Class ObjectInputStream
- All Implemented Interfaces:
Closeable
,DataInput
,ObjectInput
,ObjectStreamConstants
,AutoCloseable
Warning: Deserialization of untrusted data is inherently dangerous and should be avoided. Untrusted data should be carefully validated according to the "Serialization and Deserialization" section of the Secure Coding Guidelines for Java SE. Serialization Filtering describes best practices for defensive use of serial filters.
The key to disabling deserialization attacks is to prevent instances of
arbitrary classes from being deserialized, thereby preventing the direct or
indirect execution of their methods.
ObjectInputFilter
describes how to use filters and
ObjectInputFilter.Config
describes how to configure the filter and filter factory.
Each stream has an optional deserialization filter
to check the classes and resource limits during deserialization.
The JVM-wide filter factory ensures that a filter can be set on every ObjectInputStream
and every object read from the stream can be checked.
The ObjectInputStream constructors invoke the filter factory
to select the initial filter which may be updated or replaced by setObjectInputFilter(ObjectInputFilter)
.
If an ObjectInputStream has a filter, the ObjectInputFilter
can check that
the classes, array lengths, number of references in the stream, depth, and
number of bytes consumed from the input stream are allowed and
if not, can terminate deserialization.
ObjectOutputStream and ObjectInputStream can provide an application with persistent storage for graphs of objects when used with a FileOutputStream and FileInputStream respectively. ObjectInputStream is used to recover those objects previously serialized. Other uses include passing objects between hosts using a socket stream or for marshaling and unmarshaling arguments and parameters in a remote communication system.
ObjectInputStream ensures that the types of all objects in the graph created from the stream match the classes present in the Java Virtual Machine. Classes are loaded as required using the standard mechanisms.
Only objects that support the java.io.Serializable or java.io.Externalizable interface can be read from streams.
The method readObject
is used to read an object from the
stream. Java's safe casting should be used to get the desired type. In
Java, strings and arrays are objects and are treated as objects during
serialization. When read they need to be cast to the expected type.
Primitive data types can be read from the stream using the appropriate method on DataInput.
The default deserialization mechanism for objects restores the contents of each field to the value and type it had when it was written. Fields declared as transient or static are ignored by the deserialization process. References to other objects cause those objects to be read from the stream as necessary. Graphs of objects are restored correctly using a reference sharing mechanism. New objects are always allocated when deserializing, which prevents existing objects from being overwritten.
Reading an object is analogous to running the constructors of a new object. Memory is allocated for the object and initialized to zero (NULL). No-arg constructors are invoked for the non-serializable classes and then the fields of the serializable classes are restored from the stream starting with the serializable class closest to java.lang.object and finishing with the object's most specific class.
For example to read from a stream as written by the example in
ObjectOutputStream
:
try (FileInputStream fis = new FileInputStream("t.tmp");
ObjectInputStream ois = new ObjectInputStream(fis)) {
String label = (String) ois.readObject();
LocalDateTime dateTime = (LocalDateTime) ois.readObject();
// Use label and dateTime
} catch (Exception ex) {
// handle exception
}
Classes control how they are serialized by implementing either the java.io.Serializable or java.io.Externalizable interfaces.
Implementing the Serializable interface allows object serialization to save and restore the entire state of the object and it allows classes to evolve between the time the stream is written and the time it is read. It automatically traverses references between objects, saving and restoring entire graphs.
Serializable classes that require special handling during the serialization and deserialization process should implement methods with the following signatures:
private void writeObject(java.io.ObjectOutputStream stream)
throws IOException;
private void readObject(java.io.ObjectInputStream stream)
throws IOException, ClassNotFoundException;
private void readObjectNoData()
throws ObjectStreamException;
The method name, modifiers, return type, and number and type of parameters must match exactly for the method to be used by serialization or deserialization. The methods should only be declared to throw checked exceptions consistent with these signatures.
The readObject method is responsible for reading and restoring the state of the object for its particular class using data written to the stream by the corresponding writeObject method. The method does not need to concern itself with the state belonging to its superclasses or subclasses. State is restored by reading data from the ObjectInputStream for the individual fields and making assignments to the appropriate fields of the object. Reading primitive data types is supported by DataInput.
Any attempt to read object data which exceeds the boundaries of the custom data written by the corresponding writeObject method will cause an OptionalDataException to be thrown with an eof field value of true. Non-object reads which exceed the end of the allotted data will reflect the end of data in the same way that they would indicate the end of the stream: bytewise reads will return -1 as the byte read or number of bytes read, and primitive reads will throw EOFExceptions. If there is no corresponding writeObject method, then the end of default serialized data marks the end of the allotted data.
Primitive and object read calls issued from within a readExternal method
behave in the same manner--if the stream is already positioned at the end of
data written by the corresponding writeExternal method, object reads will
throw OptionalDataExceptions with eof set to true, bytewise reads will
return -1, and primitive reads will throw EOFExceptions. Note that this
behavior does not hold for streams written with the old
ObjectStreamConstants.PROTOCOL_VERSION_1
protocol, in which the
end of data written by writeExternal methods is not demarcated, and hence
cannot be detected.
The readObjectNoData method is responsible for initializing the state of the object for its particular class in the event that the serialization stream does not list the given class as a superclass of the object being deserialized. This may occur in cases where the receiving party uses a different version of the deserialized instance's class than the sending party, and the receiver's version extends classes that are not extended by the sender's version. This may also occur if the serialization stream has been tampered; hence, readObjectNoData is useful for initializing deserialized objects properly despite a "hostile" or incomplete source stream.
Serialization does not read or assign values to the fields of any object that does not implement the java.io.Serializable interface. Subclasses of Objects that are not serializable can be serializable. In this case the non-serializable class must have a no-arg constructor to allow its fields to be initialized. In this case it is the responsibility of the subclass to save and restore the state of the non-serializable class. It is frequently the case that the fields of that class are accessible (public, package, or protected) or that there are get and set methods that can be used to restore the state.
Any exception that occurs while deserializing an object will be caught by the ObjectInputStream and abort the reading process.
Implementing the Externalizable interface allows the object to assume complete control over the contents and format of the object's serialized form. The methods of the Externalizable interface, writeExternal and readExternal, are called to save and restore the objects state. When implemented by a class they can write and read their own state using all of the methods of ObjectOutput and ObjectInput. It is the responsibility of the objects to handle any versioning that occurs.
Enum constants are deserialized differently than ordinary serializable or
externalizable objects. The serialized form of an enum constant consists
solely of its name; field values of the constant are not transmitted. To
deserialize an enum constant, ObjectInputStream reads the constant name from
the stream; the deserialized constant is then obtained by calling the static
method Enum.valueOf(Class, String)
with the enum constant's
base type and the received constant name as arguments. Like other
serializable or externalizable objects, enum constants can function as the
targets of back references appearing subsequently in the serialization
stream. The process by which enum constants are deserialized cannot be
customized: any class-specific readObject, readObjectNoData, and readResolve
methods defined by enum types are ignored during deserialization.
Similarly, any serialPersistentFields or serialVersionUID field declarations
are also ignored--all enum types have a fixed serialVersionUID of 0L.
Records are serialized differently than ordinary serializable or externalizable objects. During deserialization the record's canonical constructor is invoked to construct the record object. Certain serialization-related methods, such as readObject and writeObject, are ignored for serializable records. See Java Object Serialization Specification, Section 1.13, "Serialization of Records" for additional information.
- Since:
- 1.1
- External Specifications
- See Also:
-
Nested Class Summary
Modifier and TypeClassDescriptionstatic class
Provide access to the persistent fields read from the input stream. -
Field Summary
Fields inherited from interface java.io.ObjectStreamConstants
baseWireHandle, PROTOCOL_VERSION_1, PROTOCOL_VERSION_2, SC_BLOCK_DATA, SC_ENUM, SC_EXTERNALIZABLE, SC_SERIALIZABLE, SC_WRITE_METHOD, SERIAL_FILTER_PERMISSION, STREAM_MAGIC, STREAM_VERSION, SUBCLASS_IMPLEMENTATION_PERMISSION, SUBSTITUTION_PERMISSION, TC_ARRAY, TC_BASE, TC_BLOCKDATA, TC_BLOCKDATALONG, TC_CLASS, TC_CLASSDESC, TC_ENDBLOCKDATA, TC_ENUM, TC_EXCEPTION, TC_LONGSTRING, TC_MAX, TC_NULL, TC_OBJECT, TC_PROXYCLASSDESC, TC_REFERENCE, TC_RESET, TC_STRING
-
Constructor Summary
ModifierConstructorDescriptionprotected
Provide a way for subclasses that are completely reimplementing ObjectInputStream to not have to allocate private data just used by this implementation of ObjectInputStream.Creates an ObjectInputStream that reads from the specified InputStream. -
Method Summary
Modifier and TypeMethodDescriptionint
Returns the number of bytes that can be read without blocking.void
close()
Closes this input stream and releases any system resources associated with the stream.void
Read the non-static and non-transient fields of the current class from this stream.protected boolean
enableResolveObject
(boolean enable) Enables the stream to do replacement of objects read from the stream.final ObjectInputFilter
Returns the deserialization filter for this stream.int
read()
Reads a byte of data.int
read
(byte[] buf, int off, int len) Reads into an array of bytes.boolean
Reads in a boolean.byte
readByte()
Reads an 8-bit byte.char
readChar()
Reads a 16-bit char.protected ObjectStreamClass
Read a class descriptor from the serialization stream.double
Reads a 64-bit double.Reads the persistent fields from the stream and makes them available by name.float
Reads a 32-bit float.void
readFully
(byte[] buf) Reads bytes, blocking until all bytes are read.void
readFully
(byte[] buf, int off, int len) Reads bytes, blocking until all bytes are read.int
readInt()
Reads a 32-bit int.readLine()
Deprecated.This method does not properly convert bytes to characters.long
readLong()
Reads a 64-bit long.final Object
Read an object from the ObjectInputStream.protected Object
This method is called by trusted subclasses of ObjectInputStream that constructed ObjectInputStream using the protected no-arg constructor.short
Reads a 16-bit short.protected void
The readStreamHeader method is provided to allow subclasses to read and verify their own stream headers.Reads an "unshared" object from the ObjectInputStream.int
Reads an unsigned 8-bit byte.int
Reads an unsigned 16-bit short.readUTF()
Reads a String in modified UTF-8 format.void
registerValidation
(ObjectInputValidation obj, int prio) Register an object to be validated before the graph is returned.protected Class
<?> Load the local class equivalent of the specified stream class description.protected Object
resolveObject
(Object obj) This method will allow trusted subclasses of ObjectInputStream to substitute one object for another during deserialization.protected Class
<?> resolveProxyClass
(String[] interfaces) Returns a proxy class that implements the interfaces named in a proxy class descriptor; subclasses may implement this method to read custom data from the stream along with the descriptors for dynamic proxy classes, allowing them to use an alternate loading mechanism for the interfaces and the proxy class.final void
Set the deserialization filter for the stream.int
skipBytes
(int len) Skips bytes.Methods inherited from class java.io.InputStream
mark, markSupported, nullInputStream, read, readAllBytes, readNBytes, readNBytes, reset, skip, skipNBytes, transferTo
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods inherited from interface java.io.ObjectInput
read, skip
-
Constructor Details
-
ObjectInputStream
Creates an ObjectInputStream that reads from the specified InputStream. A serialization stream header is read from the stream and verified. This constructor will block until the corresponding ObjectOutputStream has written and flushed the header.The constructor initializes the deserialization filter to the filter returned by invoking the serial filter factory returned from
ObjectInputFilter.Config.getSerialFilterFactory()
withnull
for the current filter and the static JVM-wide filter for the requested filter. If the serial filter or serial filter factory properties are invalid anIllegalStateException
is thrown. When the filter factoryapply
method is invoked it may throw a runtime exception preventing theObjectInputStream
from being constructed.- Parameters:
in
- input stream to read from- Throws:
StreamCorruptedException
- if the stream header is incorrectIOException
- if an I/O error occurs while reading stream headerIllegalStateException
- if the initialization ofObjectInputFilter.Config
fails due to invalid serial filter or serial filter factory properties.NullPointerException
- ifin
isnull
- See Also:
-
ObjectInputStream
Provide a way for subclasses that are completely reimplementing ObjectInputStream to not have to allocate private data just used by this implementation of ObjectInputStream.The constructor initializes the deserialization filter to the filter returned by invoking the serial filter factory returned from
ObjectInputFilter.Config.getSerialFilterFactory()
withnull
for the current filter and the static JVM-wide filter for the requested filter. If the serial filter or serial filter factory properties are invalid anIllegalStateException
is thrown. When the filter factoryapply
method is invoked it may throw a runtime exception preventing theObjectInputStream
from being constructed.- Throws:
IOException
- if an I/O error occurs while creating this streamIllegalStateException
- if the initialization ofObjectInputFilter.Config
fails due to invalid serial filter or serial filter factory properties.
-
-
Method Details
-
readObject
Read an object from the ObjectInputStream. The class of the object, the signature of the class, and the values of the non-transient and non-static fields of the class and all of its supertypes are read. Default deserializing for a class can be overridden using the writeObject and readObject methods. Objects referenced by this object are read transitively so that a complete equivalent graph of objects is reconstructed by readObject.The root object is completely restored when all of its fields and the objects it references are completely restored. At this point the object validation callbacks are executed in order based on their registered priorities. The callbacks are registered by objects (in the readObject special methods) as they are individually restored.
The deserialization filter, when not
null
, is invoked for each object (regular or class) read to reconstruct the root object. SeesetObjectInputFilter
for details.Exceptions are thrown for problems with the InputStream and for classes that should not be deserialized. All exceptions are fatal to the InputStream and leave it in an indeterminate state; it is up to the caller to ignore or recover the stream state.
- Specified by:
readObject
in interfaceObjectInput
- Returns:
- the object read from the stream
- Throws:
ClassNotFoundException
- Class of a serialized object cannot be found.InvalidClassException
- Something is wrong with a class used by deserialization.StreamCorruptedException
- Control information in the stream is inconsistent.OptionalDataException
- Primitive data was found in the stream instead of objects.IOException
- Any of the usual Input/Output related exceptions.
-
readObjectOverride
This method is called by trusted subclasses of ObjectInputStream that constructed ObjectInputStream using the protected no-arg constructor. The subclass is expected to provide an override method with the modifier "final".- Returns:
- the Object read from the stream.
- Throws:
ClassNotFoundException
- Class definition of a serialized object cannot be found.OptionalDataException
- Primitive data was found in the stream instead of objects.IOException
- if I/O errors occurred while reading from the underlying stream- Since:
- 1.2
- See Also:
-
defaultReadObject
Read the non-static and non-transient fields of the current class from this stream. This may only be called from the readObject method of the class being deserialized. It will throw the NotActiveException if it is called otherwise.- Throws:
ClassNotFoundException
- if the class of a serialized object could not be found.IOException
- if an I/O error occurs.NotActiveException
- if the stream is not currently reading objects.
-
readFields
Reads the persistent fields from the stream and makes them available by name.- Returns:
- the
GetField
object representing the persistent fields of the object being deserialized - Throws:
ClassNotFoundException
- if the class of a serialized object could not be found.IOException
- if an I/O error occurs.NotActiveException
- if the stream is not currently reading objects.- Since:
- 1.2
-
registerValidation
public void registerValidation(ObjectInputValidation obj, int prio) throws NotActiveException, InvalidObjectException Register an object to be validated before the graph is returned. While similar to resolveObject these validations are called after the entire graph has been reconstituted. Typically, a readObject method will register the object with the stream so that when all of the objects are restored a final set of validations can be performed.- Parameters:
obj
- the object to receive the validation callback.prio
- controls the order of callbacks; zero is a good default. Use higher numbers to be called back earlier, lower numbers for later callbacks. Within a priority, callbacks are processed in no particular order.- Throws:
NotActiveException
- The stream is not currently reading objects so it is invalid to register a callback.InvalidObjectException
- The validation object is null.
-
resolveClass
Load the local class equivalent of the specified stream class description. Subclasses may implement this method to allow classes to be fetched from an alternate source.The corresponding method in
ObjectOutputStream
isannotateClass
. This method will be invoked only once for each unique class in the stream. This method can be implemented by subclasses to use an alternate loading mechanism but must return aClass
object. Once returned, if the class is not an array class, its serialVersionUID is compared to the serialVersionUID of the serialized class, and if there is a mismatch, the deserialization fails and anInvalidClassException
is thrown.The default implementation of this method in
ObjectInputStream
returns the result of callingClass.forName(desc.getName(), false, loader)
loader
is the first class loader on the current thread's stack (starting from the currently executing method) that is neither the platform class loader nor its ancestor; otherwise,loader
is the platform class loader. If this call results in aClassNotFoundException
and the name of the passedObjectStreamClass
instance is the Java language keyword for a primitive type or void, then theClass
object representing that primitive type or void will be returned (e.g., anObjectStreamClass
with the name"int"
will be resolved toInteger.TYPE
). Otherwise, theClassNotFoundException
will be thrown to the caller of this method.- Parameters:
desc
- an instance of classObjectStreamClass
- Returns:
- a
Class
object corresponding todesc
- Throws:
IOException
- any of the usual Input/Output exceptions.ClassNotFoundException
- if class of a serialized object cannot be found.
-
resolveProxyClass
protected Class<?> resolveProxyClass(String[] interfaces) throws IOException, ClassNotFoundException Returns a proxy class that implements the interfaces named in a proxy class descriptor; subclasses may implement this method to read custom data from the stream along with the descriptors for dynamic proxy classes, allowing them to use an alternate loading mechanism for the interfaces and the proxy class.This method is called exactly once for each unique proxy class descriptor in the stream.
The corresponding method in
ObjectOutputStream
isannotateProxyClass
. For a given subclass ofObjectInputStream
that overrides this method, theannotateProxyClass
method in the corresponding subclass ofObjectOutputStream
must write any data or objects read by this method.The default implementation of this method in
ObjectInputStream
returns the result of callingProxy.getProxyClass
with the list ofClass
objects for the interfaces that are named in theinterfaces
parameter. TheClass
object for each interface namei
is the value returned by callingClass.forName(i, false, loader)
loader
is the first class loader on the current thread's stack (starting from the currently executing method) that is neither the platform class loader nor its ancestor; otherwise,loader
is the platform class loader. Unless any of the resolved interfaces are non-public, this same value ofloader
is also the class loader passed toProxy.getProxyClass
; if non-public interfaces are present, their class loader is passed instead (if more than one non-public interface class loader is encountered, anIllegalAccessError
is thrown). IfProxy.getProxyClass
throws anIllegalArgumentException
,resolveProxyClass
will throw aClassNotFoundException
containing theIllegalArgumentException
.- Parameters:
interfaces
- the list of interface names that were deserialized in the proxy class descriptor- Returns:
- a proxy class for the specified interfaces
- Throws:
IOException
- any exception thrown by the underlyingInputStream
ClassNotFoundException
- if the proxy class or any of the named interfaces could not be found- Since:
- 1.3
- See Also:
-
resolveObject
This method will allow trusted subclasses of ObjectInputStream to substitute one object for another during deserialization. Replacing objects is disabled until enableResolveObject is called. The enableResolveObject method checks that the stream requesting to resolve object can be trusted. Every reference to serializable objects is passed to resolveObject. To ensure that the private state of objects is not unintentionally exposed only trusted streams may use resolveObject.This method is called after an object has been read but before it is returned from readObject. The default resolveObject method just returns the same object.
When a subclass is replacing objects it must ensure that the substituted object is compatible with every field where the reference will be stored. Objects whose type is not a subclass of the type of the field or array element abort the deserialization by raising an exception and the object is not be stored.
This method is called only once when each object is first encountered. All subsequent references to the object will be redirected to the new object.
- Parameters:
obj
- object to be substituted- Returns:
- the substituted object
- Throws:
IOException
- Any of the usual Input/Output exceptions.
-
enableResolveObject
protected boolean enableResolveObject(boolean enable) Enables the stream to do replacement of objects read from the stream. When enabled, theresolveObject(Object)
method is called for every object being deserialized.- Parameters:
enable
- true for enabling use ofresolveObject
for every object being deserialized- Returns:
- the previous setting before this method was invoked
-
readStreamHeader
The readStreamHeader method is provided to allow subclasses to read and verify their own stream headers. It reads and verifies the magic number and version number.- Throws:
IOException
- if there are I/O errors while reading from the underlyingInputStream
StreamCorruptedException
- if control information in the stream is inconsistent
-
readClassDescriptor
Read a class descriptor from the serialization stream. This method is called when the ObjectInputStream expects a class descriptor as the next item in the serialization stream. Subclasses of ObjectInputStream may override this method to read in class descriptors that have been written in non-standard formats (by subclasses of ObjectOutputStream which have overridden thewriteClassDescriptor
method). By default, this method reads class descriptors according to the format defined in the Object Serialization specification.- Returns:
- the class descriptor read
- Throws:
IOException
- If an I/O error has occurred.ClassNotFoundException
- If the Class of a serialized object used in the class descriptor representation cannot be found- Since:
- 1.3
- See Also:
-
read
Reads a byte of data. This method will block if no input is available.- Specified by:
read
in interfaceObjectInput
- Specified by:
read
in classInputStream
- Returns:
- the byte read, or -1 if the end of the stream is reached.
- Throws:
IOException
- if an I/O error occurs.
-
read
Reads into an array of bytes. This method will block until some input is available. Consider using java.io.DataInputStream.readFully to read exactly 'length' bytes.- Specified by:
read
in interfaceObjectInput
- Overrides:
read
in classInputStream
- Parameters:
buf
- the buffer into which the data is readoff
- the start offset in the destination arraybuf
len
- the maximum number of bytes read- Returns:
- the total number of bytes read into the buffer, or
-1
if there is no more data because the end of the stream has been reached. - Throws:
NullPointerException
- ifbuf
isnull
.IndexOutOfBoundsException
- ifoff
is negative,len
is negative, orlen
is greater thanbuf.length - off
.IOException
- If an I/O error has occurred.- See Also:
-
available
Returns the number of bytes that can be read without blocking.- Specified by:
available
in interfaceObjectInput
- Overrides:
available
in classInputStream
- Returns:
- the number of available bytes.
- Throws:
IOException
- if there are I/O errors while reading from the underlyingInputStream
-
close
Closes this input stream and releases any system resources associated with the stream.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Specified by:
close
in interfaceObjectInput
- Overrides:
close
in classInputStream
- Throws:
IOException
- if an I/O error occurs.
-
readBoolean
Reads in a boolean.- Specified by:
readBoolean
in interfaceDataInput
- Returns:
- the boolean read.
- Throws:
EOFException
- If end of file is reached.IOException
- If other I/O error has occurred.
-
readByte
Reads an 8-bit byte.- Specified by:
readByte
in interfaceDataInput
- Returns:
- the 8-bit byte read.
- Throws:
EOFException
- If end of file is reached.IOException
- If other I/O error has occurred.
-
readUnsignedByte
Reads an unsigned 8-bit byte.- Specified by:
readUnsignedByte
in interfaceDataInput
- Returns:
- the 8-bit byte read.
- Throws:
EOFException
- If end of file is reached.IOException
- If other I/O error has occurred.
-
readChar
Reads a 16-bit char.- Specified by:
readChar
in interfaceDataInput
- Returns:
- the 16-bit char read.
- Throws:
EOFException
- If end of file is reached.IOException
- If other I/O error has occurred.
-
readShort
Reads a 16-bit short.- Specified by:
readShort
in interfaceDataInput
- Returns:
- the 16-bit short read.
- Throws:
EOFException
- If end of file is reached.IOException
- If other I/O error has occurred.
-
readUnsignedShort
Reads an unsigned 16-bit short.- Specified by:
readUnsignedShort
in interfaceDataInput
- Returns:
- the 16-bit short read.
- Throws:
EOFException
- If end of file is reached.IOException
- If other I/O error has occurred.
-
readInt
Reads a 32-bit int.- Specified by:
readInt
in interfaceDataInput
- Returns:
- the 32-bit integer read.
- Throws:
EOFException
- If end of file is reached.IOException
- If other I/O error has occurred.
-
readLong
Reads a 64-bit long.- Specified by:
readLong
in interfaceDataInput
- Returns:
- the read 64-bit long.
- Throws:
EOFException
- If end of file is reached.IOException
- If other I/O error has occurred.
-
readFloat
Reads a 32-bit float.- Specified by:
readFloat
in interfaceDataInput
- Returns:
- the 32-bit float read.
- Throws:
EOFException
- If end of file is reached.IOException
- If other I/O error has occurred.
-
readDouble
Reads a 64-bit double.- Specified by:
readDouble
in interfaceDataInput
- Returns:
- the 64-bit double read.
- Throws:
EOFException
- If end of file is reached.IOException
- If other I/O error has occurred.
-
readFully
Reads bytes, blocking until all bytes are read.- Specified by:
readFully
in interfaceDataInput
- Parameters:
buf
- the buffer into which the data is read- Throws:
NullPointerException
- Ifbuf
isnull
.EOFException
- If end of file is reached.IOException
- If other I/O error has occurred.
-
readFully
Reads bytes, blocking until all bytes are read.- Specified by:
readFully
in interfaceDataInput
- Parameters:
buf
- the buffer into which the data is readoff
- the start offset into the data arraybuf
len
- the maximum number of bytes to read- Throws:
NullPointerException
- Ifbuf
isnull
.IndexOutOfBoundsException
- Ifoff
is negative,len
is negative, orlen
is greater thanbuf.length - off
.EOFException
- If end of file is reached.IOException
- If other I/O error has occurred.
-
skipBytes
Skips bytes.- Specified by:
skipBytes
in interfaceDataInput
- Parameters:
len
- the number of bytes to be skipped- Returns:
- the actual number of bytes skipped.
- Throws:
IOException
- If an I/O error has occurred.
-
readLine
Deprecated.This method does not properly convert bytes to characters. see DataInputStream for the details and alternatives.Reads in a line that has been terminated by a \n, \r, \r\n or EOF.- Specified by:
readLine
in interfaceDataInput
- Returns:
- a String copy of the line.
- Throws:
IOException
- if there are I/O errors while reading from the underlyingInputStream
-
readUTF
Reads a String in modified UTF-8 format.- Specified by:
readUTF
in interfaceDataInput
- Returns:
- the String.
- Throws:
IOException
- if there are I/O errors while reading from the underlyingInputStream
UTFDataFormatException
- if read bytes do not represent a valid modified UTF-8 encoding of a string
-
getObjectInputFilter
Returns the deserialization filter for this stream. The filter is the result of invoking theJVM-wide filter factory
either by the constructor or the most recent invocation ofsetObjectInputFilter
.- Returns:
- the deserialization filter for the stream; may be null
- Since:
- 9
-
setObjectInputFilter
Set the deserialization filter for the stream. The deserialization filter is set to the filter returned by invoking the JVM-wide filter factory with the current filter and thefilter
parameter. The current filter was set in the ObjectInputStream constructors by invoking the JVM-wide filter factory and may benull
. setObjectInputFilter(ObjectInputFilter) This method} can be called once and only once before reading any objects from the stream; for example, by callingreadObject()
orreadUnshared()
.It is not permitted to replace a
non-null
filter with anull
filter. If the current filter isnon-null
, the value returned from the filter factory must benon-null
.The filter's
checkInput
method is called for each class and reference in the stream. The filter can check any or all of the class, the array length, the number of references, the depth of the graph, and the size of the input stream. The depth is the number of nested readObject calls starting with the reading of the root of the graph being deserialized and the current object being deserialized. The number of references is the cumulative number of objects and references to objects already read from the stream including the current object being read. The filter is invoked only when reading objects from the stream and not for primitives.If the filter returns
Status.REJECTED
,null
or throws aRuntimeException
, the activereadObject
orreadUnshared
throwsInvalidClassException
, otherwise deserialization continues uninterrupted.- Implementation Requirements:
- The filter, when not
null
, is invoked duringreadObject
andreadUnshared
for each object (regular or class) in the stream. Strings are treated as primitives and do not invoke the filter. The filter is called for:- each object reference previously deserialized from the stream
(class is
null
, arrayLength is -1), - each regular class (class is not
null
, arrayLength is -1), - each interface class explicitly referenced in the stream (it is not called for interfaces implemented by classes in the stream),
- each interface of a dynamic proxy and the dynamic proxy class itself
(class is not
null
, arrayLength is -1), - each array is filtered using the array type and length of the array (class is the array type, arrayLength is the requested length),
- each object replaced by its class'
readResolve
method is filtered using the replacement object's class, if notnull
, and if it is an array, the arrayLength, otherwise -1, - and each object replaced by
resolveObject
is filtered using the replacement object's class, if notnull
, and if it is an array, the arrayLength, otherwise -1.
checkInput
method is invoked it is given access to the current class, the array length, the current number of references already read from the stream, the depth of nested calls toreadObject
orreadUnshared
, and the implementation dependent number of bytes consumed from the input stream.Each call to
readObject
orreadUnshared
increases the depth by 1 before reading an object and decreases by 1 before returning normally or exceptionally. The depth starts at1
and increases for each nested object and decrements when each nested call returns. The count of references in the stream starts at1
and is increased before reading an object. - each object reference previously deserialized from the stream
(class is
- Parameters:
filter
- the filter, may be null- Throws:
IllegalStateException
- if an object has been read, if the filter factory returnsnull
when the current filter is non-null, or if the filter has already been set.- Since:
- 9
-