请问使用java如何获得数据库表中各字段的字段名？

Question

比如我传给rs一条SQL语句，"select * from TableName" ，我想得到TableName的字段名，这样我就可以把一条结果保存到HashTable里，整个结果同样可以放到HashList里，方便jsp页面上的JSTL取值，最好付上整个DB代码内容，谢谢

Answer 1

import java.sql.*;
import java.util.ArrayList;
import java.util.Hashtable;
import java.util.List;public class Test{ public static void main(String[] args) throws Exception {
// 驱动
String driver = "com.mysql.jdbc.Driver";
// 数据库连接
String url = "jdbc:mysql://localhost:3306/test";
// 用户名
String user = "root";
// 数据库密码
String password = "admin";
// 加载驱动
Class.forName(driver);
// 获取链接
Connection connection = DriverManager
.getConnection(url, user, password);
// 创建查询声明
PreparedStatement preparedStatement = connection
.prepareStatement("select * from dept");
// 获取结果
ResultSet resultSet = preparedStatement.executeQuery();
// 获取各个列的信息
ResultSetMetaData metaData = resultSet.getMetaData();
// 一条数据保存在一个Hashtable 将所有Hashtable存放到list
List<Hashtable<String, Object>> rows = new ArrayList<Hashtable<String, Object>>();
while (resultSet.next()) {
Hashtable<String, Object> row = new Hashtable<String, Object>();
for (int i = 1; i <= metaData.getColumnCount(); i++) {
// 打印列名
System.out.println(metaData.getColumnName(i));
row.put(metaData.getColumnName(i), resultSet.getObject(i));
}
rows.add(row);
}
resultSet.close();
preparedStatement.close();
connection.close();
}}

Answer 2

参考如下例子，利用jdbc获取到结果集后，利用ResultSetMetaData的方法就可以取到字段名了！
package com.javacodegeeks.snippets.core;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;

public class RetrieveColumnNamesExample {

public static void main(String[] args) {

Connection connection = null;
try {

// 加载jdbc驱动

String driverName = "com.mysql.jdbc.Driver";

Class.forName(driverName);

//创建连接

String serverName = "localhost";

String schema = "test";

String url = "jdbc:mysql://" + serverName + "/" + schema;

String username = "username";

String password = "password";

connection = DriverManager.getConnection(url, username, password);

System.out.println("Successfully Connected to the database!");

} catch (ClassNotFoundException e) {

System.out.println("Could not find the database driver " + e.getMessage());
} catch (SQLException e) {

System.out.println("Could not connect to the database " + e.getMessage());
}

try {

// 创建结果集

Statement statement = connection.createStatement();

ResultSet results = statement.executeQuery("SELECT * FROM test_table");

// 获取 metadata

ResultSetMetaData metadata = results.getMetaData();

// 从 metadata中获取列的个数
int columnCount = metadata.getColumnCount();

System.out.println("test_table columns : ");

//循环获取列的名字并打印

for (int i=1; i<=columnCount; i++) {

String columnName = metadata.getColumnName(i);

System.out.println(columnName);

}

} catch (SQLException e) {

System.out.println("Could not retrieve database metadata " + e.getMessage());
}
}
}

其中以下的重点代码片段：
ResultSet results = statement.executeQuery("SELECT * FROM test_table");

// 获取 metadata

ResultSetMetaData metadata = results.getMetaData();

// 从 metadata中获取列的个数
int columnCount = metadata.getColumnCount();

System.out.println("test_table columns : ");

//循环获取列的名字并打印

for (int i=1; i<=columnCount; i++) {

String columnName = metadata.getColumnName(i);

System.out.println(columnName);

}