影者东升 发表于 2021-8-12 12:02:05

Java通过apache poi生成excel实例代码

首先,jar
maven 添加依赖


<!-- https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml -->
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>3.15</version>
</dependency>
开始以为是poi,然后就直接加poi的依赖,谁知道并没有所需要的类。查了查才发现是poi-ooxml
要用到的类

[*]XSSFWorkbook , 代表一个excel文档
[*]XSSFSheet , 代表文档中的一个sheet
[*]XSSFRow , 代表sheet中的一行
[*]XSSFCell , 代表row中的每一项的值
最最基本的使用


//创建excel文档
XSSFWorkbook workbook = new XSSFWorkbook();
//创建sheet
XSSFSheet sheet = workbook.createSheet("sheetName");

int rownum=0;
//创建首行
XSSFRow firstrow = sheet.createRow(rownum++);
int cellnum = 0;
//把保存在titles中的各个列名,分别在row中创建cell
for(String key : titles){
XSSFCell cell = firstrow.createCell(cellnum++);
cell.setCellValue(key);
}


//下面可以继续创建行

//把excel写到要写的outputStream中
workbook.write(output);
//最后关闭
workbook.close();
小例子一枚
利用反射,把bean类中各属性(用getXxx取出),写入到excel中
ExcelUtil.java


package me.paul.excelDemo;

import java.io.IOException;
import java.io.OutputStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;


public class ExcelUtil {

public <T> void getExcel(List<T> list,Class<T> c,OutputStream output) throws IOException, IllegalAccessException, IllegalArgumentException, InvocationTargetException{
Map<String,Method> methodMap = new LinkedHashMap<>();
Method[] methods = c.getDeclaredMethods();
for(int i=0;i<methods.length;i++){
Method method = methods;
String name = method.getName();
Pattern pattern = Pattern.compile("get(.*)");
Matcher matcher = null;
if((matcher = pattern.matcher(name)).matches()){
name = matcher.group(1);
char ch = name.charAt(0);
char newch = (char) (ch + 32);
name = name.replace(ch,newch);
methodMap.put(name, method);
}
}

XSSFWorkbook workbook = new XSSFWorkbook();
XSSFSheet sheet = workbook.createSheet(c.getCanonicalName());
int rownum=0;
XSSFRow firstrow = sheet.createRow(rownum++);
int cellnum = 0;
for(String key : methodMap.keySet()){
XSSFCell cell = firstrow.createCell(cellnum++);
cell.setCellValue(key);
}

for(T t : list){
XSSFRow row = sheet.createRow(rownum++);
cellnum = 0;
for(String key:methodMap.keySet()){
Method method = methodMap.get(key);
                //设置可访问,之前不知道这方法,所以关于反射那篇文章有错误,见谅见谅
                method.setAccessible(true);
Object obj = method.invoke(t);
XSSFCell cell = row.createCell(cellnum++);
cell.setCellValue(obj== null ? "":obj.toString());
}

}
workbook.write(output);
workbook.close();
}
}
App.java 进行测试使用


package me.paul.excelDemo;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.List;

public class App {
public static void main(String[] args) throws IllegalAccessException, IllegalArgumentException, InvocationTargetException, IOException {
List<User> list = new ArrayList<>();
User u = new User();
u.setId(1);
u.setName("Paul");
u.setAge(18);
list.add(u);
u = new User();
u.setId(2);
u.setName("Johnson");
u.setAge(20);
list.add(u);
u = new User();
u.setId(3);
u.setName("David");
u.setAge(22);
list.add(u);
OutputStream output = new FileOutputStream("/home/paul/user.xlsx");
new ExcelUtil().getExcel(list, User.class,output);
output.close();
}
}
测试结果截图

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。
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