程序包 java.io

类 DataInputStream

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

java.io.DataInputStream

所有已实现的接口:

Closeable, DataInput, AutoCloseable

public class DataInputStream
extends FilterInputStream
implements DataInput

A data input stream lets an application read primitive Java data types from an underlying input stream in a machine-independent way. An application uses a data output stream to write data that can later be read by a data input stream.

DataInputStream is not necessarily safe for multithreaded access. Thread safety is optional and is the responsibility of users of methods in this class.

从以下版本开始:

JDK1.0

另请参阅:

DataOutputStream

字段概要

从类继承的字段 java.io.FilterInputStream

in

构造器概要

构造器

构造器	说明
DataInputStream(InputStream in)	Creates a DataInputStream that uses the specified underlying InputStream.

方法概要

限定符和类型	方法	说明
int	read(byte[] b)	Reads some number of bytes from the contained input stream and stores them into the buffer array b.
int	read(byte[] b, int off, int len)	Reads up to len bytes of data from the contained input stream into an array of bytes.
boolean	readBoolean()	See the general contract of the readBoolean method of DataInput.
byte	readByte()	See the general contract of the readByte method of DataInput.
char	readChar()	See the general contract of the readChar method of DataInput.
double	readDouble()	See the general contract of the readDouble method of DataInput.
float	readFloat()	See the general contract of the readFloat method of DataInput.
void	readFully(byte[] b)	See the general contract of the readFully method of DataInput.
void	readFully(byte[] b, int off, int len)	See the general contract of the readFully method of DataInput.
int	readInt()	See the general contract of the readInt method of DataInput.
String	readLine()	已过时。 This method does not properly convert bytes to characters. As of JDK 1.1, the preferred way to read lines of text is via the BufferedReader.readLine() method. Programs that use the DataInputStream class to read lines can be converted to use the BufferedReader class by replacing code of the form: DataInputStream d = new DataInputStream(in); with: BufferedReader d = new BufferedReader(new InputStreamReader(in));
long	readLong()	See the general contract of the readLong method of DataInput.
short	readShort()	See the general contract of the readShort method of DataInput.
int	readUnsignedByte()	See the general contract of the readUnsignedByte method of DataInput.
int	readUnsignedShort()	See the general contract of the readUnsignedShort method of DataInput.
String	readUTF()	See the general contract of the readUTF method of DataInput.
static String	readUTF(DataInput in)	Reads from the stream in a representation of a Unicode character string encoded in modified UTF-8 format; this string of characters is then returned as a String.
int	skipBytes(int n)	See the general contract of the skipBytes method of DataInput.

从类继承的方法 java.io.FilterInputStream

available, close, mark, markSupported, read, reset, skip

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

构造器详细资料

DataInputStream

public DataInputStream(InputStream in)

Creates a DataInputStream that uses the specified underlying InputStream.

参数:

in - the specified input stream

方法详细资料

read

public final int read(byte[] b)
               throws IOException

Reads some number of bytes from the contained input stream and stores them into the buffer array b. The number of bytes actually read is returned as an integer. This method blocks until input data is available, end of file is detected, or an exception is thrown.

If b is null, a NullPointerException is thrown. If the length of b is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[0], the next one into b[1], and so on. The number of bytes read is, at most, equal to the length of b. Let k be the number of bytes actually read; these bytes will be stored in elements b[0] through b[k-1], leaving elements b[k] through b[b.length-1] unaffected.

The read(b) method has the same effect as:

 read(b, 0, b.length)
 

覆盖:

read 在类中 FilterInputStream

参数:

b - the buffer into which the data is read.

返回:

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.

抛出:

IOException - if the first byte cannot be read for any reason other than end of file, the stream has been closed and the underlying input stream does not support reading after close, or another I/O error occurs.

另请参阅:

FilterInputStream.in, InputStream.read(byte[], int, int)

read

public final int read(byte[] b,
                      int off,
                      int len)
               throws IOException

Reads up to len bytes of data from the contained input stream into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read, possibly zero. The number of bytes actually read is returned as an integer.

This method blocks until input data is available, end of file is detected, or an exception is thrown.

If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k] through b[off+len-1] unaffected.

In every case, elements b[0] through b[off] and elements b[off+len] through b[b.length-1] are unaffected.

覆盖:

read 在类中 FilterInputStream

参数:

b - the buffer into which the data is read.

off - the start offset in the destination array b

len - the maximum number of bytes read.

返回:

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.

抛出:

NullPointerException - If b is null.

IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than b.length - off

IOException - if the first byte cannot be read for any reason other than end of file, the stream has been closed and the underlying input stream does not support reading after close, or another I/O error occurs.

另请参阅:

FilterInputStream.in, InputStream.read(byte[], int, int)

readFully

public final void readFully(byte[] b)
                     throws IOException

See the general contract of the readFully method of DataInput.

Bytes for this operation are read from the contained input stream.

指定者:

readFully 在接口中 DataInput

参数:

b - the buffer into which the data is read.

抛出:

EOFException - if this input stream reaches the end before reading all the bytes.

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

另请参阅:

FilterInputStream.in

readFully

public final void readFully(byte[] b,
                            int off,
                            int len)
                     throws IOException

See the general contract of the readFully method of DataInput.

Bytes for this operation are read from the contained input stream.

指定者:

readFully 在接口中 DataInput

参数:

b - the buffer into which the data is read.

off - the start offset of the data.

len - the number of bytes to read.

抛出:

EOFException - if this input stream reaches the end before reading all the bytes.

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

另请参阅:

FilterInputStream.in

skipBytes

public final int skipBytes(int n)
                    throws IOException

See the general contract of the skipBytes method of DataInput.

Bytes for this operation are read from the contained input stream.

指定者:

skipBytes 在接口中 DataInput

参数:

n - the number of bytes to be skipped.

返回:

the actual number of bytes skipped.

抛出:

IOException - if the contained input stream does not support seek, or the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

readBoolean

public final boolean readBoolean()
                          throws IOException

See the general contract of the readBoolean method of DataInput.

Bytes for this operation are read from the contained input stream.

指定者:

readBoolean 在接口中 DataInput

返回:

the boolean value read.

抛出:

EOFException - if this input stream has reached the end.

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

另请参阅:

FilterInputStream.in

readByte

public final byte readByte()
                    throws IOException

See the general contract of the readByte method of DataInput.

Bytes for this operation are read from the contained input stream.

指定者:

readByte 在接口中 DataInput

返回:

the next byte of this input stream as a signed 8-bit byte.

抛出:

EOFException - if this input stream has reached the end.

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

另请参阅:

FilterInputStream.in

readUnsignedByte

public final int readUnsignedByte()
                           throws IOException

See the general contract of the readUnsignedByte method of DataInput.

Bytes for this operation are read from the contained input stream.

指定者:

readUnsignedByte 在接口中 DataInput

返回:

the next byte of this input stream, interpreted as an unsigned 8-bit number.

抛出:

EOFException - if this input stream has reached the end.

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

另请参阅:

FilterInputStream.in

readShort

public final short readShort()
                      throws IOException

See the general contract of the readShort method of DataInput.

Bytes for this operation are read from the contained input stream.

指定者:

readShort 在接口中 DataInput

返回:

the next two bytes of this input stream, interpreted as a signed 16-bit number.

抛出:

EOFException - if this input stream reaches the end before reading two bytes.

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

另请参阅:

FilterInputStream.in

readUnsignedShort

public final int readUnsignedShort()
                            throws IOException

See the general contract of the readUnsignedShort method of DataInput.

Bytes for this operation are read from the contained input stream.

指定者:

readUnsignedShort 在接口中 DataInput

返回:

the next two bytes of this input stream, interpreted as an unsigned 16-bit integer.

抛出:

EOFException - if this input stream reaches the end before reading two bytes.

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

另请参阅:

FilterInputStream.in

readChar

public final char readChar()
                    throws IOException

See the general contract of the readChar method of DataInput.

Bytes for this operation are read from the contained input stream.

指定者:

readChar 在接口中 DataInput

返回:

the next two bytes of this input stream, interpreted as a char.

抛出:

EOFException - if this input stream reaches the end before reading two bytes.

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

另请参阅:

FilterInputStream.in

readInt

public final int readInt()
                  throws IOException

See the general contract of the readInt method of DataInput.

Bytes for this operation are read from the contained input stream.

指定者:

readInt 在接口中 DataInput

返回:

the next four bytes of this input stream, interpreted as an int.

抛出:

EOFException - if this input stream reaches the end before reading four bytes.

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

另请参阅:

FilterInputStream.in

readLong

public final long readLong()
                    throws IOException

See the general contract of the readLong method of DataInput.

Bytes for this operation are read from the contained input stream.

指定者:

readLong 在接口中 DataInput

返回:

the next eight bytes of this input stream, interpreted as a long.

抛出:

EOFException - if this input stream reaches the end before reading eight bytes.

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

另请参阅:

FilterInputStream.in

readFloat

public final float readFloat()
                      throws IOException

See the general contract of the readFloat method of DataInput.

Bytes for this operation are read from the contained input stream.

指定者:

readFloat 在接口中 DataInput

返回:

the next four bytes of this input stream, interpreted as a float.

抛出:

EOFException - if this input stream reaches the end before reading four bytes.

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

另请参阅:

readInt(), Float.intBitsToFloat(int)

readDouble

public final double readDouble()
                        throws IOException

See the general contract of the readDouble method of DataInput.

Bytes for this operation are read from the contained input stream.

指定者:

readDouble 在接口中 DataInput

返回:

the next eight bytes of this input stream, interpreted as a double.

抛出:

EOFException - if this input stream reaches the end before reading eight bytes.

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

另请参阅:

readLong(), Double.longBitsToDouble(long)

readLine

@Deprecated
public final String readLine()
                      throws IOException

已过时。 This method does not properly convert bytes to characters. As of JDK 1.1, the preferred way to read lines of text is via the BufferedReader.readLine() method. Programs that use the DataInputStream class to read lines can be converted to use the BufferedReader class by replacing code of the form:

     DataInputStream d = new DataInputStream(in);
 

with:

     BufferedReader d
          = new BufferedReader(new InputStreamReader(in));
 

See the general contract of the readLine method of DataInput.

Bytes for this operation are read from the contained input stream.

指定者:

readLine 在接口中 DataInput

返回:

the next line of text from this input stream.

抛出:

IOException - if an I/O error occurs.

另请参阅:

BufferedReader.readLine(), FilterInputStream.in

readUTF

public final String readUTF()
                     throws IOException

See the general contract of the readUTF method of DataInput.

Bytes for this operation are read from the contained input stream.

指定者:

readUTF 在接口中 DataInput

返回:

a Unicode string.

抛出:

EOFException - if this input stream reaches the end before reading all the bytes.

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

UTFDataFormatException - if the bytes do not represent a valid modified UTF-8 encoding of a string.

另请参阅:

readUTF(java.io.DataInput)

readUTF

public static final String readUTF(DataInput in)
                            throws IOException

Reads from the stream in a representation of a Unicode character string encoded in modified UTF-8 format; this string of characters is then returned as a String. The details of the modified UTF-8 representation are exactly the same as for the readUTF method of DataInput.

参数:

in - a data input stream.

返回:

a Unicode string.

抛出:

EOFException - if the input stream reaches the end before all the bytes.

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

UTFDataFormatException - if the bytes do not represent a valid modified UTF-8 encoding of a Unicode string.

另请参阅:

readUnsignedShort()