【每日一点】1. Java如何实现导出Excel单表头或多表头
一、背景
在后台项目中，经常会遇到将呈现的内容导出到Excel的需求，通过都是导出单个表头的Excel文件，如果存在级联关系的情况下，也就需要导出多表头的场景。今天这篇文章就是分享导出Excel单表头或多表头的实现，目前实现方案仅支持2行表头场景。如有更复杂的3行表头、4行表头复杂需求可以自行实现。
二、实现思路
1. 借助POI包实现表头的写入。每个表头其实就是一行，如果是多个表头，无非就是将写多行表头，然后将需要合并的表头进行合并，借助POI的函数为addMergedRegion。
2. 将导出数据进行转化为一个集合，循环写入每行数据。
三、实现代码
3.1 pom引入
<properties>
<java.version>1.8</java.version>
<poi.version>3.17</poi.version>
<mybatis.version>1.3.2</mybatis.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-aop</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-validation</artifactId>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>${mybatis.version}</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>${poi.version}</version>
</dependency>
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi</artifactId>
<version>${poi.version}</version>
</dependency>
</dependencies>
View Code
3.2 Java代码实现
@Getter
@Setter
public class ExcelHelper<T> {
/**
* 表格标题
*/
private String title;
/**
* 单元格宽度
*/
private int colWidth = 20;
/**
* 行高度
*/
private int rowHeight = 20;
private HSSFWorkbook workbook;
/**
* 表头样式
*/
private HSSFCellStyle headStyle;
/**
* 主体样式
*/
private HSSFCellStyle bodyStyle;
/**
* 日期格式化,默认yyyy-MM-dd HH:mm:ss
*/
private SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
/**
* Constructor
* @param title
*/
public ExcelHelper(String title){
this.title = title;
workbook = new HSSFWorkbook();
init();
}
/**
* Constructor
* @param title
* @param colWidth
* @param rowHeight
*/
public ExcelHelper(String title, int colWidth, int rowHeight){
this.colWidth = colWidth;
this.rowHeight = rowHeight;
this.title = title;
workbook = new HSSFWorkbook();
init();
}
/**
* Constructor
* @param title
* @param colWidth
* @param rowHeight
* @param dateFormat
*/
public ExcelHelper(String title, int colWidth, int rowHeight, String dateFormat) {
this.title = title;
this.colWidth = colWidth;
this.rowHeight = rowHeight;
workbook = new HSSFWorkbook();
sdf = new SimpleDateFormat(dateFormat);
init();
}
/**
* 导出Excel,适用于web导出excel
*
* @param sheet
* @param data
*/
private void writeSheet(HSSFSheet sheet, List<T> data,List<Column> headerList) {
try {
sheet.setDefaultColumnWidth(colWidth);
sheet.setDefaultRowHeightInPoints(rowHeight);
createHead(headerList, sheet);
writeSheetContent(headerList, data, sheet);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
/**
* 导出表格
* @param listColumn
* @param datas
* @return
* @throws Exception
*/
public InputStream exportExcel(List<Column> listColumn,List<T> datas) throws Exception {
splitDataToSheets(datas,listColumn);
return save(workbook);
}
/**
* 导出表格 支持2级表头或单表头的Excel导出
* @param headers
* @param datas
* @param filePath
* @throws FileNotFoundException
* @throws IOException
* void
*/
public void exportExcel(List<Column> headers,List<T> datas,String filePath) throws IOException {
splitDataToSheets(datas, headers);
save(workbook, filePath);
}
/**
* 把数据写入到单元格
* @param listColumn
* @param datas
* @param sheet
* @throws Exception
* void
*/
private void writeSheetContent(List<Column> listColumn,List<T> datas,HSSFSheet sheet) throws Exception {
HSSFRow row;
List<Column> listCol = getColumnList(listColumn);
for (int i = 0, index = 2; i < datas.size(); i++, index++) {
// 创建行
row = sheet.createRow(index);
for (int j = 0; j < listCol.size(); j++) {
Column c = listCol.get(j);
createCol(row, c, datas.get(i), j);
}
}
}
/**
* 创建表头
* @param listColumn 表头数组
* @return 返回表头总行数
*/
public void createHead(List<Column> listColumn, HSSFSheet sheetCo){
HSSFRow row = sheetCo.createRow(0);
HSSFRow row2 = sheetCo.createRow(1);
for(short i = 0, n = 0; i < listColumn.size(); i++){
HSSFCell cell1 = row.createCell(n);
cell1.setCellStyle(headStyle);
HSSFRichTextString text;
List<Column> columns = listColumn.get(i).getListColumn();
//双标题
if(CollectionUtils.isEmpty(columns)){
// 单标题
HSSFCell cell2 = row2.createCell(n);
cell2.setCellStyle(headStyle);
text = new HSSFRichTextString(listColumn.get(i).getContent());
sheetCo.addMergedRegion(new CellRangeAddress(0, n, 1, n));
n++;
cell1.setCellValue(text);
continue;
}
text = new HSSFRichTextString(listColumn.get(i).getContent());
cell1.setCellValue(text);
// 创建第一行大标题
sheetCo.addMergedRegion(new CellRangeAddress(0, 0, n, (short) (n + columns.size() -1)));
// 给标题赋值
for(int j = 0; j < columns.size(); j++){
HSSFCell cell2 = row2.createCell(n++);
cell2.setCellStyle(headStyle);
cell2.setCellValue(new HSSFRichTextString(columns.get(j).getContent()));
}
}
}
/**
* 创建行
* @param row
* @param column
* @param v
* @param rowIndex
* @return
* @throws Exception
*/
public int createRowVal(HSSFRow row, Column column,T v,int rowIndex) throws Exception{
// 遍历标题
if(column.getListColumn() != null && column.getListColumn().size() > 0){
for(int i = 0; i < column.getListColumn().size(); i++){
createRowVal(row,column.getListColumn().get(i),v,rowIndex);
}
}else{
createCol(row,column,v,rowIndex++);
}
return rowIndex;
}
/**
* 创建单元格
* @param row
* @param column
* @param v
* @param columnIndex
* @throws Exception
*/
public void createCol(HSSFRow row,Column column,T v,int columnIndex) throws Exception{
// 创建单元格
HSSFCell cell = row.createCell(columnIndex);
// 设置单元格样式
cell.setCellStyle(bodyStyle);
Class cls = v.getClass();
Field field = cls.getDeclaredField(column.getFieldName());
// 设置些属性是可以访问的
field.setAccessible(true);
if(field.get(v) != null){
Object value = field.get(v);
if(value instanceof Date){
value = parseDate((Date)value);
}
HSSFRichTextString richString = new HSSFRichTextString(value.toString());
cell.setCellValue(richString);
}
}
/**
* init
*/
private void init(){
// 生成表头样式
headStyle = workbook.createCellStyle();
headStyle.setFillForegroundColor(HSSFColor.HSSFColorPredefined.AQUA.getIndex());
headStyle.setFillPattern(FillPatternType.SOLID_FOREGROUND);
headStyle.setBorderBottom(BorderStyle.THIN);
headStyle.setBorderLeft(BorderStyle.THIN);
headStyle.setBorderRight(BorderStyle.THIN);
headStyle.setBorderTop(BorderStyle.THIN);
headStyle.setAlignment(HorizontalAlignment.CENTER);
headStyle.setVerticalAlignment(VerticalAlignment.CENTER);
// 生成一个字体
HSSFFont headFont = workbook.createFont();
headFont.setColor(HSSFColor.HSSFColorPredefined.VIOLET.getIndex());
headFont.setFontHeightInPoints((short) 12);
headFont.setBold(true);
// 把字体应用到当前的样式
headStyle.setFont(headFont);
// 生成并设置另一个样式
bodyStyle = workbook.createCellStyle();
bodyStyle.setFillForegroundColor(HSSFColor.HSSFColorPredefined.WHITE.getIndex());
bodyStyle.setFillPattern(FillPatternType.SOLID_FOREGROUND);
bodyStyle.setBorderBottom(BorderStyle.THIN);
bodyStyle.setBorderLeft(BorderStyle.THIN);
bodyStyle.setBorderRight(BorderStyle.THIN);
bodyStyle.setBorderTop(BorderStyle.THIN);
bodyStyle.setAlignment(HorizontalAlignment.CENTER);
bodyStyle.setVerticalAlignment(VerticalAlignment.CENTER);
// 生成另一个字体
HSSFFont bodyFont = workbook.createFont();
bodyFont.setBold(false);
// 把字体应用到当前的样式
bodyStyle.setFont(bodyFont);
}
/**
* 时间转换
* @param date
* @return
* String
*/
private String parseDate(Date date){
String dateStr = "";
try{
dateStr = sdf.format(date);
} catch (Exception e){
e.printStackTrace();
}
return dateStr;
}
/**
* 拆分sheet，因为每个sheet不能超过6526，否则会报异常
* @param data
* @param listColumn
* void
*/
private void splitDataToSheets(List<T> data,List<Column> listColumn) {
int dataCount = data.size();
int maxColumn = 65535;
int pieces = dataCount / maxColumn;
for (int i = 1; i <= pieces; i++) {
HSSFSheet sheet = workbook.createSheet(this.title + i);
List<T> subList = data.subList((i - 1) * maxColumn, i * maxColumn);
writeSheet(sheet, subList, listColumn);
}
HSSFSheet sheet = workbook.createSheet(this.title + (pieces + 1));
writeSheet(sheet, data.subList(pieces * maxColumn, dataCount), listColumn);
}
/**
* 把column的columnList整理成一个list<column>
* @param listColumn
* @return
* List<Column>
*/
private List<Column> getColumnList(List<Column> listColumn){
List<Column> listCol = new ArrayList<>();
for(int i = 0; i < listColumn.size(); i++){
List<Column> list = listColumn.get(i).getListColumn();
if(list.size() > 0){
for(Column c : list){
if(c.getFieldName() != null){
listCol.add(c);
}
}
}else{
if(listColumn.get(i).getFieldName() != null){
listCol.add(listColumn.get(i));
}
}
}
return listCol;
}
/**
* 保存Excel到InputStream，此方法适合web导出excel
*
* @param workbook
* @return
*/
private InputStream save(HSSFWorkbook workbook) {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
try {
workbook.write(bos);
InputStream bis = new ByteArrayInputStream(bos.toByteArray());
return bis;
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
/**
* 保存文件
* @param workbook
* @param filePath
* @throws IOException
*/
private void save(HSSFWorkbook workbook,String filePath) throws IOException {
workbook.write(new FileOutputStream(filePath));
}
四、测试类
public class ExportTest {
@Data
@AllArgsConstructor
public class ValueObj {
private String value1;
private String value2;
}
public static void main(String[] args) throws Exception {
//用于存放第一行单元格
List<Column> listColumn = new ArrayList<>();
// 用于存放第一列第二行的单元格
List<Column> list2 = new ArrayList<>();
// 创建一列，value1 表示这一列需要导出字段的值
list2.add(new Column("标题1","value1"));
list2.add(new Column("标题2","value1"));
list2.add(new Column("标题3","value1"));
// 用于存放第二列第二行的单元格
List<Column> list3 = new ArrayList<>();
list3.add(new Column("标题6","value2"));
list3.add(new Column("标题7","value2"));
//创建第一行大标题,大标题的fieldName 为 null
Column c1 = new Column("标题1",null);
c1.setListColumn(list2);
Column c2 = new Column("标题2",null);
c2.setListColumn(list3);
listColumn.add(c1);
listColumn.add(c2);
//需要导出的数据
List<ValueObj> valueList = new ArrayList<>();
valueList.add(new ValueObj("1","11"));
valueList.add(new ValueObj("2","22"));
valueList.add(new ValueObj("3","33"));
valueList.add(new ValueObj("4","44"));
ExcelHelper<ValueObj> ta = new ExcelHelper<ValueObj>("表格",15,20);
ta.exportExcel(listColumn, valueList,"D://outExcel.xls");
}
}
View Code
五、实现效果
正文到此结束
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