/src/main/java/com/jfinal/ext/render/excel/PoiKit.java

/**

 * Copyright (c) 2011-2013, kidzhou 周磊 (zhouleib1412@gmail.com)

 *

 * 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 com.jfinal.ext.render.excel;



import java.util.List;

import java.util.Map;

import java.util.Map.Entry;

import java.util.Set;



import org.apache.poi.hssf.usermodel.HSSFCell;

import org.apache.poi.hssf.usermodel.HSSFRow;

import org.apache.poi.hssf.usermodel.HSSFSheet;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;

import org.apache.poi.hssf.util.Region;



import com.google.common.base.Preconditions;

import com.jfinal.plugin.activerecord.Model;

import com.jfinal.plugin.activerecord.Record;



public class PoiKit {



    private static final int HEADER_ROW = 1;

    private static final int MAX_ROWS = 65536;



    private String sheetName = "new sheet";

    private int cellWidth = 8000;

    private int headerRow;

    private String[] headers = new String[] {};

    private String[] columns;

    private List<?> data;



    public PoiKit(List<?> data) {

        this.data = data;

    }



    public static PoiKit with(List<?> data) {

        return new PoiKit(data);

    }



    public HSSFWorkbook export() {

        Preconditions.checkNotNull(headers, "headers can not be null");

        Preconditions.checkNotNull(columns, "columns can not be null");

        Preconditions.checkArgument(cellWidth >= 0, "cellWidth < 0");

        HSSFWorkbook wb = new HSSFWorkbook();

        HSSFSheet sheet = wb.createSheet(sheetName);

        HSSFRow row = null;

        HSSFCell cell = null;

        if (headers.length > 0) {

            row = sheet.createRow(0);

            if (headerRow <= 0) {

                headerRow = HEADER_ROW;

            }

            headerRow = Math.min(headerRow, MAX_ROWS);

            for (int h = 0, lenH = headers.length; h < lenH; h++) {

                @SuppressWarnings("deprecation")

                Region region = new Region(0, (short) h, (short) headerRow - 1, (short) h);// 合并从第rowFrom行columnFrom列

                sheet.addMergedRegion(region);// 到rowTo行columnTo的区域

                // 得到所有区域

                sheet.getNumMergedRegions();

                if (cellWidth > 0) {

                    sheet.setColumnWidth(h, cellWidth);

                }

                cell = row.createCell(h);

                cell.setCellValue(headers[h]);

            }

        }

        if (data.size() == 0) {

            return wb;

        }

        for (int i = 0, len = data.size(); i < len; i++) {

            row = sheet.createRow(i + headerRow);

            Object obj = data.get(i);

            if (obj == null) {

                continue;

            }

            if (obj instanceof Map) {

                processAsMap(columns, row, obj);

            } else if (obj instanceof Model) {

                processAsModel(columns, row, obj);

            } else if (obj instanceof Record) {

                processAsRecord(columns, row, obj);

            }

        }

        return wb;

    }



    @SuppressWarnings("unchecked")

    private static void processAsMap(String[] columns, HSSFRow row, Object obj) {

        HSSFCell cell;

        Map<String, Object> map = (Map<String, Object>) obj;

        if (columns.length == 0) {// 未设置显示列，默认全部

            Set<String> keys = map.keySet();

            int columnIndex = 0;

            for (String key : keys) {

                cell = row.createCell(columnIndex);

                cell.setCellValue(map.get(key) + "");

                columnIndex++;

            }

        } else {

            for (int j = 0, lenJ = columns.length; j < lenJ; j++) {

                cell = row.createCell(j);

                cell.setCellValue(map.get(columns[j]) + "");

            }

        }

    }



    private static void processAsModel(String[] columns, HSSFRow row, Object obj) {

        HSSFCell cell;

        Model<?> model = (Model<?>) obj;

        Set<Entry<String, Object>> entries = model.getAttrsEntrySet();

        if (columns.length == 0) {// 未设置显示列，默认全部

            int columnIndex = 0;

            for (Entry<String, Object> entry : entries) {

                cell = row.createCell(columnIndex);

                cell.setCellValue(entry.getValue() + "");

                columnIndex++;

            }

        } else {

            for (int j = 0, lenJ = columns.length; j < lenJ; j++) {

                cell = row.createCell(j);

                cell.setCellValue(model.get(columns[j]) + "");

            }

        }

    }



    private static void processAsRecord(String[] columns, HSSFRow row, Object obj) {

        HSSFCell cell;

        Record record = (Record) obj;

        Map<String, Object> map = record.getColumns();

        if (columns.length == 0) {// 未设置显示列，默认全部

            record.getColumns();

            Set<String> keys = map.keySet();

            int columnIndex = 0;

            for (String key : keys) {

                cell = row.createCell(columnIndex);

                cell.setCellValue(record.get(key) + "");

                columnIndex++;

            }

        } else {

            for (int j = 0, lenJ = columns.length; j < lenJ; j++) {

                cell = row.createCell(j);

                cell.setCellValue(map.get(columns[j]) + "");

            }

        }

    }



    public PoiKit sheetName(String sheetName) {

        this.sheetName = sheetName;

        return this;

    }



    public PoiKit cellWidth(int cellWidth) {

        this.cellWidth = cellWidth;

        return this;

    }



    public PoiKit headerRow(int headerRow) {

        this.headerRow = headerRow;

        return this;

    }



    public PoiKit headers(String[] headers) {

        this.headers = headers;

        return this;

    }



    public PoiKit columns(String[] columns) {

        this.columns = columns;

        return this;

    }



}