Writing a Web Service Client in Java using Eclipse IDE
The steps involved in writing the Web Service Client will be
as follows:
a) Locate the service description in the form of
WSDL for the web service in question. (Actually the first step is to search
UDDI for the services. I am excluding this step here to simplify the process )
b) Once we have the WSDL document, most of the
client code is auto-generated using the wsimport
tool.
c) Run the client and invoke the web service.
Now I will demonstrate the steps to write a Web Service
client in Java using Eclipse IDE. This web service client is invoking the web
services available at the url "http://www.webservicex.net”
2)
Choose the web service you want to write the
client for. I have chosen Computer Unit converter, which gives me the
conversion from bytes to kilobytes, megabytes etc.
3) The WSDL schema location is mentioned on the page. I can go to this url and have a look at the WSDL.
4)The values worth noting here are the wsdl service
name and the wsdl port name, that we will need for invoking the web service.
5) Now we will start setting up our eclipse project. Create a new Java Project. Here in this example , we have given it the name ComputerUnitConvertor
7) Open the Windows powershell or command prompt
and go to the src directory of the project.
8)
Now, the stub has to be generated using the
wsimport tool available with Java. For that, we use the below command :
wsimport –keep . http://www.webservicex.net/ConvertComputer.asmx?WSDL
Here , wsimport is the command ; -keep is the
switch that is used if we want to retain the java files generated. If this
switch is not used, then only the class files will be retained. Next , we give
the directory name where the java files have to be retained. I want it to be
there in src directory, so I gave “.” as
the folder name. Lastly, we need to
specify the wsdl schema location. The wsdl will be read and corresponding
client code generated.
9)
The following is the folder structure and files
created after the above is run:
10)
On refreshing the eclipse project, it gets
reflected as follows:
11) Now that the stubs are generated, I can write a test client to invoke the web service. So, I create a new class TestComputerUnitConvertor with a main method in a new package.
12)
Following is the code to invoke the web service.
The comments describe what is being done in each step.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | package in.blogspot.pallavisonal; import net.webservicex.ComputerUnit; import net.webservicex.ComputerUnitSoap; import net.webservicex.Computers; public class TestComputerUnitConvertor { public static void main(String[] args) { // Use the WSDL Service name - this provides the implementation of the interface to invoke the web service ComputerUnit cunit= new ComputerUnit(); //WSDL port name - this is for sending the SOAP request to the web service host and getting the response ComputerUnitSoap cusoap=cunit.getComputerUnitSoap(); double convertedUnits=cusoap.changeComputerUnit(10.0, Computers.MEGABYTE, Computers.KILOBYTE); //Print the results System.out.println("10 MB is equal to "+convertedUnits +" KB"); } } |
13) The following is the output:
This is all for creating a web service client in Java. Next we will look at how to create a web service in java and deploy it in Tomcat web server.
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