BufferedReader 和 BufferedWriter

Java BufferedReader類別從字元輸入流中讀取文本，緩衝讀取的字元以實現字元、陣列和字串的高效讀取。您可以將緩衝區大小指定為建構函式中的第二個參數。 設計師：

BufferedReader(Reader in) // Creates a character input buffer stream that uses the default buffer size.
BufferedReader(Reader in, int sz) // Creates a character input buffer stream that uses the specified size.

方法：

close() // close the stream
mark(int readAheadLimit) // mark the position in the stream
markSupported() // does it support thread tagging
int read() // read buffer
int read(char[] cbuf, int off, int len) // read buffer
String readLine() // next line
boolean ready() // can the thread read
reset() // reset stream
skip(long n) // skip characters

使用 BufferedReader 和 BufferedWriter 類別的範例： 讀取檔案：

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class FileReaderExample {

	public static void main(String[] args) {
		String inputFileName = "file.txt";

		try (BufferedReader reader = new BufferedReader(new FileReader(inputFileName))) {
			String line;
			while ((line = reader.readLine()) != null) {
				System.out.println(line + "\n");
			}
		}
                catch (IOException e) {
			e.printStackTrace();
		}
	}

}

Java BufferedWriter 類別將文字寫入字元輸出流，對寫入的字元進行緩衝，以實現字元、陣列和字串的高效寫入。您可以將緩衝區大小指定為建構函式中的第二個參數。 設計師：

BufferedWriter(Writer out) // Creates a character output buffer stream that uses the default buffer size.
BufferedWriter(Writer out, int sz) // Creates a character output buffer stream that uses the specified size.

方法：

close() // close the stream
flush() // pass data from buffer to Writer
newLine() // wrap to new line
write(char[] cbuf, int off, int len) // write to buffer
write(int c) // write to buffer
write(String s, int off, int len) // write to buffer

使用 Java BufferedReader 和 BufferedWriter 類別的範例： 寫入文件

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;

public class FileWritterExample {

	public static void main(String[] args) {
		String outputFileName = "file.txt";
		String[] array = { "one", "two", "three", "four" };

		try (BufferedWriter writter = new BufferedWriter(new FileWriter(outputFileName))) {
			for (String value : array) {
				writter.write(value + "\n");
			}
		}
        catch (IOException e) {
			e.printStackTrace();
		}
	}

}

FileWriter立即將資料寫入磁碟並每次存取它，緩衝區充當包裝器並加速應用程式。緩衝區會將資料寫入自身，然後將一大塊檔案寫入磁碟。 我們從控制台讀取資料並將其寫入檔案：

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;

public class ConsoleReaderExample {

	public static void main(String[] args) {
		String outputFileName = "file.txt";

		try (BufferedReader reader = new BufferedReader(new InputStreamReader(System.in))) {
			try (BufferedWriter writter = new BufferedWriter(new FileWriter(outputFileName))) {
				String line;
				while (!(line = reader.readLine()).equals("exit")) { // Break the loop when writing the line exit
					writter.write(line);
				}
			}
		}
         catch (IOException e) {
			e.printStackTrace();
		}
	}

}