JAVA伊奥。Java |集合1中的ObjectInputStream类

ObjectInputStream类反序列化以前由 对象输出流 .

• ObjectOutputStream和ObjectInputStream都被用来存储对象的图形。
• 它确保它所处理的对象与JVM的类（即Java虚拟机）匹配。只有这些对象才能从支持 可序列化 或 部化的 –IO类，否则错误。 Serializable基本上是JVM（Java虚拟机）的一种标记，指示它写出流中存在的对象的状态

宣言：

public class ObjectInputStream
  extends InputStream
    implements ObjectInput, ObjectStreamConstants

施工人员：

• 受保护的ObjectInputStream（）： 如果子类正在重新实现ObjectInputStream，请帮助它们不要分配ObjectInputStream使用的私有数据。
• ObjectInputStream（InputStream源\输入）： 创建从“源输入”输入流读取数据的ObjectInputStream。

方法：

• read（）： JAVA伊奥。ObjectInputStream。读（） 在没有数据可读取的情况下读取数据字节和数据块。 语法：

  public int read()
  Parameters : 
  -----------
  Return : 
  reads byte else, return -1 if end of Stream is detected.
  Exception :
  -> IOException : in case of any IO error occurs.
  

• readBoolean（）： JAVA伊奥。ObjectInputStream。readBoolean（） 读入布尔值。 语法：

  public int readBoolean()
  Parameters : 
  -----------
  Return : 
  reads in a boolean.
  Exception :
  -> IOException : in case of any IO error occurs.
  -> EOFException : if end of the stream is reached.
  

  // Java program explaining the working of read(), readBoolean() method import java.io.*; public class NewClass { public static void main(String[] args) throws IOException { // create a new file with an ObjectOutputStream and ObjectInputStream FileOutputStream geek_out = new FileOutputStream( "GEEKS.txt" ); ObjectOutputStream geek_outStream = new ObjectOutputStream(geek_out); ObjectInputStream Geek_inStream = new ObjectInputStream( new FileInputStream( "GEEKS.txt" )); // Methods covered in later geek_outStream.writeBoolean( true ); geek_outStream.writeUTF( "Geeks For Geeks" ); geek_outStream.flush(); // Use of readBoolean() System.out.println( "USe of readBoolean() : " + Geek_inStream.readBoolean()); System.out.print( "Use of read() method in Java : " ); // Use of read() method : reading the content of file for ( int i = 0 ; i < Geek_inStream.available();) { System.out.print(( char ) Geek_inStream.read()); } } }

  输出：

  USe of readBoolean() : true
  Use of read() method in Java : Geeks For Geeks
  

• 读取（字节[]缓冲区，整数偏移量，整数最大值）： JAVA伊奥。ObjectInputStream。读取（字节[]缓冲区，整数偏移量，整数最大值） 从缓冲区的偏移位置到maxlen位置读取“缓冲区”中的部分数据。 语法：

  public int read(byte[] buffer, int offset, int maxlen)
  Parameters : 
  buffer : buffer to be read
  offset : starting position of the buffer
  maxlen : max. no. of bytes to be read
  Return : 
  reads 'maxlen' bytes of data else, return -1 if end of Stream is detected.
  Exception :
  -> IOException : in case of any IO error occurs.
  

  // Java program explaining the working of // read(byte[] buffer, int offset, int maxlen) import java.io.*; public class NewClass { public static void main(String[] args) throws IOException { // create a new file with an ObjectOutputStream and ObjectInputStream FileOutputStream geek_out = new FileOutputStream( "GEEKS.txt" ); ObjectOutputStream geek_outStream = new ObjectOutputStream(geek_out); // create an ObjectInputStream for the file we created before ObjectInputStream Geek_inStream = new ObjectInputStream( new FileInputStream( "GEEKS.txt" )); geek_outStream.writeUTF( "GeeksForGeeks" ); geek_outStream.flush(); byte [] buffer = new byte [ 25 ]; // Use of read(byte[] buffer, int offset, int maxlen) Geek_inStream.read(buffer, 2 , 20 ); System.out.print( "Use of read(buffer, offset, maxlen) : " ); for ( int i = 0 ; i < 19 ; i++) { System.out.print(( char )buffer[i]); } } }

  输出：

  GeeksForGeeks

• readByte（）： JAVA伊奥。ObjectInputStream。readByte（） 读取8位字节。 语法：

  public byte readByte()
  Parameters : 
  -----------
  Return : 
  reads 8-bit byte.
  Exception :
  -> IOException : in case of any IO error occurs.
  -> EOFException : if end of the stream is reached.
  

• readChar（）： JAVA伊奥。ObjectInputStream。readChar（） 读取16位字符。 语法：

  public int read()
  Parameters : 
  -----------
  Return : 
  reads 16-bit of char.
  Exception :
  -> IOException : in case of any IO error occurs.
  -> EOFException : if end of the stream is reached.
  

• readDouble（）： JAVA伊奥。ObjectInputStream。readDouble（） 读取64位双精度。 语法：

  public double readDouble()
  Parameters : 
  -----------
  Return : 
  reads 64 bit double.
  Exception :
  -> IOException : in case of any IO error occurs.
  -> EOFException : if end of the stream is reached.
  

• readFloat（）： JAVA伊奥。ObjectInputStream。readFloat（） 读取32位浮点。 语法：

  public float readFloat()
  Parameters : 
  -----------
  Return : 
  reads a 32 bit float.
  Exception :
  -> IOException : in case of any IO error occurs.
  -> EOFException : if end of the stream is reached.
  

• readInt（）： JAVA伊奥。ObjectInputStream。readInt（） 读取32位整数。 语法：

  public int readInt()
  Parameters : 
  -----------
  Return : 
  reads a 32 bit int.
  Exception :
  -> IOException : in case of any IO error occurs.
  -> EOFException : if end of the stream is reached.
  

• readLong（）： JAVA伊奥。ObjectInputStream。readLong（） 读取一个64位的长度。 语法：

  public long readLong()
  Parameters : 
  -----------
  Return : 
  reads a 64 bit long.
  Exception :
  -> IOException : in case of any IO error occurs.
  -> EOFException : if end of the stream is reached.
  

  // Java program explaining the working of // readChar(), writeByte(), writeDouble(), // writeFloat(), writeInt(), writeLong() import java.io.*; public class NewClass { public static void main(String[] args) throws IOException { // create a new file with an ObjectOutputStream and ObjectInputStream FileOutputStream geek_out = new FileOutputStream( "GEEKS.txt" ); ObjectOutputStream geek_outStream = new ObjectOutputStream(geek_out); // create an ObjectInputStream for the file we created before ObjectInputStream Geek_inStream = new ObjectInputStream( new FileInputStream( "GEEKS.txt" )); geek_outStream.writeChar( 'G' ); geek_outStream.writeByte( 'G' ); geek_outStream.writeDouble( 00436754746 ); geek_outStream.writeFloat( 2 .12345f); geek_outStream.writeInt( 3576 ); geek_outStream.writeLong( 368723776 ); geek_outStream.flush(); // Use of readChar() System.out.println( "Use of readChar() : " + Geek_inStream.readChar()); // Use of readByte() : System.out.println( "Use of readByte() : " + Geek_inStream.readByte()); // Use of readDouble() : System.out.println( "Use of readDouble() : " + Geek_inStream.readDouble()); // Use of readFloat() : System.out.println( "Use of readFloat() : " + Geek_inStream.readFloat()); // Use of readInt() : System.out.println( "Use of readInt() : " + Geek_inStream.readInt()); // Use of readLong() : System.out.println( "Use of readLong() : " + Geek_inStream.readLong()); } }

  输出：

  Use of readChar() : G
  Use of readByte() : 71
  Use of readDouble() : 7.5225574E7
  Use of readFloat() : 2.12345
  Use of readInt() : 3576
  Use of readLong() : 368723776

• readUnsignedByte（）： JAVA伊奥。ObjectInputStream。readUnsignedByte（） 读取一个无符号8位字节。 语法：

  public int readUnsignedByte()
  Parameters : 
  -----------
  Return : 
  reads an unsigned 8 bit byte.
  Exception :
  -> IOException : in case of any IO error occurs.
  -> EOFException : if end of the stream is reached.
  

• readUnsignedShort（）： JAVA伊奥。ObjectInputStream。readUnsignedShort（） 读取一个无符号的16位短字符。 语法：

  public int readUnsignedShort()
  Parameters : 
  -----------
  Return : 
  reads an unsigned 16 bit short.
  Exception :
  -> IOException : in case of any IO error occurs.
  -> EOFException : if end of the stream is reached.
  

  // Java program explaining the working of // readUnsignedByte() and readUnsignedShort() import java.io.*; public class NewClass { public static void main(String[] args) throws IOException { // create a new file with an ObjectOutputStream and ObjectInputStream FileOutputStream geek_out = new FileOutputStream( "GEEKS.txt" ); ObjectOutputStream geek_outStream = new ObjectOutputStream(geek_out); // create an ObjectInputStream for the file we created before ObjectInputStream Geek_inStream = new ObjectInputStream( new FileInputStream( "GEEKS.txt" )); geek_outStream.writeByte( 111 ); geek_outStream.writeShort( 121212 ); geek_outStream.flush(); // Use of readUnsignedByte() System.out.println( "readUnsignedByte() : " + Geek_inStream.readUnsignedByte()); // Use of readUnsignedShort() : System.out.println( "readUnsignedShort() : " + Geek_inStream.readUnsignedShort()); } }

  输出：

  readUnsignedByte() : 111
  readUnsignedShort() : 55676

• readUTF（）： JAVA伊奥。ObjectInputStream。readUTF（） 读取修改后的UTF-8（Unicode转换格式）格式的字符串。UTF-8表示它使用8位块来表示字符。 语法：

  public String readUTF()
  Parameters : 
  public final Object readObject()
  Return : 
  reads String in modified UTF-8 (Unicode Transformation Format) format
  Exception :
  -> IOException : in case of any IO error occurs.
  

  // Java program explaining the working of readUTF() import java.io.*; public clas // Java program explaining the working of readUTF() import java.io.*; public class NewClass { public static void main(String[] args) throws IOException, ClassNotFoundException { // create a new file with an ObjectOutputStream and ObjectInputStream FileOutputStream geek_out = new FileOutputStream( "GEEKS.txt" ); ObjectOutputStream geek_outStream = new ObjectOutputStream(geek_out); ObjectInputStream Geek_inStream = new ObjectInputStream( new FileInputStream( "GEEKS.txt" )); geek_outStream.writeUTF( "gEEKSArehERE" ); geek_outStream.flush(); // Use of readUTF() method System.out.println( "Use of readUTF() : " + Geek_inStream.readUTF()); } }

  输出：

  Use of readUTF() : gEEKSArehERE

• skipBytes（整数最大值）： JAVA伊奥。ObjectInputStream。skipBytes（整数最大值） 读取时跳过“maxlen”字节数。 语法：

  public int skipBytes(int maxlen)
  Parameters : 
  maxlen : max. no. of bytes to be skipped
  Return : 
  no. of bytes to be skipped
  Exception :
  -> IOException : in case of any IO error occurs.
  

  // Java program explaining the working of skipBytes() import java.io.*; public class NewClass { public static void main(String[] args) throws IOException, ClassNotFoundException { // create a new file with an ObjectOutputStream and ObjectInputStream FileOutputStream geek_out = new FileOutputStream( "GEEKS.txt" ); ObjectOutputStream geek_outStream = new ObjectOutputStream(geek_out); ObjectInputStream Geek_inStream = new ObjectInputStream( new FileInputStream( "GEEKS.txt" )); geek_outStream.writeUTF( "gEEKSArehERE" ); geek_outStream.flush(); // Use of skipBytes() : Geek_inStream.skipBytes( 7 ); for ( int i = 2 ; i < Geek_inStream.available(); i++) { System.out.print(( char ) Geek_inStream.readByte()); } } }

  输出：

  Are

• 准备就绪（字节[]目的地）： JAVA伊奥。ObjectInputStream。准备就绪（字节[]目的地） 读取从源阵列到目标阵列的所有字节。 语法：

  public void readFully(byte[] destination)
  Parameters : 
  destination : the buffer in which the data is to be read
  Return : 
  returns the 32 bit float read
  Exception :
  -> IOException : in case of any IO error occurs.
  -> EOFException : if End of stream is reached
  

  // Java program explaining the working of readFully() import java.io.*; public class NewClass { public static void main(String[] args) throws IOException, ClassNotFoundException { // create a new file with an ObjectOutputStream and ObjectInputStream FileOutputStream geek_out = new FileOutputStream( "GEEKS.txt" ); ObjectOutputStream geek_outStream = new ObjectOutputStream(geek_out); ObjectInputStream Geek_inStream = new ObjectInputStream( new FileInputStream( "GEEKS.txt" )); geek_outStream.writeUTF( "gEEKSArehERE" ); geek_outStream.flush(); byte [] destination = new byte [ 14 ]; // Use of readFully() Geek_inStream.readFully(destination); String str = new String(destination); System.out.println( "Use of readFully(destination, offset, maxlen) : " +str); } }

  输出：

  Use of readFully(destination, offset, maxlen) : gEEKSArehERE

• 准备就绪（字节[]目的地，整数偏移量，整数最大值）： JAVA伊奥。ObjectInputStream。准备就绪（字节[]目的地，整数偏移量，整数最大值） 从源阵列到目标阵列读取一些字节（从偏移量到maxlen位置）。 语法：

  public void readFully(byte[] destination, int offset, int maxlen)
  Parameters : 
  destination : the buffer in which the data is to be read
  offset : starting position of the buffer
  maxlen : max no. of bytes to be read
  Return : 
  void
  Exception :
  -> IOException : in case of any IO error occurs.
  -> EOFException : if End of stream is reached
  

  // Java program explaining the working of // readFully(byte[] destination, int offset, int maxlen) import java.io.*; public class NewClass { public static void main(String[] args) throws IOException, ClassNotFoundException { // create a new file with an ObjectOutputStream and ObjectInputStream FileOutputStream geek_out = new FileOutputStream( "GEEKS.txt" ); ObjectOutputStream geek_outStream = new ObjectOutputStream(geek_out); ObjectInputStream Geek_inStream = new ObjectInputStream( new FileInputStream( "GEEKS.txt" )); geek_outStream.writeUTF( "gEEKSArehERE" ); geek_outStream.flush(); byte [] destination = new byte [ 14 ]; // Use of readFully(byte[] destination, int offset, int maxlen) Geek_inStream.readFully(destination, 3 , 7 ); String str = new String(destination); System.out.println( "Use of readFully(destination, offset, maxlen) : " + str); } }

  输出：

  Use of readFully(destination, offset, maxlen) : geeks

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