In the Using
Tags lesson, we implemented a Logon form. In the
Coding Actions lesson, we interpret the Logon form,
and return a different result code depending on the
circumstances.
If you have coded along, you can open the Logon action
and enter a likely username and passowrd. Since we haven't
given the Action any behavior, the mapping redisplays the
default Logon.jsp page.
Let's add an Action class that will make the Logon form
more interesting.
The Code
Just as an example, we can examine the username and
password values. If either or both properties are empty,
return INPUT, so that we can collect a valid Logon. Otherwise,
return SUCCESS.
package tutorial;
import com.opensymphony.xwork2.ActionSupport;
public class Logon extends ActionSupport {
public String execute() throws Exception {
if (isInvalid(getUsername())) return INPUT;
if (isInvalid(getPassword())) return INPUT;
return SUCCESS;
}
private boolean isInvalid(String value) {
return (value == null || value.length() == 0);
}
private String username;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
private String password;
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
How The Code
Works
The framework automatically populates the username and
password properties for us. All that's left to do is checking
to see if either property is empty.
What to
Remember
The Actions do the "heavy lifting" in a web application.
Actions interact with data base systems and business rule
engines, so that we can turn "billboard" HTML into a rich,
dynamic web experience.
After doing its work, an Action returns a result code to
indicate what the framework should do next. Often, the next
step is to go onto the "success" result. Other times, we might
need to go to an "error" result instead. In either case, the
Action does not worry about generating the response, only
deciding which logical result to present next.
For more about Actions, see
Big
Picture
in the Core
Developers Guide.s
