前段時間簡單的看了一下poi 於是便有了上篇博文 今天正好有時間 就把這個工具的升級版拿出來與大家分享

需求：匯出一對多資料併合並單元格

開始 ：
首先 需要匯入poi依賴 這裡以maven為例

<!-- 為POI支援Office Open XML -->
    <dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi-ooxml</artifactId>
        <version>3.9</version
 
>
    </dependency>
    <dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi-ooxml-schemas</artifactId>
        <version>3.9</version>
    </dependency> 

下一步 在需要匯出的類上標識註解

這裡 簡單的介紹一下@ExcelID，@ExcelAttribute，@ExcelElement
 
這三個註解的作用
@ExcelID 用來標識身份
@ExcelAttribute 用來標識 生成excel的資料排版樣式
@ExcelElement 用來標識集合與自定義物件（map暫時只支援String作為泛型 需要同時標註@ExcelAttribute，@ExcelElement使用）

使用 這裡列舉了一個簡單的例子

首先在需要匯出的物件的欄位上標註對應的註解

public class School {

    @ExcelID
    @ExcelAttribute(name="學校編號",column="A")
    private String id;

    @ExcelAttribute
 
(name="學校名稱",column="B")
    private String name;

    @ExcelElement
    private Set<Clazz> clazzs =  new HashSet<>();

    @ExcelElement
    @ExcelAttribute(name="學校描述",column="C")
    private Map<String,String> map = new HashMap<>();

    //此處省略了get/set


}

public class Clazz{

    @ExcelID
    @ExcelAttribute(name="教室編號",column="D")
    private String id;

    @ExcelAttribute(name="教室名稱",column="E")
    private String name;

    @ExcelElement
    private Set<Student> students = new HashSet<>();

    //此處省略了get/set

}

public class Student {

    @ExcelID
    @ExcelAttribute(name="學生編號",column="F")
    private String id;

    @ExcelAttribute(name="學生姓名",column="G")
    private String name;

    @ExcelAttribute(name="學生年齡",column="H")
    private Integer age;

    @ExcelElement
    @ExcelAttribute(name="學生詳細資訊",column="I")
    private Map<String,String> map;

    //此處省略了get/set
}

然後呼叫 匯入匯出方法 即可

public class EnitiyTest2 {

    private Logger logger = LoggerFactory.getLogger(EnitiyTest2.class); 

    @Test
    public void exportExcel(){


        Set<Student> students = new HashSet<>();
        Student student = new Student();;
        student.setId("121");
        student.setAge(8);
        student.setName("小明");
        students.add(student);

        Map<String,String> sMap = new HashMap<>();
        sMap.put("性別", "男");
        sMap.put("地址", "濟南");
        Student student2 = new Student();;
        student2.setId("122");
        student2.setAge(9);
        student2.setName("小李");
        student2.setMap(sMap);
        students.add(student2);


        Set<Clazz> clazzs = new HashSet<>();

        Clazz clazz = new Clazz();
        clazz.setId("11");
        clazz.setName("一年級");
        clazz.setStudents(students);
        clazzs.add(clazz);

        Clazz clazz2 = new Clazz();
        clazz2.setId("12");
        clazz2.setName("二年級");
        clazz2.setStudents(students);
        clazzs.add(clazz2);

        Clazz clazz3 = new Clazz();
        clazz3.setId("13");
        clazz3.setName("三年級");
        clazzs.add(clazz3);

        Clazz clazz4 = new Clazz();
        clazz4.setId("14");
        clazz4.setName("四年級");
        clazz4.setStudents(students);
        clazzs.add(clazz4);

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

        School school = new School();
        school.setId("1");
        school.setName("中山");
        school.setClazzs(clazzs);
        list.add(school);

        Map<String,String> map = new HashMap<>();
        map.put("1", "紅星小學");
        map.put("2", "TOP");
        School school1 = new School();
        school1.setId("2");
        school1.setName("紅星");
        school1.setClazzs(clazzs);
        school1.setMap(map);
        list.add(school1);

        FileOutputStream output = null;  
        try {  
            output = new FileOutputStream("d:\\success3.xls");  
        } catch (FileNotFoundException e) {  
            e.printStackTrace();  
        }  
        IExcelUtil<School> eu = new ExcelUtils<>();
        eu.build(School.class).exportExcel(list, "學校資訊", output);
    }


    @Test
    public void importExcel(){
        FileInputStream fis = null;  
        try {  
            fis = new FileInputStream("d:\\success3.xls");  
            IExcelUtil<School> util = new ExcelUtils<>();//建立excel工具類  
            List<School> list = util.build(School.class).importExcel("學校資訊", fis);// 匯入  
            logger.info(JSON.toJSONString(list));  
        } catch (FileNotFoundException e) {  
            e.printStackTrace();  
        }
    }

}

匯出效果展示

更詳細程式碼可以訪問 github

這裡需要稍作宣告 並未使用get/set方法 如果需要下一版會新增上