Java Servlet ISYS 350

What is Java Servlet? It is a java class that serves a client request. Servlets are most often used to: Process or store data that was submitted from an HTML form Provide dynamic content such as the results of a database query. It is not a web page and cannot be opened by itself. A servlet is called by a HTML form’s action attribute:

Adding a Servlet Servlet is a class with a “java” extension: – Ex: FVServlet.java It must belong to a package: – Add a new package – Then add a new servelet – Ex:ServletPackage FVServlet.java

Servlet’s processRequest Method This method use the same request and response objects as JSP. For example, it uses the request.getParameter method to read the data submitted with http request: – myPV=request.getParameter("PV"); It uses the out.println statement to send HTML code to browser: out.println(" ");

Example: Future Value Calculator: Requesting FVServlet servlet Enter present value: Select interest rate: 4% 5% 6% 7% 8% Select year: 10-year 15-year 30-year

FVServlet protected void processRequest(HttpServletRequest request, HttpServletResponse response) String myPV, myRate, myYear,qString; myPV=request.getParameter("PV"); myRate=request.getParameter("Rate"); myYear=request.getParameter("Year"); double FV, PV, Rate, Year; PV=Double.parseDouble(myPV); Rate=Double.parseDouble(myRate); Year=Double.parseDouble(myYear); FV=PV*Math.pow(1+Rate,Year); out.println("FutureValue is:"+ FV); Note: Copy/paste the code between: out.println(" "); and out.println(" ");

Servlet: depTableServlet to create straight line depreciation table Straight Line Depreciation Table Enter Property Value: Enter Property Life:

String strValue, strLife; strValue=request.getParameter("pValue"); strLife=request.getParameter("pLife"); double value, life, depreciation,totalDepreciation=0; value=Double.parseDouble(strValue); life=Double.parseDouble(strLife); NumberFormat nf = NumberFormat.getCurrencyInstance(); out.println("Straight Line Depreciation Table" + " "); out.println("Property Value: "); out.println("Property Life: "); depreciation=value/life; totalDepreciation=depreciation; out.println( " "); out.println(" Year Value at BeginYr "); out.println(" Dep During Yr Total to EndOfYr "); out.println(" "); for (int count = 1; count <= life; count++) { out.write(" "); out.write(" " + count + " "); out.write(" " + nf.format(value) + " "); out.write(" " + nf.format(depreciation) + " "); out.write(" " + nf.format(totalDepreciation) + " "); value -= depreciation; totalDepreciation+=depreciation; }