public interface Group<T> {
   boolean isSameGroup(T current, T next);
}

public static <T> List<List<T>> groupList(List<T> list, Group<T> groupBy) {
    // 结果
    List<List<T>> groupResult = new ArrayList<>();
    if (list == null || list.isEmpty()) {
        return groupResult;
    }

    int len = list.size();
    // 当前元素
    T currentItem = list.get(0);
    // 分组的开始下标
    int start = 0;
    for (int i=1; i<len; i++) {
    	// 取下一个元素
        T nextItem = list.get(i);
		// 当前元素和一下元素不同分组
        if(!groupBy.isSameGroup(currentItem, nextItem)) {
        	// 保存分组
            groupResult.add(list.subList(start, i));
            // 重置当前元素
            currentItem = nextItem; 
            // 保存新分组的开始下标
            start = i;
        }
    }
    if(start == 0) {
        groupResult.add(list);
    } else {
    	// 保存余的元素
        groupResult.add(list.subList(start, len));
    }
    return groupResult;
}

public static void main(String[] args) {
        
    Group<Integer> groupBy = new Group<Integer>() {
        @Override
        public boolean isSameGroup(Integer current, Integer next) {
            return current.equals(next);
        }
    };
    
    List<Integer> list = new ArrayList<>();
    List<List<Integer>> groupResult = groupList(list, groupBy);
    System.out.println(groupResult);
    
    list.add(1);
    list.add(1);
    groupResult = groupList(list, groupBy);
    System.out.println(groupResult);
    
    list.add(2);
    groupResult = groupList(list, groupBy);
    System.out.println(groupResult);
    
    list.add(4);
    list.add(4);
    list.add(4);
    groupResult = groupList(list, groupBy);
    System.out.println(groupResult);
    
    list.add(7);
    groupResult = groupList(list, groupBy);
    System.out.println(groupResult);
    list.add(8);
    list.add(8);
    list.add(8);
    groupResult = groupList(list, groupBy);
    System.out.println(groupResult);
    
}

  /**
     * Gets the HTTP servlet request object.
     *
     * @return the HTTP servlet request object.
     */
    public static HttpServletRequest getRequest() {
        return (HttpServletRequest) ActionContext.getContext().get(HTTP_REQUEST);
    }

static ThreadLocal<ActionContext> actionContext = new ThreadLocal<ActionContext>();

private static final Logger logger = LoggerFactory.getLogger(WebAppInitializer.class);

@Override
public void onStartup(ServletContext servletContext) throws ServletException {
    logger.info("--------------------WebAppInitializer------------------------");
    try {
        String hosteName = SystemInfoUtil.getHostName();
        if(!ConfigUtil.isOnline() || (hosteName != null && hosteName.toUpperCase().contains("MASTER"))) {
            servletContext.setInitParameter("spring.profiles.active", "schedule");
            logger.info("spring.profiles.active=schedule");
        }
    } catch (Exception e) {
        logger.error("WebAppInitializerError", e);
    }
}

/**
  * 取数据的接口
 */
public interface DataExporter<T>{
    /**
     * 获取数据
     * @return
     */
    List<T> getDatas(int start, int maxSize);
    
    /**
     * 表头数据
     * @return
     */
    List<String> getTitle();
    
    /**
     *  每行数据
     * @param object
     * @return
     */
    List getExportData(T rowData);
  
    /**
     * 统计�数据
     * @param object
     * @return
     */
    List getExportTotalData();
}

public abstract class Exportor<T> {
    private static final int PAGE_SIZE = 500;

    public void export(DataExporter<T> exporter) throws IOException {
        //表头
        List<String> titles = exporter.getTitle();
        if (titles != null) {
            writeTitle(titles);
        }
        try {
            int pageIndex = 1;
            int startIndex = 0;
            List<T> list = null;
            do {
                // 取数据
                list = exporter.getDatas(startIndex, PAGE_SIZE);
                if(list != null) {
                    // 导出数据
                    for (T t : list) {
                        List rowdata = exporter.getExportData(t);
                        writeRowData(rowdata);
                    }
                }
                startIndex = pageIndex * PAGE_SIZE;
                pageIndex++;
            } while (list.size() == PAGE_SIZE);
            
            // 导出总计结果
            List<T> totalData = exporter.getExportTotalData();
            if(totalData != null && totalData.size() > 0){
                writeRowData(totalData);
            }
        } finally {
            this.close();
        }
    }
    
    /**
     * 写一行数据
     * @param rowData
     */
    protected abstract void writeRowData(List rowData) throws IOException;

    /**
     * 写表头
     * @param title
     */
    protected abstract void writeTitle(List<String> title) throws IOException;
    
    /**
     * 清理工作
     */
    protected abstract void close() throws IOException;
    
}

private ExcelWriter excelWriter = null;
private OutputStream outputStream = null;

public ExcelExportor(OutputStream outputStream) {
    super();
    this.excelWriter = new ExcelWriter();
    this.outputStream = outputStream;
}

@Override
protected void writeRowData(List rowData) {
    excelWriter.writeRowData(rowData);
}

@Override
protected void writeTitle(List<String> title) {
    excelWriter.writeRowData(title);
}

@Override
protected void close() {
    excelWriter.writeFile(outputStream);
    try {
        outputStream.flush();
        outputStream.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

private CSVWriter csvWriter = null;

public CSVExportor(Writer writer) {
    super();
    csvWriter = new CSVWriter(writer, CSVWriter.DEFAULT_SEPARATOR);
}

protected void writeTitle(List<String> title) {
    csvWriter.writeNext(title.toArray(new String[title.size()]));
}

protected void writeRowData(List rowData) {
    String[] rowArray = new String[rowData.size()];
    rowData.toArray(rowArray);
    csvWriter.writeNext(rowArray);
}

@Override
protected void close() {
    try {
        csvWriter.flush();
        csvWriter.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

public class ExcelResult<T> implements Result {

	private static final Logger logger = LoggerFactory.getLogger(ExcelResult.class);
    
    private String fileName = "export.xls";
    private DataExporter<T> exporter;
    
    
	public ExcelResult(){
		super();
	}
	
	public ExcelResult(DataExporter<T> exporter){
		this(null, exporter);
	}
	
	public ExcelResult(String fileName, DataExporter<T> exporter){
        super();
        if(fileName != null) {
            try {
                this.fileName = new String(fileName.getBytes(), "ISO8859-1");
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        }
        this.exporter = exporter;
	}
	
	@Override
    public void execute(ActionInvocation invocation) throws Exception {
        HttpServletResponse response = ServletActionContext.getResponse();
        
        ServletOutputStream outputStream = response.getOutputStream();
        try {
            response.setHeader("Pragma", "No-cache"); 
            response.setHeader("Cache-Control", "No-cache"); 
            response.setDateHeader("Expires", 0);
            response.setHeader("Content-Disposition","attachment;filename=" + fileName + DateUtil.date2String(new Date(), "_yyyyMMddHHmmss") + ".xls");
            response.setContentType("application/vnd.ms-excel;charset=gbk");
            Exportor<T> export = new ExcelExportor<>(outputStream);
            export.export(exporter);
        } catch(Exception e) {
            logger.error("导出Excel时出错了", e);
        }
    }
    public String getFileName() {
        return fileName;
    }

    public void setFileName(String fileName) {
        this.fileName = fileName;
    }

    public void setExporter(DataExporter<T> exporter) {
        this.exporter = exporter;
    } 
}

public ExcelResult<Reservation> exportResvs() {
        final Map params = _buildQueryParams();
        
        ExcelResult<Reservation> result = new ExcelResult<>("订单列表", new DataExporter<Reservation>(){

            @Override
            public List<Reservation> getDatas(int start, int maxSize) {
                return reservationService.getReservations(params, start, maxSize);
            }

            @Override
            public List<String> getTitle() {
                List<String> titles = new ArrayList<String>();
                titles.add("订单号");
                titles.add("渠道");
                titles.add("卖价");
                titles.add("创建时间");
                return titles;
            }

            @Override
            public List getExportData(Reservation resv) {
                List<Object> rowData = new ArrayList<Object>();
                
                rowData.add(resv.getReservationId());
                rowData.add(resv.getChannelName());
                rowData.add(resv.getTotalMoney());
                
                rowData.add(DateUtil.date2String(resv.getCreateDatetime(), DateUtil.DATE_FORMAT_DATE_TIME));
                return rowData;
            }

			@Override
            public List getExportTotalData() {
	            return null;
            }
            
        });
        
        return result;
    }