Java.io.RandomAccessFile 类方法 |设置 2

第 1 组，第 3 组
Java.io.RandomAccessFile 类方法的方法：

readLine() : Java.io.RandomAccessFile.readLine()从此文件中读取下一行文本，从文件指针开始读取直到文件末尾。
```
Syntax : 
public final String readLine()
Parameters : 
-----
Return : 
reads the next line of text from this file
```
readUnsignedByte() : Java.io.RandomAccessFile.readUnsignedByte()从文件中读取一个无符号的 8 位数字，从当前文件指针开始读取。
```
Syntax : 
public final int readUnsignedByte()
Parameters : 
------
Return : 
reads an unsigned 8 bit number from file
```
readUnsignedShort() : Java.io.RandomAccessFile.readUnsignedShort()从文件中读取一个无符号的 16 位数字，从当前文件指针开始读取。
```
Syntax : 
public final int readUnsignedShort()
Parameters : 
-------
Return : 
reads an unsigned 16 bit number from file
```

readUTF( ) : Java.io.RandomAccessFile.readUTF()从文件中读取字符串

Syntax : 
public final String readUTF()
Parameters : 
-------
Return : 
Unicode String

seek(long pos) : Java.io.RandomAccessFile.seek(long pos)设置文件指针位置。

Syntax : 
public void seek(long pos)
Parameters : 
pos : start position from file, measured in bytes
Return : 
--------

setLength(long len) : Java.io.RandomAccessFile.setLength(long len)文件的长度。

Syntax : 
public void setLength(long len)
Parameters : 
len : desired length of the file
Return : 
-------

skipBytes(int n) : Java.io.RandomAccessFile.skipBytes(int n)跳过 n 个字节，丢弃跳过的字节

Syntax : 
public int skipBytes(int n)
Parameters : 
n : no. of bytes to be skipped
Return : 
no. of bytes skipped

getChannel() : Java.io.RandomAccessFile.getChannel()返回与文件关联的唯一 FileChannel 对象。

Syntax : 
public final FileChannel getChannel()
Parameters : 
------
Return : 
returns unique FileChannel object

Java.io.RandomAccessFile.length() ：返回文件的长度。

Syntax : 
public long length()
Parameters : 
----
Return : 
length of the file, measured in bytes

getFilePointer() : Java.io.RandomAccessFile.getFilePointer()返回文件中的当前偏移量（以字节为单位）。
```
Syntax : 
public long getFilePointer()
Parameters : 
----
Return : 
return current offset in the file in bytes
```

getFD() : Java.io.RandomAccessFile.getFD()返回文件描述符对象和流。

Syntax : 
public final FileDescriptor getFD()
Parameters : 
-----------
Return : 
file descriptor object with the stream.

close() : Java.io.RandomAccessFile.close()关闭随机访问文件流并释放与流关联的源（如果有）。

Syntax : 
public void close()
Parameters : 
-------
Return : 
-------

// Java Program illustrating use of io.RandomAccessFile class methods
// seek(), readLine(), readUTF(), readUnsignedByte(), readUnsignedShort(),
// setLength(), length(), skipBytes(), getFilePointer(), getChannel(),
// getFD(), close()
  
import java.io.*;
public class NewClass
{
    public static void main(String[] args)
    {
        try
        {
            // Creating a new RandomAccessFile - "GEEK"
            RandomAccessFile geek = new RandomAccessFile("FILE.txt", "rw");
  
            // Writing to file
            geek.writeUTF("Hello Geeks For Geeks");
  
            geek.seek(0);
  
            // Use of readUTF() :
            System.out.println("Use of readUTF() : " + geek.readUTF());
  
            //Use of seek() :
            geek.seek(0);
  
            // Use of readLine() :
            System.out.println("1 readLine() : " + geek.readLine());
            geek.seek(0);
  
            geek.writeUTF("Hello \nGeeks For Geeks");
            geek.seek(0);
  
            System.out.println("2 readLine() : " + geek.readLine());
  
            geek.seek(3);
            // Use of readUnsignedByte() :
          System.out.println("Use of readUnsignedByte() :  " + geek.readUnsignedByte());
  
            geek.seek(4);
            // Use of readUnsignedShort() :
          System.out.println("Use of readUnsignedByte() :  " + geek.readUnsignedShort());
  
            // Use of setLength():
            geek.setLength(78);
  
            // Use of length() :
            System.out.println("Use of setLength() : " + geek.length());
  
            geek.seek(2);
            // Use of skipBytes() :
            System.out.println("Use of skipBytes() : " + geek.skipBytes(3));
  
  
            // Use of getFilePointer() :
            System.out.println("Use of getFilePointer() : " + geek.getFilePointer());
  
            // Use of getChannel() :
            System.out.println("Use of getChannel() : " + geek.getChannel());
  
            // Use of getFD() :
            System.out.println("Use of getFD() : " + geek.getFD());
  
            // Use of close() method :
            geek.close();
            System.out.println("Stream Closed.");
  
        }
        catch (IOException ex)
        {
            System.out.println("Something went Wrong");
            ex.printStackTrace();
        }
    }
}

输出：

Use of readUTF() : Hello Geeks For Geeks
1 readLine() : Hello Geeks For Geekss
2 readLine() : Hello
Use of readUnsignedByte() :  101
Use of readUnsignedByte() :  27756
Use of setLength() : 78
Use of skipBytes() : 3
Use of getFilePointer() : 5
Use of getChannel() : sun.nio.ch.FileChannelImpl@15db9742
Use of getFD() : java.io.FileDescriptor@6d06d69c
Stream Closed.