This page covers the use of the @SessionField annotation

A Simple Session Scope Mechanism

Frequently, the conversation scope is overkill or not appropriate to the problem space, but you still want data persisted across multiple requests. Using the SessionAware interface or the ScopedModelDrivenInterceptor are the two "out-of-the-box" solutions for this in Struts2. The Conversation plugin offers a third alternative: the @SessionField annotation.

Use of this approach is a matter of taste: instead of XML configuration, boiler-plate code, and String constants (the session keys), a simple annotation is used to achieve the same end.

Compare the following:

SessionAware Approach

java: ``` public class ExampleAction extends ActionSupport implements SessionAware, ModelDriven {

public static final String EXAMPLE_MODEL_SESSION_KEY = "exampleModel";
private Map<String, Object> session;

public String firstAction() {
    ExampleModel exampleModel = new ExampleModel();
    this.setModel(exampleModel);
    return SUCCESS;
}

public String secondAction() {
    ExampleModel exampleModel = this.getModel();
    //do something with the data
    return SUCCESS;
}

@Override
public void setSession(final Map<String, Object> session) {
    this.session = session;
}

@Override
public ExampleModel getModel() {
    return (ExampleModel) session.get(EXAMPLE_MODEL_SESSION_KEY);
}

protected void setModel(final ExampleModel exampleModel) {
    session.put(EXAMPLE_MODEL_SESSION_KEY, exampleModel);
}

} ```

xml: <!-- add to your interceptor stack --> <interceptor-ref name="servletConfig" />

ScopedModelDriven Approach

java: ``` public class ExampleAction extends ActionSupport implements ScopedModelDriven {

public static final String EXAMPLE_MODEL_SESSION_KEY = "exampleModel";
private ExampleModel exampleModel;

public String firstAction() {
    exampleModel = new ExampleModel();
    return SUCCESS;
}

public String secondAction() {
    //do something with the data
    return SUCCESS;
}

@Override
public ExampleModel getModel() {
    return exampleModel;
}

@Override
public void setModel(final ExampleModel exampleModel) {
    this.exampleModel = exampleModel;
}

@Override
public String getScopeKey() {
    return EXAMPLE_MODEL_SESSION_KEY;
}

@Override
public void setScopeKey(String scopeKey) {
    //not likely useful
}

} ```

xml: ``` session exampleModel com.byars.struts2.ExampleModel

```

@SessionField Approach

the java: ``` public class ExampleAction extends ActionSupport implements ModelDriven {

@SessionField private ExampleModel exampleModel;

public String firstAction() {
    exampleModel = new ExampleModel();
    return SUCCESS;
}

public String secondAction() {
    //do something with the data
    return SUCCESS;
}

@Override
public ExampleModel getModel() {
    return exampleModel;
}

} ```

the xml: <!-- add to your interceptor stack --> <interceptor-ref name="sessionField" />