MySQL——全文检索-CFANZ编程社区

5.字节流

在这里插入图片描述

5.1 利用文件字节输出流向文件写入数据FileOutputStream

public class Test01 {
	public static void main(String[] args) throws IOException {
		
		//1.创建流对象
		FileOutputStream fos = new FileOutputStream("io.txt");
		
		//2.写入数据
		//fos.write(97);//写入UniCode码
		//fos.write("123abc".getBytes());//写入byte数组
		fos.write("123abc".getBytes(), 2, 3);//写入byte数组、偏移量、写入长度
		
		//3.关闭资源
		fos.close();
		
	}
}

public class Test02 {
	public static void main(String[] args) throws IOException {
		
		//1.创建流对象 + 设置在文件末尾追加
		FileOutputStream fos = new FileOutputStream("io.txt",true);
		
		//2.写入数据
		fos.write("123abc".getBytes());//写入byte数组
		
		//3.关闭资源
		fos.close();
		
	}
}

public class Test03 {
	public static void main(String[] args) {
		
		
		FileOutputStream fos = null;
		try {
			//1.创建流对象 + 设置在文件末尾追加
			fos = new FileOutputStream("io.txt",true);
			
			//2.写入数据
			fos.write("123abc".getBytes());//写入byte数组
			
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			
			//3.关闭资源
			if(fos != null){
				try {
					fos.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}		
		
	}
}

5.2 利用文件字节输入流读取文件里的数据FileInputStream

public class Test04 {
	public static void main(String[] args) throws IOException {
		
		//1.创建流对象
		FileInputStream fis = new FileInputStream("io.txt");
		
		//2.读取数据
		//read()：一个字节一个字节的读取数据，读取到文件末尾返回-1
		//int read = fis.read();
		//System.out.println(read);
        
        int read;
		while((read = fis.read()) != -1){
			System.out.println((char)read);
		}
				
		//3.关闭资源
		fis.close();
	}
}

public class Test06 {
	public static void main(String[] args) throws IOException{
		
		//1.创建流对象
		FileInputStream fis = new FileInputStream("io.txt");
		
		//2.读取数据
		//read(bs)：读取bs长度的数据，并把数据放入数组，返回读取到的有效字节数，如果读取到文件末尾则返回-1
		byte[] bs = new byte[1024];
		int len;
		while((len = fis.read(bs)) != -1){
			System.out.println(new String(bs, 0, len));
		}	
		
		//3.关闭资源
		fis.close();
	}
}

public class Test07 {
	public static void main(String[] args){
		
		FileInputStream fis = null;
		try {
			//1.创建流对象
			fis = new FileInputStream("io.txt");
			
			//2.读取数据
			//read(bs)：读取bs长度的数据，并把数据放入数组，返回读取到的有效字节数，如果读取到文件末尾则返回-1
			byte[] bs = new byte[1024];
			int len;
			while((len = fis.read(bs)) != -1){
				System.out.println(new String(bs, 0, len));
			}
			
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			//3.关闭资源
			if(fis != null){
				try {
					fis.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}
}

5.3 深入带缓冲区的字节输出流 FileOutputStream

public class Test04 {
	public static void main(String[] args) throws IOException{
		
		FileOutputStream fos = new FileOutputStream("io.txt");  基础流
		//写几次，就和硬盘交互几次  -- 6次（内存与硬盘交互的次数）
		fos.write("1".getBytes());
		fos.write("2".getBytes());
		fos.write("3".getBytes());
		fos.write("a".getBytes());
		fos.write("b".getBytes());
		fos.write("c".getBytes());
		fos.close();
		
		BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("io.txt"));
		//将数据写入到字节缓冲数组中 -- 1次（内存与硬盘交互的次数）
		bos.write("1".getBytes());
		bos.write("2".getBytes());
		bos.write("3".getBytes());
		bos.write("a".getBytes());
		bos.write("b".getBytes());
		bos.write("c".getBytes());
		//关闭时才将数据写入到文件中
		bos.close();
		
		//默认缓冲区 -- 8192个字节(8*1024)
		BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("io.txt"));
		
		//自定义缓冲区大小 -- 2048个字节
		BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("io.txt"), 2048);
	}
}

5.4 利用带缓冲区的字节输出流向文件写入数据BufferedOutputStream

public class Test01 {
	public static void main(String[] args) throws IOException {
		
		//1.创建流对象                     处理流
		BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("io.txt"));
		
		//2.写入数据
		bos.write("123abc".getBytes());
		
		//3.关闭资源
		bos.close();
		
	}
}

public class Test02 {
	public static void main(String[] args) throws IOException {
		
		//1.创建流对象
		BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("io.txt",true));
		
		//2.写入数据
		bos.write("123abc".getBytes());
		
		//3.关闭资源
		bos.close();
		
	}
}

public class Test03 {
	public static void main(String[] args){
		
		
		BufferedOutputStream bos = null;
		try {
			//1.创建流对象
			bos = new BufferedOutputStream(new FileOutputStream("io.txt",true));
			//2.写入数据
			bos.write("123abc".getBytes());
			
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			//3.关闭资源
			if(bos != null){
				try {
					bos.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}		
		
	}
}

5.5 手撕BufferedOutputStream底层源码

public class FilterOutputStream extends OutputStream {
    
	protected OutputStream out;//0x001
    
    //out - 0x001
    public FilterOutputStream(OutputStream out) {
        this.out = out;
    }
    
    //b - [65]
    public void write(byte[] b) throws IOException {
        this.write(b, 0, b.length);
    }
    
    @SuppressWarnings("try")
    public void close() throws IOException {
        try (OutputStream ostream = out) {
            flush();
        }
    }
}

public class BufferedOutputStream extends FilterOutputStream {
    //缓冲区数组
    protected byte[] buf;//new byte[8192]
    //缓冲区存放数据的个数
    protected int count;//1
    
    //out - 0x001
    public BufferedOutputStream(OutputStream out) {
        this(out, 8192);
    }
    
    //out - 0x001
    //size - 8192
    public BufferedOutputStream(OutputStream out, int size) {
        super(out);
        if (size <= 0) {
            throw new IllegalArgumentException("Buffer size <= 0");
        }
        buf = new byte[size];
    }
    
    //b - [65]
    //off - 0
    //len - 1
    public synchronized void write(byte b[], int off, int len) throws IOException {
        //判断现在需要写出的数据长度是否大于缓冲区数组
        if (len >= buf.length) {//1 >= 8192
            //将缓冲区数组里的数据写入到文件,将缓冲区清空
            flushBuffer();
            //将线程需要写出的数据写入到文件
            out.write(b, off, len);
            return;
        }
        
        //判断现在需要写出的数据长度 超过了缓冲区剩余的存储长度
        if (len > buf.length - count) {//1 > 8192-0
            //将缓冲区数组里的数据写入到文件,将缓冲区清空
            flushBuffer();
        }
        //将数据写入到缓冲区数组里
        System.arraycopy(b, off, buf, count, len);
        //更新缓冲区数组数据个数
        count += len;
    }
    
    private void flushBuffer() throws IOException {
        //count > 0说明缓冲区数组里有数据
        if (count > 0) {
            super.out.write(buf, 0, count);//调用的是FileOutputSteam的write()
            count = 0;//缓冲区清空
        }
    }
    
    public synchronized void flush() throws IOException {
        //将缓冲区数组里的数据写入到文件,将缓冲区清空
        flushBuffer();
        super.out.flush();//调用的是FileOutputSteam的close() -- 关流
    }
}

FileOutputStream fos = new FileOutputStream("io.txt");//0x001
BufferedOutputStream bos = new BufferedOutputStream(fos);

bos.write("1".getBytes());
bos.write("2".getBytes());
bos.write("3".getBytes());
bos.write("a".getBytes());
bos.write("b".getBytes());
bos.write("c".getBytes());

bos.close();

5.6 利用带有缓冲区的字节输入流读取文件里的数据 BufferedInputStream

public class Test05 {
	public static void main(String[] args) throws IOException {
		
		//1.创建流对象 （默认缓冲区大小：8192字节）
		BufferedInputStream bis = new BufferedInputStream(new FileInputStream("io.txt"));
		
		//1.创建流对象 （自定义缓冲区大小：2048字节）
		//BufferedInputStream bis = new BufferedInputStream(new FileInputStream("io.txt"),2048);
		
		//2.读取数据 
		byte[] bs = new byte[1024];
		int len;
		while((len = bis.read(bs)) != -1){
			System.out.println(new String(bs, 0, len));
		}
		
		//3.关闭资源
		bis.close();
	}
}

5.7 拷贝文件

public class Copy {
	public static void main(String[] args) throws IOException {
		
		BufferedInputStream bis = new BufferedInputStream(new FileInputStream("麻生希.mp4"));
		BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("copy.mp4"));
		
		byte[] bs = new byte[1024];
		int len;
		while((len = bis.read(bs)) != -1){
			bos.write(bs, 0, len);
		}
		
		bis.close();
		bos.close();
	}
}