Java 使用字符流拷贝数据

使用字符流拷贝数据时，需要注意在文件末尾处的数据，因为最后一次读取的长度不会刚好与数组input长度相同，所以需要引入新的变量来存储每次读取的长度。

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;

public class RWByCharStream {

	public static void main(String[] args) {
		try {
			
			
//			File file=new File("java.txt");
			FileInputStream fis=new FileInputStream("java.txt");
			InputStreamReader isr=new InputStreamReader(fis,"UTF-8");
			FileOutputStream fos=new FileOutputStream("java_copy.txt");
			OutputStreamWriter osw=new OutputStreamWriter(fos);
			
			char input[]=new char[100];
			int f=0;
			while((f=isr.read(input))!=-1) {
//				System.out.println(new String(input,0,f));
				osw.write(input,0,f);
			}
			isr.close();
			fis.close();
			osw.close();
			fos.close();
			
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

}

---

使用缓冲字符流读写数据：

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.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;

public class RWByBufferedCharStream {

	public static void main(String[] args) {
		try {
			
//			File file=new File("java.txt");
			FileInputStream fis=new FileInputStream("java.txt");
			InputStreamReader isr=new InputStreamReader(fis,"UTF-8");
			FileOutputStream fos=new FileOutputStream("java_copy_buffer.txt");
			OutputStreamWriter osw=new OutputStreamWriter(fos);
			
			BufferedReader br=new BufferedReader(isr);
			BufferedWriter bw=new BufferedWriter(osw);
			
			String input;
			while((input=br.readLine())!=null) {
				bw.write(input);
			}
			
			bw.close();
			br.close();
			isr.close();
			fis.close();
			osw.close();
			fos.close();
			
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

}

 拷贝的文件中没有换行，全在同一行。

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.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;

public class RWByBufferedCharStream {

	public static void main(String[] args) {
		try {
			
//			File file=new File("java.txt");
			FileInputStream fis=new FileInputStream("java.txt");
			InputStreamReader isr=new InputStreamReader(fis,"UTF-8");
			FileOutputStream fos=new FileOutputStream("java_copy_buffer.txt");
			OutputStreamWriter osw=new OutputStreamWriter(fos);
			
			BufferedReader br=new BufferedReader(isr);
//			BufferedWriter bw=new BufferedWriter(osw);
			PrintWriter pw=new PrintWriter(osw);
			
			String input;
			while((input=br.readLine())!=null) {
//				bw.write(input);
				pw.println(input);
			}
			
//			bw.close();
			pw.flush();  //将最后一次读取的内容从缓冲区读出来
			pw.close();
			br.close();
			isr.close();
			fis.close();
			osw.close();
			fos.close();
			
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

}

 使用PrintWriter代替BufferedWriter，方便处理最后一次读取的内容和每行里的换行。