导出数据库中所有数据到Excle中

 Workbook wb = new HSSFWorkbook();//创建工作簿
         Connection conn = DataSourceUtils.getDataSource().getConnection();//获取数据库连接
         Statement stmt = conn.createStatement();
         DatabaseMetaData dbmd = conn.getMetaData();//获取结果集conn的所有信息
         ResultSet dnset = dbmd.getCatalogs();//获取数据库目录
         while (dnset.next()) {//遍历所有数据库
             String dbName = dnset.getString("TABLE_CAT");//获取所有数据库名称
             {
                 ResultSet tSet = dbmd.getTables(dbName, dbName, null,new String[] { "TABLE" });
                 while (tSet.next()) {//遍历数据库中所有表
                     String tName = tSet.getString("TABLE_NAME");
                     stmt.execute("use " + dbName);//
                     String sql = "select * from " + tName;
                     Sheet sheet = wb.createSheet(tName);//为表创建一个sheet
                     Row row = sheet.createRow();//
                     ResultSet rSet = stmt.executeQuery(sql);
                     ResultSetMetaData rsmd = rSet.getMetaData();
                     int count = rsmd.getColumnCount();
                     List<String> list = new ArrayList<String>();
                     for (int i = ; i < count; i++) {//获取表头并保存到cell中
                         String name = rsmd.getColumnName(i + );
                         row.createCell(i).setCellValue(name);
                         list.add(name);
                     }
                     int i = ;
                     while (rSet.next()) {//讲查询数据保存到cell中
                         i++;
                         int j = ;
                         Row row2 = sheet.createRow(i);
                         for (String s : list) {
                             String value = rSet.getString(s);
                             Cell cell = row2.createCell(j);
                             cell.setCellValue(value);
                             j++;
                         }
                     }
                     FileOutputStream out = new FileOutputStream("d:/a.xls");//写入workbook
                     wb.write(out);
                     out.close();
                 }
             }
         }

         System.out.println("Success");

加强：有的数据库中不允许Result嵌套，所以需要把数据暂存到List中进行加强，提高兼容性

 Workbook wb = new HSSFWorkbook();//创建工作簿
         Connection conn = DataSourceUtils.getDataSource().getConnection();//获取数据库连接
         Statement stmt = conn.createStatement();
         DatabaseMetaData dbmd = conn.getMetaData();//获取结果集conn的所有信息
         ResultSet dnset = dbmd.getCatalogs();//获取数据库目录
         List<String> dbnameList=new ArrayList<String>();//数据库名
         while (dnset.next()) {//遍历所有数据库
             String dbName = dnset.getString("TABLE_CAT");//获取所有数据库名称
             dbnameList.add(dbName);
         }

         for(String dbName:dbnameList)
         {
             List<String> tanameList=new ArrayList<String>();//数据库中表名
             ResultSet tSet = dbmd.getTables(dbName, dbName, null,new String[] { "TABLE" });
             while (tSet.next()) {//遍历数据库中所有表
                 String tName = tSet.getString("TABLE_NAME");
                 tanameList.add(tName);
             }

             stmt.execute("use " + dbName);//
             for(String tName:tanameList)
             {
                 String sql = "select * from " + tName;
                 Sheet sheet = wb.createSheet(tName);//为表创建一个sheet
                 Row row = sheet.createRow(0);//
                 ResultSet rSet = stmt.executeQuery(sql);
                 ResultSetMetaData rsmd = rSet.getMetaData();
                 int count = rsmd.getColumnCount();
                 List<String> list = new ArrayList<String>();
                 for (int i = 0; i < count; i++) {//获取表头并保存到cell中
                     String name = rsmd.getColumnName(i + 1);
                     row.createCell(i).setCellValue(name);
                     list.add(name);
                 }
                 int i = 0;
                 while (rSet.next()) {//讲查询数据保存到cell中
                     i++;
                     int j = 0;
                     Row row2 = sheet.createRow(i);
                     for (String s : list) {
                         String value = rSet.getString(s);
                         Cell cell = row2.createCell(j);
                         cell.setCellValue(value);
                         j++;
                     }
                 }
                 FileOutputStream out = new FileOutputStream("d:/a.xls");//写入workbook
                 wb.write(out);
                 out.close();
             }
         }
         System.out.println("Success");