Java IO流文件操作

字节流

以字节为单位来读取文件，适用所有文件（mp3 mp4 txt exe docx .......）

字符流

以字符为单位来读取文件, 只适用 txt文件文本文档的读取

FileInputStream 、FileOutputStream实现文件的删除复制

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;


public class Dome_FMove {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		//移动目标文件  #
		File file_del =  new File("#");
		File file_new =  new File("#");
		FileInputStream fis = null;
		FileOutputStream fos = null;
		
		try {
			fis = new FileInputStream(file_del);
			fos = new FileOutputStream(file_new);
			
			//缓冲区
			byte[] buffer = new byte[2048];
			int len = -1;
			
			while((len = fis.read(buffer)) != -1) {
				fos.write(buffer, 0, len);
			}
			
//			file_del.delete();  无法删除   因为文件流还在占用
			
			// 2. 在虚拟机运行后删除
			file_del.deleteOnExit();
			
			
		}catch(Exception e) {
			e.printStackTrace();
		}finally {
			try {
				if(fis != null) fis.close();
				if(fos != null) fos.close();
			}catch(Exception e) {
				e.printStackTrace();
			}
		}
		
		// 1.在关闭后删除
//		file_del.delete();
		
	}

}

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

/**
	 * 备注：
	 *    
	 *    文件的复制  字节流适用于 所有文件
	 *    
	 *    .write(buffer, 0, len);  防止 缓冲区的数据多余  截取文件内容
	 *    
	 * @version    
	 *    
	 */
public class Dome_Copy {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		FileInputStream fis = null;
		FileOutputStream fos = null;
		
		try {
			fis = new FileInputStream("d:/java.txt");
			fos = new FileOutputStream("src/dome/day09/test.ignore");
			
//			缓冲区
			byte[] buffer = new byte[2048];
			int len = -1;
			
			while((len = fis.read(buffer)) != -1) {
				//将读取出的内容   写入一个文件中
				//从 0 开始  文件末尾结束  
				fos.write(buffer, 0, len);
			}
			
			fos.flush();
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				if(fis != null) {
					fis.close();
				}
				if(fos != null) {
					fos.close();
				}
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}

}

BufferedReader、BufferedWriter实现文件的复制

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

/** 
	 * 备注：
	 *    BufferReader   BufferWriter    缓冲字符流
	 *    需要接收一个  字符流   new FileReader  or  new FileWrither
	 *    
	 *    readLine()  读一行 
	 *    利用 
	 *    StringBuffer sb = new StringBuffer(); 
	 *    sb.append(); 字符拼接
	 *    
	 *    bw.write(sb.toString());
	 *    sb.toString()  利用toString() 转为字符 写入其中
	 *    优点：
	 *    	 读写	效率高
	 *    
	 * @version    
	 *    
	 */
public class Demo_BufferReader {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		FileReader fr = null;
		BufferedReader br = null;
		FileWriter fw = null;
		BufferedWriter bw = null;
		try {
			
			fr = new FileReader("");
			br = new BufferedReader(fr);
			fw = new FileWriter("");
			bw = new BufferedWriter(fw);
			
		    StringBuffer sb = new StringBuffer(); 
		    String line = null;
		    while((line = br.readLine()) != null) {
		    	sb.append(line+"\n");
		    }
		    
		    bw.write(sb.toString());
		    bw.flush();
		} catch(Exception e) {
			e.printStackTrace();
		} finally {
			try {
				//关闭流  顺序和 new的 顺序相反
				if( bw != null) bw.close();
				if( fw != null) fw.close();
				if( br != null) br.close();
				if( fr != null) fr.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		
		
	}

}

FileReader、FileWriter 实现文件的复制

import java.io.FileReader;
import java.io.FileWriter;

/**      * 备注：
	 *    
	 *    字符流            FileReader     FileWriter
	 *    	字符占两个字节  --> char
	 *     	定义一个 char数组 作为缓冲区
	 *		char[] buffer = new char[128];
	 *		fw.write("可以接受字符");
	 * @version    
	 *    
	 */
public class Dome_FRString {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		
		FileReader fr = null;
		FileWriter fw = null;
		
		try {
			fr = new FileReader("#");
			fw = new FileWriter("#");
			
			fw.write("可以接受字符");
			
			// 1 .
//			int c= -1;
//			while((c = fr.read()) != -1) {
//				System.out.println((char)c);
//			}
			
			// 2. 定义一个 char数组
			char[] buffer = new char[128];
			int len = -1 ;
			while((len = fr.read(buffer)) != -1) {
				fw.write(buffer, 0, len);
			}
			
			fw.flush();
		} catch(Exception e) {
			e.printStackTrace();
		} finally {
			try {
				if(fr != null) fr.close();
				if(fw != null) fw.close();
			} catch(Exception e) {
				e.printStackTrace();
			}
			
		}
		
	}

}

字符替换 str.replace(old , new)

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

/**
	 * 备注：
	 *    
	 *    字符替换   str.replace(old , new);  
	 *    
	 *    读取文件    输出文件    实例化Student  替换相关信息 写入文件 输出文件
	 *    Student.java 	
	 *      private String name;
	 *		private Integer age;
	 * @version    
	 *    
	 */
public class Demo_replace {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		File file = new File("src/demo/day09/Student.txt");
		File file_up = new File("src/demo/day09/test.ignore");
		
		FileReader fr = null;
		FileWriter fw = null;
		BufferedReader br = null;
		BufferedWriter bw = null;
		
		try {
			fr = new FileReader(file);
			br = new BufferedReader(fr);
			fw = new FileWriter(file_up);
			bw = new BufferedWriter(fw);
			String line = null;
			StringBuffer sb = new StringBuffer();
			while((line = br.readLine()) != null) {
				sb.append(line);
			}
			System.out.println("old:"+sb.toString());
			Student student = new Student("李元芳",28);
//			sb.replace(0, "{name}", student.getName());
//			sb.replace(sb.indexOf("{"), sb.indexOf("}")+1, student.getName());
//			sb.replace(sb.indexOf("{"), sb.indexOf("}")+1, student.getAge().toString());
			String str = sb.toString();
			
			String str2 = str.replace("{name}", student.getName()).replace("{age}", student.getAge().toString());
//			str.replace("{name}", "aaaa");
			System.out.println("new:"+str2);
			bw.write(str2.toString());
			bw.flush();
//			fr1 = new FileReader(file_up);
//			br = new BufferedReader(fr1);
//			String line1 = null;
//			while((line1 = br.readLine()) != null) {
//				System.out.println(line1);
//			}
//			
		} catch(Exception e) {
			e.printStackTrace();
		} finally {
			try {
				if(bw != null) bw.close();
				if(fw != null) fw.close();
				if(br != null) br.close();
				if(fr != null) fr.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		
	}

}

以上都是自己在学Java时的笔记

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Java IO流 文件操作

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