Java Apache POI和JDBC：将大量数据导入Excel的智能方法

参见英文答案 > Writing a large resultset to an Excel file using POI????????????????????????????????????6个
我想使用Java Apache POI和Oracle JDBC从Oracle数据库中获取大量数据(超过100.000行,包含50列)到Excel文件中.这对于少量数据很有效,但处理这样的任务的最聪明方法是什么？也许使用多线程？我得到像“java.lang.OutOfMemoryError：Java堆空间”这样的错误,虽然我已经将内存增加到1024MB.

这是我目前的代码：

public void fetchDataIntoExcelFile(String sqlStmt){

    // Check whether jdbc driver exists or not
    try {
        Class.forName("oracle.jdbc.driver.OracleDriver");
    } catch (ClassNotFoundException e) {
        System.out.println("Please install the Oracle JDBC Driver!");
        e.printStackTrace();
        return;
    }

    // Try to establish a connection to the db
    try {
        conn = DriverManager.getConnection("jdbc:oracle:thin:@myserver","user","password");
    } catch (SQLException e) {
        e.printStackTrace();
        return;
    }

    XSSFWorkbook wbx = new XSSFWorkbook();
    XSSFSheet sheet = wbx.createSheet();
    FileOutputStream fos = null;

    try {
        fos = new FileOutputStream("filename.xlsx");
        wbx.write(fos);
    } catch (IOException e) {
        e.printStackTrace();
        System.out.println("Error occured while creating file.");
    }

    // Execute SQL Statement if connection was successful
    if (conn != null) {
        try {

            Statement stmt = conn.createStatement();
            ResultSet rs = stmt.executeQuery(sqlStmt);
            ResultSetMetaData columns   = rs.getMetaData();
            XSSFRow row                 = null;
            XSSFCell cell               = null;

            // Start writing results into the excel file
            int i = 0;
            while (rs.next()){
                row = sheet.createRow(i++);


                for (int j = 1; j <= columns.getColumnCount(); j++){


                    cell = row.createCell(j);

                    if (i == 1){
                        cell.setCellValue(columns.getColumnLabel(j));
                    }else{
                        cell.setCellValue(rs.getString(columns.getColumnLabel(j)));
                    }
                }
            }

            try {
                wbx.write(fos);
                fos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }

        } catch (SQLException e) {
            System.out.println("Connection Failed!");
            e.printStackTrace();
            return;

        } 
    } else {
        System.out.println("Failed to make connection!");
    }

}