i am getting an error message: org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.ClassCastException: java.lang.Object cannot be cast to com.crimetrack.business.Login
Login.java
public class Login {
private String userName;
private String password;
private boolean loggedin;
public Login(){};
/**
* @return the loggedin
*/
public boolean isLoggedin() {
return loggedin;
}
/**
* @param loggedin the loggedin to set
*/
public void setLoggedin(boolean loggedin) {
this.loggedin = loggedin;
}
/**
* @param userName
* @param password
*/
public Login(String userName, String password) {
this.userName = userName;
this.password = password;
}
/**
* @return the userName
*/
public String getUserName() {
return userName;
}
/**
* @param userName the userName to set
*/
public void setUserName(String userName) {
this.userName = userName;
}
/**
* @return the password
*/
public String getPassword() {
return password;
}
/**
* @param password the password to set
*/
public void setPassword(String password) {
this.password = password;
}
}
@Controller
public class AuthenticationController {
private final Logger logger = Logger.getLogger(getClass());
private AuthenticationManager authenticationManager;
private Login login = new Login();
String message = "Congrulations You Have Sucessfully Login";
String errorMsg = "Login Unsucessful";
@RequestMapping(value="login.htm")
public ModelAndView onSubmit(Object command) throws ServletException {
String userName = ((Login)command).getUserName();
String password = ((Login)command).getPassword();
login.setUserName(userName);
login.setPassword(password);
logger.info("Login was set");
logger.info("the username was set to " + login.getUserName());
logger.info("the password was set to " + login.getPassword());
if (authenticationManager.Authenticate(login) == true){
return new ModelAndView("main","welcomeMessage", message);
}
//return new ModelAndView("main","welcomeMessage", message);
return new ModelAndView("login","errorMsg", "Error!!!");
}
}
Try this solution:
JSP
<form:form action="yourUrl" modelAttribute="login" method="POST">
<% ... %>
</form:form>
Controller
// your method that prints the form
public ModelAndView onGet(@ModelAttribute Login login) {
// return ...
}
@RequestMapping(value="login.htm")
public ModelAndView onSubmit(@ModelAttribute Login login) {
String userName = login.getUserName();
String password = login.getPassword();
// ...
}
Explanation
The annotation @ModelAttribute
does exactly the same as model.addAttribute(String name, Object value)
. For example, @ModelAttribute Login login
is the same as model.addAttribute("login", new Login());
.
That said, with the onGet
method, you passing such an object to your view. Thanks to the attribute modelAttribute="login"
, the tag <form:form>
will look into the model's list of attributes to find one which name is login
. If it doesn't find, an exception is thrown.
Then, that's the magic part: with the tag <form:input path="userName" />
, Spring MVC will automatically set the property userName
of the bean which is in the modelAttribute="login"
attribute, i.e. in your case, login
. If you had put something like <form:input path="wtf" />
, it would have thrown an exception, because the bean Login
doesn't have such a property.
So, finally, on your onSubmit
method (thanks once again the to annotation @ModelAttribute
), you can access to the login
bean, previously autobinded by Spring MVC.
Note
I personally (almost) never use a ModelAndView
instance, but proceed as follow:
// the methods can have the name you want
// not only onGet, onPost, etc. as in servlets
@RequestMapping("url1.htm")
public String loadAnyJsp(@ModelAttribute Login login) {
return "path/to/my/views/login";
}
@RequestMapping("url2.htm")
public String redirectToAnotherController(@ModelAttribute Login login) {
return "redirect:url1.htm";
}
The path to the JSP is specified within your web.xml file, for example:
...
<bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver" p:favorPathExtension="true" p:favorParameter="true" p:ignoreAcceptHeader="true" p:defaultContentType="text/html">
<description>Depending on extension, return html with no decoration (.html), json (.json) or xml (.xml), remaining pages are decoracted</description>
<property name="mediaTypes">
<map>
<entry key="xml" value="application/xml" />
<entry key="json" value="application/json" />
<entry key="html" value="text/html" />
<entry key="action" value="text/html" />
</map>
</property>
<property name="defaultViews">
<list>
<bean class="org.springframework.web.servlet.view.xml.MarshallingView" p:marshaller-ref="xstreamMarshaller" />
<bean class="org.springframework.web.servlet.view.json.MappingJacksonJsonView" />
</list>
</property>
<property name="viewResolvers">
<list>
<bean id="nameViewResolver" class="org.springframework.web.servlet.view.BeanNameViewResolver">
<description>Maps a logical view name to a View instance configured as a Spring bean</description>
</bean>
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" p:prefix="/WEB-INF/views/" p:suffix=".jsp" />
</list>
</property>
</bean>
...
You should read the doc to get more information (cf. 16.5 Resolving views).