Defining a Java Class Containing Methods for the Web Service

Create a Java Web Service by writing or supplying a Java class with methods that are deployed as a Web Service. In the sample supplied in the java_services sample directory, the .ear file, ws_example.earcontains the Web Service source, class, and configuration files. In the expanded .ear file, the class StatefulExampleImpl provides the stateful Java service and StatelessExampleImpl provides the stateless Java service.

When writing a Java Web Service, if you want to place the Java service in a package, use the Java package specification to name the package. The first line of StatefulExampleImpl.java specifies the package name, as follows:

package oracle.j2ee.ws_example;

The stateless sample Web Service is implemented with StatelessExampleImpl, a public class. The class defines a public method, helloWorld(). In general, a Java class for a Web Service defines one or more public methods.

Example 3-1 shows StatelessExampleImpl.

The stateful sample Web Service is implemented with StatefulExampleImpl, a public class. The class initializes the count and defines two public methods, count() and helloWorld().

Example 3-2 shows StatefulExampleImpl.

Example 3-1 Defining A Public Class with Java Methods for a Stateless Web Service

package oracle.j2ee.ws_example;

public class StatelessExampleImpl {
    public StatelessExampleImpl() {
  }
  public String helloWorld(String param) {
    return "Hello World, " + param;
  }
}

Example 3-2 Defining a Public Class with Java Methods for a Stateful Web Service

package oracle.j2ee.ws_example;

public class StatefulExampleImpl {
  int count = 0;
  public StatefulExampleImpl() {
  }
  public int count() {
    return count++;
  }
  public String helloWorld(String param) {
    return "Hello World, " + param;
  }
}

A Java class implementation for a Web Service must include a public constructor that takes no arguments. Example 3-1 shows the public constructor StatelessExampleImpl() and Example 3-2 showsStatefulExampleImpl().

When an error occurs while running a Web Service implemented as a Java class, the Java class should throw an exception. When an exception is thrown, the Web Services Servlet returns a Web Services (SOAP) fault. Use the standard J2EE and OC4J administration facilities to view the logs of Servlet errors for a Web Service that uses Java classes for its implementation.

When you create a Java class containing methods that implement a Web Service, the method's parameters and return values must use supported types, or you need to use an interface class to limit the methods exposed to those methods using only supported types