首先新建一个maven项目，添加相关依赖：
使用poi导出excel依赖：
org.apache.poi poi 3.16 org.apache.poi poi-ooxml 3.16
添加csv相关工具类依赖：
net.sourceforge.javacsv javacsv 2.0
2、构建执行代码
（1）、数据导出为excel文件：
package com.hwinfo.excel.poi.export;import com.hwinfo.excel.poi.util.OutputUtil;import org.apache.poi.hssf.usermodel.*;import org.apache.poi.ss.usermodel.HorizontalAlignment;import org.apache.poi.ss.util.CellRangeAddress;import java.io.FileOutputStream;import java.io.IOException;import java.sql.*;/** * @Time : 2019/4/8 0008 14:05 * @Author : lisheng * @Description: **/public class ExportExcel { // private static final String URL = "jdbc:mysql://192.168.101.217:3306/test";// private static final String NAME = "dev";// private static final String PASSWORD = "lJZx2Ik5eqX3xBDp"; private static final String URL = "jdbc:mysql://localhost:3306/test?serverTimezone=GMT%2B8"; private static final String NAME = "root"; private static final String PASSWORD = "123456"; public static void main(String[] args) throws Exception { //1.加载驱动程序 Class.forName("com.mysql.jdbc.Driver"); //2.获得数据库的连接 Connection conn = DriverManager.getConnection(URL, NAME, PASSWORD); //3.通过数据库的连接操作数据库，实现增删改查 Statement stmt = conn.createStatement(); Statement statement = conn.createStatement(); // TODO 获取数据 ResultSet resultSet = statement.executeQuery(" select * from area_code order by code limit 50000"); ResultSetMetaData metaData = resultSet.getMetaData(); int columnCount = metaData.getColumnCount(); // TODO 创建HSSFWorkbook对象(excel的文档对象) HSSFWorkbook wb = new HSSFWorkbook(); // TODO 设置字体格式大小 HSSFFont font = wb.createFont(); font.setFontName("宋体"); font.setFontHeightInPoints((short) 14);//设置字体大小 HSSFCellStyle cellStyle = wb.createCellStyle(); cellStyle.setAlignment(HorizontalAlignment.CENTER); // 居中 cellStyle.setFont(font); //建立新的sheet对象（excel的表单） HSSFSheet sheet = wb.createSheet("用户表"); //在sheet里创建第一行，参数为行索引(excel的行)，可以是0～65535之间的任何一个 HSSFRow row1 = sheet.createRow(0); row1.setHeight((short)500); //创建单元格（excel的单元格，参数为列索引，可以是0～255之间的任何一个 HSSFCell cell = row1.createCell(0); //设置单元格内容 cell.setCellStyle(cellStyle); cell.setCellValue("用户信息表"); //合并单元格CellRangeAddress构造参数依次表示起始行，截至行，起始列， 截至列 sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, columnCount-1)); //在sheet里创建第二行 HSSFRow row2 = sheet.createRow(1); row2.setHeight((short) 500); //创建单元格并设置单元格内容 for (int i = 0; i < columnCount; i++) { sheet.setColumnWidth(i,30*256); HSSFCell cell1 = row2.createCell(i); cell1.setCellStyle(cellStyle); cell1.setCellValue(metaData.getColumnName(i + 1)); } int b = 2; //数据导入单元格 while (resultSet.next()) { HSSFRow row = sheet.createRow(b); row.setHeight((short) 500); for (int i = 0; i < columnCount; i++) { HSSFCell cell1 = row.createCell(i); cell1.setCellStyle(cellStyle); cell1.setCellValue(resultSet.getString(metaData.getColumnName(i + 1))); } b++; } //输出Excel文件 try { FileOutputStream output = new FileOutputStream("d:\\detail.xls"); wb.write(output); output.close(); } catch (Exception e) { e.printStackTrace(); } statement.close(); conn.close(); System.out.println("文件成功导出"); }}
（2）、导出为csv
package com.hwinfo.excel.poi.export;import com.csvreader.CsvWriter;import java.io.*;import java.nio.charset.Charset;import java.sql.*;/** * @Time : 2019/6/5 0005 15:27 * @Author : lisheng * @Description: **/public class ExportCsv { // private static final String URL = "jdbc:mysql://localhost:3306/test?serverTimezone=GMT%2B8";// private static final String NAME = "root";// private static final String PASSWORD = "123456"; private static final String URL = "jdbc:postgresql://host:port/db"; private static final String NAME = "user"; private static final String PASSWORD = "pwd"; public static void main(String[] args) throws Exception { //1.加载驱动程序// Class.forName("com.mysql.jdbc.Driver"); Class.forName("org.postgresql.Driver"); //2.获得数据库的连接 Connection conn = DriverManager.getConnection(URL, NAME, PASSWORD); //3.通过数据库的连接操作数据库，实现增删改查 Statement stmt = conn.createStatement(); Statement statement = conn.createStatement(); // TODO 获取数据// ResultSet resultSet = statement.executeQuery(" select * from area_code order by code limit 50000"); ResultSet resultSet = statement.executeQuery("select * from area_code;"); ResultSetMetaData metaData = resultSet.getMetaData(); int columnCount = metaData.getColumnCount(); FileOutputStream out = new FileOutputStream("d:\\detail.csv"); try { System.out.println("d:\\detail.csv"); CsvWriter csvWriter = new CsvWriter("d:\\detail.csv", ',', Charset.forName("UTF-8")); //写入表头信息 String[] header = new String[columnCount]; for (int i = 0; i < columnCount; i++) { header[i] = metaData.getColumnName(i + 1); } csvWriter.writeRecord(header); //写入内容信息 while (resultSet.next()) { for (int i = 0; i < columnCount; i++) { csvWriter.write(resultSet.getString(metaData.getColumnName(i + 1))); } csvWriter.endRecord(); } //关闭写入的流 csvWriter.close(); File fileLoad = new File("d:\\detail.csv"); FileInputStream in = new java.io.FileInputStream(fileLoad); //每次写入10240个字节 byte[] b = new byte[10240]; int n; while ((n = in.read(b)) != -1) { out.write(b, 0, n); //每次写入out1024字节 } out.close(); in.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } }}