Java Java类
用于读取过滤字符流的抽象类。抽象类 FilterReader 本身提供了将所有请求传递给包含的流的默认方法。 FilterReader 的子类应该覆盖其中的一些方法，并且还可以提供额外的方法和字段。
构造函数：
- protected FilterReader(Reader in) : 创建一个新的过滤阅读器。
方法：
- void close() :关闭流并释放与之关联的任何系统资源。一旦流被关闭，进一步的 read()、ready()、mark()、reset() 或 skip() 调用将抛出 IOException .关闭以前关闭的流没有效果。
Syntax :public void close() throws IOException Throws: IOException - void mark(int readAheadLimit) ：标记流中的当前位置。
Syntax :public void mark(int readAheadLimit) throws IOException Parameters: 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. Throws: IOException - boolean markSupported() ：判断此流是否支持 mark() 操作。
Syntax :public boolean markSupported() Returns: true if and only if this stream supports the mark operation. - int read() ：读取单个字符。
Syntax :public int read() throws IOException Returns: 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 Throws: IOException - int read(char[] cbuf, int off, int len) ：字符读入数组的一部分。
Syntax :public int read(char[] cbuf, int off, int len) throws IOException Parameters: cbuf - Destination buffer off - Offset at which to start storing characters len - Maximum number of characters to read Returns: The number of characters read, or -1 if the end of the stream has been reached Throws: IOException - boolean ready() ：判断该流是否准备好被读取。
Syntax :public boolean ready() throws IOException Returns: 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. Throws: IOException - void reset() ：重置流。
Syntax :public void reset() throws IOException Throws: IOException - long skip(long n) ：跳过字符。
Syntax :public long skip(long n) throws IOException Parameters: n - The number of characters to skip Returns: The number of characters actually skipped Throws: IOException
程序 ：
//Java program illustrating FilterReader class methods
import java.io.*;
class FilterReaderdemo
{
public static void main(String[] args) throws IOException
{
Reader r = new StringReader("GeeksforGeeks");
FilterReader fr = new FilterReader(r)
{
};
char ch[] = new char[8];
//illustrating markSupported()
if(fr.markSupported())
{
//illustrating mark() method
System.out.println("mark method is supported");
fr.mark(100);
}
//illustrating skip() method
fr.skip(5);
//illustrating ready()
if(fr.ready())
{
//illustrating read(char[] cbuff,int off,int len)
fr.read(ch);
for (int i = 0; i < 8; i++)
{
System.out.print(ch[i]);
}
//illustrating reset()
fr.reset();
for (int i = 0; i <5 ; i++)
{
//illustrating read()
System.out.print((char)fr.read());
}
}
//closing the stream
fr.close();
}
}
输出 ：
mark method is supported
forGeeksGeeks