/JFOA/core/net/loyin/jFinal/render/excel/ExcelKit.java

package net.loyin.jFinal.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.jfinal.plugin.activerecord.Model;
import com.jfinal.plugin.activerecord.Record;
/**
 * description:
 * 
 * @author liyupeng
 * 
 *         2012-8-17
 */
public class ExcelKit {
	private final static int MAX_ROWS = 65536;
	public final static int HEADER_ROW = 1;
	public final static int DEFAULT_CELL_WIDTH = 8000;
	/**
	 * 
	 * @param sheetName sheet名称
	 * @param cellWidth 设置单元格宽度
	 * @param headerRow 设置头列占的行数
	 * @param headers 头列值
	 * @param columns 列key(即 list<Map<String ,Ojbect>> 中 map的key)
	 * @param list 数据
	 * @return
	 */

	@SuppressWarnings("deprecation")
	private static HSSFWorkbook export(String sheetName, int cellWidth,
			int headerRow, String[] headers, String[] columns,List  list,int columnNum,  boolean hasHeaders) {
		if (sheetName == null || sheetName.isEmpty()) {
			sheetName = "new sheet";
		}
		HSSFWorkbook wb = null;
		try {
			wb = new HSSFWorkbook();
			HSSFSheet sheet = wb.createSheet(sheetName);
			HSSFRow row = null;
			HSSFCell cell = null;
			setCellWidth(sheet, cellWidth, columnNum);
			if (hasHeaders) {
				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++) {
					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();
					sheet.setColumnWidth(h, cellWidth);
					cell = row.createCell(h);
					cell.setCellValue(headers[h]);
				}
			}

			if (list==null||list.size()==0) {
				return wb;
			}
			for (int i = 0, len = list.size(); i < len; i++) {
				row = sheet.createRow(i + headerRow);
				Object obj = list.get(i);
				if(obj==null){
					continue;
				}
				//obj : record map model
				if(obj instanceof Map){
					@SuppressWarnings("unchecked")
					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])+"");
						}
					}
				}else if(obj instanceof Model){
					@SuppressWarnings("rawtypes")
					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])+"");
						}
					}

				}else if(obj instanceof Record){
					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])+"");
						}
					}

				}
			}
		} catch (Exception ex) {
			ex.printStackTrace();
		}
		return wb;
	}
	/**
	 * 设置单元格宽度
	 * @param sheet
	 * @param cellWidth
	 * @param columnNum
	 */
	private static void setCellWidth(HSSFSheet sheet, int cellWidth, int columnNum){
		for (int i = 0; i < columnNum; i++) {
			sheet.setColumnWidth(i, cellWidth);
		}

	}
	/**
	 * @param String sheetName sheet名称
	 * @param int headerRow 设置头列占的行数
	 * @param String[] headers 头列值
	 * @param String[] columns 列key(即 list<Map<String ,Ojbect>> 中 map的key)
	 * @param List<Map<String, Object>> list 数据
	 * @param int cellWidth 设置单元格宽度
	 * @return
	 */
	public static HSSFWorkbook export(String sheetName,int headerRow, String[] headers, String[] columns,
			List<Object> list, int cellWidth) {
		boolean hasHeaders = false;
		int columnNum = 0;
		if (headers != null && headers.length >0) {
			hasHeaders = true;
			columnNum = headers.length;
		} 
		if (columns == null ) {
			columns = new String[]{};
		} 
		columnNum = Math.max(columnNum, columns.length);
		if (cellWidth <= 0) {
			cellWidth = DEFAULT_CELL_WIDTH;
		}
		return export(sheetName, cellWidth, headerRow, headers, columns, list, columnNum , hasHeaders);

	}
}