The origin server did not find a current representation for the target resource or is not 解決方法

Tomcat 404 error: The origin server did not find a current representation for the target resource or 添加映射即可解決，添加@webServlet與路徑檔案名

package com.cjky;

import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class UpdateServlet
 */
@WebServlet("/UpdateServlet_modify") //缺少此句話就會出現“Tomcat 404 error: The origin server did not find a current representation for the target resource or”
public class UpdateServlet_modify extends HttpServlet {
	private static final long serialVersionUID = 1L;
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	//	int id = Integer.valueOf(request.getParameter("id"));
	//	int bookCount = Integer.valueOf(request.getParameter("bookCount")); 
		String mc_name=request.getParameter("mc_name");
		String modify_content=request.getParameter("modify_content");
		try {
			// 加載資料庫驅動，注冊到驅動管理器
			Class.forName("com.mysql.jdbc.Driver");
			// 資料庫連接配接字元串
			String url = "jdbc:mysql://localhost:3306/db_cjky_pm";
			// 資料庫使用者名
			String username = "sa";
			// 資料庫密碼
			String password = "123456";
			// 建立Connection連接配接
			Connection conn = DriverManager.getConnection(url,username,password);
			// 更新SQL語句
			String sql = "update tb_books set modify_content=? where mc_name=?";
			// 擷取PreparedStatement
			PreparedStatement ps = conn.prepareStatement(sql);
			// 對SQL語句中的第一個參數指派
			ps.setString(1, modify_content);
			// 對SQL語句中的第二個參數指派
			ps.setString(2, mc_name);
			// 執行更新操作
			ps.executeUpdate();
			// 關閉PreparedStatement
			ps.close();
			// 關閉Connection
			conn.close();
		} catch (Exception e) {
			e.printStackTrace();
		} 
		// 重定向到FindServlet
		response.sendRedirect("data_query_servlet");
	}

}