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GitLab4J-API (gitlab4j-api) provides a full featured Java client library for working with GitLab repositories and servers via the GitLab REST API.
package org.gitlab4j.api;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.core.Response;
import org.gitlab4j.api.utils.JacksonJson;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
/**
* This class defines an Iterator implementation that is used as a paging iterator for all API methods that
* return a List of objects. It hides the details of interacting with the GitLab API when paging is involved
* simplifying accessing large lists of objects.
*
* Example usage:
*
*
* // Get a Pager instance that will page through the projects with 10 projects per page
* Pager<Project> projectPager = gitlabApi.getProjectsApi().getProjectsPager(10);
*
* // Iterate through the pages and print out the name and description
* while (projectsPager.hasNext())) {
* List<Project> projects = projectsPager.next();
* for (Project project : projects) {
* System.out.println(project.getName() + " -: " + project.getDescription());
* }
* }
*
*
* @param the GitLab4J type contained in the List.
*/
public class Pager implements Iterator>, Constants {
private int itemsPerPage;
private int totalPages;
private int totalItems;
private int currentPage;
private List pageParam = new ArrayList<>(1);
private List currentItems;
private AbstractApi api;
private MultivaluedMap queryParams;
private Object[] pathArgs;
private static JacksonJson jacksonJson = new JacksonJson();
private static ObjectMapper mapper = jacksonJson.getObjectMapper();
private JavaType javaType;
/**
* Creates a Pager instance to access the API through the specified path and query parameters.
*
* @param api the AbstractApi implementation to communicate through
* @param type the GitLab4J type that will be contained in the List
* @param itemsPerPage items per page
* @param queryParams HTTP query params
* @param pathArgs HTTP path arguments
* @throws GitLabApiException if any error occurs
*/
Pager(AbstractApi api, Class type, int itemsPerPage, MultivaluedMap queryParams, Object... pathArgs) throws GitLabApiException {
javaType = mapper.getTypeFactory().constructCollectionType(List.class, type);
// Make sure the per_page parameter is present
if (queryParams == null) {
queryParams = new GitLabApiForm().withParam(PER_PAGE_PARAM, itemsPerPage).asMap();
} else {
queryParams.remove(PER_PAGE_PARAM);
queryParams.add(PER_PAGE_PARAM, Integer.toString(itemsPerPage));
}
// Set the page param to 1
pageParam = new ArrayList<>();
pageParam.add("1");
queryParams.put(PAGE_PARAM, pageParam);
Response response = api.get(Response.Status.OK, queryParams, pathArgs);
try {
currentItems = mapper.readValue((InputStream) response.getEntity(), javaType);
} catch (IOException e) {
throw new GitLabApiException(e);
}
this.api = api;
this.queryParams = queryParams;
this.pathArgs = pathArgs;
this.itemsPerPage = getHeaderValue(response, PER_PAGE);
totalPages = getHeaderValue(response, TOTAL_PAGES_HEADER);
totalItems = getHeaderValue(response, TOTAL_HEADER);
}
/**
* Get the specified integer header value from the Response instance.
*
* @param response the Response instance to get the value from
* @param key the HTTP header key to get the value for
* @return the specified integer header value from the Response instance
* @throws GitLabApiException if any error occurs
*/
private int getHeaderValue(Response response, String key) throws GitLabApiException {
String value = response.getHeaderString(key);
value = (value != null ? value.trim() : null);
if (value == null || value.length() == 0)
throw new GitLabApiException("Missing '" + key + "' header from server");
try {
return (Integer.parseInt(value));
} catch (NumberFormatException nfe) {
throw new GitLabApiException("Invalid '" + key + "' header value (" + value + ") from server");
}
}
/**
* Sets the "page" query parameter.
*
* @param page the value for the "page" query parameter
*/
private void setPageParam(int page) {
pageParam.set(0, Integer.toString(page));
queryParams.put(PAGE_PARAM, pageParam);
}
/**
* Get the items per page value.
*
* @return the items per page value
*/
public int getItemsPerPage() {
return (itemsPerPage);
}
/**
* Get the total number of pages returned by the GitLab API.
*
* @return the total number of pages returned by the GitLab API
*/
public int getTotalPages() {
return (totalPages);
}
/**
* Get the total number of items (T instances) returned by the GitLab API.
*
* @return the total number of items (T instances) returned by the GitLab API
*/
public int getTotalItems() {
return (totalItems);
}
/**
* Get the current page of the iteration.
*
* @return the current page of the iteration
*/
public int getCurrentPage() {
return (currentPage);
}
/**
* Returns the true if there are additional pages to iterate over, otherwise returns false.
*
* @return true if there are additional pages to iterate over, otherwise returns false
*/
@Override
public boolean hasNext() {
return (currentPage < totalPages);
}
/**
* Returns the next List in the iteration containing the next page of objects.
*
* @return the next List in the iteration
* @throws NoSuchElementException if the iteration has no more elements
* @throws RuntimeException if a GitLab API error occurs, will contain a wrapped GitLabApiException with the details of the error
*/
@Override
public List next() {
return (page(currentPage + 1));
}
/**
* Returns the first page of List. Will rewind the iterator.
*
* @return the first page of List
* @throws GitLabApiException if any error occurs
*/
public List first() throws GitLabApiException {
return (page(1));
}
/**
* Returns the last page of List. Will set the iterator to the end.
*
* @return the last page of List
* @throws GitLabApiException if any error occurs
*/
public List last() throws GitLabApiException {
return (page(totalPages));
}
/**
* Returns the previous page of List. Will set the iterator to the previous page.
*
* @return the previous page of List
* @throws GitLabApiException if any error occurs
*/
public List previous() throws GitLabApiException {
return (page(currentPage - 1));
}
/**
* Returns the current page of List.
*
* @return the current page of List
* @throws GitLabApiException if any error occurs
*/
public List current() throws GitLabApiException {
return (page(currentPage));
}
/**
* Returns the specified page of List.
*
* @param pageNumber the page to get
* @return the specified page of List
* @throws NoSuchElementException if the iteration has no more elements
* @throws RuntimeException if a GitLab API error occurs, will contain a wrapped GitLabApiException with the details of the error
*/
public List page(int pageNumber) {
if (pageNumber > totalPages) {
throw new NoSuchElementException();
} else if (pageNumber < 1) {
throw new NoSuchElementException();
}
if (currentPage == 0 && pageNumber == 1) {
currentPage = 1;
return (currentItems);
}
if (currentPage == pageNumber) {
return (currentItems);
}
try {
setPageParam(pageNumber);
Response response = api.get(Response.Status.OK, queryParams, pathArgs);
currentItems = mapper.readValue((InputStream) response.getEntity(), javaType);
currentPage = pageNumber;
return (currentItems);
} catch (GitLabApiException | IOException e) {
throw new RuntimeException(e);
}
}
}