Accessing Restful web service using RestTemplate or How does RestTemplate work?

Questions : How does RestTemplate work?

Rest Client Program using RestTemplate

Spring configuration file......
rest-config.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
xmlns:aop="http://www.springframework.org/schema/aop" xmlns:context="http://www.springframework.org/schema/context"
xmlns:jee="http://www.springframework.org/schema/jee" xmlns:task="http://www.springframework.org/schema/task"
xsi:schemaLocation="
            http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
            http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
            http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.0.xsd
            http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
            http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.0.xsd">

<bean id="restTemplate" class="org.springframework.web.client.RestTemplate">
</bean>   
</beans>



@Service("ProgramServiceImpl")
public class ProgramServiceImpl implements IProgramService{
    
    @Autowired
    @Qualifier("restTemplate")
   private  RestTemplate restTemplate;

    @Override
    public void addProgram(ProgramVO programVo) {

       //Defining what output we are expecting from rest web service
       List<MediaType> acceptableMediaTypes = new ArrayList<MediaType>();
        acceptableMediaTypes.add(MediaType.APPLICATION_JSON);

        //Here we are creating header object......................
        HttpHeaders headers = new HttpHeaders();
        
        // what output we are expecting from server = ie. rest provider
        headers.setAccept(acceptableMediaTypes);
        
         //the format of data which we are sending from client to server
        headers.setContentType(MediaType.APPLICATION_JSON);

       // setting header
       HttpEntity<ProgramVO> requestEntity = new HttpEntity<ProgramVO>(programVo,      headers);

       ResponseEntity<String> response = restTemplate.exchange(
                "http://www.gpsprogramys.co.in/com.gps.quiz/android/v1/program/padd", HttpMethod.POST,          requestEntity,String.class);

      String output = response.getBody();

}

ProgramVOWrapper .java (Wrapper class)

public class ProgramVOWrapper {
    List<ProgramVO> programVOs;
    public List<ProgramVO> getProgramVOs() {
        return programVOs;
    }
    public void setProgramVOs(List<ProgramVO> programVOs) {
        this.programVOs = programVOs;
    }
    @Override
    public String toString() {
        return "ProgramVOWrapper [programVOs=" + programVOs + "]";
    }

}

public class ProgramVO {
    private String id;
    private String programTiitle;
    private String code;
    private String topic;
    private String language;
    private String level;
    private Timestamp timestamp;
    private String userid;
     private Date cdate;
     
     //getter and setter of all above attributes.............. 
}

Accessing image in Rest web service client 

// Prepare acceptable media type

List<MediaType> acceptableMediaTypes = new ArrayList<MediaType>();

acceptableMediaTypes.add(MediaType.IMAGE_JPEG);

// Prepare header

HttpHeaders headers = new HttpHeaders();

headers.setAccept(acceptableMediaTypes);

HttpEntity<String> entity = new HttpEntity<String>(headers); 

// Send the request as GET

//                /http://localhost:8090/ImageProvider/rest/images/bella

//This is calling restful web service

             

RestTemplate restTemplate = new RestTemplate();

ResponseEntity<byte[]> result = restTemplate.exchange(ApplicationConstants.APPLICATION_BASE_URL+"/images/"+imageName, HttpMethod.GET, entity, byte[].class);

Note: In above URI we are sending "imageName" as a part of rest URI