PageWrapper.java

package de.ppi.fuwesta.spring.mvc.util;

import java.util.ArrayList;
import java.util.List;

import org.springframework.data.domain.Page;

/**
 * A wrapper for {@link Page} which makes pagination easier.
 *
 * @param <T> the generic type
 */
// TODO Test schreiben.
public class PageWrapper<T> {

    /** The Constant MAX_PAGE_ITEM_DISPLAY. */
    public static final int MAX_PAGE_ITEM_DISPLAY = 5;

    /** The page. */
    private final Page<T> page;

    /** The items. */
    private final List<PageItem> items;

    /** The current number. */
    private int currentNumber;

    /** The URL to the list. */
    private String url;

    /**
     * Gets the url.
     *
     * @return the url
     */
    public String getUrl() {
        return url;
    }

    /**
     * Instantiates a new page wrapper.
     *
     * @param page the page
     * @param url the url
     */
    public PageWrapper(Page<T> page, String url) {
        this.page = page;
        this.url = url;
        items = new ArrayList<PageItem>();

        currentNumber = page.getNumber() + 1; // start from 1 to match page.page

        int start;
        int size;
        if (page.getTotalPages() <= MAX_PAGE_ITEM_DISPLAY) {
            start = 1;
            size = page.getTotalPages();
        } else {
            if (currentNumber <= MAX_PAGE_ITEM_DISPLAY - MAX_PAGE_ITEM_DISPLAY
                    / 2) {
                start = 1;
                size = MAX_PAGE_ITEM_DISPLAY;
            } else if (currentNumber >= page.getTotalPages()
                    - MAX_PAGE_ITEM_DISPLAY / 2) {
                start = page.getTotalPages() - MAX_PAGE_ITEM_DISPLAY + 1;
                size = MAX_PAGE_ITEM_DISPLAY;
            } else {
                start = currentNumber - MAX_PAGE_ITEM_DISPLAY / 2;
                size = MAX_PAGE_ITEM_DISPLAY;
            }
        }

        for (int i = 0; i < size; i++) {
            items.add(new PageItem(start + i, (start + i) == currentNumber));
        }
    }

    /**
     * Gets the items.
     *
     * @return the items
     */
    public List<PageItem> getItems() {
        return items;
    }

    /**
     * Return the page-object.
     *
     * @return the page-object.
     */
    public Page<T> getPage() {
        return page;
    }

    /**
     * Gets the number.
     *
     * @return the number
     */
    public int getNumber() {
        return currentNumber;
    }

    /**
     * Gets the content.
     *
     * @return the content
     */
    public List<T> getContent() {
        return page.getContent();
    }

    /**
     * Gets the size.
     *
     * @return the size
     */
    public int getSize() {
        return page.getSize();
    }

    /**
     * Gets the total pages.
     *
     * @return the total pages
     */
    public int getTotalPages() {
        return page.getTotalPages();
    }

    /**
     * Checks if is first page.
     *
     * @return true, if is first page
     */
    public boolean isFirstPage() {
        return page.isFirst();
    }

    /**
     * Checks if is last page.
     *
     * @return true, if is last page
     */
    public boolean isLastPage() {
        return page.isLast();
    }

    /**
     * Checks if is checks for previous page.
     *
     * @return true, if is checks for previous page
     */
    public boolean isHasPreviousPage() {
        return page.hasPrevious();
    }

    /**
     * Checks if is checks for next page.
     *
     * @return true, if is checks for next page
     */
    public boolean isHasNextPage() {
        return page.hasNext();
    }

    /**
     * Gets the sort-attributes from the page-object and returns a String
     * representation which was modified from: attribute: order to
     * attribute,order. This is necessary in order to built the correct
     * request-url for sorting.
     *
     * @return the modified string representation of the Sort-object.
     */
    public String getSort() {

        if (page.getSort() != null) {
            return page.getSort().toString().replace(':', ',');
        }

        return "";

    }

    /**
     * A PageItem holds some information about the page.
     */
    public class PageItem {

        /** The number. */
        private int number;

        /** The current. */
        private boolean current;

        /**
         * Instantiates a new page item.
         *
         * @param number the number
         * @param current the current
         */
        public PageItem(int number, boolean current) {
            this.number = number;
            this.current = current;
        }

        /**
         * Gets the number.
         *
         * @return the number
         */
        public int getNumber() {
            return this.number;
        }

        /**
         * Checks if is current.
         *
         * @return true, if is current
         */
        public boolean isCurrent() {
            return this.current;
        }
    }
}