POI

1、在Java工程中使用POI

　　一、導入jar包

<dependencies>
    <dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi</artifactId>
        <version>3.9</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml -->
    <dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi-ooxml</artifactId>
        <version>3.9</version>
     </dependency>
</dependencies>    

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  二、Excel文件的結構

Excel文件

|
sheet:工做表，在這個級別對列寬進行控制
|
row:行
|
cell:單元格

三、導入一個Excel表格

@Test
public void testRead() throws Exception {
//1.建立Workbook對象
Workbook wb = WorkbookFactory.create(new File("C:\\Users\\Administrator\\Desktop\\1.xlsx"));
//2.從Workbook對象中獲取第一個sheet
Sheet sheet = wb.getSheetAt(0);
//3.從第一個sheet中獲得第一行數據
Row row = sheet.getRow(0);
//4.從第一行中獲取第一列數據
Cell cell = row.getCell(0);
System.out.println(cell.getCellType());
System.out.println(cell.getStringCellValue());
}

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四、遍歷一個Excel表格

//將不一樣的數據類型，轉換成string類型的！
private String getCellValue(Cell c){
String o = null;
switch(c.getCellType()){
case Cell.CELL_TYPE_BLANK:
o = "";
break;
case Cell.CELL_TYPE_BOOLEAN:
o = String.valueOf(c.getBooleanCellValue());
break;
case Cell.CELL_TYPE_FORMULA:
o = String.valueOf(c.getCellFormula());
break;
case Cell.CELL_TYPE_NUMERIC:
o = String.valueOf(c.getNumericCellValue());
break;
case Cell.CELL_TYPE_STRING:
o = c.getStringCellValue();
break;
default:
o = null;
break;
}
return o;
}

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　　 測試 

@Test
public void testForeachExcel() throws Exception{
Workbook wb = WorkbookFactory.create(new File("C:\\Users\\Administrator\\Desktop\\1.xlsx"));
Sheet sheet = wb.getSheetAt(0);

Row row = null;
//獲取每一行
for(int i = 0 ; i< sheet.getLastRowNum();i++){
row = sheet.getRow(i);
//對每一行的每一列遍歷！
for(int j=0;j<row.getLastCellNum();j++){
System.out.print(getCellValue(row.getCell(j))+"======");
}
System.out.println();
}
} 

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        變1：固然上面的讀取方式從POI3.8開始也是支持加強for循環讀取數據的！

@Test
public void testForeachExcel() throws Exception{
Workbook wb = WorkbookFactory.create(new File("C:\\Users\\Administrator\\Desktop\\1.xlsx"));
Sheet sheet = wb.getSheetAt(0);
//獲取每一行
for(Row row : sheet){
for(Cell cell:row){
System.out.print(getCellValue(cell)+"---");
}
System.out.println();
}
}

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2、建立Excel表格

一、建立一個空白的Excel表格 

 

@Test
public void testWriteExcel() throws Exception{
Workbook wb = new HSSFWorkbook();
FileOutputStream fos = new FileOutputStream("D:/1.xlsx");
wb.write(fos);

if(fos != null){
fos.close();
}
}    

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二、建立Excel步驟

　　1）建立表明一個Excel文件的HSSFWorkbook對象

　　　　HSSFWorkbook workbook = new HSSFWorkbook();
　　2）建立表明一個工做表的HSSFSheet對象
　　　　HSSFSheet sheet = workbook.createSheet("工做表名稱");
　　3）建立表明行的HSSFRow對象
　　　　HSSFRow row = sheet.createRow(index);    //index表示行的索引，從0開始
　　4)建立表明單元格的HSSFCell對象
　　　　HSSFCell cell = row.createCell(index);           //index表示單元格的索引，從0開始
　　5)將Excel文件寫入到文件系統中
　　　　①.建立一個文件輸出流對象
　　　　　　FileOutputStream outputStream = new FileOutputStream("文件路徑");
　　　　②.將文件內容寫入到這個輸出流
　　　　　　workbook.write(outputStream);

　　案例1：

@Test
public void test() throws Exception {
//1.建立表明Excel文件的HSSFWorkBook對象
HSSFWorkbook workbook = new HSSFWorkbook();
//2.在當前Excel文件中建立工做表
HSSFSheet sheet = workbook.createSheet();
//3.在當前工做表中，建立行
HSSFRow row = sheet.createRow(0);
//4.在當前行中，建立單元格
HSSFCell cell = row.createCell(0);
//5.給單元格設置值
cell.setCellValue("不要迷戀哥，哥只是個傳說！");
//6.建立輸出流，寫入到硬盤上!
FileOutputStream out = new FileOutputStream("d:\\text.xls");
workbook.write(out);
}

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　   案例2：

@Test
public void test() throws Exception {
//1.建立表明Excel文件的HSSFWorkBook對象
HSSFWorkbook workbook = new HSSFWorkbook();
//2.在當前Excel文件中建立工做表
HSSFSheet sheet = workbook.createSheet();
//3.在當前工做表中，建立行
HSSFRow row = sheet.createRow(0);
//4.在當前行中，建立單元格
HSSFCell cell = row.createCell(0);
//5.①.給單元格設置字符串值
cell.setCellValue("不要迷戀哥，哥只是個傳說！");

//②.給單元格設置布爾型值
HSSFCell cell2 = row.createCell(1);
cell2.setCellValue(true);
//③.給單元格設置整數值
HSSFCell cell3 = row.createCell(2);
cell3.setCellValue(10);

HSSFCell cell4 = row.createCell(3);
cell4.setCellValue(3.4);

//④.給單元格設置時間值
HSSFCell cell5 = row.createCell(4);
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date date = sdf.parse("1990-12-12 10:38:40");
cell5.setCellValue(date);

//⑤.給單元格設置Calendar時間
HSSFCell cell6 = row.createCell(5);
Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.YEAR, 1990);
calendar.set(Calendar.MONTH,12);
calendar.set(Calendar.DAY_OF_MONTH,20);
calendar.set(Calendar.HOUR,10);
calendar.set(Calendar.MINUTE,50);
calendar.set(Calendar.SECOND,55);

cell6.setCellValue(calendar);
//6.建立輸出流，寫入到硬盤上!
FileOutputStream out = new FileOutputStream("d:\\text.xls");
workbook.write(out);
}

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3、調整工做表格式

爲了不處理工做表數據時內存溢出，相關對象要儘量重用，而不是每次都建立新的。
　　HSSFDataFormat format = workbook.createDataFormat();

①.日期格式
　　HSSFCellStyle styleDate = workbook.createCellStyle();
　　styleDate.setDataFormat(format.getFormat("yyyy/MM/dd HH:dd:ss"));

③.迴繞文本
　　HSSFCellStyle styleWrapText = workbook.createCellStyle();
　　styleWrapText.setWrapText(true);

　　④.指定列寬:單位1/20像素
　　　　sheet.setColumnWidth(columnIndex,width);

　　　　案例：設置時間的格式

@Test
public void test() throws Exception {
//1.建立表明Excel文件的HSSFWorkBook對象
HSSFWorkbook workbook = new HSSFWorkbook();
//2.在當前Excel文件中建立工做表
HSSFSheet sheet = workbook.createSheet();
//3.在當前工做表中，建立行
HSSFRow row = sheet.createRow(0);

HSSFDataFormat dataFormat = workbook.createDataFormat();
short format = dataFormat.getFormat("yyyy-MM-dd HH:mm:ss");
HSSFCellStyle cellStyle = workbook.createCellStyle();
cellStyle.setDataFormat(format);
//④.給單元格設置時間值
HSSFCell cell5 = row.createCell(4);
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date date = sdf.parse("1990-12-12 10:38:40");
cell5.setCellValue(date);
cell5.setCellStyle(cellStyle);

//⑤.給單元格設置Calendar時間
HSSFCell cell6 = row.createCell(5);
Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.YEAR, 1990);
calendar.set(Calendar.MONTH,12);
calendar.set(Calendar.DAY_OF_MONTH,20);
calendar.set(Calendar.HOUR,10);
calendar.set(Calendar.MINUTE,50);
calendar.set(Calendar.SECOND,55);

cell6.setCellValue(calendar);
cell6.setCellStyle(cellStyle);

}

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　　　    案例：設置迴繞文本

@Test
public void test() throws Exception {
//1.建立表明Excel文件的HSSFWorkBook對象
HSSFWorkbook workbook = new HSSFWorkbook();
//2.在當前Excel文件中建立工做表
HSSFSheet sheet = workbook.createSheet();
//3.在當前工做表中，建立行
HSSFRow row = sheet.createRow(0);

HSSFCell cell = row.createCell(0);
cell.setCellValue("這是一個迴繞文本數據哦!!!!!!!!!");
HSSFCellStyle cellStyle = workbook.createCellStyle();
cellStyle.setWrapText(true);
cell.setCellStyle(cellStyle);

//6.建立輸出流，寫入到硬盤上!
FileOutputStream out = new FileOutputStream("d:\\text.xls");
workbook.write(out);
}

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　　　　案例:設置固定列寬

@Test
public void test() throws Exception {
//1.建立表明Excel文件的HSSFWorkBook對象
HSSFWorkbook workbook = new HSSFWorkbook();
//2.在當前Excel文件中建立工做表
HSSFSheet sheet = workbook.createSheet();
//設置固定列寬
sheet.setColumnWidth(1,10000);
//3.在當前工做表中，建立行
HSSFRow row = sheet.createRow(0);

HSSFCell cell = row.createCell(0);
cell.setCellValue("這是一個迴繞文本數據哦!!!!!!!!!");
HSSFCellStyle cellStyle = workbook.createCellStyle();
cellStyle.setWrapText(true);
cell.setCellStyle(cellStyle);

//6.建立輸出流，寫入到硬盤上!
FileOutputStream out = new FileOutputStream("d:\\text.xls");
workbook.write(out);
}

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4、在項目中使用POI

一、導入jar包

commons-codec-1.5.jar
poi-3.9-20121203.jar

2.導出方式：使用stream結果類型

①提供文件輸入流：inputstream
②提供文件名：fileName

@Component
public class MyView extends AbstractView{

@Override
protected void renderMergedOutputModel(Map<String, Object> map,
HttpServletRequest request, HttpServletResponse response) throws Exception {
HSSFWorkbook wb = new HSSFWorkbook();
HSSFDataFormat format = wb.createDataFormat();
HSSFCellStyle style = wb.createCellStyle();

HSSFSheet sheet = wb.createSheet("sheet001");
HSSFRow row = sheet.createRow(0);

style = wb.createCellStyle();

HSSFCell cell = row.createCell(1);
System.out.println(map.get("name"));
cell.setCellValue((String)(map.get("name")));
cell.setCellStyle(style);
sheet.autoSizeColumn(1);
response.setContentType("application/vnd.ms-excel");
String fileName = "DFS.xls";
response.setHeader("Content-Disposition","attachment; filename="+fileName);
wb.write(response.getOutputStream());

}
}

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