Java Java.io.FilterInputStream用法及代碼示例

過濾流在讀取和寫入輸入流中的數據時過濾數據，過濾數據並將其傳遞到底層流。過濾流是

FilterInputStream
Java.io.FilterOutputStream

FilterInputStream：Java.io.FilterInputStream 類的工作方式與 Java 中的 InputStream 類幾乎類似，但它所做的隻是重寫 InputStream 類方法，將請求傳遞給 InputStream。 FilterInputStream 類的 read() 方法過濾數據並讀取數據，並將數據傳遞到底層流過濾，該過濾是根據流完成的。

聲明：

public class FilterInputStream
   extends InputStream

構造函數：

受保護的FilterInputStream(InputStream中)：通過將參數分配給字段this.in來創建FilterInputStream，以便記住它以供以後使用。

方法：

讀取(字節[]緩衝區)：java.io.FilterInputStream.read(byte[] 緩衝區)將 buffer.length 的字節數從過濾器輸入流讀取到緩衝區數組。
Syntax :

public int read(byte[] buffer)
Parameters :
buffer : buffer to be read
Return : 
reads number of bytes of buffer.length to the buffer 
else, -1 i.e. when end of file is reached.
Exception :
->  IOException : If I/O error occurs.

執行：


// Java program illustrating the working of read(byte[] buffer) method 
  
import java.io.*; 
  
public class NewClass 
{ 
    public static void main(String[] args) throws IOException 
    { 
        // LineNumberInputStream & FileInputStream initailly null 
        FilterInputStream geek_input = null; 
        InputStream geek = null; 
  
        try{ 
            char c; 
            int a; 
            byte[] buffer = new byte[6]; 
  
            // New InputStream : 'GEEKS' is created 
            geek = new FileInputStream("GEEKS.txt"); 
            geek_input = new BufferedInputStream(geek); 
  
            a = geek.read(buffer); 
            // read() method returning Bytes of Input Stream as integer 
            // '-1' indicating to read till end Of Input Stream 
            int length = 1 ; 
              
            for(byte g : buffer) 
            { 
                // Since read() method returns Integer value 
                // So, we convert each integer value to char 
                c = (char)g; 
  
                System.out.println("At position " + length  +  " : "  + c); 
                length++; 
            } 
        } 
        catch(Exception e) 
        { 
            // In case of error 
            e.printStackTrace(); 
            System.out.println("ERROR Occurs "); 
        } 
        finally
        { 
            // Closing the streams, Once the End of Input Stream is reached 
            if(geek != null) 
                geek.close(); 
  
            if(geek_input != null) 
                geek_input.close(); 
        } 
    } 
}

注意：
以下 Java 代碼不會在這裏運行，因為我們無法訪問在線 IDE 上的任何文件。
因此，將該程序複製到您的係統並在那裏運行。

程序中使用的GEEKS.txt文件包含：

HelloGeeks

在給定的代碼中 buffer.length = 6 ，因此隻有 HelloG 會通過 read(byte[] buffer) 方法讀取
輸出：

At position 1 : H
At position 2 : e
At position 3 : l
At position 4 : l
At position 5 : o
At position 6 : G

讀取(字節[]緩衝區，int偏移量，int maxlen)：java.io.FilterInputStream.read(byte[] 緩衝區, int 偏移量, int maxlen)將 FilterInputStream 中最多 maxlen 的數據讀取到緩衝區中。
Syntax :

public int read(byte[] buffer, int offset, int maxlen)
Parameters :
buffer : Destination buffer
offset : start position to read
maxlen : max. length of bytes to be read
Return : 
total no. of bytes to be written else, -1 i.e. when end of Stream is reached.
Exception :
->  IOException : If I/O error occurs.

執行：


// Java program illustrating the working of 
// read(byte[] buffer, int offset, int maxlen) method 
  
import java.io.*; 
  
public class NewClass 
{ 
    public static void main(String[] args) throws IOException 
    { 
        // LineNumberInputStream & FileInputStream initailly null 
        FilterInputStream geek_input = null; 
        InputStream geek = null; 
  
        try{ 
            char c; 
            int a; 
            byte[] buffer = new byte[4]; 
  
            // New InputStream : 'ABC' is created 
            geek = new FileInputStream("ABC.txt"); 
            geek_input = new BufferedInputStream(geek); 
  
            // Offset = 1(*), Maxlen = 3 (MOH) 
            a = geek.read(buffer, 1, 3); 
            // read() method returning Bytes of Input Stream as integer 
            // '-1' indicating to read till end Of Input Stream 
             
            for(byte g : buffer) 
            { 
                // Since read() method returns Integer value 
                // So, we convert each integer value to char 
                c = (char)g; 
  
                if(g == 0) 
                    c = '*'; 
  
                System.out.print(c); 
            } 
        } 
        catch(Exception e) 
        { 
            // In case of error 
            e.printStackTrace(); 
            System.out.println("ERROR Occurs "); 
        } 
        finally
        { 
            // Closing the streams, Once the End of Input Stream is reached 
            if(geek != null) 
                geek.close(); 
  
            if(geek_input != null) 
                geek_input.close(); 
        } 
    } 
}

注意：
以下 Java 代碼不會在這裏運行，因為我們無法訪問在線 IDE 上的任何文件。
因此，將該程序複製到您的係統並在那裏運行。

程序中使用的ABC.txt文件包含：

MOHIT

偏移 = 1 即 * 且 Maxlen = 3 即 MOH
輸出：

*MOH

available():java.io.FilterInputStream.available()返回編號。可以從輸入流讀取的字節數。
Syntax :

public int available()
Parameters : 
-------
Return : 
returns the no. of bytes that can be read from the FilterInputStream.
Exception: 
IOException : in case I/O error occurs

執行：


// Java program illustrating the working of available() method 
  
import java.io.*; 
public class NewClass 
{ 
    public static void main(String[] args) throws IOException 
    { 
        // FilterInputStream & FileInputStream initailly null 
        FilterInputStream geek_input = null; 
  
        InputStream geek = null; 
  
        try{ 
            char c; 
            int a, b; 
  
            // New InputStream : 'ABC' is created 
            geek = new FileInputStream("ABC.txt"); 
            geek_input = new BufferedInputStream(geek); 
  
            while((a = geek_input.read()) != -1) 
            { 
                // So, we convert each integer value to char 
                c = (char)a; 
  
                // Use of available method : return no. of bytes that can be read 
                a = geek_input.available(); 
                System.out.println(c + " Bytes available : " + a); 
  
            } 
        } 
        catch(Exception e) 
        { 
            // In case of error 
            e.printStackTrace(); 
            System.out.println("ERROR Occurs "); 
        } 
        finally
        { 
            // Closing the streams, Once the End of FilterInputStream is reached 
            if(geek != null) 
                geek.close(); 
  
            if(geek_input != null) 
                geek_input.close(); 
        } 
    } 
}

注意：
以下 Java 代碼不會在這裏運行，因為我們無法訪問在線 IDE 上的任何文件。
因此，將該程序複製到您的係統並在那裏運行。

程序中使用的ABC.txt文件包含：

MOHIT

輸出：

M Bytes available : 4
O Bytes available : 3
H Bytes available : 2
I Bytes available : 1
T Bytes available : 0

read():java.io.FilterInputStream.read()從過濾器輸入流讀取下一個數據字節。返回的字節值範圍為 0 到 255。如果由於已到達流末尾而沒有可用字節，則返回值 -1。
Syntax :
```
public int read()
Parameters :
------
Return : 
Reads next data else, -1 i.e. when end of Stream is reached.
Exception :
->  IOException : If I/O error occurs.
```
close():java.io.FilterInputStream.close()關閉過濾器輸入流並將與該流關聯的係統資源釋放到垃圾Collector。
Syntax :
```
public void close()
Parameters :
------
Return : 
void
Exception :
->  IOException : If I/O error occurs.
```
標記(int arg)：java.io.FilterInputStream.mark(int arg)標記 FilterInputStream 的當前位置。它設置讀取限製，即標記位置無效之前可以讀取的最大字節數。
Syntax :
```
public void mark(int arg)
Parameters :
arg : integer specifying the read limit of the input Stream
Return : 
void
```

skip():java.io.FilterInputStream.skip(長參數)跳過並丟棄FilterInputStream 數據中的‘arg’ 字節。
Syntax :

public long skip(long arg)
Parameters : 
arg : no. of bytes of FilterInputStream data to skip.
Return : 
no. of bytes to be skipped
Exception: 
IOException : in case I/O error occurs

reset():java.io.FilterInputStream.reset()由mark()方法調用。它將 FilterInputStream 重新定位到標記位置。
Syntax :
```
public void reset()
Parameters :
----
Return : 
void
Exception :
->  IOException : If I/O error occurs.
```
markSupported():java.io.FilterInputStream.markSupported()方法測試此輸入流是否支持標記和重置方法。 InputStream 的 markSupported 方法默認返回 false。
Syntax :
```
public boolean markSupported()
Parameters :
-------
Return : 
true if input stream supports the mark() and reset() method  else,false
```

Java程序講解：markSupported()、close()、reset()、mark()、read()、skip()方法


// Java program illustrating the working of FilterInputStream method 
// mark(), read(), skip() 
// markSupported(), close(), reset() 
  
import java.io.*; 
  
public class NewClass 
{ 
    public static void main(String[] args) throws Exception 
    { 
        InputStream geek = null; 
        // FilterInputStream initialised to null here 
        FilterInputStream geek_input = null; 
        try { 
  
            geek = new FileInputStream("GEEKS.txt"); 
              
        geek_input = new BufferedInputStream(geek); 
  
            // read() method : reading and printing Characters 
            // one by one 
            System.out.println("Char : " + (char)geek_input.read()); 
            System.out.println("Char : " + (char)geek_input.read()); 
            System.out.println("Char : " + (char)geek_input.read()); 
  
            // mark() : read limiing the 'geek' input stream 
            geek_input.mark(0); 
  
            // skip() : it results in redaing of 'e' in G'e'eeks 
            geek_input.skip(1); 
            System.out.println("skip() method comes to play"); 
            System.out.println("mark() method comes to play"); 
            System.out.println("Char : " + (char)geek_input.read()); 
            System.out.println("Char : " + (char)geek_input.read()); 
            System.out.println("Char : " + (char)geek_input.read()); 
  
            boolean check = geek_input.markSupported(); 
            if (geek_input.markSupported()) 
            { 
                // reset() method : repositioning the stream to 
                // marked positions. 
                geek_input.reset(); 
                System.out.println("reset() invoked"); 
                System.out.println("Char : " + (char)geek_input.read()); 
                System.out.println("Char : " + (char)geek_input.read()); 
            } 
            else
                System.out.println("reset() method not supported."); 
                System.out.println("geek_input.markSupported() supported" 
                                                + " reset() : " + check); 
  
        } 
        catch(Exception excpt) 
        { 
            // in case of I/O error 
            excpt.printStackTrace(); 
        } 
        finally
        { 
            // releasing the resources back to the 
            // GarbageCollector when closes 
            if (geek != null) 
            { // Use of close() : closing the file 
                // and releasing resources 
                geek.close(); 
            } 
  
            if(geek_input != null) 
                geek_input.close(); 
        } 
    } 
}

注意：
此代碼不會在在線 IDE 上運行，因為此處不存在此類文件。
您可以在係統上運行此代碼來檢查工作情況。
GEEKS.txt代碼中使用的文件有

HelloGeeks

輸出：

Char : H
Char : e
Char : l
skip() method comes to play
mark() method comes to play
Char : o
Char : G
Char : e
reset() invoked
Char : l
Char : o
geek_input.markSupported() supported reset() : true

相關用法

注：本文由純淨天空篩選整理自佚名大神的英文原創作品 Java.io.FilterInputStream Class in Java。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。