ProductServlet.java Source code

Introduction

Here is the source code for ProductServlet.java

Source

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import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;

/**
 *
 * @author Qiaochu Li - c0649623
 */

@WebServlet("/products")
public class ProductServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
        try (PrintWriter out = response.getWriter()) {
            Connection conn = getConnection();
            Statement stmt = conn.createStatement();

            if (!request.getParameterNames().hasMoreElements()) {
                out.println(getResults("SELECT * FROM product"));
            } else {
                if (request.getParameter("productID") == null) {
                    out.println(getResults("SELECT * FROM product ORDER BY productID DESC LIMIT 1"));
                } else {
                    int id = Integer.parseInt(request.getParameter("productID"));
                    out.println(getResults("SELECT * FROM product WHERE productID = ?", String.valueOf(id)));
                }
            }
        } catch (SQLException ex) {
            Logger.getLogger(ProductServlet.class.getName()).log(Level.SEVERE, null, ex);
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(ProductServlet.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws IOException, ServletException {
        Set<String> keySet = request.getParameterMap().keySet();
        try (PrintWriter out = response.getWriter()) {
            Connection conn = getConnection();
            if (keySet.contains("name") && keySet.contains("description") && keySet.contains("quantity")) {
                PreparedStatement pstmt = conn
                        .prepareStatement("INSERT INTO `product`(`productID`, `name`, `description`, `quantity`) "
                                + "VALUES (" + "null, '" + request.getParameter("name") + "', '"
                                + request.getParameter("description") + "', " + request.getParameter("quantity")
                                + ");");
                try {
                    pstmt.executeUpdate();
                    request.setAttribute("productID", 2);
                    request.getParameter("productID");
                    doGet(request, response); //shows updated row
                } catch (SQLException ex) {
                    Logger.getLogger(ProductServlet.class.getName()).log(Level.SEVERE, null, ex);
                    out.println("Error with inserting values.");
                    response.setStatus(500);
                }
            } else {
                out.println("Error: Not enough data to input");
                response.setStatus(500);
            }
        } catch (SQLException ex) {
            Logger.getLogger(ProductServlet.class.getName()).log(Level.SEVERE, null, ex);
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(ProductServlet.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    protected void doPut(HttpServletRequest request, HttpServletResponse response)
            throws IOException, ServletException {
        Set<String> keySet = request.getParameterMap().keySet();
        try (PrintWriter out = response.getWriter()) {
            Connection conn = getConnection();
            if (keySet.contains("productID") && keySet.contains("name") && keySet.contains("description")
                    && keySet.contains("quantity")) {
                PreparedStatement pstmt = conn.prepareStatement("UPDATE `product` SET `name`='"
                        + request.getParameter("name") + "',`description`='" + request.getParameter("description")
                        + "',`quantity`=" + request.getParameter("quantity") + " WHERE `productID`="
                        + request.getParameter("productID"));
                try {
                    pstmt.executeUpdate();
                    doGet(request, response); //shows updated row
                } catch (SQLException ex) {
                    Logger.getLogger(ProductServlet.class.getName()).log(Level.SEVERE, null, ex);
                    out.println("Error updating values.");
                    response.setStatus(500);
                }
            } else {
                out.println("Error: Not enough data to update");
                response.setStatus(500);
            }
        } catch (SQLException ex) {
            Logger.getLogger(ProductServlet.class.getName()).log(Level.SEVERE, null, ex);
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(ProductServlet.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    protected void doDelete(HttpServletRequest request, HttpServletResponse response) throws IOException {
        Set<String> keySet = request.getParameterMap().keySet();
        try (PrintWriter out = response.getWriter()) {
            Connection conn = getConnection();
            if (keySet.contains("productID")) {
                PreparedStatement pstmt = conn.prepareStatement(
                        "DELETE FROM `product` WHERE `productID`=" + request.getParameter("productID"));
                try {
                    pstmt.executeUpdate();
                } catch (SQLException ex) {
                    Logger.getLogger(ProductServlet.class.getName()).log(Level.SEVERE, null, ex);
                    out.println("Error deleting entry.");
                    response.setStatus(500);
                }
            } else {
                out.println("Error: Not enough data to delete");
                response.setStatus(500);
            }
        } catch (SQLException ex) {
            Logger.getLogger(ProductServlet.class.getName()).log(Level.SEVERE, null, ex);
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(ProductServlet.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    private String getResults(String query, String... params) throws SQLException, ClassNotFoundException {
        StringBuilder results = new StringBuilder();
        String result = "a";

        try (Connection conn = getConnection()) {
            PreparedStatement pstmt = conn.prepareStatement(query);

            for (int i = 1; i <= params.length; i++) {
                pstmt.setString(i, params[i - 1]);
            }

            ResultSet rs = pstmt.executeQuery();
            JSONObject resultObj = new JSONObject();
            JSONArray productArr = new JSONArray();

            while (rs.next()) {
                Map productMap = new LinkedHashMap();
                productMap.put("productID", rs.getInt("productID"));
                productMap.put("name", rs.getString("name"));
                productMap.put("description", rs.getString("description"));
                productMap.put("quantity", rs.getInt("quantity"));
                productArr.add(productMap);
            }
            resultObj.put("product", productArr);
            result = resultObj.toString();

        } catch (SQLException ex) {
            Logger.getLogger(ProductServlet.class.getName()).log(Level.SEVERE, null, ex);
        }
        return result;
    }

    private Connection getConnection() throws SQLException, ClassNotFoundException {
        Connection conn = null;

        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException ex) {
            System.err.println("JDBC Driver Not Found: " + ex.getMessage());
        }

        try {
            String jdbc = "jdbc:mysql://ipro.lambton.on.ca/inventory";
            conn = DriverManager.getConnection(jdbc, "products", "products");
        } catch (SQLException ex) {
            System.err.println("Failed to Connect: " + ex.getMessage());
        }
        return conn;
    }
}