java把class类写入excel和读取出来的通用方法

这个例子中用了反射，泛型实现了通用的excel读写方法。

我们常常遇到要把一个类class写入excel的时候,有时候class的字段非常多，我们不可能一个个的去get写入excel。这里写了一个通用方法。只要传入数据的list和类型，就能很方便的把数据写入excel,也能很方便的读取出来。

例子下载:

java通过class读写excel的例子

首先要引用这两个包

jxl.jar

poi-3.9-20121203.jar

相关代码如下:

BeanRefUtil 反射代码---自动get类class的属性和值  详情可看本文:  

java反射调用set和get方法的通用类

package Io;import java.lang.reflect.Field;import java.lang.reflect.Method;import java.text.SimpleDateFormat;import java.util.Date;import java.util.HashMap;import java.util.Locale;import java.util.Map;public class BeanRefUtil {/** * 取Bean的属性和值对应关系的MAP *  * @param bean * @return Map */public static Map<String, String> getFieldValueMap(Object bean) {Class<?> cls = bean.getClass();Map<String, String> valueMap = new HashMap<String, String>();Method[] methods = cls.getDeclaredMethods();Field[] fields = cls.getDeclaredFields();for (Field field : fields) {try {String fieldType = field.getType().getSimpleName();String fieldGetName = parGetName(field.getName());if (!checkGetMet(methods, fieldGetName)) {continue;}Method fieldGetMet = cls.getMethod(fieldGetName, new Class[] {});Object fieldVal = fieldGetMet.invoke(bean, new Object[] {});String result = null;if ("Date".equals(fieldType)) {result = fmtDate((Date) fieldVal);} else {if (null != fieldVal) {result = String.valueOf(fieldVal);}}//String fieldKeyName = parKeyName(field.getName());valueMap.put(field.getName(), result);} catch (Exception e) {continue;}}return valueMap;}/** * set属性的值到Bean *  * @param bean * @param valMap */public static void setFieldValue(Object bean, Map<String, String> valMap) {Class<?> cls = bean.getClass();// 取出bean里的所有方法Method[] methods = cls.getDeclaredMethods();Field[] fields = cls.getDeclaredFields();for (Field field : fields) {try {String fieldSetName = parSetName(field.getName());if (!checkSetMet(methods, fieldSetName)) {continue;}Method fieldSetMet = cls.getMethod(fieldSetName,field.getType());//String fieldKeyName = parKeyName(field.getName());String  fieldKeyName = field.getName();String value = valMap.get(fieldKeyName);if (null != value && !"".equals(value)) {String fieldType = field.getType().getSimpleName();if ("String".equals(fieldType)) {fieldSetMet.invoke(bean, value);} else if ("Date".equals(fieldType)) {Date temp = parseDate(value);fieldSetMet.invoke(bean, temp);} else if ("Integer".equals(fieldType)|| "int".equals(fieldType)) {Integer intval = Integer.parseInt(value);fieldSetMet.invoke(bean, intval);} else if ("Long".equalsIgnoreCase(fieldType)) {Long temp = Long.parseLong(value);fieldSetMet.invoke(bean, temp);} else if ("Double".equalsIgnoreCase(fieldType)) {Double temp = Double.parseDouble(value);fieldSetMet.invoke(bean, temp);} else if ("Boolean".equalsIgnoreCase(fieldType)) {Boolean temp = Boolean.parseBoolean(value);fieldSetMet.invoke(bean, temp);} else {System.out.println("not supper type" + fieldType);}}} catch (Exception e) {continue;}}}/** * 格式化string为Date *  * @param datestr * @return date */public static Date parseDate(String datestr) {if (null == datestr || "".equals(datestr)) {return null;}try {String fmtstr = null;if (datestr.indexOf(':') > 0) {fmtstr = "yyyy-MM-dd HH:mm:ss";} else {fmtstr = "yyyy-MM-dd";}SimpleDateFormat sdf = new SimpleDateFormat(fmtstr, Locale.UK);return sdf.parse(datestr);} catch (Exception e) {return null;}}/** * 日期转化为String *  * @param date * @return date string */public static String fmtDate(Date date) {if (null == date) {return null;}try {SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss",Locale.US);return sdf.format(date);} catch (Exception e) {return null;}}/** * 判断是否存在某属性的 set方法 *  * @param methods * @param fieldSetMet * @return boolean */public static boolean checkSetMet(Method[] methods, String fieldSetMet) {for (Method met : methods) {if (fieldSetMet.equals(met.getName())) {return true;}}return false;}/** * 判断是否存在某属性的 get方法 *  * @param methods * @param fieldGetMet * @return boolean */public static boolean checkGetMet(Method[] methods, String fieldGetMet) {for (Method met : methods) {if (fieldGetMet.equals(met.getName())) {return true;}}return false;}/** * 拼接某属性的 get方法 *  * @param fieldName * @return String */public static String parGetName(String fieldName) {if (null == fieldName || "".equals(fieldName)) {return null;}int startIndex = 0;if (fieldName.charAt(0) == '_')startIndex = 1;return "get"+ fieldName.substring(startIndex, startIndex + 1).toUpperCase()+ fieldName.substring(startIndex + 1);}/** * 拼接在某属性的 set方法 *  * @param fieldName * @return String */public static String parSetName(String fieldName) {if (null == fieldName || "".equals(fieldName)) {return null;}int startIndex = 0;if (fieldName.charAt(0) == '_')startIndex = 1;return "set"+ fieldName.substring(startIndex, startIndex + 1).toUpperCase()+ fieldName.substring(startIndex + 1);}/** * 获取存储的键名称（调用parGetName） *  * @param fieldName * @return 去掉开头的get */public static String parKeyName(String fieldName) {String fieldGetName = parGetName(fieldName);if (fieldGetName != null && fieldGetName.trim() != ""&& fieldGetName.length() > 3) {return fieldGetName.substring(3);}return fieldGetName;}}

User.class

package Io;public class User {private String name;private String password;public String getName() {return name;}public void setName(String name) {this.name = name;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}}

通用读写方法 ExcelIo

package Io;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.lang.reflect.Field;import java.util.ArrayList;import java.util.HashMap;import java.util.Iterator;import java.util.List;import java.util.Map;import java.util.UUID;import org.apache.poi.hssf.usermodel.HSSFCell;import org.apache.poi.hssf.usermodel.HSSFRow;import org.apache.poi.hssf.usermodel.HSSFSheet;import org.apache.poi.hssf.usermodel.HSSFWorkbook;import org.apache.poi.poifs.filesystem.POIFSFileSystem;import org.apache.poi.ss.usermodel.Row;import jxl.Workbook;import jxl.write.Label;import jxl.write.WritableSheet;import jxl.write.WritableWorkbook;import jxl.write.WriteException;import jxl.write.biff.RowsExceededException;/** * EXCEL IO操作 *  * @作者 joe * @版本 V1.0 * @更新时间 2014-4-18 下午4:28:01 */public class ExcelIo {private static   <T> String[][] parseLand(List<T> objects,Class<T> clazz) {int size = objects.size();Field[] fields = clazz.getDeclaredFields();String[][] content = new String[size + 1][fields.length];for (int i = 0; i < fields.length; i++) {Field f = fields[i];content[0][i] = f.getName();}for (int i = 0 ; i < size; i++) {T school = objects.get(i);for (int j = 0; j < fields.length; j++) {Field f = fields[j];f.setAccessible(true);try {String value = "";if (f.get(school) != null) {value = f.get(school).toString();}content[i+1][j] = value;} catch (IllegalArgumentException e) {e.printStackTrace();} catch (IllegalAccessException e) {e.printStackTrace();}}}return content;}public static String writeFile(String fileName, String[][] content) {WritableWorkbook wwb = null;String filePath = "c:\\" + fileName +".xls";try {wwb = Workbook.createWorkbook(new File(filePath));} catch (IOException e) {e.printStackTrace();}if (wwb != null) {WritableSheet ws = wwb.createSheet(fileName, 1);for (int row = 0; row < content.length; row++) {for (int j = 0; j < content[row].length; j++) {Label labelC = new Label(j, row, content[row][j]);try {ws.addCell(labelC);} catch (RowsExceededException e) {e.printStackTrace();} catch (WriteException e) {e.printStackTrace();}}}try {wwb.write();wwb.close();return filePath;} catch (IOException e) {e.printStackTrace();} catch (WriteException e) {e.printStackTrace();}}return null;}public static <T> List<T> excelToClass(File file,Class<T> clazz){List<T> lands = new ArrayList<T>();try {FileInputStream fileInputStream = new FileInputStream(file);POIFSFileSystem poifs = new POIFSFileSystem(fileInputStream);HSSFWorkbook workbook = new HSSFWorkbook(poifs);HSSFSheet sheet = workbook.getSheetAt(0);Iterator<Row> rows = sheet.rowIterator();int index = 0;List<String> keys = new ArrayList<String>();while (rows.hasNext()) {HSSFRow row = (HSSFRow) rows.next();if(index == 0){//int num = row.getRowNum();int num = row.getLastCellNum();for(int i = 0 ; i < num;i++ ){HSSFCell cell = row.getCell(i);if(cell!=null){String value = getStringCellValue(cell);keys.add(value);}}}if(index>=1){ //决定从哪一行开始提取,这里从第一行Map<String,String> map = new HashMap<String, String>();int num = row.getLastCellNum();for(int i = 0 ; i < num;i++ ){HSSFCell cell = row.getCell(i);if(cell!=null){map.put(keys.get(i), getStringCellValue(cell));}}try {T land = newTclass(clazz);BeanRefUtil.setFieldValue(land, map);lands.add(land);} catch (InstantiationException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IllegalAccessException e) {// TODO Auto-generated catch blocke.printStackTrace();}}index++;}} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}return lands;}private static <T> T newTclass(Class<T> clazz) throws InstantiationException, IllegalAccessException{T a=clazz.newInstance();return a;}private static String getStringCellValue(HSSFCell cell) {// 获取单元格数据内容为字符串类型的数据String strCell = "";switch (cell.getCellType()) {case HSSFCell.CELL_TYPE_STRING:strCell = cell.getStringCellValue();break;case HSSFCell.CELL_TYPE_NUMERIC:strCell = String.valueOf(cell.getNumericCellValue());break;case HSSFCell.CELL_TYPE_BOOLEAN:strCell = String.valueOf(cell.getBooleanCellValue());break;case HSSFCell.CELL_TYPE_BLANK:strCell = "";break;default:strCell = "";break;}if (strCell.equals("") || strCell == null) {return "";}return strCell;}private static String getUUID() {UUID uuid = UUID.randomUUID();String str = uuid.toString();return str.substring(0, 8);}public static void main(String[] args) {//写入测试List<User> users=new ArrayList<User>();   User u=new User();   u.setName("joe");   u.setPassword("123");   users.add(u);   User s=new User();   s.setName("sophia");   s.setPassword("123456");   users.add(s);   String[][] content = parseLand(users,User.class);String uuid = getUUID(); writeFile(uuid, content);    System.out.println("写入完成");// //读取测试 User temp=new User();File file = new File("c:\\" + uuid +".xls"); List<User> us=excelToClass(file,User.class); for(User i:us) { System.out.println(i.getName()); System.out.println(i.getPassword()); } System.out.println("读取完成");}}

结果: