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Handling FORM Data using Servlets
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HTML Forms An interface controls to collect data from the user and transmit it to server.
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Element in Forms TEXT CONTROLS: PASSWORD FIELDS: TEXT AREAS: Checkbox
<INPUT TYPE="TEXT" NAME="NAME" VALUE="INIT"> PASSWORD FIELDS: <INPUT TYPE="PASSWORD" NAME="PASSWORD"> TEXT AREAS: <TEXTAREA NAME="RESUME" ROWS=5 COLS=30>INPUT YOUR RESUME HERE </TEXTAREA> Checkbox <input type="checkbox" name="checkbox" checked> <input type="checkbox" name="checkbox"> Radio Button <input type="radio" name="radio" checked> <input type="radio" name="radio">
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Cont. List Multilist <select name="list">
<option value="Item 1">Item 1</option> <option value="Item 2">Item 2</option> <option value="Item 3">Item 3</option> </select> Multilist <select name="multilist" size="3" multiple>
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Cont. Submit Button Reset Button Image Button File
<input type="submit" name="submit" value="Submit"> Reset Button <input type="reset" name="reset" value="Reset Fields"> Image Button <input type="image" name="image" src="go.gif"> File <input type="file" name="file">
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HttpServletRequest - Methods
Enumeration getParameterNames() an Enumeration of String objects, each String containing the name of a request parameter; or an empty Enumeration if the request has no parameters java.lang.String[] getParameterValues (java.lang.String name) Returns an array of String objects containing all of the values the given request parameter has, or null if the parameter does not exist. java.lang.String getParameter (java.lang.String name) Returns the value of a request parameter as a String, or null if the parameter does not exist.
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Example <html> <body> <form action="CheckBox" method="POST" target="_blank"> <input type="checkbox" name="maths" checked="checked" /> Maths <input type="checkbox" name="physics" /> Physics <input type="checkbox" name="chemistry" checked="checked" /> Chemistry <input type="submit" value="Select Subject" /> </form> </body> </html>
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Servlet CODE –Using getParameter import java. io. ; import javax
Servlet CODE –Using getParameter import java.io.*; import javax.servlet.*; import javax.servlet.http.*; public class CheckBox extends HttpServlet { public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { PrintWriter out = response.getWriter(); out.println("<html>\n" + "<head><title>" + title + "</title></head>\n" + "<body >\n" + "<ul>\n" + " <li><b>Maths Flag : </b>: " + request.getParameter("maths") + "\n" + " <li><b>Physics Flag: </b>: " + request.getParameter("physics") + "\n" + " <li><b>Chemistry Flag: </b>: " + request.getParameter("chemistry") + "\n" + "</ul>\n" + "</body></html>"); }
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Servlet Code -Using getParameterValues
import java.io.*; import javax.servlet.*; import javax.servlet.http.*; public class CheckBox extends HttpServlet { public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { PrintWriter out = response.getWriter(); Enumeration paramNames = request.getParameterNames(); while(paramNames.hasMoreElements()) { String paramName = (String)paramNames.nextElement(); out.print("<tr><td>" + paramName + "</td>\n<td>"); String[] paramValues = request.getParameterValues(paramName); if (paramValues.length == 1) { String paramValue = paramValues[0]; if (paramValue.length() == 0) out.println("<i>No Value</i>"); else out.println(paramValue); } else { out.println("<ul>"); for(int i=0; i < paramValues.length; i++) { out.println("<li>" + paramValues[i]); } out.println("</ul>"); } } out.println("</tr>\n</table>\n</body></html>"); }
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Using getparameternames
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DEMO
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