Java学习笔记-全栈-web开发-06-Request&Response

@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) 
			throws ServletException, IOException {
		// 设置响应类型和字符编码为UTF-8, 这样支持汉字显示
//		resp.setContentType("text/html");
//		resp.setCharacterEncoding("UTF-8");
		
		//设置客户编码类型
		resp.setHeader("Content-Type", "text/html;charset=utf-8");
		//不设置编译类型，默认编码发送数据 ISO-8859-1（没有中国二字编码），此时会发生乱码
		resp.getWriter().write("hello你好");
	}

Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) 
			throws ServletException, IOException {
		String filename = "Java基础考试题卷.docx";
		
		//下载文件
		String path = "C:/Users//Desktop/upload/" + filename;
		FileInputStream fis = new FileInputStream(path);
		
		//设置请求头,文件名需要UTF-8编码
		filename = URLEncoder.encode(filename, "UTF-8");
		resp.setHeader("Content-disposition", "attachment;filename=" + filename);
		byte[] bs = new byte[1024];
		ServletOutputStream sos = resp.getOutputStream();
		int len = 0;
		while((len = fis.read(bs)) != -1){
			sos.write(bs, 0, len);
		}
		
		fis.close();
	}

@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) 
			throws ServletException, IOException {
		int WIDTH=120;
		int HEIGHT=30;
		//创建画布
		BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
	
		//创建画笔
		Graphics g = image.getGraphics();
		
		//设置画笔颜色
		g.setColor(Color.YELLOW);
		
		//画背景
		g.fillRect(0, 0, WIDTH, HEIGHT);
		
		//设置干扰线颜色
		g.setColor(Color.BLUE);
		
		//加干扰线
		for(int i=0;i<6;i++){
			int xStart = new Random().nextInt(WIDTH);
			int yStart = new Random().nextInt(HEIGHT);
			int xEnd = new Random().nextInt(WIDTH);
			int yEnd = new Random().nextInt(HEIGHT);
			g.drawLine(xStart, yStart, xEnd, yEnd);
		}
		
		int x = 5;
		//画随机数
		for(int i = 0; i< 4;i++){
			g.drawString(new Random().nextInt(9) + "", x+i*30, 20);
		}
		
		//输出图片 设置响应格式
		resp.setContentType("image/jpeg");
		ImageIO.write(image, "JPEG",resp.getOutputStream());
	}

response.sendRedirect(request.getContextPath()+”/转发注解”)

request.getRequestDispatcher(“/转发注解”).forward(request,response)

@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse response) 
			throws ServletException, IOException {
		//浏览器刷新时就不会有缓存
		response.addHeader("Pragma", "no-cache"); 
		response.setHeader("Cache-Control", "no-cache"); 
		response.setHeader("Expires", "0");
		ValidateCode code = new ValidateCode(WIDTH, HEIGHT, 4, 6);
		
		code.write(response.getOutputStream());
	}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.setContentType("text/html;charset=UTF-8");
		//response.setHeader("Refresh", "1");//每隔一秒刷新一次
		
		response.setHeader("Refresh", "5;URL=index.html");//3秒后转到另一页面
		response.getWriter().write("注册成功!3秒后会自动跳转，苦没有中转点击<a href='index.html'>这里</a>");
	}

<form action="/项目名/注解内的地址" method="post">
用户名：<input type="text" name="username"><br>
密---码：<input type="password" name="password"><br>
性---别：<input type="radio" name="gender" value="男">男
	<input type="radio" name="gender" value="女">女<br>
爱---好：<input type="checkbox" name="hobby" value="写代码">写代码
<input type="checkbox" name="hobby" value="看书">看书
<input type="checkbox" name="hobby" value="听课">听课<br>
备---注：<textarea rows="5" cols="20" name="remark"></textarea><br>
<input type="submit" value="提交">
</form>

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws 	ServletException, IOException {
		//接收表单请求参数
	request.setCharacterEncoding("UTF-8");
	String username = request.getParameter("username");
	String password = request.getParameter("password");
	String gender = request.getParameter("gender");
	String remark = request.getParameter("remark");
	String[] hobby = request.getParameterValues("hobby");
	
	System.out.println(username);
	System.out.println(password);
	System.out.println(gender);
	System.out.println(remark);
	System.out.println(Arrays.toString(hobby));	
}

public class Test extends HttpServlet{
	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse resp) throws ServletException, IOException {
		//post请求时，中文会乱码,解决方法setCharacterEncoding,只针对post请求有效
		request.setCharacterEncoding("UTF-8");
		
		//创建用户对象
		User user = new User();
		
		//获取请求参数
		/**
		 * key			value
		 * username		{"shunxu"};
		 * password     {"123"};
		 * hobby		{"study","reading"}
		 */
		Map<String, String[]> map = request.getParameterMap();
		try {
			for(Entry<String, String[]> entry : map.entrySet()){
				String pname = entry.getKey();
				//通过name创建对象
				if(pname.equals("username")){
					user.setUsername(entry.getValue()[0]);
				}else if(pname.equals("hobby")){
					user.setHobby(entry.getValue());
				}
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		System.out.println(user);
	}
}

@WebServlet("/test")
public class Test extends httpServlet{
	private static final long serialVersionUID =1L;
	protected void doGet(HttpServletRequest request,HttpServeltResponse response)
			throws Exception{
		String cp = request.getContextPath();
		System.out.println(cp);   //打印上下文路径
		response.sendRedirect(cp+"/login.jsp"); //跳转到jsp页面，需要加上contextPath
}