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netbeans에서 데이터베이스에 액세스하려고하는데이 작업을 처음 수행 한 것입니다. finally 성명서를 읽었을 때 문제가 있습니다. Connection과 PrintWriter은 등록하지 않은 것 같아서 내가 잘못한 것을 잘 모릅니다. 문제는 try/catch에서 변수 con을 사용한 다음 변수 out을 사용하면 발생합니다.try/catch java에서 finally 문이 작동하지 않습니까?
import java.io.IOException;
import java.io.PrintWriter;
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 java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
@WebServlet(name = "DBServlet1", urlPatterns = {"/db1"})
public class DBServlet1 extends HttpServlet {
/**
* Processes requests for both HTTP <code>GET</code> and <code>POST</code>
* methods.
*
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
*/
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
//Connection con = null;
//PrintWriter out = response.getWriter();
try (PrintWriter out = response.getWriter()) {
Connection con = null;
// Load the Driver class file
Class.forName("org.apache.derby.jdbc.ClientDriver");
// Make a connection to the ODBC datasource Movie Catalog
// In this example we are opening a connection to the
// database with every request.
con = DriverManager.getConnection("jdbc:derby://localhost:1527/movies","user1", "password");
if (con != null) {
out.println("<html>\n<body>\n<table border=\"1\" width=\"100%\">");
// Create the statement
Statement statement = con.createStatement();
ResultSet rs = statement.executeQuery("SELECT * FROM USER1.TMovie");
ResultSetMetaData rsmd = rs.getMetaData();
int columnCount = rsmd.getColumnCount();
out.println("<tr>");
for(int i=1; i<=columnCount; i++) {
out.println("<td><h3>" +rsmd.getColumnName(i) + "</td>");
}
out.println("</tr>");
while (rs.next()) {
out.println("<tr>");
// get the id, which is an int
out.println("<td>" + rs.getInt("id") + "</td>");
// get the name, which is a String
out.println("<td>" + rs.getString("title") + "</td>");
// get the rating, which is a String
out.println("<td>" + rs.getString("rating") + "</td>");
// get the price, which is a Float
out.println("<td>" + rs.getFloat("price") + "</td>");
// get the Quantity, which is a Integer
out.println("<td>" + rs.getInt("quantity") + "</td>");
// get the Category, which is a Integer
out.println("<td>" + rs.getString("category") + "</td>");
out.println("</tr>");
}// end while
// Close the ResultSet
rs.close();
out.println("</table>");
}// end if
else {
out.println("Data Not Found");
}
}catch (Exception e) {
System.err.println(e.getMessage());
}// end try-catch
finally {
try{
if (con != null) {
// Close the connection no matter what
con.close();
}// end if
}
catch (SQLException sqle) {
System.err.println(sqle.getMessage());
}// end try-catch
}// end finally
out.close();
감사합니다, 내가 어떤이 없습니다 오류 코드를 지금 조금 더 나은 이해가 있지만 여전히 db 값을 표시하지 않습니다 – Jaqtaris
나는 DB에 대한 잘못된 주소를 모두 고정! 자세한 설명 주셔서 감사합니다 :) – Jaqtaris