JAVA------IO流复制总结

IO流复制文件

方法一
字符
注意点：写和读需要保持一致的编码形式。

 public class eee {
	public static void main(String[] args) {
		FileInputStream in = null;
		FileOutputStream out = null;
		OutputStreamWriter outw = null;
		InputStreamReader inr = null;
		try{
			
			out = new FileOutputStream("D:\\远程\\11.txt");
			in = new FileInputStream("D:\\远程\\22.txt");
			outw = new OutputStreamWriter(out,"UTF-8");
			inr = new InputStreamReader(in,"UTF-8");
			
			int len = 0;
			char[] c = new char[1024];
			while((len=inr.read(c))!=-1){
				outw.write(c, 0, len);
			}
		}catch(IOException ex){
			System.out.println(ex);
			throw new RuntimeException("文件写入失败,重试");
		}finally{
			try{
				if(outw!=null)
					out.flush();
					outw.close();
			}catch(IOException e){
				throw new RuntimeException("关闭资源失败");
			}finally{
				try{
					if(inr!=null){
						inr.close();
					}
				}catch(IOException ea){
					throw new RuntimeException("关闭资源失败");
				}
			}
		}
	}
}

方法二

/*
 *  将数据源 c:\\a.txt
 *  复制到 d:\\a.txt  数据目的
 *  字节输入流,绑定数据源
 *  字节输出流,绑定数据目的
 *  
 *  输入,读取1个字节
 *  输出,写1个字节
 */
public class Copy {
	public static void main(String[] args) {
		//定义两个流的对象变量
		FileInputStream fis = null;
		FileOutputStream fos = null;
		try{
			//建立两个流的对象,绑定数据源和数据目的
			fis = new FileInputStream("c:\\t.zip");
			fos = new FileOutputStream("d:\\t.zip");
			//字节输入流,读取1个字节,输出流写1个字节
			int len = 0 ;
			while((len = fis.read())!=-1){
				fos.write(len);
			}
		}catch(IOException ex){
			System.out.println(ex);
			throw new RuntimeException("文件复制失败");
		}finally{
			try{
				if(fos!=null)
					fos.close();
			}catch(IOException ex){
				throw new RuntimeException("释放资源失败");
			}finally{
				try{
					if(fis!=null)
						fis.close();
				}catch(IOException ex){
					throw new RuntimeException("释放资源失败");
				}
			}
		}
	}
}

方法二可以参考：

	public static void main(String[] args) throws IOException {
		FileInputStream fis = new FileInputStream("c:\\a.txt");
		//创建字节数组
		byte[] b = new byte[1024];
		
		int len = 0 ;
		while( (len = fis.read(b)) !=-1){
			System.out.print(new String(b,0,len));
		}
		fis.close();
	}

方法三

/*
 *  字符流复制文本文件,必须文本文件
 *  字符流查询本机默认的编码表,简体中文GBK
 *  FileReader读取数据源
 *  FileWriter写入到数据目的
 */
public class Copy_2 {
	public static void main(String[] args) {
		FileReader fr = null;
		FileWriter fw = null;
		try{
			fr = new FileReader("c:\\1.txt");
			fw = new FileWriter("d:\\1.txt");
			char[] cbuf = new char[1024];
			int len = 0 ;
			while(( len = fr.read(cbuf))!=-1){
				fw.write(cbuf, 0, len);
				fw.flush();
			}
			
		}catch(IOException ex){
			System.out.println(ex);
			throw new RuntimeException("复制失败");
		}finally{
			try{
				if(fw!=null)
					fw.close();
			}catch(IOException ex){
				throw new RuntimeException("释放资源失败");
			}finally{
				try{
					if(fr!=null)
						fr.close();
				}catch(IOException ex){
					throw new RuntimeException("释放资源失败");
				}
			}
		}
	}
}

知识点

缓冲流

字节缓冲流

/*
 *  文件复制方式,字节流,一共4个方式
 *  1. 字节流读写单个字节                    125250 毫秒
 *  2. 字节流读写字节数组                    193    毫秒  OK
 *  3. 字节流缓冲区流读写单个字节     1210   毫秒
 *  4. 字节流缓冲区流读写字节数组     73     毫秒  OK
 */
public class Copy {
	public static void main(String[] args)throws IOException {
		long s = System.currentTimeMillis();
		copy_4(new File("c:\\q.exe"), new File("d:\\q.exe"));
		long e = System.currentTimeMillis();
		System.out.println(e-s);
	}
	/*
	 * 方法,实现文件复制
	 *  4. 字节流缓冲区流读写字节数组
	 */
	public static void copy_4(File src,File desc)throws IOException{
		BufferedInputStream bis = new BufferedInputStream(new FileInputStream(src));
		BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(desc));
		int len = 0 ;
		byte[] bytes = new byte[1024];
		while((len = bis.read(bytes))!=-1){
			bos.write(bytes,0,len);
		}
		bos.close();
		bis.close();
	}
	/*
	 * 方法,实现文件复制
	 *  3. 字节流缓冲区流读写单个字节
	 */
	public static void copy_3(File src,File desc)throws IOException{
		BufferedInputStream bis = new BufferedInputStream(new FileInputStream(src));
		BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(desc));
		int len = 0 ;
		while((len = bis.read())!=-1){
			bos.write(len);
		}
		bos.close();
		bis.close();
	}
	
	/*
	 * 方法,实现文件复制
	 *  2. 字节流读写字节数组
	 */
	public static void copy_2(File src,File desc)throws IOException{
		FileInputStream fis = new FileInputStream(src);
		FileOutputStream fos = new FileOutputStream(desc);
		int len = 0 ;
		byte[] bytes = new byte[1024];
		while((len = fis.read(bytes))!=-1){
			fos.write(bytes,0,len);
		}
		fos.close();
		fis.close();
	}
	
	/*
	 * 方法,实现文件复制
	 *  1. 字节流读写单个字节
	 */
	public static void copy_1(File src,File desc)throws IOException{
		FileInputStream fis = new FileInputStream(src);
		FileOutputStream fos = new FileOutputStream(desc);
		int len = 0 ;
		while((len = fis.read())!=-1){
			fos.write(len);
		}
		fos.close();
		fis.close();
	}
}

推荐用缓冲流！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！

字符缓冲流

/*
 *  使用缓冲区流对象,复制文本文件
 *  数据源  BufferedReader+FileReader 读取
 *  数据目的 BufferedWriter+FileWriter 写入
 *  读取文本行, 读一行,写一行,写换行
 */
public class Copy_1 {
	public static void main(String[] args) throws IOException{
		BufferedReader bfr = new BufferedReader(new FileReader("c:\\w.log"));	
		BufferedWriter bfw = new BufferedWriter(new FileWriter("d:\\w.log"));
		//读取文本行, 读一行,写一行,写换行
		String line = null;
		while((line = bfr.readLine())!=null){
			bfw.write(line);
			bfw.newLine();
			bfw.flush();
		}
		bfw.close();
		bfr.close();
	}
}

/*
 * 打印流实现文本复制
 *   读取数据源  BufferedReader+File 读取文本行
 *   写入数据目的 PrintWriter+println 自动刷新
 */
public class PrintWriterDemo1 {
	public static void main(String[] args) throws IOException{
		BufferedReader bfr = new BufferedReader(new FileReader("c:\\a.txt"));
		PrintWriter pw = new PrintWriter(new FileWriter("d:\\a.txt"),true);//比BufferedWriter还要省事
		String line = null;
		while((line = bfr.readLine())!=null){
			pw.println(line);
		}
		pw.close();
		bfr.close();
	}
}