         out.writeFields();
      }
   }
}

让我们编译并运行上面的程序，这将产生以下结果 -

76458