將數據庫表結構導出為EXCEL

想必大家在交付項目時，都遇到這種情況，甲方需要數據庫的表結構，但光一個數據庫就有幾十張表，一個一個手寫的話，那肯定會浪費掉很多摸魚的時間，如果使用Navicat導出為Excel的話，你又會發現連同數據一起導出了，這必然是不妥的，那如何優雅而省時的將這幾十張表導出呢？這個時候就應該想到poi，附上代碼：

首先導入依賴：

點擊查看代碼

<dependency>
            <groupid>org.apache.poi</groupid>
            <artifactid>poi</artifactid>
            <version>4.1.0</version>
        </dependency>
        <dependency>
            <groupid>org.apache.poi</groupid>
            <artifactid>poi-ooxml</artifactid>
            <version>4.1.0</version>
        </dependency>
        <dependency>
            <groupid>mysql</groupid>
            <artifactid>mysql-connector-java</artifactid>
            <version>5.1.48</version>
        </dependency>

其次開始優雅導出

點擊查看代碼

import org.apache.poi.openxml4j.opc.OPCPackage;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.streaming.SXSSFSheet;
import org.apache.poi.xssf.streaming.SXSSFWorkbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import java.io.*;
import java.sql.*;

import java.util.*;
public class TabelToExcel {
    private String tableName = "";//表名
    private String[] colNames; // 列名數組
    private String[] colComment; // 列名數組
    private String[] colTypes; //列名類型數組
    private int[] colSizes; //列名大小數組
    //數據庫連接
    private static final String URL ="jdbc:mysql://localhost:3306/test?useSSL=false&rewriteBatchedStatements=true&useUnicode=true&characterEncoding=utf8&characterSetResults=utf8";
    private static final String NAME = "root";
    private static final String PASS = "Qroot";
    private static final String DRIVER ="com.mysql.jdbc.Driver";

    public void genEntitySomeTable(List<String> tableNames){
        for(int p=0;p<tableNames.size();p++){
            tableName=tableNames.get(p);
            //創建連接
            Connection con = null;
            //查要生成實體類的表
            String sql = "select * from " + tableName;
            String sql2 = "show full fields from " + tableName;
            PreparedStatement pStemt = null;
            PreparedStatement pStemt2 = null;
            try {
                try {
                    Class.forName(DRIVER);
                } catch (ClassNotFoundException e1) {
                    e1.printStackTrace();
                }
                con = DriverManager.getConnection(URL,NAME,PASS);
                pStemt = con.prepareStatement(sql);
                ResultSetMetaData rsmd = pStemt.getMetaData();
                pStemt2 = con.prepareStatement(sql2);
                ResultSet rsResultSet=pStemt2.executeQuery();
                int size = rsmd.getColumnCount();    //統計列
                colNames = new String[size];
                colTypes = new String[size];
                colSizes = new int[size];
                colComment = new String[size];
                int j=0;
                while (rsResultSet.next()) {
                    //System.out.println(rsResultSet.getObject(9));
                    colComment[j]=rsResultSet.getObject(9).toString();
                    j++;
                }
                for (int i = 0; i < size; i++) {
                    colNames[i] = rsmd.getColumnName(i + 1);
                    colTypes[i] = rsmd.getColumnTypeName(i + 1);
                    if (colTypes[i] .equals("INT")){
                        colTypes[i] = "INTEGER";
                    }
                    colSizes[i] = rsmd.getColumnDisplaySize(i + 1);
                }

                createExcel();

            } catch (Exception e) {
                e.printStackTrace();
            } finally{
                try {
                    if (con != null){
                        con.close();
                    }
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }
        System.out.println("生成完畢！");
    }


    public void createExcel() throws Exception{
        //獲取Excel模版文件目錄
        String path = "C:\\Users\\Desktop\\test.xlsx";
        path = path.replaceAll("%20", " ");
        try(InputStream fileInputStream = new FileInputStream(path);
            //通過Excel模板目錄獲取Excel模版文件
            XSSFWorkbook workbook1 = new XSSFWorkbook(OPCPackage.open(fileInputStream));
            //利用POI3.8及其以上，每個Sheet可以存1,048,576行數據，每行可以有16,384列數據
            Workbook workbook = new SXSSFWorkbook(workbook1, 100)){
            //重命名sheet工作表名稱：第幾個工作表
            workbook.setSheetName(0, tableName);
            //創建sheet工作表
            SXSSFSheet sheet = (SXSSFSheet) workbook.getSheetAt(0);
            //從模板sheet工作表第幾行開始插入（注意行、列、單元格都是從0開始數）
            int startRow =1;
            for (int i = 0;i<colSizes.length;i++){
                Row row = sheet.createRow(startRow++);
                row.createCell(1).setCellValue(colNames[i]);
                row.createCell(2).setCellValue(colTypes[i] + "(" + colSizes[i] + ")");
                row.createCell(3).setCellValue(colComment[i]);
            }
            try(ByteArrayOutputStream outputStream = new ByteArrayOutputStream()) {
                workbook.write(outputStream);
                //輸出目錄
                String filePath = "C:\\Users\\Desktop\\" + tableName + ".xlsx";
                File file = new File(filePath);
                try(FileOutputStream fileOutputStream = new FileOutputStream(file);
                    ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(outputStream.toByteArray())) {
                    byte[] bytes = new byte[1024];
                    int len;
                    while ((len = byteArrayInputStream.read(bytes)) != -1){
                        fileOutputStream.write(bytes,0,len);
                    }
                }
            }
        }
    }

    public static void main(String[] args) {
        TabelToExcel tableToExcel = new TabelToExcel();
        List<String> dataList = new ArrayList<>();
        //添加表名
        dataList.add("test");
        tableToExcel.genEntitySomeTable(dataList);
    }

}

整個邏輯還是很好理解的，但是這里需要注意修改自己excel模板的路徑，導出路徑，以及數據庫的連接路徑。好了，到此，只需要你輸入表名稱，就可以將表結構導出為excel了！
excel模板：

導出效果：