基于注解的方式导出Excel

利用Java反射机制实现。

1.自定义注解：

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Excel {
    public String colName();   //列明
    public int order();   //顺序
}

2.在需要导出的字段的get方法上使用：因为get方法可以获取该字段的数据

@Excel(colName = "座位号", order = 17)
public String getNo() {
    return no;
}

3.编写导出Excel工具类：

package com.***.common.utils;

import java.io.BufferedOutputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.lang.reflect.Method;
import java.util.Date;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;

import javax.servlet.http.HttpServletResponse;

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 com.***.common.annotation.Excel;

public class POIExportUtils<T>{

    public void ResponseInit(HttpServletResponse response, String fileName){
        response.reset();
        //设置content-disposition响应头控制浏览器以下载的形式打开文件
        response.setHeader("Content-Disposition", "attachment;filename="+ fileName + new Date() + ".xls");
        //让服务器告诉浏览器它发送的数据属于excel文件类型
        response.setContentType("application/vnd.ms-excel;charset=UTF-8");
        response.setHeader("Prama", "no-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expires", 0);
    }
    
    public void POIOutPutStream(HttpServletResponse response, HSSFWorkbook wb){
        
        try {
            BufferedOutputStream out = new BufferedOutputStream(response.getOutputStream());
            wb.write(out);
            out.flush();
            out.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
    @SuppressWarnings({ "unchecked", "rawtypes" })
    public void export(Class<T> objClass, List<T> dataList, HttpServletResponse response, String fileName) throws Exception{
        
        ResponseInit(response,fileName);
        
        Class excelClass = Class.forName(objClass.toString().substring(6));
        Method[] methods = excelClass.getMethods();
        
        Map<Integer, String> mapCol = new TreeMap<>();
        Map<Integer, String> mapMethod = new TreeMap<>();
        
        for (Method method : methods) {
            Excel excel = method.getAnnotation(Excel.class);
            if (excel != null) {
                mapCol.put(excel.order(), excel.colName());
                mapMethod.put(excel.order(), method.getName());
            }
        }
        HSSFWorkbook wb = new HSSFWorkbook();
        POIBuildBody(POIBuildHead(wb,"sheet1",mapCol),excelClass,mapMethod,dataList);
        
        POIOutPutStream(response,wb);
    }
    
    public HSSFSheet POIBuildHead(HSSFWorkbook wb, String sheetName, Map<Integer, String> mapCol){
        HSSFSheet sheet01 = wb.createSheet(sheetName);
        HSSFRow row = sheet01.createRow(0);
        HSSFCell cell;
        int i = 0;
        for (Map.Entry<Integer, String> entry : mapCol.entrySet()) {
            cell = row.createCell(i++);
            cell.setCellValue(entry.getValue());
        }
        return sheet01;
    }
    
    public void POIBuildBody(HSSFSheet sheet01, Class<T> excelClass, Map<Integer, String> mapMethod, List<T> dataList) throws Exception{
        
        HSSFRow r = null;
        HSSFCell c = null;
        
        if(dataList != null && dataList.size() > 0){                
            for(int i = 0;i<dataList.size();i++){
                r= sheet01.createRow(i+1);
                //r.setHeightInPoints(25);
                int j = 0;
                for (Map.Entry<Integer, String> entry : mapMethod.entrySet()) {
                    c = r.createCell(j++);
                    Object obj = excelClass.getDeclaredMethod(entry.getValue()).invoke(dataList.get(i));
                    c.setCellValue(obj==null?"":obj+"");
                }
            }
        }
    }
    
}

4.测试：

new POIExportUtils<CaseInfo>().export(CaseInfo.class, dataList, response, "caseInfo_");