org.faster.orm.pagination.Page.java Source code

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Here is the source code for org.faster.orm.pagination.Page.java

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/*
 * Copyright (c) 2013 @iSQWEN. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.faster.orm.pagination;

import org.apache.commons.lang3.builder.ToStringBuilder;
import org.apache.commons.lang3.builder.ToStringStyle;

/**
 * ?
 *
 * @author sqwen
 */
public class Page implements Pagination {

    private static final long serialVersionUID = -1950200411752637394L;

    private final int totalRecordCount;

    private int startIndexOfCurrentPage;

    private int pageSize = 50;

    private int currentPageIndex = 0;

    private int pageCount = 0;

    /**
     * ??
     *
     * @param totalCount 
      * @param startIndexOfCurrentPage ??
     * @param pageSize ?
     */
    public Page(int totalCount, int startIndexOfCurrentPage, int pageSize) {
        if (totalCount < 0) {
            throw new IllegalArgumentException("Record count can't be negative!");
        }
        if (startIndexOfCurrentPage < 0) {
            throw new IllegalArgumentException("StartIndexOfCurrentPage count can't be negative!");
        }
        if (pageSize <= 0) {
            throw new IllegalArgumentException("Page size must be positive!");
        }

        this.totalRecordCount = totalCount;
        this.pageSize = pageSize;
        if (totalCount == 0) {
            this.startIndexOfCurrentPage = 0;
            currentPageIndex = 0;
            pageCount = 0;
        } else {
            // startIndexOfCurrentPage
            this.startIndexOfCurrentPage = startIndexOfCurrentPage;
            currentPageIndex = startIndexOfCurrentPage / pageSize;
            if (totalCount % pageSize == 0) {
                pageCount = totalCount / pageSize;
            } else {
                pageCount = totalCount / pageSize + 1;
            }

            // startIndexOfCurrentPage??
            // if (startIndexOfCurrentPage == 0) {
            // currentPageIndex = 0;
            // } else if (startIndexOfCurrentPage < pageSize) {
            // currentPageIndex = 1;
            // } else {
            // if ((startIndexOfCurrentPage) % pageSize == 0) {
            // currentPageIndex = (startIndexOfCurrentPage + 1) / pageSize ;
            // } else {
            // currentPageIndex = (startIndexOfCurrentPage + 1) / pageSize + 1;
            // }
            // }
            //
            // if (totalCount - startIndexOfCurrentPage - 1 <= pageSize) {
            // pageCount = currentPageIndex + 1;
            // } else {
            // if ((totalCount - startIndexOfCurrentPage - 1) % pageSize == 0) {
            // pageCount = currentPageIndex + (totalCount -
            // startIndexOfCurrentPage - 1) / pageSize;
            // } else {
            // pageCount = currentPageIndex + (totalCount -
            // startIndexOfCurrentPage - 1) / pageSize + 1;
            // }
            // }
        }

    }

    /**
     * ?
     *
     * @return 
     */
    @Override
    public boolean isFirstPage() {
        return pageCount == 0 || currentPageIndex == 0;
    }

    /**
     * ??
     *
     * @return 
     */
    @Override
    public boolean isLastPage() {
        return pageCount == 0 || currentPageIndex == pageCount - 1;
    }

    /**
     * ?
     *
     * @return 
     */
    @Override
    public boolean hasPreviousPage() {
        return !isFirstPage();
    }

    /**
     * ?
     *
     * @return 
     */
    @Override
    public boolean hasNextPage() {
        return !isLastPage();
    }

    /**
     * ??
     *
     * @return ?
     */
    @Override
    public int getCurrentPageIndex() {
        return currentPageIndex;
    }

    /**
     * 
     */
    public void previousPage() {
        if (isFirstPage()) {
            throw new IllegalStateException("No previous page!");
        }
        currentPageIndex--;
        resetCurrentPage();
    }

    private void resetCurrentPage() {
        startIndexOfCurrentPage = currentPageIndex * pageSize;
    }

    /**
     * 
     */
    public void nextPage() {
        if (isLastPage()) {
            throw new IllegalStateException("No next page!");
        }
        currentPageIndex++;
        resetCurrentPage();
    }

    public void turnPageTo(int pageIndex) {
        verifyPageIndex(pageIndex);
        if (currentPageIndex != pageIndex) {
            currentPageIndex = pageIndex;
            resetCurrentPage();
        }
    }

    private void verifyPageIndex(int pageIndex) {
        if (pageIndex >= pageCount) {
            throw new IllegalArgumentException(
                    "Page index '" + pageIndex + "' is out of valid page index range[0," + (pageCount - 1) + "].");
        }
    }

    /**
     * ?
     *
     * @return 
     */
    @Override
    public int getPageCount() {
        return pageCount;
    }

    /**
     * ??
     *
     * @return ??
     */
    @Override
    public int getPageSize() {
        return pageSize;
    }

    /**
     * ??
     */
    @Override
    public int getCurrentPageRecordCount() {
        if (!isLastPage()) {
            return pageSize;
        }
        return getLastIndexOfCurrentPage() - getFirstIndexOfCurrentPage() + 1;
    }

    /**
     * ?
     */
    @Override
    public int getTotalRecordCount() {
        return totalRecordCount;
    }

    /**
     * ???
     *
     * @return ??
     */
    @Override
    public int getFirstIndexOfCurrentPage() {
        return startIndexOfCurrentPage;
    }

    /**
     * ????
     *
     * @return ???
     */
    @Override
    public int getLastIndexOfCurrentPage() {
        if (isLastPage()) {
            return totalRecordCount - 1;
        }
        return getFirstIndexOfCurrentPage() + pageSize - 1;
    }

    /**
     * ??
     *
     * @param pageIndex ?
     * @return ?
     */
    @Override
    public int getFirstIndexOfPage(int pageIndex) {
        verifyPageIndex(pageIndex);
        return pageIndex * pageSize;
    }

    /**
     * ???
     *
     * @param pageIndex ?
     * @return ??
     */
    @Override
    public int getLastIndexOfPage(int pageIndex) {
        verifyPageIndex(pageIndex);
        if (pageIndex == pageCount - 1) {
            return totalRecordCount - 1;
        }
        return (pageIndex + 1) * pageSize - 1;
    }

    @Override
    public String toString() {
        ToStringBuilder.setDefaultStyle(ToStringStyle.SHORT_PREFIX_STYLE);
        return new ToStringBuilder(this).append("TotalRecordCount", totalRecordCount).append("PageCount", pageCount)
                .append("PageSize", pageSize).append("CurrentPageIndex", currentPageIndex)
                .append("hasPreviousPage", hasPreviousPage()).append("hasNextPage", hasNextPage()).toString();
    }

    @Override
    public int getFirstIndexOfNextPage() {
        return getFirstIndexOfPage(getCurrentPageIndex() + 1);
    }

    @Override
    public int getFirstIndexOfPreviousPage() {
        return getFirstIndexOfPage(getCurrentPageIndex() - 1);
    }

    @Override
    public int getPageNo() {
        return getCurrentPageIndex() + 1;
    }

}