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！？？)

清疚 2022-08-02 15:50 52阅读 0赞

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