通过InputStream访问文件中的数据的四种方法

//方法一(每次只读取一个字节)
	public static void getFile() throws IOException {
		
		File file = new File("D:\a.txt");
		
		FileInputStream fileinputstream = new FileInputStream(file);
		
		int data = fileinputstream.read();
		int data1 = fileinputstream.read();
		
		System.out.println("获取的数据"+data1);
		fileinputstream.close();
		
		
	}

　　只是输出目标文件的第一个字符，所以说很不实用

//方法二

public static void getFile2() throws IOException {
		File file = new File("D:\a.txt");
		
		FileInputStream fileInputStream = new FileInputStream(file);
		
		for (int i = 0; i <file.length(); i++) {
	
			System.out.print((char)fileInputStream.read());
		}
		fileInputStream.close();
	}

通用步骤：

　　1.找到目标文件:注意操作的是文件而不是文件夹（切记！！！！！）

　　2.建立通道

　　3.[创建缓冲区]

　　4.读取数据:read()只获取一个字节

　　5.释放之原文件

　　

需要不断地运行一个循环内存占用过大

public static void getFile3() throws IOException {
		File file = new File("D:\a.txt");
		
		FileInputStream fileInputStream = new FileInputStream(file);
		
		byte[] b = new byte[(int) file.length()];
		
		int count = fileInputStream.read(b);
		
		System.out.println(count);
		
		System.out.println(new String(b));
		
		fileInputStream.close();
		
		
	}

　　

	public static void getFile4() throws IOException {
		
		File file = new File("D:\java\第十八次课\代码\Day18\src\com\beiwo\File\Demo1.java");                       
		
		FileInputStream fileInputStream = new FileInputStream(file);
		
		byte[] b = new byte[1024];
		
		int count = 0;
		
		while ((count = fileInputStream.read(b))!= -1) {
		System.out.println(new String(b,0,count));
			
		}
		
		fileInputStream.close();
	}

　　终极版