java中复制文本文件的方式我总结为14种(按字符读取4中，按字节读取8种！？？)

java中复制文件的方式

如果按照字符来读取的话，可以有4种，基本的2种，高效的2种，高效特殊的1种

第0种：

public class CopyFileDemo {
	public static void main(String[] args) throws Exception{
		//封裝数据源
		BufferedReader reader = new BufferedReader(new FileReader("a.txt"));
		//封装目的地
		BufferedWriter writer = new BufferedWriter(new FileWriter("b.txt"));
		
		//读写数据
		String line = null;
		while((line=reader.readLine())!=null){
			writer.write(line);
			writer.newLine();//添加新行，不然写到文件里面的内容就没有换行
			writer.flush();
		}
		//释放资源
		writer.close();
		writer.close();
	}
}

第一种：加入缓冲区Buffered一次读取一个字符数组

public class CopyFileTest {
	public static void main(String[] args) throws Exception{
		//封装数据源
		BufferedReader reader = new BufferedReader(new FileReader("a.txt"));
		//封装目的地
		BufferedWriter writer = new BufferedWriter(new FileWriter("b.txt"));
		
		//两种方式其中一种一次读取一个字符数组
		char[] chs = new char[1024];
		int len=0;
		while((len=reader.read(chs))!=-1){
			writer.write(chs,0,len);
			writer.flush();//记得刷新
		}
		//释放资源
		writer.close();
		reader.close();
	}
}

第二种：加入缓冲区Buffered一次读取一个字符

public class CopyFileTest {
	public static void main(String[] args) throws Exception{
		
		//封装数据源
		BufferedReader reader = new BufferedReader(new FileReader("a.txt"));
		//封装目的地
		BufferedWriter writer = new BufferedWriter(new FileWriter("b.txt"));
		//一次读取一个字符
		int ch=0;
		while((ch=reader.read())!=-1){
			writer.write(ch);
		}
		//释放资源
		writer.close();
		reader.close();
		
	}
}

第三种：普通的一次读取一个字符数组

public class BufferedCopyFileTest {
	public static void main(String[] args) throws Exception{
		
		//封装数据源
		FileReader reader = new FileReader("a.txt");
		//封装目的地
		FileWriter writer = new FileWriter("b.txt");
		//一次读取一个字符数组
		char[] chs = new char[1024];
		int len=0;
		while((len=reader.read(chs))!=-1){
			writer.write(chs,0,len);
			writer.flush();
		}
		writer.close();
		reader.close();
	}
}

第三种：普通的一次读取一个字符

public class BufferedCopyFileTest {
	public static void main(String[] args) throws Exception{
		//封装数据源
		FileReader reader = new FileReader("a.txt");
		//封装目的地
		FileWriter writer = new FileWriter("b.txt");
		//一次读取一个字符
		int ch=0;
		while((ch=reader.read())!=-1){
			writer.write(ch);
		}
		writer.close();
		reader.close();
		
	}
}

如果按照字节来读取的话，可以有8中

第一种：把字节流转换为字符流来一次读取一个字符

public class Copy {
	public static void main(String[] args) throws Exception {
		//封装数据源（把字节流转换为字符流）
		InputStreamReader isr = new InputStreamReader(new FileInputStream("a.txt"));
		//封装目的地（把字节流转换为字符流）
		OutputStreamWriter osw = new OutputStreamWriter(new FileOutputStream("b.txt"));
		//一次读取一个字符
		int ch=0;
		while((ch=isr.read())!=-1){
			osw.write(ch);
		}
		//关闭资源
		osw.close();
		isr.close();
	}
}

第二种：把字节流转换为字符流来一次读取一个字符数组

public class Copy {
	public static void main(String[] args) throws Exception {
		//封装数据源（把字节流转换为字符流）
		InputStreamReader isr = new InputStreamReader(new FileInputStream("a.txt"));
		//封装目的地（把字节流转换为字符流）
		OutputStreamWriter osw = new OutputStreamWriter(new FileOutputStream("b.txt"));
		//一次读取一个字符数组
		char[] chs = new char[1024];
		int len=0;
		while((len=isr.read(chs))!=-1){
			osw.write(chs,0,len);
			osw.flush();
		}
		//关闭资源
		osw.close();
		isr.close();
	}
}

第三种：高效字节流一次读写一个字节数组：

public static void method4(String srcString, String destString)  
                throws IOException {  
            BufferedInputStream bis = new BufferedInputStream(new FileInputStream(  
                    srcString));  
            BufferedOutputStream bos = new BufferedOutputStream(  
                    new FileOutputStream(destString));  
      
            byte[] bys = new byte[1024];  
            int len = 0;  
            while ((len = bis.read(bys)) != -1) {  
                bos.write(bys, 0, len);  
            }  
      
            bos.close();  
            bis.close();  
        }

第四种：高效字节流一次读取一个字符：

public static void method3(String srcString, String destString)  
                throws IOException {  
            BufferedInputStream bis = new BufferedInputStream(new FileInputStream(  
                    srcString));  
            BufferedOutputStream bos = new BufferedOutputStream(  
                    new FileOutputStream(destString));  
      
            int by = 0;  
            while ((by = bis.read()) != -1) {  
                bos.write(by);  
      
            }  
      
            bos.close();  
            bis.close();  
        }

第五种：普通的字节流对象一次读取一个字节数组

public static void method2(String srcString, String destString)  
                throws IOException {  
            FileInputStream fis = new FileInputStream(srcString);  
            FileOutputStream fos = new FileOutputStream(destString);  
      
            byte[] bys = new byte[1024];  
            int len = 0;  
            while ((len = fis.read(bys)) != -1) {  
                fos.write(bys, 0, len);  
            }  
      
            fos.close();  
            fis.close();  
        }

第六种：普通的字节流对象一次读取一个字节

public static void method1(String srcString, String destString)  
                throws IOException {  
            FileInputStream fis = new FileInputStream(srcString);  
            FileOutputStream fos = new FileOutputStream(destString);  
      
            int by = 0;  
            while ((by = fis.read()) != -1) {  
                fos.write(by);  
            }  
      
            fos.close();  
            fis.close();  
        }

第七种：BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream("a.txt")));

BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("b,txt")));然后一次读取一个字符

第八种：BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream("a.txt")));

BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("b,txt")));然后一次读取一个字符数组

注意复制图片、视频、音频的话，只有4种方式（字节流读取方式），不能用字符流读取