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
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Nested Class Summary
Nested Classes Modifier and Type Class Description protected static class
ProxyInputStream.AbstractBuilder<T,B extends AbstractStreamBuilder<T,B>>
Abstracts builder properties for subclasses.
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Constructor Summary
Constructors Modifier Constructor Description ProxyInputStream(java.io.InputStream proxy)
Constructs a new ProxyInputStream.protected
ProxyInputStream(java.io.InputStream proxy, ProxyInputStream.AbstractBuilder<?,?> builder)
Constructs a new ProxyInputStream.protected
ProxyInputStream(ProxyInputStream.AbstractBuilder<?,?> builder)
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)
Called by theread
methods after the proxied call has returned successfully.int
available()
Invokes the delegate'sInputStream.available()
method.protected void
beforeRead(int n)
Invoked by theread
methods before the call is proxied.void
close()
Invokes the delegate'sInputStream.close()
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'sInputStream.mark(int)
method.boolean
markSupported()
Invokes the delegate'sInputStream.markSupported()
method.int
read()
Invokes the delegate'sInputStream.read()
method unless the stream is closed.int
read(byte[] b)
Invokes the delegate'sInputStream.read(byte[])
method.int
read(byte[] b, int off, int len)
Invokes the delegate'sInputStream.read(byte[], int, int)
method.void
reset()
Invokes the delegate'sInputStream.reset()
method.long
skip(long n)
Invokes the delegate'sInputStream.skip(long)
method.java.io.InputStream
unwrap()
Unwraps this instance by returning the underlyingInputStream
.
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Constructor Detail
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ProxyInputStream
protected ProxyInputStream(ProxyInputStream.AbstractBuilder<?,?> builder) throws java.io.IOException
Constructs a new ProxyInputStream.- Parameters:
builder
- How to build an instance.- Throws:
java.io.IOException
- if an I/O error occurs.- Since:
- 2.18.0
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ProxyInputStream
public ProxyInputStream(java.io.InputStream proxy)
Constructs a new ProxyInputStream.- Parameters:
proxy
- the InputStream to proxy.
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ProxyInputStream
protected ProxyInputStream(java.io.InputStream proxy, ProxyInputStream.AbstractBuilder<?,?> builder)
Constructs a new ProxyInputStream.- Parameters:
proxy
- the InputStream to proxy.builder
- How to build an instance.- Since:
- 2.18.0
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Method Detail
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afterRead
protected void afterRead(int n) throws java.io.IOException
Called by theread
methods after the proxied call has returned successfully. The argument is the number of bytes returned to the caller orEOF
if the end of stream was reached.The default delegates to the consumer given to
ProxyInputStream.AbstractBuilder.setAfterRead(IOIntConsumer)
.Alternatively, a subclasses can override this method to add post-processing functionality without having to override all the read methods.
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, orEOF
if the end of stream was reached.- Throws:
java.io.IOException
- Thrown by a subclass or the consumer given toProxyInputStream.AbstractBuilder.setAfterRead(IOIntConsumer)
.- Since:
- 2.0
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available
public int available() throws java.io.IOException
Invokes the delegate'sInputStream.available()
method.- Overrides:
available
in classjava.io.FilterInputStream
- Returns:
- the number of available bytes, 0 if the stream is closed.
- 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'sInputStream.close()
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'sInputStream.mark(int)
method.- Overrides:
mark
in classjava.io.FilterInputStream
- Parameters:
readLimit
- read ahead limit.
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markSupported
public boolean markSupported()
Invokes the delegate'sInputStream.markSupported()
method.
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read
public int read() throws java.io.IOException
Invokes the delegate'sInputStream.read()
method unless the stream is closed.- Overrides:
read
in classjava.io.FilterInputStream
- Returns:
- the byte read or
EOF
if we reached 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'sInputStream.read(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 we reached the end of stream. - Throws:
java.io.IOException
-- If the first byte cannot be read for any reason other than the end of the file,
- if the input stream has been closed, or
- if some other 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'sInputStream.read(byte[], int, int)
method.- Overrides:
read
in classjava.io.FilterInputStream
- Parameters:
b
- the buffer to read the bytes into.off
- The start offset.len
- The number of bytes to read.- Returns:
- the number of bytes read or
EOF
if we reached the end of stream. - Throws:
java.io.IOException
-- If the first byte cannot be read for any reason other than the end of the file,
- if the input stream has been closed, or
- if some other I/O error occurs.
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reset
public void reset() throws java.io.IOException
Invokes the delegate'sInputStream.reset()
method.- Overrides:
reset
in classjava.io.FilterInputStream
- Throws:
java.io.IOException
- if this stream has not been marked or if the mark has been invalidated.
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skip
public long skip(long n) throws java.io.IOException
Invokes the delegate'sInputStream.skip(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 the stream does not support seek, or if some other I/O error occurs.
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unwrap
public java.io.InputStream unwrap()
Unwraps this instance by returning the underlyingInputStream
.Use with caution; useful to query the underlying
InputStream
.- Returns:
- the underlying
InputStream
. - Since:
- 2.16.0
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