POI3.10 根据Excel模版导出数据测试

1：所需jar包

2：Mysql数据库表内容如下：

3：代码结构如下：

（1）User.java

public class User {
    private int id;
    private String name;
    private String no;
    private String nativePlace;
    private String edu;
    private Double math;
    private Double computer;
    private Double english;
    private Double sumcount;
    private Double avgcount;

   //setter-getter ...  
}

（2）JdbcUtil.java

public class JdbcUtil {

    private static final String URL = "jdbc:mysql://localhost:3306/test";
    private static final String USER = "root";
    private static final String PASSWORD = "mysql";

    private JdbcUtil() {
    }

    static {
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(JdbcUtil.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    public static Connection getConnection() throws Exception {//建立连接
        return DriverManager.getConnection(URL, USER, PASSWORD);
    }

    public static void free(ResultSet rs, Statement st, Connection conn) {//释放资源
        try {
            if (rs != null) {
                rs.close();
            }
        } catch (SQLException ex) {
            Logger.getLogger(JdbcUtil.class.getName()).log(Level.SEVERE, null, ex);
        } finally {
            try {
                if (st != null) {
                    st.close();
                }
            } catch (SQLException ex) {
                Logger.getLogger(JdbcUtil.class.getName()).log(Level.SEVERE, null, ex);
            } finally {
                if (conn != null) {
                    try {
                        conn.close();
                    } catch (SQLException ex) {
                        Logger.getLogger(JdbcUtil.class.getName()).log(Level.SEVERE, null, ex);
                    }
                }
            }
        }
    }
}

（3）UserService.java

public class UserService {
    
    public static List<User> getUserList(){
        User user;
        List<User> list = new ArrayList<>();
        String sql = "select id,name,no,nativeplace,edu,math,computer,english,sumcount,avgcount from t_user";
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        try {
            conn = JdbcUtil.getConnection();
            ps = conn.prepareStatement(sql);
            rs = ps.executeQuery();
            
            while(rs.next()){
                user = new User();
                user.setId(rs.getInt("id"));
                user.setName(rs.getString("name"));
                user.setNo(rs.getString("no"));
                user.setNativePlace(rs.getString("nativeplace"));
                user.setEdu(rs.getString("edu"));
                user.setMath(rs.getDouble("math"));
                user.setComputer(rs.getDouble("computer"));
                user.setEnglish(rs.getDouble("english"));
                user.setSumcount(rs.getDouble("sumcount"));
                user.setAvgcount(rs.getDouble("avgcount"));
                
                list.add(user);
            }
        } catch (Exception ex) {
            Logger.getLogger(UserService.class.getName()).log(Level.SEVERE, null, ex);
        }finally{
            JdbcUtil.free(rs, ps, conn);
        }
        return list;
    }
    
}

（4）Poitest.java

public class Poitest {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        InputStream inputStream = null;
        OutputStream outputStream =null;
        try {
            inputStream = new FileInputStream(new File("E:\\hello_temp.xls"));
            outputStream = new FileOutputStream(new File("E:\\hello1.xls"));
            
            writeToExcelByTemp2(inputStream,outputStream);
            
            System.out.println("成功生成");
        } catch (FileNotFoundException ex) {
            Logger.getLogger(Poitest.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(Poitest.class.getName()).log(Level.SEVERE, null, ex);
        }finally{
            if(null!=outputStream){
                try {
                    outputStream.close();
                } catch (IOException ex) {
                    Logger.getLogger(Poitest.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
            if(null!=inputStream){
                try {
                    inputStream.close();
                } catch (IOException ex) {
                    Logger.getLogger(Poitest.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
        }
        
    }
    
    /**
     * 根据模版生成Excel
     * @param inputStream
     * @param outputStream
     * @throws IOException 
     */
     public static void writeToExcelByTemp2(InputStream inputStream, OutputStream outputStream) throws IOException{
        List<User> list = UserService.getUserList();
        int length = list.size();
        //New Workbook
        Workbook wb = new HSSFWorkbook(inputStream);
        
        //New Sheet
        Sheet sheet = wb.getSheetAt(0);
        
        int curRowIndex = 0;
        for(int rowIndex=1; rowIndex<=length;rowIndex++){
            curRowIndex = rowIndex;
            //获取一行，如果为空则新建
            Row row = sheet.getRow(rowIndex);
            if(row == null){ 
                row = sheet.createRow(rowIndex);
            }
            
            User user = list.get(rowIndex-1);
            //根据user的对象个数创建列数
            for(int cellNum=0; cellNum<10;cellNum++){
                Cell cell = row.getCell(cellNum);
                if(cell==null){
                    cell = row.createCell(cellNum);
                }
                switch(cellNum){
                    case 0:
                        cell.setCellValue(user.getId());
                        break;
                    case 1:
                        cell.setCellValue(user.getName());
                        break;
                    case 2:
                        cell.setCellValue(user.getNo());
                        break;
                    case 3:
                        cell.setCellValue(user.getNativePlace());
                        break;
                    case 4:
                        cell.setCellValue(user.getEdu());
                        break;
                    case 5:
                        cell.setCellValue(user.getMath());
                        break;
                    case 6:
                        cell.setCellValue(user.getComputer());
                        break;
                    case 7:
                        cell.setCellValue(user.getEnglish());
                        break;
                    case 8:
                        cell.setCellFormula("SUM(F"+(rowIndex+1)+":H"+(rowIndex+1)+")");
                        break;
                    case 9:
                       cell.setCellFormula("I" + (rowIndex+1) +"/3");
                        break;
                }
            }
        }
        
        curRowIndex++;
        
        Row row = sheet.createRow(curRowIndex);
        Cell cell0 = row.createCell(0);
        cell0.setCellValue("总计");
        Cell cell5 = row.createCell(5);
        cell5.setCellFormula("SUM(F2:"+"F"+(curRowIndex)+")");
        Cell cell6 = row.createCell(6);
        cell6.setCellFormula("SUM(G2:"+"G"+(curRowIndex)+")");
        Cell cell7 = row.createCell(7);
        cell7.setCellFormula("SUM(H2:"+"H"+(curRowIndex)+")");
        Cell cell8 = row.createCell(8);
        cell8.setCellFormula("SUM(I2:"+"I"+(curRowIndex)+")");
        Cell cell9 = row.createCell(9);
        cell9.setCellFormula("AVERAGE(J2:"+"J"+(curRowIndex)+")");
        
        wb.write(outputStream);
     }
}

Excel模版：

生成结果：