Reader

java.lang.Object
- java.io.Reader

所有已实现的接口:

Closeable, AutoCloseable, Readable

直接已知子类:

BufferedReader, CharArrayReader, FilterReader, InputStreamReader, PipedReader, StringReader
```
public abstract class Reader
extends Object
implements Readable, Closeable
```
Abstract class for reading character streams. The only methods that a subclass must implement are read(char[], int, int) and close(). Most subclasses, however, will override some of the methods defined here in order to provide higher efficiency, additional functionality, or both.

从以下版本开始:

JDK1.1

另请参阅:

BufferedReader, LineNumberReader, CharArrayReader, InputStreamReader, FileReader, FilterReader, PushbackReader, PipedReader, StringReader, Writer

字段概要

字段
限定符和类型字段说明

protected Object lock
The object used to synchronize operations on this stream.

字段
限定符和类型	字段	说明
`protected Object`	`lock`	The object used to synchronize operations on this stream.

构造器概要

构造器
限定符	构造器	说明
`protected`	`Reader()`	Creates a new character-stream reader whose critical sections will synchronize on the reader itself.
`protected`	`Reader(Object lock)`	Creates a new character-stream reader whose critical sections will synchronize on the given object.

方法概要

所有方法实例方法抽象方法具体方法
限定符和类型	方法	说明
`abstract void`	`close()`	Closes the stream and releases any system resources associated with it.
`void`	`mark(int readAheadLimit)`	Marks the present position in the stream.
`boolean`	`markSupported()`	Tells whether this stream supports the mark() operation.
`int`	`read()`	Reads a single character.
`int`	`read(char[] cbuf)`	Reads characters into an array.
`abstract int`	`read(char[] cbuf, int off, int len)`	Reads characters into a portion of an array.
`int`	`read(CharBuffer target)`	Attempts to read characters into the specified character buffer.
`boolean`	`ready()`	Tells whether this stream is ready to be read.
`void`	`reset()`	Resets the stream.
`long`	`skip(long n)`	Skips characters.

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- 字段详细资料
  - lock
```
protected Object lock
```
    The object used to synchronize operations on this stream. For efficiency, a character-stream object may use an object other than itself to protect critical sections. A subclass should therefore use the object in this field rather than this or a synchronized method.
- 构造器详细资料
  - Reader
```
protected Reader()
```
    Creates a new character-stream reader whose critical sections will synchronize on the reader itself.
  - Reader
```
protected Reader(Object lock)
```
    Creates a new character-stream reader whose critical sections will synchronize on the given object.
    
    参数:
    
    lock - The Object to synchronize on.
- 方法详细资料
  - read
```
public int read(CharBuffer target)
         throws IOException
```
    Attempts to read characters into the specified character buffer. The buffer is used as a repository of characters as-is: the only changes made are the results of a put operation. No flipping or rewinding of the buffer is performed.
    
    指定者:
    
    read 在接口中 Readable
    
    参数:
    
    target - the buffer to read characters into
    
    返回:
    
    The number of characters added to the buffer, or -1 if this source of characters is at its end
    
    抛出:
    
    IOException - if an I/O error occurs
    
    NullPointerException - if target is null
    
    ReadOnlyBufferException - if target is a read only buffer
    
    从以下版本开始:
    
    1.5
  - read
```
public int read()
         throws IOException
```
    Reads a single character. This method will block until a character is available, an I/O error occurs, or the end of the stream is reached.
    Subclasses that intend to support efficient single-character input should override this method.
    
    返回:
    
    The character read, as an integer in the range 0 to 65535 (0x00-0xffff), or -1 if the end of the stream has been reached
    
    抛出:
    
    IOException - If an I/O error occurs
  - read
```
public int read(char[] cbuf)
         throws IOException
```
    Reads characters into an array. This method will block until some input is available, an I/O error occurs, or the end of the stream is reached.
    
    参数:
    
    cbuf - Destination buffer
    
    返回:
    
    The number of characters read, or -1 if the end of the stream has been reached
    
    抛出:
    
    IOException - If an I/O error occurs
  - read
```
public abstract int read(char[] cbuf,
                         int off,
                         int len)
                  throws IOException
```
    Reads characters into a portion of an array. This method will block until some input is available, an I/O error occurs, or the end of the stream is reached.
    
    参数:
    
    cbuf - Destination buffer
    
    off - Offset at which to start storing characters
    
    len - Maximum number of characters to read
    
    返回:
    
    The number of characters read, or -1 if the end of the stream has been reached
    
    抛出:
    
    IOException - If an I/O error occurs
  - skip
```
public long skip(long n)
          throws IOException
```
    Skips characters. This method will block until some characters are available, an I/O error occurs, or the end of the stream is reached.
    
    参数:
    
    n - The number of characters to skip
    
    返回:
    
    The number of characters actually skipped
    
    抛出:
    
    IllegalArgumentException - If n is negative.
    
    IOException - If an I/O error occurs
  - ready
```
public boolean ready()
              throws IOException
```
    Tells whether this stream is ready to be read.
    
    返回:
    
    True if the next read() is guaranteed not to block for input, false otherwise. Note that returning false does not guarantee that the next read will block.
    
    抛出:
    
    IOException - If an I/O error occurs
  - markSupported
```
public boolean markSupported()
```
    Tells whether this stream supports the mark() operation. The default implementation always returns false. Subclasses should override this method.
    
    返回:
    
    true if and only if this stream supports the mark operation.
  - mark
```
public void mark(int readAheadLimit)
          throws IOException
```
    Marks the present position in the stream. Subsequent calls to reset() will attempt to reposition the stream to this point. Not all character-input streams support the mark() operation.
    
    参数:
    
    readAheadLimit - Limit on the number of characters that may be read while still preserving the mark. After reading this many characters, attempting to reset the stream may fail.
    
    抛出:
    
    IOException - If the stream does not support mark(), or if some other I/O error occurs
  - reset
```
public void reset()
           throws IOException
```
    Resets the stream. If the stream has been marked, then attempt to reposition it at the mark. If the stream has not been marked, then attempt to reset it in some way appropriate to the particular stream, for example by repositioning it to its starting point. Not all character-input streams support the reset() operation, and some support reset() without supporting mark().
    
    抛出:
    
    IOException - If the stream has not been marked, or if the mark has been invalidated, or if the stream does not support reset(), or if some other I/O error occurs
  - close
```
public abstract void close()
                    throws IOException
```
    Closes the stream and releases any system resources associated with it. Once the stream has been closed, further read(), ready(), mark(), reset(), or skip() invocations will throw an IOException. Closing a previously closed stream has no effect.
    
    指定者:
    
    close 在接口中 AutoCloseable
    
    指定者:
    
    close 在接口中 Closeable
    
    抛出:
    
    IOException - If an I/O error occurs

类 Reader

字段概要

构造器概要

方法概要

从类继承的方法 java.lang.Object

字段详细资料

lock

构造器详细资料

Reader

Reader

方法详细资料

read

read

read

read

skip

ready

markSupported

mark

reset

close