實際應用中，Excel匯入匯出很常見的操作，例項通過Java反射和註解的機制實現任意類Excel操作。
註解可理解為程式的標記語言，無任何語義，Java虛擬機器不解釋執行該行程式碼。程式設計人員可運用這一特性為特定的方法，屬性，類加上自定義語義，在利用Java的反射機制field.getAnnotation實現自己的邏輯判斷，比如本例項中@Excel註解標記類屬性是否為Excel操作欄位。

package annotate;

import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import
 
 java.lang.annotation.ElementType;
import java.lang.annotation.RetentionPolicy;

@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
//excel表格註解     
public @interface Excel {
    //欄位excel表頭名稱
    public String name() default "";

    //欄位是否為必填項
    public boolean require() default false;

}

package
 
 test;

import annotate.Excel;

public class Student {
@Excel(name="編碼",require=true)
private int id;
@Excel(name="姓名",require=true)
private String name;
@Excel(name="性別",require=true)
private String sex;
@Excel(name="年齡")
private int age;
private int num;
public Student(){

}
public Student(int id, String name, String sex, int
 
 age) {
this.id = id;
this.name = name;
this.sex = sex;
this.age = age;
}

public int getNum() {
return num;
}
public void setNum(int num) {
this.num = num;
}
public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public String getSex() {
return sex;
}

public void setSex(String sex) {
this.sex = sex;
}

public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}

@Override
public String toString() {
return "Student [id=" + id + ", name=" + name + ", sex=" + sex + ", age=" + age + "]";
}
}

package test;

import java.io.File;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import annotate.Excel;
import jxl.Sheet;
import jxl.Workbook;
import jxl.format.Colour;
import jxl.format.UnderlineStyle;
import jxl.format.VerticalAlignment;
import jxl.write.Label;
import jxl.write.NumberFormats;
import jxl.write.WritableCellFormat;
import jxl.write.WritableFont;
import jxl.write.WritableSheet;
import jxl.write.WritableWorkbook;
import unity.SpellHelper;


@SuppressWarnings("unchecked")
public class excel {

    public static void main(String[] args){
        List<Student> students = new ArrayList<Student>();
        for(int i=0;i<10;i++){
            Student student = new Student(i, "測試"+i,i%2==0?"男":"女" , i*10);
            students.add(student);
        }
        out(Student.class,new File("D:\\學生資訊.xls"),students, "學生資訊","紅色為必填項\n編碼為數字\n");
        List<Student> list = (List<Student>)in(new File("D:\\學生資訊.xls"),Student.class);
        //JDK1.8 Lambda表示式
        list.stream().forEach(student -> System.out.println(student.toString()));
    }

    /***
     * 匯入Excel
     * @param file Excel檔案
     * @param classz 例項類
     * @return
     */
    public static Object in(File file,Class<?> classz){
        int i=0,j=0;
        try {
            Workbook rwb=Workbook.getWorkbook(file);
            Sheet rs=rwb.getSheet(0);
            int clos=rs.getColumns();//得到所有的列
            int rows=rs.getRows();//得到所有的行
            Map<String, String> fieldMap = new HashMap<String, String>();
            StringBuffer fieldNames = new StringBuffer("");
            for(Field field: classz.getDeclaredFields()){
                if(field.isAnnotationPresent(Excel.class)){
                    Excel excel = field.getAnnotation(Excel.class);
                    fieldMap.put(excel.name(), field.getName());
                }
            }
            for(j=0;j<clos;j++){
                String name = rs.getCell(j, 0).getContents();
                fieldNames.append(fieldMap.get(name.trim())+",");
            }
            if(fieldNames.length()>1)
                fieldNames.setLength(fieldNames.length()-1);
            String filedNames[] = fieldNames.toString().split(",");
            List<Object> list = new ArrayList<Object>();
            for (i = 1; i < rows; i++) {
                Object entity = classz.newInstance();
                for (j = 0; j < clos; j++) {
                    Field field = classz.getDeclaredField(filedNames[j]);
                    String data = rs.getCell(j, i).getContents().trim();
                    Excel excel = field.getAnnotation(Excel.class);
                    if((null == data || data.isEmpty()) && field.getAnnotation(Excel.class).require())
                        return "第"+(i+1)+"行"+(j+1)+"必填項不能為空值";
                    if("性別".equals(excel.name().trim()) && !("男".equals(data) || "女".equals(data)))
                        return "性別只能為男，女"; 
                    Object object = null;
                    Method method = classz.getMethod("set"+SpellHelper.captureName(filedNames[j]),field.getType());
                    if(null != data && !data.isEmpty()){
                        //單元格資料型別校驗
                        if(field.getType() == int.class || field.getType() == Integer.class)
                            object = Integer.parseInt(data);
                        else if(field.getType() == long.class || field.getType() == Long.class)
                            object = Long.parseLong(data);
                        else if(field.getType() == short.class || field.getType() == Short.class)
                            object = Short.parseShort(data);
                        else if(field.getType() == float.class || field.getType() == Float.class)
                            object = Float.parseFloat(data);
                        else if(field.getType() == double.class || field.getType() == Double.class)
                            object = Double.parseDouble(data);
                        //日期格式校驗
                        else if(filedNames[j].endsWith("date") && excel.require()){
                            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
                            sdf.parse(data);
                            object = data;
                        }
                        else
                            object = data;
                        method.invoke(entity, object);
                    }
                }
                list.add(entity);
            }
            return list;

        } catch (Exception e) {
            e.printStackTrace();
            return "第"+(i+1)+"行"+(j+1)+"列資料格式不正確";
        }
    }

    /***
     * 匯出Excel
     * @param file Excel檔案
     * @param obj 待匯出資料（只支援列表或實體）
     * @param sheetName（Excel表Sheet名稱）
     * @param 格式說明
     */
    public static void out(Class<?> clazz,File file,Object obj,String sheetName,String str_intro){
        try {
            List<Object> list;
            //傳入物件是否為列表
            if(obj instanceof List){
                list = (List<Object>)obj;
            }
            else{
                list = new ArrayList<Object>();
                list.add(obj);
            }
            if (!file.exists()) {
                file.getParentFile().mkdirs();
                file.createNewFile();
            }
            WritableWorkbook wwb = Workbook.createWorkbook(file);
            //建立工作表
            WritableSheet ws = wwb.createSheet(sheetName, 0);
            //Excel字型樣式
            WritableFont blackFont = new WritableFont(WritableFont.ARIAL,12,WritableFont.NO_BOLD,false,UnderlineStyle.NO_UNDERLINE,Colour.BLACK);  
            WritableFont redFont = new WritableFont(WritableFont.ARIAL,12,WritableFont.NO_BOLD,false,UnderlineStyle.NO_UNDERLINE,Colour.RED);  
            //設定為文字格式
            WritableCellFormat blackFormat = new WritableCellFormat(NumberFormats.TEXT);
            WritableCellFormat redFormat = new WritableCellFormat(NumberFormats.TEXT);
            blackFormat.setFont(blackFont);
            redFormat.setFont(redFont);
            Field[] fields = clazz.getDeclaredFields();
            //註解@excel屬性集合
            StringBuffer fileNames = new StringBuffer();
            //Excel預設行寬高
            ws.getSettings().setDefaultColumnWidth(15);
            ws.getSettings().setDefaultRowHeight(300);
            //寫入表頭資訊
            int col=0;
            for(Field field : fields){
                if (field.isAnnotationPresent(Excel.class)) {  
                    Excel excel = field.getAnnotation(Excel.class);
                    fileNames.append("get"+SpellHelper.captureName(field.getName())+",");
                    ws.addCell(new Label(col++,0,excel.name(),excel.require()?redFormat:blackFormat));
                }  
            }
            //寫入元資料
            for(int i=0;i<list.size();i++){
                setCell(ws,blackFormat,i+1,list.get(i),fileNames.toString().split(","));
            }
            //格式說明表
            WritableSheet intro = wwb.createSheet("格式說明", 1);
            //合併單元格
            intro.mergeCells(0, 0, 20, 20);
            WritableFont introFont = new WritableFont(WritableFont.ARIAL,14,WritableFont.NO_BOLD,false,UnderlineStyle.NO_UNDERLINE,Colour.RED);  
            WritableCellFormat introFormat = new WritableCellFormat(introFont);  
            //自動換行
            introFormat.setWrap(true);
            //頂部對齊
            introFormat.setVerticalAlignment(VerticalAlignment.TOP);
            //提示資訊
            intro.addCell(new Label(0, 0, str_intro, introFormat));
            wwb.write();
            wwb.close();
        } catch (Exception e) {
            e.printStackTrace();
            // TODO: handle exception
        }

    }

    /***
     * 初始化excel單元格內容
     * @param ws Excel單元頁Sheet名稱
     * @param row 單元格行號
     * @param obj 待寫入物件
     * @param fieldName 待寫入物件屬性名稱集合
     */
    private static void setCell(WritableSheet ws,WritableCellFormat format,int row,Object obj,String[] fieldName){
        try {
            for(int i=0;i<fieldName.length;i++){
                if(!fieldName[i].isEmpty()){
                    Method method = obj.getClass().getMethod(fieldName[i], new Class[]{});
                    Object value = method.invoke(obj, new Object[]{});
                    ws.addCell(new Label(i,row,value==null?"":String.valueOf(value),format));
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
            // TODO: handle exception
        }
    }
}