add excelsheet

user-infrastructure/src/main/kotlin/com/xquare/v1userservice/user/spi/CreateExcelSheetSpiImpl.kt

@@ -0,0 +1,65 @@
+package com.xquare.v1userservice.user.spi
+
+import org.apache.poi.ss.usermodel.BorderStyle
+import org.apache.poi.ss.usermodel.Row
+import org.apache.poi.ss.usermodel.Workbook
+import org.apache.poi.xssf.usermodel.XSSFCellStyle
+import org.apache.poi.xssf.usermodel.XSSFWorkbook
+import org.springframework.stereotype.Component
+import org.springframework.web.server.ServerWebExchange
+import reactor.core.publisher.Mono
+
+@Component
+class CreateExcelSheetSpiImpl {
+    fun createExcelSheet(serverWebExchange: ServerWebExchange) {
+        val workbook = createExcelWorkbook()
+
+        serverWebExchange.response.headers.add("Content-Disposition", "attachment; filename=spring_excel_download.xlsx")
+
+        val response = serverWebExchange.response
+
+        val dataMono = Mono.fromCallable {
+            val outputStream = response.bufferFactory().allocateBuffer()
+            workbook.write(outputStream.asOutputStream())
+            outputStream
+        }
+
+        response.writeWith(dataMono)
+    }
+
+    private fun createExcelWorkbook(): Workbook {
+        val workbook = XSSFWorkbook()
+        val sheet = workbook.createSheet("Sheet1")
+        sheet.defaultColumnWidth = 28
+
+        val headerCellStyle = createHeaderCellStyle(workbook)
+
+        val headerNames = arrayOf("name", "birthDay", "")
+        var rowCount = 0
+
+        // Header
+        val headerRow: Row = sheet.createRow(rowCount++)
+        headerNames.forEachIndexed { i, header ->
+            val headerCell = headerRow.createCell(i)
+            headerCell.setCellValue(header)
+            headerCell.cellStyle = headerCellStyle
+        }
+
+        return workbook
+    }
+
+
+    fun createHeaderCellStyle(workbook: Workbook): XSSFCellStyle {
+        val font = workbook.createFont().apply {
+            //color = XSSFColor(255, 255)
+        }
+
+        return (workbook.createCellStyle() as XSSFCellStyle).apply {
+            setFont(font)
+            borderLeft = BorderStyle.THIN
+            borderRight = BorderStyle.THIN
+            borderTop = BorderStyle.THIN
+            borderBottom = BorderStyle.THIN
+        }
+    }
+}