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【Django】使用captcha自动创建验证码

小飞侠熙熙 04-13 07:00 阅读 1
学习java-ee各种流

各种流

1.对象流

1.1 利用对象输出流 向文件写入数据ObjectOutputStream
public class Test01 {
	public static void main(String[] args) throws FileNotFoundException, IOException {
		
		//1.创建流对象
		ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("io.txt"));
		
		//2.写入数据
		oos.writeInt(100);//写入int值
		oos.writeDouble(123.123);//写入double值
		oos.writeUTF("用良心做教育");//写入字符串
		oos.writeObject(new Date());//写入对象
		
		//3.关闭资源
		oos.close();
	}
}
1.2 利用对象输入流 读取文件里的数据ObjectInputStream
public class Test02 {
	public static void main(String[] args) throws FileNotFoundException, IOException, ClassNotFoundException {
		
		//1.创建流对象
		ObjectInputStream ois = new ObjectInputStream(new FileInputStream("io.txt"));
		
		//2.读取数据（读取顺序必须和写入顺序一致）
		int readInt = ois.readInt();
		double readDouble = ois.readDouble();
		String str = ois.readUTF();
		Date date = (Date) ois.readObject();
		
		System.out.println(readInt);
		System.out.println(readDouble);
		System.out.println(str);
		System.out.println(date);
		
		//3.关闭资源
		ois.close();
		
	}
}
1.3 利用对象输出流 向文件写入自定义对象ObjectOutputStream
public class Test03 {
	/**
	 * 知识点：利用对象输出流 向文件写入自定义对象
	 */
	public static void main(String[] args) throws FileNotFoundException, IOException {
		
		//1.创建流对象
		ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("io.txt"));
		
		//2.写入自定义对象
		oos.writeObject(new User("1445584980", "123123"));
		oos.writeObject(new User("1534534534", "111222"));
		oos.writeObject(new User("5345356683", "123456"));
		oos.writeObject(null);
		
		//3.关闭资源
		oos.close();
		
	}
}

public class User implements Serializable{//要实现序列化接口（Serializable）
	
	private static final long serialVersionUID = 4907921883130742331L;
	
	private String username;
	private transient String password;
	
    //无参构造，有参构造，get，set方法省略
1.4 利用对象输入流 读取文件中的自定义对象ObjectInputStream
public class Test04 {
	public static void main(String[] args) throws FileNotFoundException, IOException, ClassNotFoundException {
		
		//1.创建流对象
		ObjectInputStream ois = new ObjectInputStream(new FileInputStream("io.txt"));
		
		//2.读取自定义对象
		User user;
		while((user = (User)ois.readObject()) != null){
			System.out.println(user);
		}
		
		//3.关闭资源
		ois.close();
	}
}

2.内存流

2.1 内存输出流ByteArrayOutputStream
public class Test01 {
	public static void main(String[] args) throws IOException {
		
		//1.创建流对象
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		
		//关闭资源(内存流是程序到内存的通道，是关闭不掉的)
		//baos.close();
		
		//2.写入数据 -- 将数据写入到baos对象中的byte数组里
		baos.write("123abc木头人".getBytes());
		
		//获取流对象里的数据
		System.out.println(new String(baos.toByteArray()));
		System.out.println(baos.toString());
	}
}
2.2 内存输入流ByteArrayInputStream
public class Test02 {
	public static void main(String[] args) throws IOException {
		
		//1.创建流对象
		ByteArrayInputStream bais = new ByteArrayInputStream("123abc木头人".getBytes());
		
		//关闭资源(内存流是程序到内存的通道，是关闭不掉的)
		//bais.close();
		
		//2.读取数据
		byte[] bs = new byte[1024];
		int len;
		while((len = bais.read(bs)) != -1){
			System.out.println(new String(bs, 0,len));
		}		
		
	}
}

3.打印流

3.1 字节打印流PrintStream
public class Test01 {
	public static void main(String[] args) throws IOException {
		
		//1.创建流对象
		//PrintStream ps = new PrintStream("io.txt");
		
		//1.创建流对象(字节流 -> 字节打印流)
		//PrintStream ps = new PrintStream(new FileOutputStream("io.txt"));
		
		//1.创建流对象(字节流 -> 字节打印流) + 在末尾追加
		PrintStream ps = new PrintStream(new FileOutputStream("io.txt",true));
		
		//2.写入数据
		ps.write("好好学习".getBytes());
		
		//3.关闭资源
		ps.close();		
		
	}
}
3.2 字符打印流PrintWriter
public class Test02 {
	public static void main(String[] args) throws IOException {
		
		//1.创建流对象
		//PrintWriter pw = new PrintWriter("io.txt");
		
		//1.创建流对象(字节流 -> 字节打印流)
		//PrintWriter pw = new PrintWriter(new FileOutputStream("io.txt"));
		
		//1.创建流对象(字节流 -> 字节打印流) + 在末尾追加
		//PrintWriter pw = new PrintWriter(new FileOutputStream("io.txt",true));
		
		//1.创建流对象(字符流 -> 字符打印流)
		//PrintWriter pw = new PrintWriter(new FileWriter("io.txt"));
		
		//1.创建流对象(字符流 -> 字符打印流) + 在末尾追加
		//PrintWriter pw = new PrintWriter(new FileWriter("io.txt",true));
		
		//1.创建流对象(设置编码格式 + 在末尾追加 + 考虑到效率)
		PrintWriter pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(new FileOutputStream("io.txt",true), "GBK")));
		
		//2.写入数据
		pw.write("好好学习");
		
		//3.关闭资源
		pw.close();		
		
	}
}

4.扩展：重定向

4.1 System.in
public class Test03 {
	public static void main(String[] args) throws FileNotFoundException {
		
		//重定向：重新定义系统标准输入流的方向(文件->程序)
		System.setIn(new FileInputStream("io.txt"));
		
		InputStream in = System.in;
		
		Scanner scan = new Scanner(in);
		String str = scan.next();
		System.out.println(str);
		scan.close();
	}
	
}
4.2 System.out
public class Test04 {
	public static void main(String[] args) throws FileNotFoundException {
		
		//重定向：重新定义系统标准输出流的方向(程序->文件)
		System.setOut(new PrintStream(new FileOutputStream("io.txt",true)));
		
		PrintStream ps = System.out;
		ps.println("好好学习");
	}
	
}
4.3 System.err
public class Test05 {
	public static void main(String[] args) throws FileNotFoundException {
		
		//重定向：重新定义系统标准错误输出流的方向(程序->文件)
		System.setErr(new PrintStream(new FileOutputStream("io.txt",true)));
		
		PrintStream ps = System.err;
		ps.println("好好学习");
	}
	
}

5.随机访问流

5.1 利用随机访问流 向文件写入数据 RandomAccessFile
public class Test01 {
	public static void main(String[] args) throws IOException {
		
		//1.创建流对象
		RandomAccessFile w = new RandomAccessFile("io.txt", "rw");
		
		//2.写入数据
		w.write("123abc木头人".getBytes());
		
		//3.关闭资源
		w.close();
	}
}

public class Test02 {
	public static void main(String[] args) throws IOException {
		
		//1.创建流对象
		File file = new File("io.txt");
		RandomAccessFile w = new RandomAccessFile(file, "rw");
		
		//设置指针的位置
		w.seek(file.length());
		
		//2.写入数据
		w.write("123abc木头人".getBytes());
		
		//3.关闭资源
		w.close();
	}
}

5.2 利用随机访问流 读取文件里的数据 RandomAccessFile

public class Test03 {
	public static void main(String[] args) throws IOException {
		
		//1.创建流对象
		RandomAccessFile r = new RandomAccessFile("io.txt", "r");

		//2.读取数据
		byte[] bs = new byte[1024];
		int len;
		while((len = r.read(bs)) != -1){
			System.out.println(new String(bs, 0, len));
		}
		
		//3.关闭资源
		r.close();
	}
}
5.2 利用随机访问流 读取文件里的数据 RandomAccessFile
public class Test04 {
	public static void main(String[] args) throws IOException {
		
		//1.创建流对象
		RandomAccessFile r = new RandomAccessFile("io.txt", "r");

		//设置指针的位置
		r.seek(3);
		
		//2.读取数据
		byte[] bs = new byte[1024];
		int len;
		while((len = r.read(bs)) != -1){
			System.out.println(new String(bs, 0, len));
		}
		
		//3.关闭资源
		r.close();
	}
}
5.3 拷贝文件 – 断点续传
public class Copy {
	public static void main(String[] args) throws IOException {
		
		RandomAccessFile r = new RandomAccessFile("视频.mp4", "r");
		File targetFile = new File("copy.mp4");
		RandomAccessFile w = new RandomAccessFile(targetFile, "rw");
		
		//设置指针
		long fileLength = targetFile.length();
		r.seek(fileLength);
		w.seek(fileLength);
		
		byte[] bs = new byte[1024];
		int len;
		while((len = r.read(bs)) != -1){
			w.write(bs, 0, len);
		}
		
		r.close();
		w.close();
	}
}

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