THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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In
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the
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...
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lesson,
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we
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implemented
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a
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use
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case
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that
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displayed
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a
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message
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with
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a
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dynamic
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timestamp.
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In
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this
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lesson,
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we
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create
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a
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workflow
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that
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displays
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input
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from
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a
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data-entry
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form.
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The
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form
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will
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ask
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for
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your
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name.
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If
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you
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enter
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"Bob"
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and
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click
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the
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submit
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button,
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the
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page
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will
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display
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"Hello,
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Bob
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!".
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If
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you
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don't
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enter
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a
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name,
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the
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page
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will
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display:
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"Hmmm,
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you
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did
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not
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enter
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a
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name.
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Please
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try
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again
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!"
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In
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the
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...
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lesson,
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there
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were
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three
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components:
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the
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Action
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class,
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the
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result
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page,
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and
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the
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action
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mapping.
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In
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this
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lesson,
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we
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will
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add
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a
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fourth
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component:
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an
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input
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form.
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HTML
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Form
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With
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Data,
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Using
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Getters
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and Setters
Create the HTML form
The framework includes a library of special tags that you can use to write more powerful forms, but "plain old HTML forms" work just fine too.
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Setters h3. Create the HTML form The framework includes a library of special tags that you can use to write more powerful forms, but "plain old HTML forms" work just fine too. {code:html|title=helloName.html} <html> <head> <title>A simple form with data</title> </head> <body> <p>What is your name?</p> <form action="helloName.action" method="post"> <p><input type="text" name="name"></p> <p><input type="submit" value="Submit your name." /></p> </form> </body> </html> {code} h3. Create the Action class The HTML form submits an attribute called |
Create the Action class
The HTML form submits an attribute called "name",
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and
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the
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Action
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class
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provides
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a
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corresponding
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JavaBean
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property.
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{code:java|title= package tutorial; import com.opensymphony.xwork.ActionSupport; public class HelloHelloWorld extends ActionSupport { String name; public void setName(String value) { { name = value; } public String getName() { { return name; } public String execute() throws Exception { { if (name == null || name.length() == 0) return ERROR; else return SUCCESS; } } {null} h3. |
Create
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the
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action
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mapping
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We
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can
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just
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add
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a
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new
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action
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mapping
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to
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the
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file
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we
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started
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in
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the
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...
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lesson.
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} <!DOCTYPE xwork PUBLIC "-//OpenSymphony Group//XWork 1.0//EN" "http://www.opensymphony.com/xwork/xwork-1.0.dtd"> <xwork> <include file="action-default.xml" /> <package name="default" extends="action-default"> <action name="helloWorld" class="tutorial.HelloWorld"> <result name="success">helloWorld.jsp</result> </action> <action name="helloName" class="tutorial.HelloName"> <result name="success">helloName-success.jsp</result> <result name="error">helloName-error.jsp</result> </action> </package> </xwork> {code} h3. Create the success and error pages The Action can select between two outcomes, "success" and |
Create the success and error pages
The Action can select between two outcomes, "success" and "failure".
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} <%@ taglib uri="action2" prefix="saf" %> <html> <head> <title>Success Page</title> </head> <body> <p> Hello, <saf:property value="name" />! </p> </body> </html> {code} {code:html|title= |
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} <html> <head> <title>Error Page</title> </head> <body> <p> Hmmm, you did not enter a name. Please try again! </p> </body> </html> {code} h3. Try it\! If you are coding along, go ahead and try your form now. Open the input page ([ |
Try it!
If you are coding along, go ahead and try your form now. Open the input page (http://localhost/tutorial/helloName.html
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),
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and
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click
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the
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submit
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button
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to
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see
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what
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happens.
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Try
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it
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with
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and
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without
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entering
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a
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name.
| Warning | ||||||
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| =
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| }
Compile your Action to {{
and restart your container if necessary. |
How the code works
There are two differences between this example and the Hello World lesson.
- When the Action is called,
setNameis passed the contents of thenameform field. - When the Action's
executemethod returns, the framework has two options. If the string "error" returns, the framework will selecthelloName-error.jspas the result. If the string "success" returns, thenhelloName-success.jspis selected.
Let's try a slightly different approach to solve the same user case.
HTML Form With Data, Without Using Getters and Setters
In our first form, we needed to capture the field name and to do that we added the getters and setters getName and setName to the Action class, as well as the private variable name. A larger application with dozens of forms and hundreds of form fields could need several hundred getters and setters. Let's try that same use case again, but without the JavaBean methods.
Create the HTML form
Let's use the same HTML form, but change the form Action to helloName2.action:
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{warning} h3. How the code works There are two differences between this example and the [Hello World] lesson. # When the Action is called, {{setName}} is passed the contents of the {{name}} form field. # When the Action's {{execute}} method returns, the framework has two options. If the string "error" returns, the framework will select {{helloName-error.jsp}} as the result. If the string "success" returns, then {{helloName-success.jsp}} is selected. Let's try a slightly different approach to solve the same user case. h2. HTML Form With Data, Without Using Getters and Setters In our first form, we needed to capture the field {{name}} and to do that we added the getters and setters {{getName}} and {{setName}} to the Action class, as well as the private variable {{name}}. A larger application with dozens of forms and hundreds of form fields could need several hundred getters and setters. Let's try that same use case again, but without the JavaBean methods. h3. Create the HTML form Let's use the same HTML form, but change the form Action to {{helloName2.action}}: {code:html|title=helloName.html} <html> <head> <title>A simple form with data</title> </head> <body> <p>What is your name?</p> <form action="helloName2.action" method="post"> <p><input type="text" name="name"></p> <p><input type="submit" value="Submit your name." /></p> </form> </body> </html> {code} h3. Create the Action class {code:java|title=HelloName2.java} |
Create the Action class
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package tutorial;
import com.opensymphony.xwork.ActionSupport;
import org.apache.struts.action2.interceptor.ParameterAware;
import java.util.Map;
public class HelloName2 extends ActionSupport implements ParameterAware {
Map parameters;
public Map getParameters() {
return parameters;
}
public void setParameters(Map parameters) {
this.parameters = parameters;
}
public String execute() {
String[] name = (String[]) parameters.get("name");
if(name == null || name[0] == null || name[0].length() == 0)
return ERROR;
else
return SUCCESS;
}
}
{code}
h3. Create the action mapping
{code:xml|title=action.xml} |
Create the action mapping
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<!DOCTYPE xwork PUBLIC "-//OpenSymphony Group//XWork 1.0//EN" "http://www.opensymphony.com/xwork/xwork-1.0.dtd">
<xwork>
<include file="action-default.xml" />
<package name="default" extends="action-default">
<action name="helloWorld" class="tutorial.HelloWorld">
<result name="success">helloWorld.jsp</result>
</action>
<action name="helloName" class="tutorial.HelloName">
<result name="success">helloName-success.jsp</result>
<result name="error">helloName-error.jsp</result>
</action>
<action name="helloName2" class="tutorial.HelloName2">
<result name="success">helloName2-success.jsp</result>
<result name="error">helloName-error.jsp</result>
</action>
</package>
</xwork>
{code}
h3. Create the success and error pages
We can use the same error page, but we'll need a slightly different success page {{ |
Create the success and error pages
We can use the same error page, but we'll need a slightly different success page helloName2-success.jsp
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.
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The
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only
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difference
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is
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the
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<saf:property>
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tag.
| Code Block | ||||
|---|---|---|---|---|
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{code:html} <%@ taglib uri="action2" prefix="saf" %> <html> <head> <title>Success Page - Without Using Getters and Setters</title> </head> <body> <p> Hello, <saf:property value="parameters.yourName" />! </p> </body> </html> {code} h3. Try it\! Go ahead and try it now. Load {{helloName.html}}, enter "Bob" in the text field, and click the form submit button. You should see {{ |
Try it!
Go ahead and try it now. Load helloName.html, enter "Bob" in the text field, and click the form submit button. You should see helloName2-success.jsp
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saying
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"Hello,
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Bob
...
!"
| Warning | ||||||
|---|---|---|---|---|---|---|
| =
|
| ||||
| }
Compile your Action to {{
and restart your container if necessary. {warning} h2. How the code works Instead of a setter {{setName}} accessing a private variable {{name}} in the Action class, {{setParameters}} magically extracts everything from the {{request}} object and puts the attributes into a private local Map, {{parameters}}. In the {{execute}} method, we can get the value from the {{parameters}} Map instead of looking for a {{name}} property. So far so good. Back on the {{helloName2-success.jsp}} page, {{<saf:property value="name" />}} isn't going to work any more, because there is no {{getName()}} method in the Action. Instead, {{<saf:property |
How the code works
Instead of a setter setName accessing a private variable name in the Action class, setParameters magically extracts everything from the request object and puts the attributes into a private local Map, parameters. In the execute method, we can get the value from the parameters Map instead of looking for a name property. So far so good.
Back on the helloName2-success.jsp page, <saf:property value="name" /> isn't going to work any more, because there is no getName() method in the Action. Instead, <saf:property value="parameters.name"
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/>
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calls
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the
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getParameters
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method,
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and
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is
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able
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to
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get
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the
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value
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of
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the
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"name"
...
field.
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Pretty
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neat
...
!
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Summary
Before processing an Action, the framework matches any Action properties with request attributes. If a match is found, the attribute value is set to the Action property. The Action can process the value, and the SAF tags can present the value too. Rather than define a separate property for each attribute, you can define a single Map property instead. In that case, all the request attributes will be set to the Map automatically.
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|---|---|
Prev | Return to Hello World |