package example;

import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;
import javax.sql.rowset.serial.SerialBlob;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Blob;
import java.sql.SQLException;
import java.text.ParseException;
import java.text.SimpleDateFormat;

@WebServlet(name = "StudentServlet", urlPatterns = {"/student/create", "/student/edit", "/student/photo", "/student/delete"})
// 允许上传文件,最大1M,
@MultipartConfig(
 fileSizeThreshold = 1024 * 1024, // 小于1m的文件保存在内存中
 maxRequestSize = 1024 * 1024
)
public class StudentServlet extends HttpServlet {
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 String path = request.getServletPath();
 switch (path) {
 case "/student/create":
 create(request, response);
 break;
 case "/student/edit":
 edit(request, response);
 break;
 default:
 request.setAttribute("msg", "不支持的url: " + path);
 request.getRequestDispatcher("/student/list.jsp").forward(request, response);
 }
 }

 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 String path = request.getServletPath();
 switch (path) {
 case "/student/delete":
 delete(request, response);
 break;
 case "/student/photo":
 getPhoto(request, response);
 break;
 default:
 request.setAttribute("msg", "不支持的url: " + path);
 request.getRequestDispatcher("/student/list.jsp").forward(request, response);
 }
 }

 // 新建学生
 private void create(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
 try {
 Student s = new Student();
 updateStudent(s, request);
 StudentDAO dao = new StudentDAO();
 dao.save(s);
 // 设置用于显示给用户的成功消息
 String msg = "已成功添加学生:" + s.getName();
 // 传递给 jsp
 request.setAttribute("msg", msg);
 request.getRequestDispatcher("list.jsp")
 .forward(request, response);
 } catch (SQLException e) {
 throw new IOException("save failed", e);
 }
 }

 // 使用客户端提交的信息更新student对象
 private void updateStudent(Student s, HttpServletRequest request) throws ServletException, SQLException, IOException {
 s.setNo(request.getParameter("No"));
 s.setName(request.getParameter("Name"));
 String a = request.getParameter("Age");
 if (a != null && a.length() > 0) {
 s.setAge(Integer.parseInt(a));
 }
 String b = request.getParameter("Birthday");
 SimpleDateFormat sf = new SimpleDateFormat("yyyy-MM-dd");
 if (b != null && b.length() > 0) {
 try {
 s.setBirthday(new java.sql.Date(sf.parse(b).getTime()));
 } catch (ParseException e) {
 e.printStackTrace();
 }
 }
 uploadPhoto(s, request);
 }

 // 处理照片上传
 private void uploadPhoto(Student s, HttpServletRequest request) throws IOException, ServletException, SQLException {
 Part filePart = request.getPart("Photo");
 if (filePart == null || filePart.getSize() <= 0) {
 return;
 }
 InputStream is = filePart.getInputStream();
 ByteArrayOutputStream os = new ByteArrayOutputStream();
 copy(is, os);
 Blob photo = new SerialBlob(os.toByteArray());
 s.setPhoto(photo);
 }

 private void edit(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
 try {
 String id = request.getParameter("Id");
 StudentDAO dao = new StudentDAO();
 Student s = dao.findById(id);
 updateStudent(s, request);
 dao.update(s);
 // 设置用于显示给用户的成功消息
 String msg = "已成功修改学生信息:" + s.getName();
 // 传递给 jsp
 request.setAttribute("msg", msg);
 request.getRequestDispatcher("list.jsp")
 .forward(request, response);
 } catch (SQLException e) {
 throw new IOException("save failed", e);
 }
 }

 // 删除学生
 private void delete(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 String id = request.getParameter("id");
 try {
 StudentDAO dao = new StudentDAO();
 dao.delete(id);
 // 传递给 jsp
 request.setAttribute("msg", "删除学生成功");
 request.getRequestDispatcher("list.jsp")
 .forward(request, response);
 } catch (SQLException e) {
 throw new IOException("cannot delete student by id: " + id, e);
 }
 }

 // 输出学生照片
 private void getPhoto(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 String id = request.getParameter("id");
 StudentDAO dao = new StudentDAO();
 try {
 Student s = dao.findById(id);
 if (s == null || s.getPhoto() == null) {
 response.sendError(404, "cannot found student by id:" + id);
 }
 // 设置结果MIME
 response.setContentType("image/jpg");
 // 照片直接写入输出流
 OutputStream os = response.getOutputStream();
 Blob photo = s.getPhoto();
 InputStream is = photo.getBinaryStream();
 copy(is, os);
 os.close();
 } catch (SQLException e) {
 throw new IOException("cannot found student by id: " + id, e);
 }
 }

 // 把数据从输入流is,复制到输出流os中
 public static void copy(InputStream is, OutputStream os) throws IOException {
 int rlen;
 byte[] buffer = new byte[1024];
 while ((rlen = is.read(buffer)) != -1) {
 os.write(buffer, 0, rlen);
 }
 }
}