通过Excel认识POI

1、POI是什么

Apache POI - the Java API for Microsoft Documents，顾名思义，Apache的三方包，用来操作微软office文档的，多数时候用来操作excel，所以这里就以excel方面来说明。

需要引入两个包，maven地址如下（version 3.9）：

<!-- https://mvnrepository.com/artifact/org.apache.poi/poi -->
<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>

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1

<!-- https://mvnrepository.com/artifact/org.apache.poi/poi --> 

2

<dependency>

3

    <groupId>org.apache.poi</groupId>

4

    <artifactId>poi</artifactId>

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    <version>3.9</version>

6

</dependency>

7

8

<!-- https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml -->

9

<dependency>

10

    <groupId>org.apache.poi</groupId>

11

    <artifactId>poi-ooxml</artifactId>

12

    <version>3.9</version>

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</dependency>

POI的组件列表中，针对excel的主要是HSSF和XSSF组件，前者针对97-2007的通用版excel，即后缀xls；后者针对2007或更高版的excel，即后缀xlsx。官方概要如下：

HSSF is the POI Project's pure Java implementation of the Excel '97(-2007) file format.
XSSF is the POI Project's pure Java implementation of the Excel 2007 OOXML (.xlsx) file format.

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1

HSSF is the POI Project's pure Java implementation of the Excel '97(-2007) file format. 

2

XSSF is the POI Project's pure Java implementation of the Excel 2007 OOXML (.xlsx) file format.

2、POI核心类

面向对象面向对象，既然如此，自然去找找一些能表示excel中内容的类。

2.1 工作簿 Workbook

创建或维护Excel工作簿的所有类的超接口，Workbook，属于org.apache.poi.ss.usermodel包。其下有两个实现类：

• HSSFWorkbook : 有读取.xls 格式和写入Microsoft Excel文件的方法。它与微软Office97-2003版本兼容
• XSSFWorkbook : 有读写Microsoft Excel和OpenOffice的XML文件的格式.xls或.xlsx的方法。它与MS-Office版本2007或更高版本兼容

所以在针对不同版本的excel时，需要对应以上使用不同的Workbook。构造函数中，常用的：

HSSFWorkbook

//直接创建新的
HSSFWorkbook()
//通过输入流创建
HSSFWorkbook(java.io.InputStream s)

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1

//直接创建新的

2

HSSFWorkbook()

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//通过输入流创建

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HSSFWorkbook(java.io.InputStream s)

XSSFWorkbook

//直接创建新的
XSSFWorkbook()
//通过File类创建
XSSFWorkbook(java.io.File file)
//通过输入流创建
XSSFWorkbook(java.io.InputStream is)

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//直接创建新的

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XSSFWorkbook()

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4

//通过File类创建

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XSSFWorkbook(java.io.File file)

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//通过输入流创建

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XSSFWorkbook(java.io.InputStream is)

2.2 标签页 Sheet

HSSFSheet 和 XSSFSheet 都是Sheet接口的实现类，Sheet可以使用Workbook的两个方法获得：

workbook.createSheet();
workbook.createSheet(String sheetName);

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workbook.createSheet();

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workbook.createSheet(String sheetName);

2.3 行 Row

同理，Row是 HSSFRow 和 XSSFRow 的接口，通过Sheet获取：

sheet.createRow(int rownum);

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sheet.createRow(int rownum);

2.4 单元格 Cell

同理，Cell是 HSSFCell 和 XSSFCell 的接口，通过Row获取：

row.createCell(int column);
row.createCell(int column, int type);

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row.createCell(int column);

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row.createCell(int column, int type);

3、创建和读取

其实如果能理解面向对象，就很简单了，另外包括字体，公式，超链接等，都有对应的封装类，此处只提出了核心的几个，需要了解更多的需要自行展开。

例子的话，直接从别人教程里摘出来吧，另，读取的workbook，可以debug瞅瞅内容。

3.1 创建空白工作簿

import java.io.*;
import org.apache.poi.xssf.usermodel.*;
public class CreateWorkBook
{
   public static void main(String[] args)throws Exception
   {
      //Create Blank workbook
      XSSFWorkbook workbook = new XSSFWorkbook();
      //Create file system using specific name
      FileOutputStream out = new FileOutputStream(
      new File("createworkbook.xlsx"));
      //write operation workbook using file out object
      workbook.write(out);
      out.close();
      System.out.println("
      createworkbook.xlsx written successfully");
   }
}

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1

import java.io.*;

2

import org.apache.poi.xssf.usermodel.*;

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public class CreateWorkBook 

4

{

5

   public static void main(String[] args)throws Exception 

6

   {

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      //Create Blank workbook

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      XSSFWorkbook workbook = new XSSFWorkbook(); 

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      //Create file system using specific name

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      FileOutputStream out = new FileOutputStream(

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      new File("createworkbook.xlsx"));

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      //write operation workbook using file out object 

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      workbook.write(out);

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      out.close();

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      System.out.println("

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      createworkbook.xlsx written successfully");

17

   }

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}

3.2 打开现有的工作簿

import java.io.*;
import org.apache.poi.xssf.usermodel.*;
public class OpenWorkBook
{
   public static void main(String args[])throws Exception
   {
      File file = new File("openworkbook.xlsx");
      FileInputStream fIP = new FileInputStream(file);
      //Get the workbook instance for XLSX file
      XSSFWorkbook workbook = new XSSFWorkbook(fIP);
      if(file.isFile() && file.exists())
      {
         System.out.println(
         "openworkbook.xlsx file open successfully.");
      }
      else
      {
         System.out.println(
         "Error to open openworkbook.xlsx file.");
      }
   }
}

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1

import java.io.*;

2

import org.apache.poi.xssf.usermodel.*;

3

public class OpenWorkBook

4

{

5

   public static void main(String args[])throws Exception

6

   { 

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      File file = new File("openworkbook.xlsx");

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      FileInputStream fIP = new FileInputStream(file);

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      //Get the workbook instance for XLSX file 

10

      XSSFWorkbook workbook = new XSSFWorkbook(fIP);

11

      if(file.isFile() && file.exists())

12

      {

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         System.out.println(

14

         "openworkbook.xlsx file open successfully.");

15

      }

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      else

17

      {

18

         System.out.println(

19

         "Error to open openworkbook.xlsx file.");

20

      }

21

   }

22

}

4、方法示例：任意对象List转至为Excel文档（可用注解定义标签名和列名）

写了个方法，可以将某个类的List转换为对应的Excel文档，列名如果在不使用注解的情况下默认为属性名：

类：

@Excel(name = "学生标签页")
public class Student {
    @Excel(name = "姓名")
    private String name;
    private boolean male;
    @Excel(name = "身高")
    private int height;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public boolean isMale() {
        return male;
    }
    public void setMale(boolean male) {
        this.male = male;
    }
    public int getHeight() {
        return height;
    }
    public void setHeight(int height) {
        this.height = height;
    }
}

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1

@Excel(name = "学生标签页")

2

public class Student {

3

4

    @Excel(name = "姓名")

5

    private String name;

6

7

    private boolean male;

8

9

    @Excel(name = "身高")

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    private int height;

11

12

    public String getName() {

13

        return name;

14

    }

15

16

    public void setName(String name) {

17

        this.name = name;

18

    }

19

20

    public boolean isMale() {

21

        return male;

22

    }

23

24

    public void setMale(boolean male) {

25

        this.male = male;

26

    }

27

28

    public int getHeight() {

29

        return height;

30

    }

31

32

    public void setHeight(int height) {

33

        this.height = height;

34

    }

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}

测试方法：

public static void main(String[] args) {
    List<Student> list = new ArrayList<Student>();
    Student student1 = new Student();
    student1.setName("小红");
    student1.setMale(false);
    student1.setHeight(167);
    Student student2 = new Student();
    student2.setName("小明");
    student2.setMale(true);
    student2.setHeight(185);
    list.add(student1);
    list.add(student2);
    File file = new File("C:/Users/Dulk/Desktop/1314.xls");
    createExcel(list, file);
}

18

 

1

public static void main(String[] args) {

2

    List<Student> list = new ArrayList<Student>();

3

    Student student1 = new Student();

4

    student1.setName("小红");

5

    student1.setMale(false);

6

    student1.setHeight(167);

7

8

    Student student2 = new Student();

9

    student2.setName("小明");

10

    student2.setMale(true);

11

    student2.setHeight(185);

12

13

    list.add(student1);

14

    list.add(student2);

15

16

    File file = new File("C:/Users/Dulk/Desktop/1314.xls");

17

    createExcel(list, file);

18

}

输出结果：

 

注解：

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
@Retention(RetentionPolicy.RUNTIME)
public @interface Excel {
    //设置名称
    public String name() default "";
}

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import java.lang.annotation.Retention;

2

import java.lang.annotation.RetentionPolicy;

3

4

5

@Retention(RetentionPolicy.RUNTIME)

6

public @interface Excel {

7

    //设置名称

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    public String name() default "";

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}

方法：

import org.apache.log4j.Logger;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
/**
 * Excel的操作工具类
 */
public class ExcelUtil {
    private static Logger log = Logger.getLogger(ExcelUtil.class);
    /**
     * 获取某个File文件对应的Workbook工作簿对象
     */
    public static Workbook gainWorkbook(File file) throws ExcelException {
        if (!isExcel(file)) {
            throw new ExcelException("文件不是Excel类型");
        }
        //如果文件不存在则新建
        if (!file.exists()) {
            try {
                OutputStream os = new FileOutputStream(file);
                Workbook workbook = isOlderEdition(file) ? new HSSFWorkbook() : new XSSFWorkbook();
                workbook.write(os);
                log.debug("文件不存在，新建该Excel文件");
                os.close();
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        try {
            InputStream is = new FileInputStream(file);
            return isOlderEdition(file) ? new HSSFWorkbook(is) : new XSSFWorkbook(is);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
    /**
     * 判断某个Excel文件是否是2003-2007通用旧版
     */
    private static boolean isOlderEdition(File file) {
        return file.getName().matches(".+\\.(?i)xls");
    }
    /**
     * 判断文件是否是一个Excel文件
     */
    private static boolean isExcel(File file) {
        String fileName = file.getName();
        String regXls = ".+\\.(?i)xls";
        String regXlsx = ".+\\.(?i)xlsx";
        return fileName.matches(regXls) || fileName.matches(regXlsx);
    }
    /**
     * 将某个对象的List转换为Excel工作簿
     */
    public static <E> Workbook createExcel(List<E> list, File file) {
        String sheetName = "default";
        if (list.size() == 0) {
            return null;
        }
        Workbook workbook = null;
        try {
            Class clazz = list.get(0).getClass();
            Field[] fields = clazz.getDeclaredFields();
            if (clazz.isAnnotationPresent(Excel.class)) {
                Excel excel = (Excel) clazz.getAnnotation(Excel.class);
                sheetName = excel.name();
            }
            workbook = gainWorkbook(file);
            Sheet sheet = workbook.createSheet(sheetName);
            //创建首行
            Row line = sheet.createRow(0);
            for (int k = 0; k < fields.length; k++) {
                Cell cell = line.createCell(k);
                String columnName = fields[k].getName();
                if (fields[k].isAnnotationPresent(Excel.class)) {
                    Excel excel = fields[k].getAnnotation(Excel.class);
                    columnName = excel.name();
                }
                cell.setCellValue(columnName);
            }
            //创建数据
            for (int i = 1; i <= list.size(); i++) {
                Row row = sheet.createRow(i);
                for (int j = 1; j <= fields.length; j++) {
                    Cell cell = row.createCell(j - 1);
                    String fieldName = fields[j - 1].getName();
                    String fieldFirstLetterUpper = fieldName.substring(0, 1).toUpperCase();
                    String prefix = "get";
                    if ("boolean".equals(fields[j - 1].getType().getName())) {
                        prefix = "is";
                    }
                    String methodName = prefix + fieldFirstLetterUpper + fieldName.substring(1);
                    Method method = clazz.getMethod(methodName);
                    cell.setCellValue(String.valueOf(method.invoke(list.get(i - 1))));
                }
            }
            log.debug("List读入完毕");
            OutputStream os = new FileOutputStream(file);
            workbook.write(os);
            os.close();
        } catch (ExcelException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return workbook;
    }
}

x

 

1

import org.apache.log4j.Logger;

2

import org.apache.poi.hssf.usermodel.HSSFWorkbook;

3

import org.apache.poi.ss.usermodel.Cell;

4

import org.apache.poi.ss.usermodel.Row;

5

import org.apache.poi.ss.usermodel.Sheet;

6

import org.apache.poi.ss.usermodel.Workbook;

7

import org.apache.poi.xssf.usermodel.XSSFWorkbook;

8

9

import java.io.File;

10

import java.io.FileInputStream;

11

import java.io.FileNotFoundException;

12

import java.io.FileOutputStream;

13

import java.io.IOException;

14

import java.io.InputStream;

15

import java.io.OutputStream;

16

import java.lang.reflect.Field;

17

import java.lang.reflect.InvocationTargetException;

18

import java.lang.reflect.Method;

19

import java.util.ArrayList;

20

import java.util.List;

21

22

/**

23

 * Excel的操作工具类

24

 */

25

public class ExcelUtil {

26

    private static Logger log = Logger.getLogger(ExcelUtil.class);

27

28

    /**

29

     * 获取某个File文件对应的Workbook工作簿对象

30

     */

31

    public static Workbook gainWorkbook(File file) throws ExcelException {

32

        if (!isExcel(file)) {

33

            throw new ExcelException("文件不是Excel类型");

34

        }

35

        //如果文件不存在则新建

36

        if (!file.exists()) {

37

            try {

38

                OutputStream os = new FileOutputStream(file);

39

                Workbook workbook = isOlderEdition(file) ? new HSSFWorkbook() : new XSSFWorkbook();

40

                workbook.write(os);

41

                log.debug("文件不存在，新建该Excel文件");

42

                os.close();

43

44

            } catch (FileNotFoundException e) {

45

                e.printStackTrace();

46

            } catch (IOException e) {

47

                e.printStackTrace();

48

            }

49

        }

50

51

        try {

52

            InputStream is = new FileInputStream(file);

53

            return isOlderEdition(file) ? new HSSFWorkbook(is) : new XSSFWorkbook(is);

54

55

        } catch (FileNotFoundException e) {

56

            e.printStackTrace();

57

        } catch (IOException e) {

58

            e.printStackTrace();

59

        }

60

61

        return null;

62

    }

63

64

    /**

65

     * 判断某个Excel文件是否是2003-2007通用旧版

66

     */

67

    private static boolean isOlderEdition(File file) {

68

        return file.getName().matches(".+\\.(?i)xls");

69

    }

70

71

    /**

72

     * 判断文件是否是一个Excel文件

73

     */

74

    private static boolean isExcel(File file) {

75

        String fileName = file.getName();

76

        String regXls = ".+\\.(?i)xls";

77

        String regXlsx = ".+\\.(?i)xlsx";

78

        return fileName.matches(regXls) || fileName.matches(regXlsx);

79

    }

80

81

    /**

82

     * 将某个对象的List转换为Excel工作簿

83

     */

84

    public static <E> Workbook createExcel(List<E> list, File file) {

85

        String sheetName = "default";

86

        if (list.size() == 0) {

87

            return null;

88

        }

89

90

        Workbook workbook = null;

91

        try {

92

            Class clazz = list.get(0).getClass();

93

            Field[] fields = clazz.getDeclaredFields();

94

            if (clazz.isAnnotationPresent(Excel.class)) {

95

                Excel excel = (Excel) clazz.getAnnotation(Excel.class);

96

                sheetName = excel.name();

97

            }

98

99

            workbook = gainWorkbook(file);

100

            Sheet sheet = workbook.createSheet(sheetName);

101

            //创建首行

102

            Row line = sheet.createRow(0);

103

            for (int k = 0; k < fields.length; k++) {

104

                Cell cell = line.createCell(k);

105

                String columnName = fields[k].getName();

106

                if (fields[k].isAnnotationPresent(Excel.class)) {

107

                    Excel excel = fields[k].getAnnotation(Excel.class);

108

                    columnName = excel.name();

109

                }

110

                cell.setCellValue(columnName);

111

            }

112

            //创建数据

113

            for (int i = 1; i <= list.size(); i++) {

114

                Row row = sheet.createRow(i);

115

                for (int j = 1; j <= fields.length; j++) {

116

                    Cell cell = row.createCell(j - 1);

117

                    String fieldName = fields[j - 1].getName();

118

                    String fieldFirstLetterUpper = fieldName.substring(0, 1).toUpperCase();

119

                    String prefix = "get";

120

                    if ("boolean".equals(fields[j - 1].getType().getName())) {

121

                        prefix = "is";

122

                    }

123

                    String methodName = prefix + fieldFirstLetterUpper + fieldName.substring(1);

124

                    Method method = clazz.getMethod(methodName);

125

                    cell.setCellValue(String.valueOf(method.invoke(list.get(i - 1))));

126

                }

127

            }

128

            log.debug("List读入完毕");

129

            OutputStream os = new FileOutputStream(file);

130

            workbook.write(os);

131

            os.close();

132

133

        } catch (ExcelException e) {

134

            e.printStackTrace();

135

        } catch (InvocationTargetException e) {

136

            e.printStackTrace();

137

        } catch (NoSuchMethodException e) {

138

            e.printStackTrace();

139

        } catch (IllegalAccessException e) {

140

            e.printStackTrace();

141

        } catch (FileNotFoundException e) {

142

            e.printStackTrace();

143

        } catch (IOException e) {

144

            e.printStackTrace();

145

        }

146

        return workbook;

147

    }

148

}

5、参考链接

• 易百教程 POI教程