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How to test Methods from a SongServlet with JUnit 5

my Task ist to test a HttpServlet written in Java, which connects to a database and has the following methods implemented:
doGet(), doPost(), doDelete(), doOptions()
To test the functionality independently from the database connection I've implemented an InMemoryDao which populates a H2 database with test data from a Json file and gets injected into my ServletTest class.
Here's an example of the doGet() Method:
#Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) {
boolean all = req.getParameter("all") != null;
boolean specific = req.getParameter("songId") != null;
if (all == specific) {
resp.setStatus(400);
writePlaintext(resp, "Specify either 'all' or 'songId'.");
return;
}
if (all) doGetAll(req, resp);
if (specific) doGetSpecific(req, resp);
}
My InMemorySongDao class looks like this:
public class InMemorySongDao extends MysqlSongDao {
public InMemorySongDao() throws SQLException {
super(new ComboPooledDataSource());
UUID uuid = UUID.randomUUID();
// Connect to a unique in-memory database identified by a random uuid
this.dataSource.setJdbcUrl("jdbc:h2:mem:" + uuid);
try (PreparedStatement st = this.dataSource.getConnection().prepareStatement(
"CREATE TABLE songs (" +
"id int not null primary key auto_increment," +
"title varchar(100) not null," +
"artist varchar(100)," +
"label varchar(100)," +
"released int" +
")")) {
st.execute();
}
}
/**
* Creates a songs dao prefilled with the songs from the given resource.
*/
public InMemorySongDao(String resourceName) throws SQLException, IOException {
this();
final ObjectMapper mapper = new ObjectMapper();
JsonNode rootNode = mapper.readTree(getClass().getResource(resourceName));
// Read array node or use empty node
ArrayNode array = (rootNode.isArray()) ? (ArrayNode) rootNode : mapper.createArrayNode();
try (PreparedStatement st = this.dataSource.getConnection().prepareStatement("INSERT INTO songs (id, title, artist, label, released) values (?,?,?,?,?)")) {
// Iterate over the array and populate the database with the songs
Iterator<JsonNode> elements = array.elements();
while (elements.hasNext()) {
JsonNode node = elements.next();
if (!node.isObject()) continue;
st.setInt(1, node.get("id").asInt());
st.setString(2, node.get("title").asText());
st.setString(3, node.get("artist").asText());
st.setString(4, node.get("label").asText());
st.setInt(5, node.get("released").asInt());
st.addBatch();
}
st.executeBatch();
}
}
}
Would be very thankful if somebody could provide me any help with this. Unfortunately I couldn't find any proper examples by research...
Kind Regards,
Mic

Problem to implement FindById to a return statement in java with MongoDB

UPDATE: The return statement is still not working as expected to show single user detail by id in the DAO. I could only use for loop to iterate through the _id to match the userId, but when I click the edit button for the number of user will show all previous user Id in the console.
Another problem is when I call this method in the Service class, the output is null. Still crave for the solution to help me get over it.
#Override
public User get(Object userId) {
User user = new User();
FindIterable<Document> userTbl = database.getCollection("User").find();
for (Document doc : userTbl) {
String id = doc.getObjectId("_id").toString();
System.out.println("_id = " + id);
if (id.equals(userId)) {
return user;
}
}
return null;
}
edit user in Service class
public void editUser() throws ServletException, IOException {
Object userId = request.getParameter("id"); // get query string from the jsp
User user = userDAO.get(userId);
System.out.println("User full name is? " + user.getFullName());
}

After getting hints from #Smutje and think through it again, finally figured it out at my 2nd weeks of learning MongoDB. At my level I need to iterate the user document then find the id and return it.it
#Override
public User get(Object userId) {
FindIterable<User> userTbl = database.getCollection("User", User.class).find();
for (User doc : userTbl) {
String id = doc.getId().toHexString();
System.out.println("_id = " + id);
if (id.equals(userId)) {
return doc;
}
}
return null;
}

Print output in TextArea(append-way) from different class in JSP/Servlet

I have below Dynamic web project setup
Index.jsp
<form action="submitClick" method ="post"
<textarea> id="textarea" name="textarea" rows="25" cols="100">${result}</textarea>
<input type="submit">
SubmitClick.java //servlet class
public class SubmitClick extends HttpServlet{
public void doPost(HttpServletRequest request, HttpServletResponse response){
MainLogicClass mainLogic = new MainLogicClass(username,password); //let's suppose hardcoded
request.setAttribute("result", "Hello");// Hello is getting printed on textarea, but I want to print output text on textarea from MainLogicClass.
getServletContext().getRequestDispatcher("/index.jsp").forward(request,response);
}
}
MainLogicClass//different class, present in same package
public class MainLogicClass{
public MainLogicClass(String username, String password){
//DB Connection logic
System.out.println("Database Connection successful");
/* I want to print "Database Connection successful" on textarea which presents on index.jsp
And after that, I need to print few more output so that the text gets appended to textarea like-
"Database Connection successful
DB query executed
DB connection closed"
*/
}
}
How can I print text from MainLogicClass to Servlet using request.setAttribute method or any other workaround.

Constructor doesn't have any return type so instead of constructor you can create a method and put your logic code there and return some value from there . So , your method inside MainLogicClass will look like somewhat below :
public String Something(String username, String password){
String msg = "" ;
msg +="Something to return";
msg +="soemthing more";
//your logic code
return msg;//return back
}
And then in your servlets doPost method do like below :
MainLogicClass mainLogic = new MainLogicClass();
String message = mainLogic.Something(String username, String password);//call that function
request.setAttribute("result", message );

getAttribute() returns null for drop down list in jsp

I am trying to pass value from database to drop down menu using getAttribute(). However, it returns null.
This is my jsp (updateLecturer.jsp) file:
<form action="updateLecturer" class="sky-form">
<header>Update Lecturer Information</header>
<center>
<fieldset>
<section>
<label class="select">
<select name="selectLecturer" id="lecturerFullname">
<option value="0" selected disabled>Lecturers Name</option>
**<option name="lecturerFullname"><%=((LecturerBean)request.getAttribute("LecturerFullname"))%></option>**
</select>
</label>
</section>
</center>
<footer>
<center><button type="submit" class="button">Update</button></center>
</footer>
</form>
This is my servlet UpdateLecturerServlet.java) :
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
String lecturerFullname = request.getParameter("LecturerFullame");
LecturerBean lecturer = new LecturerBean();
lecturer.setLecturerFullname(lecturerFullname);
request.setAttribute("LecturerFullname",lecturerFullname);
RequestDispatcher view = getServletContext().getRequestDispatcher("/updateLecturer.jsp");
view.forward(request,response);
}
This is my UpdateLecturerDAO :
static Connection currentCon = null;
static ResultSet rs = null;
public static LecturerBean selectlecturer(LecturerBean Lbean) {
// preparing some objects for connection
System.out.println("JIJIJI");
Statement stmt = null;
String lecturerFullname = Lbean.getLecturerFullname();
System.out.println("j444444");
String searchQuery = "select lecturerfullname from lecturer";
System.out.println("Your lecturer is " + lecturerFullname);
System.out.println("Query: " + searchQuery);
try {
// connect to DB
currentCon = JavaConnectionDB.getConnection();
stmt = currentCon.createStatement();
rs = stmt.executeQuery(searchQuery);
// boolean more = rs.next();
while(rs.next())
{
LecturerBean lecturer = new LecturerBean();
lecturer.setLecturerFullname(rs.getString("LecturerFullname"));
lecturer.add(lecturer);
}
}
catch (Exception ex) {
System.out.println("Select failed: An Exception has occurred! " + ex);
}
PLEASEEEE HELP :( thank you very much

If you set some attribute in request like this
request.setAttribute("key",obj);
You can get it display in jsp by a scriplet like this
<%=request.getAttribute("key")%>
In your case please check the following points
Check whether the following code is giving you a null.
String lecturerFullname = request.getParameter("LecturerFullame");
If this gives you null then check whether your passing parameter LecturerFullame in url.
In the jsp please cast the following to correct object
<option name="lecturerFullname"><%=((String)request.getAttribute("LecturerFullname"))%></option>
And let me know.

I've never worked with any of this type of code before, so I'm not sure how the attribute system works, but I noticed an anomaly in your code:
Where you are setting:
request.setAttribute("LecturerFullname",lecturerFullname);
Where you are getting:
lecturer.setLecturerFullname(request.getAttribute("lecturerFullname",lecturer));
Notice it yet? Where you are setting it, you put a capital "L" and I believe it's case sensitive. Doesn't hurt to try.

In UpdateLecturerServlet.java.
//calling selectlecturer() to retrieve list full names and store it in session
request.setAttribute("LecturerFullname",selectlecturer());
RequestDispatcher view = getServletContext().getRequestDispatcher("/updateLecturer.jsp");
view.forward(request,response);
Now selectlecturer() method.
public static List<LecturerBean> selectlecturer() {
//DB query to retrieve all lecturer fullnames
List<LecturerBean> lecturers = new ArrayList<LecturerBean>();
while(rs.next())
{
LecturerBean lecturer = new LecturerBean();
lecturer.setLecturerFullname(rs.getString("LecturerFullname"));
lecturers.add(lecturer);
}
return lecturers;//return the list lecturer fullnames
}
In updateLecturer.jsp.
<%
java.util.List<LecturerBean> lists = (java.util.List<LecturerBean>)request.getAttribute("LecturerFullname"));
for(LecturerBean bean:lists)
{
%>
<option name="lecturerFullname"><%=bean.getLecturerFullname()%></option>
<%
}
%>
But you should avoid Java code in JSP. Just for the reference here I'm giving this code.

JQuery/AJAX code error - text not displayed on typing in textbox

I have this jsp document (below). Basically, when user types in the textbox, I want to show an error if the username exists in the database/ length<5, etc.
I want these errors to be simultaneously displayed without any refresh through jQuery/AJAX. I did this but it doesn't seem to be working. Here, CheckAvailability and Success are servlets and CheckAVailability checks the existence in database.
the JSP file:
<!DOCTYPE html>
<html>
<head>
<script src="js/jquery-1.11.3.js"></script>
<script>
$(document).ready(function() {
$('#username').keyup(function() {
var name = $('#username').val();
$.get('CheckAvailability?username='+name,function(responseText){
$('#status').text(responseText);});}); 
</script>
</head>
<body>
<form id="login_form" ><input type="text" placeholder="username" name="username" class="style-4" required="required" action="Success"/>
<div id="status"> </div>
CheckAvailability Servlet
public class CheckAvailability extends HttpServlet {
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
Connection conn=null;
Statement s=null;
ResultSet rs=null;
PreparedStatement ps;
try {
//make connection
String userid = request.getParameter("username");
String arr;
Class.forName("oracle.jdbc.OracleDriver");
if (userid.equals("")) {
arr = "Error: User name cannot be empty";
} else if(userid.length()<5){
arr="Error: Username cannot be less than 5 characters.";
}
else
{
String table="user1.app_users";
String p = "alpha";//database password
String query = "select userid from " + table + " where userid='" + userid + "'";
String url = "jdbc:oracle:thin:system/" + p + "#localhost:1521:XE";
conn = DriverManager.getConnection(url);
s = conn.createStatement();
ps = conn.prepareStatement(query);
rs = ps.executeQuery();
if (!rs.next()) {
arr="UserID <b>" + userid + "</b> is available.";
} else {
arr= "Error: UserID <b>" + userid + "</b> is already in use.";
}
}
response.setContentType("text/plain");
response.getWriter().write(arr);
}catch (SQLException se) {
out.println("Error ->" + se.getMessage());
} catch(ClassNotFoundException ce)
{
out.println("Error ->" + ce.getMessage());
}finally {
out.close();
}
}
}
But this isn't displaying anything as I type in the text box. The servlet did fire on hitting on submit. What didn't happen was that the text didn't display alongside. The code executes, no error in my IDE on that. I can't exclusively run the servlet, it gives the error: 'HTTP method GET is not supported by this URL', i.e. when I run it with parameters. I took the input inside as in, String username="user12", and that didn't run either. Can anybody point out my mistake? I'm new to jQuery/AJAX.

This worked for me:
$(document).ready(function() {
$('#userid').keyup(function(event) {
var user=$('#userid').val();
$.get('CheckValidity',{username:user},function(responseText) {
$('#status').text(responseText);
});
});
});
Had to use a different JQuery.

Overrride doGet, because javax.servlet.http.HttpServlet doesn't have any processRequest method.
#Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
PrintWriter writer = resp.getWriter();
writer.print("hi " + req.getParameter("username"));
}
Read this
Anyway.. how are you declaring your servlet? Through annotations? In web.xml? And what's the URL pattern?
if using web.xml:
<servlet>
<servlet-name>CheckAvailability Servlet</servlet-name>
<servlet-class>your.package.CheckAvailability</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>CheckAvailability Servlet</servlet-name>
<url-pattern>/CheckAvailability</url-pattern>
</servlet-mapping>
if using annotations:
#WebServlet("/CheckAvailability")
public class Serv extends HttpServlet {
// ...
}