2022-11-14 서블릿 메소드 분리하기, DB와 연결하기

서블릿 생성

 

- 톰캣4.0v

: 클래스 상단부분에 자동생성됨

@WebServlet(name = "서블릿이름",urlPatterns = {"/서블릿path"})
@WebServlet(name = "emplist",urlPatterns = {"/emp/list.do"})

 

- 톰캣5.0v

web.xml파일 생성되고 여기에 자동추가됨

<servlet>
    <description></description>
    <display-name>basic</display-name>
    <servlet-name>basic</servlet-name>
    <servlet-class>basic.basic</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>basic</servlet-name>
    <url-pattern>/basic.do</url-pattern>
  </servlet-mapping>

 

 

 

메소드 분리하기

 

package basic;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

@WebServlet(name = "calc2",urlPatterns = {"/calc2.do"})
public class CalcServlet2 extends HttpServlet {

	protected void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
		req.setCharacterEncoding("UTF-8");
		res.setContentType("text/html;charset=UTF-8");
		PrintWriter pw = res.getWriter();
		// 클라이언트의 요청 정보 추출
		int num1 = Integer.valueOf(req.getParameter("num1"));
		String method = req.getParameter("method");
		int num2 = Integer.valueOf(req.getParameter("num2"));
		
            switch (method) {
            case "+":
                result = num1 + num2;
                break;
            case "-":
                result = num1 - num2;
                break;
            case "*":
                result = num1 * num2;
                break;
            case "/":
                result = num1 / num2;
                break;
            }

		pw.print("<h1>계산결과</h1>");
		pw.print("<hr/");
		pw.println("<h3>num1의 "+num1+"과 num2의 "+num2+"을(를) 연산한 결과는"+result+"입니다.</h3>");

=========메소드 분리========>

public class Calc {
	public int clac(int num1, int num2, String method) {
		System.out.println("비지니스메소드 호출 성공~~"); //연결됐는지 확인하기
		int result = 0;
		switch (method) {
		case "+":
			result = num1 + num2;
			break;
		case "-":
			result = num1 - num2;
			break;
		case "*":
			result = num1 * num2;
			break;
		case "/":
			result = num1 / num2;
			break;
		}
		return result;
	}
}

=> 매개변수를 만들어 결과 리턴하기

 

int num1 = Integer.valueOf(req.getParameter("num1"));
	String method = req.getParameter("method");
	int num2 = Integer.valueOf(req.getParameter("num2"));
		
	// 비지니스메소드 call
	Calc calc = new Calc();
	int result = calc.clac(num1, num2, method);
	
	//응답메세지생성
	pw.print("<h1>계산결과</h1>");
	pw.print("<hr/");
	pw.println("<h3>num1의 "+num1+"과 num2의 "+num2+"을(를) 연산한 결과는"+result+"입니다.</h3>");

=> 리턴값의 타입과 같은 타입의 변수를 만들어 리턴값(result)받아주기

 

 

 

 

메소드 분리하기 + DB와 연결하기

 

1. 서블릿 작성하기

2. DTO작성하기(생성자, get,set메소드, toString메소드 생성)

3. DAO(메소드 클래스)작성하기

* 단계별로 sysout찍으면서 디버깅하기

 

① 사원등록하기(insert)

package kr.multicampus.erp.user;
import 생략

@WebServlet(name = "empinsert",urlPatterns = {"/emp/insert.do"})
public class EmpInsertServlet extends HttpServlet{
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
		//요청과 응답에 한글을 셋팅
		req.setCharacterEncoding("UTF-8");
		res.setContentType("text/html;charset=UTF-8");
		PrintWriter pw = res.getWriter();
		System.out.println("서블릿요청성공");
		int deptno = Integer.parseInt(req.getParameter("deptno"));  //리퀘스트 안의 값을 꺼냄
		String name = req.getParameter("name");
		String id = req.getParameter("id");
		String pass = req.getParameter("pass");
		String addr = req.getParameter("addr");
		int grade = Integer.parseInt(req.getParameter("grade"));
		
		empDAO dao = new empDAO();
		empDTO emp = new empDTO(deptno, name, id, pass, addr, deptno, grade);
		System.out.println(emp);   //emp.tiString()
		int result = dao.insert(emp);
		System.out.println(result);
		if(result > 0) {
			pw.println("<img src=/serverweb/images/yc05.jpg />");
			pw.print("삽입성공!");
		}else {
			pw.print("삽입실패...");
		}
	}
	
}

 

package kr.multicampus.erp.user;
import생략

public class empDAO {
	public int insert(empDTO emp) {  //사원등록
		System.out.println("비지니스메소드 호출 성공~~");
		String sql = "insert into myemp values(?, ?, ?, ?, ?, 1000, ?)";
		Connection con = null;
		PreparedStatement ptmt = null;
		int result = 0;
		try {
			con = DBUtil.getConnect();
			ptmt = con.prepareStatement(sql);
			System.out.println("Statement객체 생성 : "+ptmt);
			ptmt.setInt(1, emp.getDeptno());
			ptmt.setString(2, emp.getName());
			ptmt.setString(3, emp.getId());
			ptmt.setString(4, emp.getPass());
			ptmt.setString(5, emp.getAddr());
			ptmt.setInt(6, emp.getGrade());
			result = ptmt.executeUpdate();
		}catch(SQLException e) {
			e.printStackTrace();
		}finally {
			DBUtil.close(null, ptmt, con);
		}
		return result;
	}	
}

 

 

② 전체사원조회하기(select)

package kr.multicampus.erp.user;

@WebServlet(name = "emplist",urlPatterns = {"/emp/list.do"})
public class EmpListServlet extends HttpServlet{
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
		req.setCharacterEncoding("UTF-8");
		res.setContentType("text/html;charset=UTF-8");
		PrintWriter pw = res.getWriter();
		System.out.println("서블릿요청성공");
		req.getParameterNames();
		
		empDAO dao = new empDAO();
		ArrayList<empDTO> allList = dao.select();
		System.out.println(allList);
		int size = allList.size();
		for (int i = 0; i < size; i++) {
			empDTO user = allList.get(i);
			pw.print("부서번호 : " + user.getDeptno()+", ");
			pw.print("이름 : " + user.getName()+", ");
			pw.print("아이디 : " + user.getId()+", ");
			pw.print("비밀번호 : " + user.getPass()+", ");
			pw.print("주소 : " + user.getAddr()+", ");
			pw.print("포인트 : " + user.getPoint()+", ");
			pw.print("등급 : " + user.getGrade());
			pw.print("<hr/>");
		}

	}
	
}

=> 전체내용 가져와야 하기 때문에 req.getParameterNames(); 사용하기

 

public ArrayList<empDTO> select() {  //2.전체사원조회
		//조회된 레코드를 CustomerDTO에 담아서 ArrayList에 저장하는 작업
		String sql = "select * from myemp";
		ArrayList<empDTO> userlist = new ArrayList<empDTO>();
		empDTO user = null;
		Connection con = null;
		PreparedStatement ptmt = null;
		ResultSet rs = null;
		try {
			con = DBUtil.getConnect();
			ptmt = con.prepareStatement(sql);
			rs = ptmt.executeQuery();
			System.out.println("조회된 ResultSet객체 : "+rs);
			while(rs.next()) {
				System.out.print(rs.getString("id")+"\t");
				user = new empDTO(rs.getInt(1), rs.getString(2), rs.getString(3), rs.getString(4), rs.getString(5),
						rs.getInt(6), rs.getInt(7));
				userlist.add(user);
			}
			System.out.println("리스트 사이즈 : "+userlist.size());
		}catch(SQLException e) {
			e.printStackTrace();
		}finally{
			DBUtil.close(rs, ptmt, con);
		}
		return userlist;
	}