Java 中的 Java.io.FilterReader 类
原文:https://www . geesforgeks . org/Java-io-filter reader-class-Java/
用于读取过滤字符流的抽象类。抽象类 FilterReader 本身提供默认方法，将所有请求传递给包含的流。FilterReader 的子类应该覆盖这些方法中的一些，并且还可以提供额外的方法和字段。 建造师:
- 受保护的筛选读取器(读取器 in) :创建新的筛选读取器。
方法:
-
void close() : 关闭流并释放与其相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()调用将引发 IOException。关闭以前关闭的流没有效果。
java Syntax :public void close() throws IOException Throws: IOException -
空标记(int readAheadLimit) : 标记溪流中的当前位置。
java 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 -
布尔型 markSupported() : 告知此流是否支持 mark()操作。
java Syntax :public boolean markSupported() Returns: true if and only if this stream supports the mark operation. -
int read() : 读取单个字符。
java 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) : 将字符读入数组的一部分。
java 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 -
布尔就绪():告知该流是否准备好被读取。
java 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 -
无效重置():重置流。
java Syntax :public void reset() throws IOException Throws: IOException -
长跳过(长 n) : 跳过字符。
java 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
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