EasyExcel 不使用实体类把 SQL 查询结果动态写入 Excel

Posted 2022-11-27 菠萝蚊鸭

EasyExcel 不使用实体类把 SQL 查询结果动态写入 Excel

• 一、依赖
• 二、工具类
• 三、测试

一、依赖

commons-collections4-4.4.jar
commons-compress-1.20.jar
commons-logging-1.2.jar
easyexcel-3.0.0-beta3.jar
fastjson-1.2.15.jar
log4j-1.2.17.jar
mysql-connector-java-5.1.26.jar
poi-4.1.2.jar
poi-ooxml-4.1.2.jar
poi-ooxml-schemas-4.1.2.jar
slf4j-api-1.6.4.jar
slf4j-simple-1.6.4.jar
xmlbeans-3.1.0.jar

二、工具类

package com;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.List;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

public class Utils 

	private static Connection conn;
	
	/**
	 * 数据库连接
	 * 
	 * @return
	 */
	public static Connection getSourceData() 

		String dburl = "jdbc:mysql://xxx.xxx.xxx.xxx:3306/test?useUnicode=true&characterEncoding=utf8&useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=GMT%2B8";
		String username = "root";
		String password = "123456";

		try 
			Class.forName("com.mysql.jdbc.Driver");
			conn = DriverManager.getConnection(dburl, username, password);
		 catch (Exception e) 
			e.printStackTrace();
		
		return conn;
	

	/**
	 * 查询数据库获取结果
	 * 
	 * @param sql "SQL语句"
	 * @return 查询结果
	 */
	public static Map<String, List<List<String>>> searchSql(String sql, Connection con) 

		//返回hashmap
		Map<String, List<List<String>>> resultMap = new HashMap<String, List<List<String>>>();
		//SQL查询结果列表，用于easyExcel写入数据
		List<List<String>> listMaps = new ArrayList<List<String>>();

		PreparedStatement pstmt = null;

		System.out.println("searchSql_<sql>: " + sql);

		//获取列名列表，用于easyExcel写入header
		List<List<String>> listField = new ArrayList<List<String>>();
		//列名key，用于resultset获取字段值
		List<String> fieldList = new ArrayList<String>();
		
		try 
			pstmt = con.prepareStatement(sql);
			ResultSet result = pstmt.executeQuery();
			//获取结果集resultSet的结果集元数据metaData
			ResultSetMetaData resultSetMetaData = result.getMetaData();
			//列下标用1开始
			for (int i = 1; i <= resultSetMetaData.getColumnCount(); i++) 
				//获取用于打印输出和显示的指定列的建议标题，包括别名
				String columnLabel = resultSetMetaData.getColumnLabel(i);
				listField.add(createHeader(columnLabel));
				fieldList.add(columnLabel);
			
			while (result.next()) 
				//单行数据
				ArrayList<String> list = new ArrayList<String>();
				for (String string : fieldList) 
					list.add(result.getString(string));
				
				listMaps.add(list);
			
			pstmt.close();
		 catch (SQLException e) 
			e.printStackTrace();
			try 
				con.close();
			 catch (SQLException e1) 
				e1.printStackTrace();
			
		
		resultMap.put("result", listMaps);
		resultMap.put("headers", listField);
		
		return resultMap;
	
	
	/**
	 * 生成单个列名列表
	 * @param headName 列名
	 * @return
	 */
	public static List<String> createHeader(String headName) 
		return new ArrayList<>(Arrays.asList(headName));
	

三、测试

package com;

import java.io.File;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import com.alibaba.excel.EasyExcel;

public class Main 

	private static File file = new File("1.txt");
	private static String excelFilePathString = file.getAbsolutePath().replace("1.txt", "") + "\\\\excelfile";
	
	private static String EXCEL_FILE_NAME = "text.xlsx";
	
	
	public static void main(String[] args) 
		// TODO 自动生成的方法存根
		
		String sqlString = "SELECT * FROM `test`;";
		excelWriteBySqlConnection(sqlString);
		
	
	
	public static void excelWriteBySqlConnection(String sqlString) 
		
		Connection conn = Utils.getSourceData();
		Map<String, List<List<String>>> listMaps = new HashMap<String, List<List<String>>>();
		listMaps = Utils.searchSql(sqlString,conn);
		
		String fileName = excelFilePathString + "\\\\" + EXCEL_FILE_NAME;
		Long t1 = System.currentTimeMillis();
		System.out.println("数据总行数：" + listMaps.get("result").size());
		System.out.println("写入Excel文件开始----------");
        // 文件流会自动关闭
        EasyExcel.write(fileName).head(listMaps.get("headers"))
	        .sheet(EXCEL_FILE_NAME.replace(".xlsx", ""))
	        .doWrite(listMaps.get("result"));
		
        Long t2 = System.currentTimeMillis();
		
		System.out.println("写入Excel文件结束，总用时：" + ((t2 - t1) / 1000.00) + "s");
        
		if (null != conn) 
			try 
				conn.close();
			 catch (SQLException e) 
				// TODO 自动生成的 catch 块
				e.printStackTrace();