I cannot get my out string to print to my .jsp file after the post method is run. Below are my .java and .jsp files. I have removed the code there as by this time I know what I was trying was far from intuitive. I have simply left comments where I know the two respective lines of code need to go. I am simply trying to print the string “out” in my .jsp file after the servlet has executed the SQL command.
EDIT:
I finally have all of my output going to the JSP page. The only problem I’m having now is that my less-than-ideal method of storing my query results in the out string is leading to my output being one long line of results, instead of a nice spacing or table. I know I would be better off looping through the results in a table in the jsp, but I can’t seem to get that to work either.
dbServlet.jsp
<?xml version = "1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<!-- dbServlet.html -->
<html xmlns = "http://www.w3.org/1999/xhtml">
<head>
<title>MySQL Servlet</title>
<style type="text/css">
body{background-color: green;}
</style>
</head>
<body>
<h1>Hello World!</h1>
<h2>This is the MySQL Servlet</h2>
<form action = "/database/database" method = "post">
<p>
<label>Enter your query and click the button to invoke a MySQL Servlet
<input type = "text" name = "query" />
<input type = "submit" value = "Run MySQL Servlet" />
</label>
</p>
</form>
<hr>
<%= request.getAttribute("queryResults") %>
</body>
</html>
databaseServlet.java
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.sql.*;
@SuppressWarnings("serial")
public class databaseServlet extends HttpServlet {
private Connection conn;
private Statement statement;
public void init(ServletConfig config) throws ServletException {
try {
Class.forName(config.getInitParameter("databaseDriver"));
conn = DriverManager.getConnection(
config.getInitParameter("databaseName"),
config.getInitParameter("username"),
config.getInitParameter("password"));
statement = conn.createStatement();
}
catch (Exception e) {
e.printStackTrace();
}
}
protected void doPost (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String out = "\n";
String query = request.getParameter("query");
if (query.toString().toLowerCase().contains("select")) {
//SELECT Queries
try {
ResultSet resultSet = statement.executeQuery(query.toString());
ResultSetMetaData metaData = resultSet.getMetaData();
int numberOfColumns = metaData.getColumnCount();
for(int i = 1; i<= numberOfColumns; i++){
out = out + "\t" + metaData.getColumnName(i) + "\n";
}
out = out + "\n";
while (resultSet.next()){
for (int i = 1; i <= numberOfColumns; i++){
out = out + "\t" + resultSet.getObject(i) + "\n";
}
out = out + "\n";
}
}
catch (Exception f) {
f.printStackTrace();
}
}
else if (query.toString().toLowerCase().contains("delete") || query.toLowerCase().contains("insert")) {
//DELETE and INSERT commands
try {
conn.prepareStatement(query.toString()).executeUpdate(query.toString());
out = "\t\t Database has been updated!";
}
catch (Exception l){
l.printStackTrace();
}
}
else {
//Not a valid response
out = "\t\t Not a valid command or query!";
}
request.setAttribute("queryResults", out);
RequestDispatcher dispatcher = request.getRequestDispatcher("/dbServlet.jsp");
dispatcher.forward(request, response);
}
}
You cannot just do an out.println and print on the JSP. YOu need to put it into your response object and forward to the JSP. The JSP can then pick it up and print.