POI实现导出Excel数据工具类

  项目中很多地方需要导出excel数据，因此需要将导出excel数据封装成工具类。
实现思路:
      1、将查询结果List<T>以及T作为入参。
      2、新建一个注解，在T对象需要生成表格数据的字段加上这个注解。
供外部调用的方法:
import java.io.IOException;
import java.util.List;

import javax.servlet.http.HttpServletResponse;

import com.coolpad.store.common.export.DataExportUtil;

public class WebDataExporter {
static public <T> boolean exportWebExcelWithAnnotation(HttpServletResponse resp, List<T> dataList, Class<T> clzz) throws IOException {
resp.setContentType("application/vnd.ms-excel");
resp.setHeader("Content-disposition", "attachment;filename=ExportData.xls");
return DataExportUtil.<T> exportExcelWithAnnotation(resp.getOutputStream(),dataList,clzz);
}
}
导出Excel实现方法:

import java.io.OutputStream;
import java.lang.reflect.Field;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import org.apache.commons.beanutils.BeanMap;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFFont;
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.HSSFColor;

public class DataExportUtil {

static public <T> boolean exportExcelWithAnnotation(OutputStream ouputStream, List<T> dataList, Class<T> clzz) {

HSSFWorkbook wb = new HSSFWorkbook();

HSSFSheet sheet = wb.createSheet("导出数据");

sheet.setColumnWidth(0, 20 * 256);

HSSFCellStyle style = wb.createCellStyle();
// style.setAlignment(HSSFCellStyle.ALIGN_LEFT); // 创建一个居中格式

HSSFFont font = wb.createFont();
font.setFontHeightInPoints((short) 12);
font.setColor(HSSFColor.BLACK.index);
// font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
font.setFontName("宋体");
style.setFont(font);

HSSFCellStyle styleHeader = wb.createCellStyle();
styleHeader.setAlignment(HSSFCellStyle.ALIGN_CENTER); // 创建一个居中格式
styleHeader.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);// 垂直居中

HSSFFont fontHeader = wb.createFont();
fontHeader.setFontHeightInPoints((short) 15);
fontHeader.setColor(HSSFColor.BLACK.index);
fontHeader.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
fontHeader.setFontName("黑体");
styleHeader.setFont(font);
// 背景色HSSFColor.LIGHT_GREEN.index
styleHeader.setFillForegroundColor(HSSFColor.LIGHT_GREEN.index);
styleHeader.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
styleHeader.setFillBackgroundColor(HSSFColor.YELLOW.index);
// row.setRowStyle(styleHeader);
HSSFRow row = sheet.createRow((int) 0);
row.setHeightInPoints(30);
HSSFCell cell = row.createCell((short) 0);
cell.setCellValue("序号");
cell.setCellStyle(styleHeader);

Map<String, String> headerMap = new LinkedHashMap<String, String>();
List<String> headers = new LinkedList<String>();

Field[] fields = clzz.getDeclaredFields();
for (Field field : fields) {
ExportHeader exHeader = field.getAnnotation(ExportHeader.class);
if(null==exHeader){
continue;
}
String header = exHeader.value();
headers.add(header);

headerMap.put(header, field.getName());
}
for (int i = 0; i < headers.size(); i++) {
cell = row.createCell((short) i + 1);
cell.setCellValue(headers.get(i));
cell.setCellStyle(styleHeader);
}
for (int i = 0; i < dataList.size(); i++) {
sheet.setColumnWidth(i, 20 * 256);

row = sheet.createRow((int) i + 1);
row.setHeightInPoints(20);
BeanMap beanMap = new BeanMap(dataList.get(i));

cell = row.createCell((short) 0);
cell.setCellValue(i + 1);
cell.setCellStyle(style);

int j = 0;
for (Map.Entry<String, String> kv : headerMap.entrySet()) {
String header = kv.getKey();
String fieldName = kv.getValue();
Object val = beanMap.get(fieldName);

cell = row.createCell((short) j + 1);
cell.setCellValue(val!=null?val.toString():"");
cell.setCellStyle(style);
j++;
}
}
try {
wb.write(ouputStream);
ouputStream.flush();
ouputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
return true;
}
}
注解类:
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
public @interface ExportHeader {
String value();
}
查询结果数据对象:
public class User {
private int id;//没有注解，不需要导出这个字段

@ExportHeader("姓名")
private String name;

@ExportHeader("年龄")
private int age;

@ExportHeader("地址")
private String address;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}

}  至此，已经完成了Excel导出工具的编写。在项目的其他地方调用WebDataExporter的exportWebExcelWithAnnotation方法即可。