基于 Java 泛型和反射导入 Excel

1，数据迁移，存量备份等功能会有Excel批量导入。如果针对每个excel都做相应的POI解析，并调用javabean的set方法生成事例无疑，将会浪费大量工作量。

本篇文章基于Java泛型和反射技术，封装POI，对excel解析，生成javabean。SpringBoot做TDD

Maven Dependency

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.0.3.RELEASE</version>
</parent>
<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>            
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-autoconfigure</artifactId>          
    </dependency>

    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>cn.afterturn</groupId>
        <artifactId>easypoi-base</artifactId>
        <version>3.0.3</version>
    </dependency>
    <dependency>
        <groupId>cn.afterturn</groupId>
        <artifactId>easypoi-web</artifactId>
        <version>3.0.3</version>
    </dependency>
    <dependency>
        <groupId>cn.afterturn</groupId>
        <artifactId>easypoi-annotation</artifactId>
        <version>3.0.3</version>
    </dependency>

直接搞代码

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.lang.reflect.Field;
import java.lang.reflect.Type;
import java.text.DecimalFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.DateUtil;
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;

@SuppressWarnings(“hiding”)
public class ExcelUtil2 {

private Workbook workbook;

public List<T> importExcel(String sheetName, File f, Class<T> item) {
    List<T> list = null;

    try {
        if(f.getName().endsWith("xlsx")){
            workbook = new XSSFWorkbook(new FileInputStream(f));
        }else{
            workbook = new HSSFWorkbook(new FileInputStream(f));
        }
        Sheet sheet = workbook.getSheet(sheetName);
        if (!"".equals(sheetName.trim())) {
            sheet = workbook.getSheet(sheetName);// 如果指定sheet名,则取指定sheet中的内容.
        }
        if (sheet == null) {
            sheet = workbook.getSheetAt(0); // 如果传入的sheet名不存在则默认指向第1个sheet.
        }

        // 获取数据
        list = dispatch(sheet, item);

    } catch (IOException e) {
        e.printStackTrace();
    }

    return list;
}

/** 生成实体类的 List<T> 
 *  由于采取反射技术，所以要传入 实体类的类型 ,例如Entity.class
 * 
 */
public List<T> dispatch(Sheet sheet, Class<T> clazz) {
    List<T> instances = new ArrayList<>();

    List<Map<String, String>> sheetValue = parseExcelSheet(sheet);

    for (int i = 0; i < sheetValue.size(); i++) {
        Map<String, String> map = sheetValue.get(i);
        Field[] fields = clazz.getDeclaredFields();

        try {
            T t2 = clazz.newInstance();
            for (Field field : fields) {
                field.setAccessible(true);
                Type type = field.getType();
                field.set(t2, getTypeValue(map.get(field.getName()), type.getTypeName()));
            }
            instances.add(t2);
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (SecurityException e) {
            e.printStackTrace();
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        }
    }
    return instances;
}

//赋值判断类型
public Object getTypeValue(String value, String type) {
    Object obj = new Object();
    if ("int".equals(type) || type.indexOf("Integer") > -1) {
        obj = Integer.valueOf(value);
    } else if ("short".equals(type) || type.indexOf("Short") > -1) {
        obj = Short.valueOf(value);
    } else if ("long".equals(type) || type.indexOf("Long") > -1) {
        obj = Long.valueOf(value);
    } else if ("float".equals(type) || type.indexOf("Float") > -1) {
        obj = Float.valueOf(value);
    } else if ("double".equals(type) || type.indexOf("Double") > -1) {
        obj = Double.valueOf(value);
    } else if ("boolean".equals(type) || type.indexOf("Boolean") > -1) {
        obj = Boolean.valueOf(value);
    } else {
        obj = value;
    }
    return obj;
}
/**
 * 解析Excel第一行，并生成以第一行表头为key，每一行的值为value的map
 * 例如: excel内容如下
 * id   alarm
    1   abcd1
    2   abcd2
    3   abcd3
    那么List<Map>就是的内容就是
    List: map1( id: 1, alarm: abcd1 ),map2(( id: 2, alarm: abcd2 ).....
 */
public List<Map<String, String>> parseExcelSheet(Sheet sheet) {
    List<Map<String, String>> result = new ArrayList<>();
    Map<String, String> rowValue = null;
    int rows = sheet.getPhysicalNumberOfRows();
    String[] headers = getHeaderValue(sheet.getRow(0));

    for (int i = 1; i < rows; i++) {
        rowValue = new HashMap<>();
        Row row = sheet.getRow(i);
        for (int kk = 0; kk < headers.length; kk++) {
            rowValue.put(headers[kk], String.valueOf(getCellValue(row.getCell(kk))));
        }
        result.add(rowValue);
    }
    return result;
}

/** 获取第一行，表头，也就是实体类的字段，支持中英文，及下划线，忽略大小写，但是绝笔不能重复，表头有重复字段则不能解析  **/
private String[] getHeaderValue(Row rowHeader) {
    int colNum = rowHeader.getPhysicalNumberOfCells();
    String[] headValue = new String[rowHeader.getPhysicalNumberOfCells()];
    for (int i = 0; i < colNum; i++) {
        headValue[i] = rowHeader.getCell(i).getStringCellValue();
    }
    return headValue;
}

@SuppressWarnings("deprecation")
public Object getCellValue(Cell cell) {
    Object value = null;
    switch (cell.getCellType()) {
    case Cell.CELL_TYPE_NUMERIC: // 数字
        // 如果为时间格式的内容
        if (DateUtil.isCellDateFormatted(cell)) {
            // 注：format格式 yyyy-MM-dd hh:mm:ss
            // 中小时为12小时制，若要24小时制，则把小h变为H即可，yyyy-MM-dd HH:mm:ss
            SimpleDateFormat sdf = new SimpleDateFormat( "yyyy-MM-dd hh:mm:ss");
            value = sdf.format( DateUtil.getJavaDate(cell.getNumericCellValue())).toString();
            break;
        } else {
            value = new DecimalFormat("0").format(cell.getNumericCellValue());
        }
        break;
    case Cell.CELL_TYPE_STRING: // 字符串
        value = cell.getStringCellValue();
        break;
    case Cell.CELL_TYPE_BOOLEAN: // Boolean
        value = cell.getBooleanCellValue() + "";
        break;
    case Cell.CELL_TYPE_FORMULA: // 公式
        value = cell.getCellFormula() + "";
        break;
    case Cell.CELL_TYPE_BLANK: // 空值
        value = "";
        break;
    case Cell.CELL_TYPE_ERROR: // 故障
        value = "非法字符";
        break;
    default:
        value = "未知类型";
        break;
    }
    return value;
}

}

实体类
public class Alarm implements Serializable {

/**  */
private int id;
/**  */
private String alarm;


/** 
 * 获取 主键
 */ 
public int getId() {
    return id;
}

/** 
 * 设置 主键
 */
public void setId(int id) {
    this.id = id;
}

/** 
 * 获取 
 */ 
public String getAlarm() {
    return alarm;
}

/** 
 * 设置 
 */
public void setAlarm(String alarm) {
    this.alarm = alarm;
}

@Override
public String toString() {
    return "Alarm [id=" + id + ", alarm=" + alarm + "]";
}

}

测试代码

@Test
public void testImport() {

    ExcelUtil2<Alarm> excelUtil = new ExcelUtil2<>() ;
    //"alarm"为excel 的 sheet名字，也就是表名，暂时未做批量功能
    List<Alarm> acfForms = excelUtil.importExcel("alarm",   new File(path)  , Alarm.class);

    for (Alarm a : acfForms) {
        System.out.println(a.toString());
    }

}

表格
id alarm
1 abcd1
2 abcd2
3 abcd3
4 abcd4
5 abcd5
6 abcd6
7 abcd7

基于 Java 泛型和反射 导入 Excel

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