Java IO流之字符缓冲流实例详解

/字符输入缓冲流
	private static void charReader() {
		//目标文件
		File file = new File("F:\\javatest\\lemon1.txt");
		try {
			//字符流
			Reader reader = new FileReader(file);
			//为字符流提供缓冲，已达到高效读取的目的
			BufferedReader bufr = new BufferedReader(reader);
			
			char[] chars = new char[1024];
			int len = -1;
			while((len = bufr.read(chars)) != -1) {
				System.out.println(new String(chars,0,len));
			}
      bufr.close();
				
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

//字符输出缓存流
	private static void charWriter() {
		//目标文件
		File file = new File("F:\\javatest\\lemon1.txt");
		try {
			//字符流
			Writer writer = new FileWriter(file,true);//追加
			//为字符流提供缓冲，已达到高效读取的目的
			BufferedWriter bufr = new BufferedWriter(writer);
			bufr.write("这里是字符缓冲流\r\n");
			bufr.flush();
			bufr.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

package com.lemon;
 
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Reader;
import java.io.Writer;
/**
 * 缓存的目的：
 * 解决在写入文件操作时，频繁的操作文件所带来的性能降低问题
 * BufferedOutputStream内部默认的缓存大小是8kb，每次写入时存储到缓存中的byte数组中，当数组存满时，会把数组中的数据写入文件
 * 并且缓存下标归零 
 * 
 * 字符流：
 * 1、加入字符缓存流，增强读取功能（readLine）
 * 2、更高效的读取数据
 * FileReader：内部使用InputStreamReader，解码过程，byte->char，默认缓存大小为8k
 * BufferReader：默认缓存大小为8k，但可以手动指定缓存大小，把数据读取到缓存中，减少每次转换过程，效率更高
 * BufferedWriter：同上
 * @author lemonSun
 *
 * 2019年5月4日下午8:12:53
 */
public class BufferStreamDemo {
 
	public static void main(String[] args) {
	//	byteWriter();
	//	byteReader();
//		byteReader1();
//		charReader();
		charWriter();
	}
	
	//字符输出缓存流
	private static void charWriter() {
		//目标文件
		File file = new File("F:\\javatest\\lemon1.txt");
		try {
			//字符流
			Writer writer = new FileWriter(file,true);//追加
			//为字符流提供缓冲，已达到高效读取的目的
			BufferedWriter bufr = new BufferedWriter(writer);
			bufr.write("这里是字符缓冲流\r\n");
			bufr.flush();
			bufr.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	
	
	//字符输入缓存流
	private static void charReader() {
		//目标文件
		File file = new File("F:\\javatest\\lemon1.txt");
		try {
			//字符流
			Reader reader = new FileReader(file);
			//为字符流提供缓冲，已达到高效读取的目的
			BufferedReader bufr = new BufferedReader(reader);
			
			char[] chars = new char[1024];
			int len = -1;
			while((len = bufr.read(chars)) != -1) {
				System.out.println(new String(chars,0,len));
			}
			bufr.close();
				
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	
	
	//缓存流输入 不用关闭 try自动关闭 必须实现Closeable接口
	private static void byteReader1(){
		//目标文件
		File file = new File("F:\\javatest\\lemon1.txt");
		
		//buf作用域在try大括号里面多条语句try(;)，;隔开 
		try(BufferedInputStream buf = new BufferedInputStream(new FileInputStream(file))) {	
			byte[] bytes = new byte[1024];
			int len = -1;
			while((len = buf.read(bytes)) != -1) {
				System.out.println(new String(bytes,0,len));
			}
		
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		
	}
	
	//缓存流输入
	private static void byteReader(){
		//目标文件
		File file = new File("F:\\javatest\\lemon1.txt");
		
		try {
			//字节输出流
			InputStream in = new FileInputStream(file);
			//字节缓冲流
			BufferedInputStream buf = new BufferedInputStream(in);
			byte[] bytes = new byte[1024];
			int len = -1;
			while((len = buf.read(bytes)) != -1) {
				System.out.println(new String(bytes,0,len));
			}
			buf.close();//自动关闭 in.close
		
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		
	}
	
	
	//缓存流输出
	private static void byteWriter(){
		//目标文件
		File file = new File("F:\\javatest\\lemon1.txt");
		
		try {
			//字节输出流
			OutputStream out = new FileOutputStream(file,true);
			//缓冲流
			BufferedOutputStream buf = new BufferedOutputStream(out);
			//内容
			String info = "这里是缓冲流\r\n";
			//写入
			buf.write(info.getBytes());
			buf.close(); //jdk1.7以后自动关闭 out
		//	out.close();
				
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		
	}
 
}