将结果集写入 csv答案

【问题标题】：Writing result set to csv将结果集写入 csv
【发布时间】：2013-09-19 09:22:57
【问题描述】：

我正在尝试使用以下代码将结果集写入 csv 文件，

public static String getstaffid(String var_1, Connection connection,
        FileWriter fw) throws SQLException, Exception
// Create a statement
{
    String record = null;
    ResultSet rs = null;
    Statement stmt = connection.createStatement();
    boolean empty = true;
    try {
        rs = stmt
                .executeQuery("select username, firstname, lastname, middlename, street, city, stateorprovince, ziporpostalcode, countryorregion, fax, phone, extension, mobile, pager, title, primaryemail, secondaryemail, officename, description, comments, suspendeddate, userdata, employeeid, createuser, updateuser, createdate, updatedate, employeetype, servicedeskticketnumber, startdate, enddate, manager, businessapprover, technicalapprover, delegate, location, jobcodes, customproperty1, customproperty2, customproperty3, customproperty4, customproperty5, customproperty6, customproperty7, customproperty8, customproperty9, customproperty10 from globalusers where username = '"+ var_1 + "'");
        ResultSetMetaData metaData = rs.getMetaData();
        int columns = metaData.getColumnCount();


            while (rs.next()) {
            empty = false;
            record = rs.getString(1) + " " + rs.getString(2) + " " + rs.getString(3) + " " + rs.getString(4) + " " + rs.getString(5) + " " + rs.getString(6) + " " + rs.getString(7) + " " + rs.getString(8) + " " + rs.getString(9) + " " + rs.getString(10) + " " + rs.getString(11) + " " + rs.getString(12) + " " + rs.getString(13) + " " + rs.getString(14) + " " + rs.getString(15) + " " + rs.getString(16) + " " + rs.getString(17) + " " + rs.getString(18) + " " + rs.getString(19) + " " + rs.getString(20) + " " + rs.getString(21) + " " + rs.getString(22) + " " + rs.getString(23) + " " + rs.getString(24) + " " + rs.getString(25) + " " + rs.getString(26) + " " + rs.getString(27) + " " + rs.getString(28) + " " + rs.getString(29) + " " + rs.getString(30) + " " + rs.getString(31) + " " + rs.getString(32) + " " + rs.getString(33) + " " + rs.getString(34) + " " + rs.getString(35) + " " + rs.getString(36) + " " + rs.getString(37) + " " + rs.getString(38) + " " + rs.getString(39) + " " + rs.getString(40) + " " + rs.getString(41) + " " + rs.getString(42) + " " + rs.getString(43) + " " + rs.getString(44) + " " + rs.getString(45) + " " + rs.getString(46) + " " + rs.getString(47);
            fw.append(rs.getString(1));
            fw.append(',');
            fw.append(rs.getString(2));
            fw.append(',');
            fw.append(rs.getString(3));
            fw.append('\n'); 
            }
            System.out.println(record);
        }
         finally {
        fw.flush();
        rs.close();
        stmt.close();
    }

    return record;
}

这工作得很好。但是要检索字符串记录，我必须编写类似的东西记录 = rs.getString(1) + " " +........+ " " + rs.getString(47)。如果明天说如果查询请求更多属性，我必须添加更多 rs.getString(48) 等等。

所以我写了一个类似下面的函数，

for (int i = 1; i <= columns; i++) {
                 record = rs.getString(i) + " ";
                  }

列的值在哪里，

ResultSetMetaData metaData = rs.getMetaData();
    int columns = metaData.getColumnCount();

但现在我才明白

空无效的 . . . 空。

除了附加 fw.append(rs.getString(1)).....fw.append(rs.getSting(n)) 之外，是否有一个我可以编写的小函数来避免添加更多这些附加.

非常感谢

【问题讨论】：

与其自己编写，不如使用 OpenCSV
这是一个 prod 环境，我只能使用标准 jdk 1.6 并且不能导出任何第三方库来完成此操作。
@navman 你是在 while 循环之外写 for 循环吗？
No.. forloop 在 while 循环内。
@navman 显示完整代码（在一段时间内）

标签： java resultset

【解决方案1】：

修复它。谢谢。对于可以使用它的人，我附上代码

public static String getstaffid(String var_1, Connection connection,
        FileWriter fw) throws SQLException, Exception
// Create a statement
{
    String record = null;
    ResultSet rs = null;
    Statement stmt = connection.createStatement();
    boolean empty = true;
    try {
            rs = stmt
                .executeQuery("select username, firstname, lastname, middlename, street, city, stateorprovince, ziporpostalcode, countryorregion, fax, phone, extension, mobile, pager, title, primaryemail, secondaryemail, officename, description, comments, suspendeddate, userdata, employeeid, createuser, updateuser, createdate, updatedate, employeetype, servicedeskticketnumber, startdate, enddate, manager, businessapprover, technicalapprover, delegate, location, jobcodes, customproperty1, customproperty2, customproperty3, customproperty4, customproperty5, customproperty6, customproperty7, customproperty8, customproperty9, customproperty10 from globalusers where username = '"+ var_1 + "'");
            ResultSetMetaData metaData = rs.getMetaData();
            int columns = metaData.getColumnCount();


            while (rs.next()) 
            {
                empty = false;
                for (int i = 1; i <= columns; i++) 
                {
                 record = rs.getString(i);
                 fw.append(rs.getString(i));
                 fw.append(',');
                }
                fw.append('\n');

            }
        }
        finally 
        {
            fw.flush();
            rs.close();
            stmt.close();
        }

    return record;
}

【讨论】：

【解决方案2】：

尝试使用查询

 "SELECT id,text,price into OUTFILE  '"+your-filename+
                    "' FIELDS TERMINATED BY ',' FROM testtable t"

【讨论】：