如何将列数未知的 ResultSet 映射到 List 并将其显示在 HTML 表中? [英] How to map a ResultSet with unknown amount of columns to a List and display it in a HTML table?
问题描述
我使用 Netbeans、GlassFish 和 JavaDB 创建了一个数据库应用程序.现在我的控制器 Servlet 代码执行一些动态 SQL 查询并返回结果集(或者我可以更改为字符串).现在,如何以表格格式显示返回的结果集(我不知道结果集的结构).有人可以帮我解决这个问题吗?
I have created a Database Application using Netbeans, GlassFish and JavaDB. Now my controller Servlet code executes some dynamic SQL queries and get back a Result Set (or I can ahange toString). Now, how can I show the returned Result Set in a tabular format ( I have no idea about structure of result set). Can anybody help me about this ?
推荐答案
您可以使用 Map
表示一个动态"行,即iterable.您可以使用 ResultSetMetaData
收集有关列的信息,例如 列数 和 列标签.
You can use Map<String, Object>
to represent a "dynamic" row, which is iterable in <c:forEach>
. You can use ResultSetMetaData
to collect information about the columns such as the column count and the column labels.
所以,这个映射应该:
List<Map<String, Object>> rows = new ArrayList<Map<String, Object>>();
ResultSetMetaData metaData = resultSet.getMetaData();
int columnCount = metaData.getColumnCount();
while (resultSet.next()) {
Map<String, Object> columns = new LinkedHashMap<String, Object>();
for (int i = 1; i <= columnCount; i++) {
columns.put(metaData.getColumnLabel(i), resultSet.getObject(i));
}
rows.add(columns);
}
可以在JSP中显示如下:
You can display it in JSP as follows:
<table>
<thead>
<tr>
<c:forEach items="${rows[0]}" var="column">
<td><c:out value="${column.key}" /></td>
</c:forEach>
</tr>
</thead>
<tbody>
<c:forEach items="${rows}" var="columns">
<tr>
<c:forEach items="${columns}" var="column">
<td><c:out value="${column.value}" /></td>
</c:forEach>
</tr>
</c:forEach>
</tbody>
</table>
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