Java Java.io.FilterReader用法及代碼示例

用於讀取過濾字符流的抽象類。抽象類FilterReader本身提供了將所有請求傳遞到所包含流的默認方法。 FilterReader 的子類應該重寫其中一些方法，並且還可以提供其他方法和字段。
構造函數：

• protected FilterReader(讀入)：創建一個新的過濾閱讀器。

方法：

• 無效close()：關閉流並釋放與其關聯的所有係統資源。關閉流後，進一步的 read()、ready()、mark()、reset() 或 skip() 調用將引發 IOException。關閉之前關閉的流沒有任何效果。

  Syntax :public void close()
             throws IOException
  Throws:
  IOException

• 無效標記(int readAheadLimit)：標記流中的當前位置。

  Syntax :public void mark(int readAheadLimit)
            throws IOException
  參數：
  readAheadLimit - Limit on the number of characters that may be read 
  while still preserving the mark. After reading this many characters,
   attempting to reset the stream may fail.
  Throws:
  IOException

• 布爾值markSupported()：告知此流是否支持mark()操作。

  Syntax :public boolean markSupported()
  返回：
  true if and only if this stream supports the mark operation.

• int read()：讀取單個字符。

  Syntax :public int read()
           throws IOException
  Returns:
  The character read, as an integer in the range 0 to 65535 (0x00-0xffff), 
  or -1 if the end of the stream has been reached
  Throws:
  IOException

• int 讀取(char[] cbuf，int 關閉，int len)：將字符讀入數組的一部分。

  Syntax :public int read(char[] cbuf,
         int off,
         int len)
           throws IOException
  參數：
  cbuf - Destination buffer
  off - Offset at which to start storing characters
  len - Maximum number of characters to read
  返回：
  The number of characters read, or -1 if the end of the stream has been reached
  Throws:
  IOException

• 布爾值ready()：告知該流是否已準備好讀取。

  Syntax :public boolean ready()
                throws IOException
  返回：
  True if the next read() is guaranteed not to block for input, 
  false otherwise. Note that returning false does not guarantee
  that the next read will block.
  Throws:
  IOException

• 無效reset()：重置流。

  Syntax :public void reset()
             throws IOException
  Throws:
  IOException

• 長跳過(長n)：跳過字符。

  Syntax :public long skip(long n)
            throws IOException
  參數：
  n - The number of characters to skip
  返回：
  The number of characters actually skipped
  Throws:
  IOException

程序：

//Java program illustrating FilterReader class methods 
  
import java.io.*; 
class FilterReaderdemo 
{ 
    public static void main(String[] args) throws IOException 
    { 
        Reader r = new StringReader("GeeksforGeeks"); 
        FilterReader fr = new FilterReader(r)  
        { 
        }; 
        char ch[] = new char[8]; 
          
        //illustrating markSupported() 
        if(fr.markSupported()) 
        { 
            //illustrating mark() method 
            System.out.println("mark method is supported"); 
            fr.mark(100); 
        } 
          
        //illustrating skip() method 
        fr.skip(5); 
          
        //illustrating ready() 
        if(fr.ready()) 
        { 
            //illustrating read(char[] cbuff,int off,int len) 
            fr.read(ch); 
            for (int i = 0; i < 8; i++)  
            { 
                System.out.print(ch[i]); 
            } 
              
            //illustrating reset() 
            fr.reset(); 
            for (int i = 0; i <5 ; i++) 
            { 
                //illustrating read() 
                System.out.print((char)fr.read()); 
            } 
        } 
          
        //closing the stream 
        fr.close(); 
    } 
} 

輸出：

mark method is supported
forGeeksGeeks