java简易excel导入导出工具（封装POI）

java简易excel导⼊导出⼯具（封装POI）
Octopus
Octopus是⼀个简单的java excel导⼊导出⼯具.
如何导⼊excel
下⾯是⼀个excel⽂件中sheet的数据，有四个学⽣信息.
studentId name sex inTime score
20134123John M2013-9-189
20124524Joyce F20123-8-3179
20156243P2015-5-1594
20116522Nemo F2011-2-26
⼀个学⽣类，⽤来保存从excel中读取的学⽣信息.
//lombok annotations
@Getter
@Setter
@NoArgsConstructor
@ToString
public class Student {
@ModelLineNumber
private int lineNum;
@ModelProperty(value = "id",blankable = false)
private String studentId;
@ModelProperty(value = "name",defaultValue = "anonymous")
private String name;
@ModelProperty(value = "sex",wrongMsg = "sex must be M or F",pattern = "^M|F$")
private String sex;
@ModelProperty(value = "admission",wrongMsg = "admission must be a date")
private LocalDate inTime;
@ModelProperty(value = "score",wrongMsg = "score must be numeric",defaultValue = "100")
private Double score;
}
⽤代码读取excel，并输出学⽣信息：
InputStream is = getClass().getResourceAsStream("/test.xlsx");
Workbook workbook = WorkbookFactory.create(is);
Sheet sheet = workbook.getSheetAt(0);
//read students with ReusableSheetReader
SheetReader<ModelEntity<Student>> students = new ReusableSheetReader<>(sheet,1,0,Student.class);
//print students information
for (ModelEntity<Student> student:students) {
System.out.println(student.toString());
}
输出的学⽣信息
SimpleModelEntity(entity=Student(lineNum=2, studentId=20134123, name=John, sex=M, inTime=2013-09-01, score=89.0, gradeAndClazz=null), exceptions=[])
SimpleModelEntity(entity=Student(lineNum=3, studentId=20124524, name=Joyce, sex=F, inTime=null, score=79.0, gradeAndClazz=null), exceptions=[cn.chenhuanming.octopus.exception.DataFormatException: in cell (3,4) ,20123-8-31 can not SimpleModelEntity(entity=Student(lineNum=4, studentId=20156243, name=anonymous, sex=null, inTime=2015-05-15, score=94.0, gradeAndClazz=null), exceptions=[cn.chenhuanming.octopus.exception.PatternNotMatchException: P and ^M|F$ SimpleModelEntity(entity=Student(lineNum=5, studentId=20116522, name=Nemo, sex=F, inTime=2011-02-26, score=100.0, gradeAndClazz=null), exceptions=[])
通过ModelEntity<Student>，可以获取更多异常信息，例如@ModelProperty的配置信息和所发⽣的异常.
完整的测试⽤例：src/test/cn/chenhuanming/octopus/core/SheetReaderTest
如何导出excel
为了说明导出的特性，我们给Student类增加⼀个属性GradeAndClazz⽤来表⽰年级和班级.下⾯是最终的Student类，可以⽤来导⼊导出.
@Getter
@Setter
@NoArgsConstructor
@ToString
public class Student {
@ModelLineNumber
private int lineNum;
@ModelProperty(value = "id",blankable = false)
private String studentId;
@ModelProperty(value = "name",defaultValue = "anonymous")
private String name;
@ModelProperty(value = "sex",wrongMsg = "sex must be M or F",pattern = "^M|F$")
private String sex;
//jackson annotation to format output
@JsonFormat(pattern = "yyyy-MM-dd")
@ModelProperty(value = "admission",wrongMsg = "admission must be a date")
private LocalDate inTime;
@ModelProperty(value = "score",wrongMsg = "score must be numeric",defaultValue = "100")
private Double score;
@ModelIgnore
private GradeAndClazz gradeAndClazz;
public Student(String studentId, String name, String sex, LocalDate inTime, Double score,GradeAndClazz gradeAndClazz) {
this.studentId = studentId;
= name;
this.sex = sex;
this.inTime = inTime;
this.score = score;
this.gradeAndClazz = gradeAndClazz;
}
}
GradeAndClazz类，只有年级和班级两个信息.
@Getter
@Setter
@AllArgsConstructor
public class GradeAndClazz{
private String grade;
private String clazz;
}
需要⼀个xml来配置导出的属性和属性描述作为表头
<?xml version="1.0" encoding="UTF-8"?>
<ExportModel class="entity.Student">
<Field name="studentId" description="id"></Field>
<Field name="name" description="name"></Field>
<Field name="sex" description="sex"></Field>
<Field name="inTime" description="admission"></Field>
<Field name="score" description="score"></Field>
<Field name="gradeAndClazz" description="class info">
<Field name="grade" description="grade"></Field>
<Field name="clazz" description="class"></Field>
</Field>
</ExportModel>
⽤代码导出学⽣信息
//prepare workbook and stuednts objects
Workbook workbook = new XSSFWorkbook();
String rootPath = this.getClass().getClassLoader().getResource("").getPath();
FileOutputStream os = new FileOutputStream(rootPath+"/export.xlsx");
GradeAndClazz gradeAndClazz = new GradeAndClazz("2014","R6");
Student student1 = new Student("201223","John","M", LocalDate.now(),98.00,gradeAndClazz);
Student student2 = new Student("204354","Tony","M", LocalDate.now(),87.00,gradeAndClazz);
Student student3 = new Student("202432","Joyce","F", LocalDate.now(),90.00,gradeAndClazz);
//write excel with OneSheetExcelWriter
ExcelWriter<Student> studentExcelWriter = new OneSheetExcelWriter<>(getClass().getClassLoader().getResourceAsStream("studentExport.xml"));
studentExcelWriter.write(workbook,Arrays.asList(student1,student2,student3));
workbook.write(os);
导出结果
| class info |
id name M admission score |---------|----------|
| grade | class |
---------------------------------------------------------------|
201223 John M 2017-07-06 98.0 | 2014 | R6 |
204354 Tony M 2017-07-06 87.0 | 2014 | R6 |
202432 Joyce F 2017-07-06 90.0 | 2014 | R6 |
可以看到，对于gradeAndClazz属性，会⽤⼀个合并单元格来表⽰.admission因为被@JsonFormat标记，因此会格式化输出⽇期。

事实上Octopus会调⽤jackson来格式化json后再写⼊excel.
详细例⼦在src/test/cn/chenhuanming/octopus/core/OneSheetExcelWriterTest。