java反射构建excel导出工具类

一、定义注解，用于vo类中标记使用到的属性

import java.lang.annotation.elementtype;
import java.lang.annotation.retention;
import java.lang.annotation.retentionpolicy;
import java.lang.annotation.target;
/**
 * @author fc
 * @date 2018-09-18
 */
@target(value = {elementtype.field})
@retention(retentionpolicy.runtime)
public @interface allow {
    string title() default "undefined";
}
二、反射工具类

import org.apache.poi.hssf.usermodel.hssfworkbook;
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.streaming.sxssfworkbook;
import org.apache.poi.xssf.usermodel.xssfworkbook;

import java.lang.reflect.field;
import java.lang.reflect.method;
import java.util.list;

/**
 * @author fc
 * @date 2018-09-18
 * @msg 反射工具类
 * @tips 字段必须使用@allow注解 title属性定义标题
 */
public class excelcreateutil {
    /**
     *
     * @param o object是vo类
     * @param suf 返回的excel文件后缀
     * @return
     * @throws exception
     */
    public static workbook createworkbook(list<object> o,returnsuf suf) throws exception {
        //定义一个新的工作簿
        workbook wb = suf.getvalue().equals(returnsuf.xlsx.getvalue())?new xssfworkbook():new hssfworkbook();
        //创建sheet
        sheet sheet = wb.createsheet(string.valueof(system.currenttimemillis()));
        //创建行
        row row = sheet.createrow(0);
        //第一行以注解@allow title属性命名

        class<?> aclass = o.get(0).getclass();
        field[] fields1 = aclass.getdeclaredfields();
        int bj2 = 0;
        for (int j = 0; j < fields1.length; j++) {
            allow annotation = fields1[j].getannotation(allow.class);
            if (annotation != null) {
                fields1[j].setaccessible(true);
                row.createcell(bj2).setcellvalue(annotation.title());
                bj2++;
            }
        }
        int bj1 = 1;
        for (int i = 0; i < o.size(); i++) {
            //获取当前对象
            object o1 = o.get(i);
            //获取当前类类型
            class<?> c = o.get(i).getclass();
            //获取当前类类型的所有属性
            field[] fields = c.getdeclaredfields();
            //创建行-从第二行起
            row row1 = sheet.createrow(bj1);
            bj1++;
            int bj = 0;
            for (int j = 0; j < fields.length; j++) {
                allow annotation = fields1[j].getannotation(allow.class);
                if (annotation != null) {
                    fields[j].setaccessible(true);
                    //得到属性名
                    string name = fields[j].getname();
                    //获取属性对应的get方法
                    method method = c.getdeclaredmethod(toget(name));
                    object invoke = method.invoke(o1);
                    string value = invoke == null ? "" : invoke.tostring();
                    //赋值
                    row1.createcell(bj).setcellvalue(value);
                    bj++;
                }
            }
        }
        return wb;
    }

    //获取属性的set方法
    public static string toset(string s) {
        final string set = "set";
        if (character.isuppercase(s.charat(0))) {
            return set + s;
        } else {
            return set + (new stringbuilder()).append(character.touppercase(s.charat(0))).append(s.substring(1)).tostring();
        }
    }

    //获取属性的get方法
    public static string toget(string s) {
        final string get = "get";
        if (character.isuppercase(s.charat(0))) {
            return get + s;
        } else {
            return get + (new stringbuilder()).append(character.touppercase(s.charat(0))).append(s.substring(1)).tostring();
        }
    }

    public enum returnsuf {
        xls(".xls后缀", ".xls"),
        /**
         *大数据量建议使用.xlsx
         */
        xlsx(".xlsx后缀", ".xlsx"),;
        private string key;
        private string value;

        returnsuf(string key, string value) {
            this.key = key;
            this.value = value;
        }

        public string getkey() {
            return key;
        }

        public void setkey(string key) {
            this.key = key;
        }

        public string getvalue() {
            return value;
        }

        public void setvalue(string value) {
            this.value = value;
        }
    }
}