Class ProxyInputStream
- java.lang.Object
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- java.io.InputStream
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- java.io.FilterInputStream
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- org.apache.commons.io.input.ProxyInputStream
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
- Direct Known Subclasses:
AutoCloseInputStream
,BOMInputStream
,BoundedInputStream
,CloseShieldInputStream
,CountingInputStream
,MarkShieldInputStream
,ObservableInputStream
,SwappedDataInputStream
,TaggedInputStream
,TeeInputStream
public abstract class ProxyInputStream extends java.io.FilterInputStream
A proxy stream which acts as aFilterInputStream
, by passing all method calls on to the proxied stream, not changing which methods are called.It is an alternative base class to
FilterInputStream
to increase reusability, becauseFilterInputStream
changes the methods being called, such as read(byte[]) to read(byte[], int, int).In addition, this class allows you to:
- notify a subclass that n bytes are about to be read through
beforeRead(int)
- notify a subclass that n bytes were read through
afterRead(int)
- notify a subclass that an exception was caught through
handleIOException(IOException)
unwrap()
itself
This class does not add any state (no additional instance variables).
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Constructor Summary
Constructors Constructor Description ProxyInputStream(java.io.InputStream proxy)
Constructs a new ProxyInputStream.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected void
afterRead(int n)
Invoked by theread
methods after the proxied call has returned successfully.int
available()
Invokes the delegate'savailable()
method.protected void
beforeRead(int n)
Invoked by theread
methods before the call is proxied.void
close()
Invokes the delegate'sclose()
method.protected void
handleIOException(java.io.IOException e)
Handles any IOExceptions thrown; by default, throws the given exception.void
mark(int readLimit)
Invokes the delegate'smark(int)
method.boolean
markSupported()
Invokes the delegate'smarkSupported()
method.int
read()
Invokes the delegate'sread()
method.int
read(byte[] b)
Invokes the delegate'sread(byte[])
method.int
read(byte[] b, int off, int len)
Invokes the delegate'sread(byte[], int, int)
method.void
reset()
Invokes the delegate'sreset()
method.long
skip(long n)
Invokes the delegate'sskip(long)
method.java.io.InputStream
unwrap()
Unwraps this instance by returning the underlying InputStream.
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Constructor Detail
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ProxyInputStream
public ProxyInputStream(java.io.InputStream proxy)
Constructs a new ProxyInputStream.- Parameters:
proxy
- the InputStream to delegate to
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Method Detail
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afterRead
protected void afterRead(int n) throws java.io.IOException
Invoked by theread
methods after the proxied call has returned successfully. The number of bytes returned to the caller (or -1 if the end of stream was reached) is given as an argument.Subclasses can override this method to add common post-processing functionality without having to override all the read methods. The default implementation does nothing.
Note this method is not called from
skip(long)
orreset()
. You need to explicitly override those methods if you want to add post-processing steps also to them.- Parameters:
n
- number of bytes read, or -1 if the end of stream was reached.- Throws:
java.io.IOException
- if the post-processing fails in a subclass.- Since:
- 2.0
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available
public int available() throws java.io.IOException
Invokes the delegate'savailable()
method.- Overrides:
available
in classjava.io.FilterInputStream
- Returns:
- the number of available bytes
- Throws:
java.io.IOException
- if an I/O error occurs.
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beforeRead
protected void beforeRead(int n) throws java.io.IOException
Invoked by theread
methods before the call is proxied. The number of bytes that the caller wanted to read (1 for theread()
method, buffer length forread(byte[])
, etc.) is given as an argument.Subclasses can override this method to add common pre-processing functionality without having to override all the read methods. The default implementation does nothing.
Note this method is not called from
skip(long)
orreset()
. You need to explicitly override those methods if you want to add pre-processing steps also to them.- Parameters:
n
- number of bytes that the caller asked to be read.- Throws:
java.io.IOException
- if the pre-processing fails in a subclass.- Since:
- 2.0
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close
public void close() throws java.io.IOException
Invokes the delegate'sclose()
method.- Specified by:
close
in interfacejava.lang.AutoCloseable
- Specified by:
close
in interfacejava.io.Closeable
- Overrides:
close
in classjava.io.FilterInputStream
- Throws:
java.io.IOException
- if an I/O error occurs.
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handleIOException
protected void handleIOException(java.io.IOException e) throws java.io.IOException
Handles any IOExceptions thrown; by default, throws the given exception.This method provides a point to implement custom exception handling. The default behavior is to re-throw the exception.
- Parameters:
e
- The IOException thrown- Throws:
java.io.IOException
- if an I/O error occurs.- Since:
- 2.0
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mark
public void mark(int readLimit)
Invokes the delegate'smark(int)
method.- Overrides:
mark
in classjava.io.FilterInputStream
- Parameters:
readLimit
- read ahead limit
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markSupported
public boolean markSupported()
Invokes the delegate'smarkSupported()
method.- Overrides:
markSupported
in classjava.io.FilterInputStream
- Returns:
- true if mark is supported, otherwise false
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read
public int read() throws java.io.IOException
Invokes the delegate'sread()
method.- Overrides:
read
in classjava.io.FilterInputStream
- Returns:
- the byte read or -1 if the end of stream
- Throws:
java.io.IOException
- if an I/O error occurs.
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read
public int read(byte[] b) throws java.io.IOException
Invokes the delegate'sread(byte[])
method.- Overrides:
read
in classjava.io.FilterInputStream
- Parameters:
b
- the buffer to read the bytes into- Returns:
- the number of bytes read or EOF if the end of stream
- Throws:
java.io.IOException
- if an I/O error occurs.
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read
public int read(byte[] b, int off, int len) throws java.io.IOException
Invokes the delegate'sread(byte[], int, int)
method.- Overrides:
read
in classjava.io.FilterInputStream
- Parameters:
b
- the buffer to read the bytes intooff
- The start offsetlen
- The number of bytes to read- Returns:
- the number of bytes read or -1 if the end of stream
- Throws:
java.io.IOException
- if an I/O error occurs.
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reset
public void reset() throws java.io.IOException
Invokes the delegate'sreset()
method.- Overrides:
reset
in classjava.io.FilterInputStream
- Throws:
java.io.IOException
- if an I/O error occurs.
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skip
public long skip(long n) throws java.io.IOException
Invokes the delegate'sskip(long)
method.- Overrides:
skip
in classjava.io.FilterInputStream
- Parameters:
n
- the number of bytes to skip- Returns:
- the actual number of bytes skipped
- Throws:
java.io.IOException
- if an I/O error occurs.
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unwrap
public java.io.InputStream unwrap()
Unwraps this instance by returning the underlying InputStream.Use with caution; useful to query the underlying InputStream.
- Returns:
- the underlying InputStream.
- Since:
- 2.16.0
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