java导出数据库的全部表到excel

@Test 
public void createXls() throws Exception{
 //声明一个工作薄
 HSSFWorkbook wb = new HSSFWorkbook();
 //声明表
 HSSFSheet sheet = wb.createSheet("第一个表");
 //声明行
 HSSFRow row = sheet.createRow(7);
 //声明列
 HSSFCell cel = row.createCell(3);
 //写入数据
 cel.setCellValue("你也好");
 
 FileOutputStream fileOut = new FileOutputStream("d:/a/b.xls");
 wb.write(fileOut);
 fileOut.close();
 }

@Test
 public void export() throws Exception{
 //声明需要导出的数据库
 String dbName = "focus";
 //声明book
 HSSFWorkbook book = new HSSFWorkbook();
 //获取Connection,获取db的元数据
 Connection con = DataSourceUtils.getConn();
 //声明statemen
 Statement st = con.createStatement();
 //st.execute("use "+dbName);
 DatabaseMetaData dmd = con.getMetaData();
 //获取数据库有多少表
 ResultSet rs = dmd.getTables(dbName,dbName,null,new String[]{"TABLE"});
 //获取所有表名　－　就是一个sheet
 List<String> tables = new ArrayList<String>();
 while(rs.next()){
  String tableName = rs.getString("TABLE_NAME");
  tables.add(tableName);
 }
 for(String tableName:tables){
  HSSFSheet sheet = book.createSheet(tableName);
  //声明sql
  String sql = "select * from "+dbName+"."+tableName;
  //查询数据
  rs = st.executeQuery(sql);
  //根据查询的结果，分析结果集的元数据
  ResultSetMetaData rsmd = rs.getMetaData();
  //获取这个查询有多少行
  int cols = rsmd.getColumnCount();
  //获取所有列名
  //创建第一行
  HSSFRow row = sheet.createRow(0);
  for(int i=0;i<cols;i++){
  String colName = rsmd.getColumnName(i+1);
  //创建一个新的列
  HSSFCell cell = row.createCell(i);
  //写入列名
  cell.setCellValue(colName);
  }
  //遍历数据
  int index = 1;
  while(rs.next()){
  row = sheet.createRow(index++);
  //声明列
  for(int i=0;i<cols;i++){
   String val = rs.getString(i+1);
   //声明列
   HSSFCell cel = row.createCell(i);
   //放数据
   cel.setCellValue(val);
  }
  }
 }
 con.close();
 book.write(new FileOutputStream("d:/a/"+dbName+".xls"));
 }