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java.io.ObjectOutputStream.PutField.put(String name, byte val)方法实例

java.io.ObjectOutputStream.PutField.put(String name, byte val) 方法把指定的字节字段的值放到持久性字段。

声明

以下是java.io.ObjectOutputStream.PutField.put()方法的声明

public abstract void put(String name, byte val)

参数

  • name -- 可序列化字段的名称

  • val -- 分配给字段的值

返回值

此方法无返回值。

异常

  • IllegalArgumentException -- 如果name不匹配序列化字段正被写入,或者指定字段的类型不是字节的类的名称

例子

下面的示例演示java.io.ObjectOutputStream.PutField.put()方法的用法。

package com.yiibai;

import java.io.*;

public class ObjectOutputStreamDemo implements Serializable {

   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();
         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 byte var = 5;
      // assign a new serialPersistentFields 
      private static final ObjectStreamField[] serialPersistentFields = {
         new ObjectStreamField("var", Byte.TYPE)
      };

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

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

         // check if string is defaulted, meaning if it has no value
         byte b = 0;
         var = (byte) fields.get("var", b);
      }

      private void writeObject(ObjectOutputStream out)
              throws IOException {

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

      }
   }
}

让我们编译和运行上面的程序,这将产生以下结果:

5