Java Platform, Enterprise Edition (Java EE) 8 The Java EE Tutorial

## The interceptor Example Application

The `interceptor` example demonstrates how to use an interceptor class, containing an `@AroundInvoke` interceptor method, with a stateless session bean.

The `HelloBean` stateless session bean is a simple enterprise bean with two business methods, `getName` and `setName`, to retrieve and modify a string. The `setName` business method has an `@Interceptors` annotation that specifies an interceptor class, `HelloInterceptor`, for that method:

    @Interceptors(HelloInterceptor.class)
    public void setName(String name) {
        this.name = name;
    }

The `HelloInterceptor` class defines an `@AroundInvoke` interceptor method, `modifyGreeting`, that converts the string passed to `HelloBean.setName` to lowercase:

    @AroundInvoke
    public Object modifyGreeting(InvocationContext ctx) throws Exception {
        Object[] parameters = ctx.getParameters();
        String param = (String) parameters[0];
        param = param.toLowerCase();
        parameters[0] = param;
        ctx.setParameters(parameters);
        try {
            return ctx.proceed();
        } catch (Exception e) {
            logger.warning("Error calling ctx.proceed in modifyGreeting()");
            return null;
        }
    }

The parameters to `HelloBean.setName` are retrieved and stored in an `Object` array by calling the `InvocationContext.getParameters` method. Because `setName` only has one parameter, it is the first and only element in the array. The string is set to lowercase and stored in the `parameters` array, then passed to `InvocationContext.setParameters`. To return control to the session bean, `InvocationContext.proceed` is called.

The user interface of `interceptor` is a JavaServer Faces web application that consists of two Facelets views: `index.xhtml`, which contains a form for entering the name, and `response.xhtml`, which displays the final name.

### Running the interceptor Example

You can use either NetBeans IDE or Maven to build, package, deploy, and run the `interceptor` example.

The following topics are addressed here:

- To Run the interceptor Example Using NetBeans IDE

- To Run the interceptor Example Using Maven

#### To Run the interceptor Example Using NetBeans IDE

1. Make sure that GlassFish Server has been started (see Starting and Stopping GlassFish Server).

2. From the File menu, choose Open Project.

3. In the Open Project dialog box, navigate to:

       tut-install/examples/ejb

4. Select the `interceptor` folder and click Open Project.

5. In the Projects tab, right-click the `interceptor` project and select Run.

   This will compile, deploy, and run the `interceptor` example, opening a web browser to the following URL:

       http://localhost:8080/interceptor/

6. Enter a name into the form and click Submit.

   The name will be converted to lowercase by the method interceptor defined in the `HelloInterceptor` class.

#### To Run the interceptor Example Using Maven

1. Make sure that GlassFish Server has been started (see Starting and Stopping GlassFish Server).

2. Go to the following directory:

       tut-install/examples/ejb/interceptor/

3. To compile the source files and package the application, use the following command:

       mvn install

   This command builds and packages the application into a WAR file, `interceptor.war`, located in the `target` directory. The WAR file is then deployed to GlassFish Server.

4. Open the following URL in a web browser:

       http://localhost:8080/interceptor/

5. Enter a name into the form and click Submit.

   The name will be converted to lowercase by the method interceptor defined in the `HelloInterceptor` class.

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