Java Java.io.ObjectOutputStream.writeFields() 方法

描述

java.io.ObjectOutputStream.writeFields()方法缓冲流中的字段。

声明

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

 public void writeFields()

参数

不适用

返回值

此方法不返回值。

异常

IOException如果在写入基础流时发生I / O错误。
NotActiveException在未调用类writeObject方法写入对象状态时调用。

例子

以下示例显示java.io.ObjectOutputStream.writeFields()方法的用法。

 
package com.jc2182;
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();
      }
   }
}

让我们编译并运行以上程序，这将产生以下结果-