Java Java.io.BufferedInputStream用法及代碼示例

BufferedInputStream 為另一個輸入 stream-namely 添加了函數，即緩衝輸入並支持標記和重置方法的能力。創建BufferedInputStream 時，會創建一個內部緩衝區數組。當讀取或跳過流中的字節時，內部緩衝區會根據需要從包含的輸入流中重新填充，一次填充多個字節。

構造函數和說明

• BufferedInputStream(輸入流中)：創建 BufferedInputStream 並保存其參數(輸入流)以供以後使用。
• BufferedInputStream(輸入流，int大小)：創建具有指定緩衝區大小的BufferedInputStream，並保存其參數(輸入流)以供以後使用。

方法：

• int available()：返回字節數的估計值
  可以從此輸入流中讀取(或跳過)，而無需
  下次調用該輸入流的方法時會阻塞。

  用法：public int available()
                throws IOException
  Returns:
  an estimate of the number of bytes that can be 
  read (or skipped over) from this input stream without blocking.
  Throws:
  IOException
  

• 無效close()：關閉此輸入流並釋放與該流關聯的所有係統資源。

  用法：public void close()
             throws IOException
  Overrides:
  close in class FilterInputStream
  Throws:
  IOException 
  

• 無效標記(int readlimit)：標記此輸入流中的當前位置。

  用法：public void mark(int readlimit)
  Overrides:
  mark in class FilterInputStream
  參數：
  readlimit - the maximum limit of bytes that can be read 
  before the mark position becomes invalid.
  

• 布爾值markSupported()：測試此輸入流是否支持標記和重置方法。

  用法：public boolean markSupported()
  Overrides:
  markSupported in class FilterInputStream
  Returns:
  a boolean indicating if this stream type supports the mark and reset methods.
  

• int read()：從輸入流讀取下一個數據字節。

  用法：public int read()
           throws IOException
  Returns:
  the next byte of data, or -1 if the end of the stream is reached.
  Throws:
  IOException 
  

• int 讀取(字節[] b，int 關閉，int len)：從給定的偏移量開始，將此 byte-input 流中的字節讀取到指定的字節數組中。

  用法：public int read(byte[] b,
         int off,
         int len)
           throws IOException
  參數：
  b - destination buffer.
  off - offset at which to start storing bytes.
  len - maximum number of bytes to read.
  返回：
  the number of bytes read, or -1 if the end of the stream has been reached.
  Throws:
  IOException 
  

• 無效reset()：將此流重新定位到上次在此輸入流上調用 mark 方法時的位置。

  用法：public void reset()
             throws IOException
  Overrides:
  reset in class FilterInputStream
  Throws:
  IOException
  

• 長跳過(長n)：跳過並丟棄此輸入流中的 n 個字節的數據

  用法：public long skip(long n)
            throws IOException
  Parameters:
  n - the number of bytes to be skipped.
  返回：
  the actual number of bytes skipped.
  Throws:
  IOException

程序：

// Java program to demonstrate working of BufferedInputStream 
import java.io.BufferedInputStream; 
import java.io.FileInputStream; 
import java.io.IOException; 
  
// Java program to demonstrate BufferedInputStream methods 
class BufferedInputStreamDemo 
{ 
    public static void main(String args[]) throws IOException 
    { 
        // attach the file to FileInputStream 
        FileInputStream fin = new FileInputStream("file1.txt"); 
  
        BufferedInputStream bin = new BufferedInputStream(fin); 
  
        // illustrating available method 
        System.out.println("Number of remaining bytes:" + 
                                            bin.available()); 
  
        // illustrating markSupported() and mark() method 
        boolean b=bin.markSupported(); 
        if (b) 
            bin.mark(bin.available()); 
  
        // illustrating skip method 
        /*Original File content: 
        * This is my first line 
        * This is my second line*/
        bin.skip(4); 
        System.out.println("FileContents :"); 
  
        // read characters from FileInputStream and 
        // write them 
        int ch; 
        while ((ch=bin.read()) != -1) 
            System.out.print((char)ch); 
  
        // illustrating reset() method 
        bin.reset(); 
        while ((ch=bin.read()) != -1) 
            System.out.print((char)ch); 
  
        // close the file 
        fin.close(); 
    } 
} 

輸出：

Number of remaining bytes:47
FileContents :
 is my first line
This is my second line
This is my first line
This is my second line

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