useresultsetmetadata.java

jsp 应用开发技术光盘 是《jsp应用开发技术》这本书的源代码

package ch13;

import java.sql.*;

public class UseResultSetMetaData {
	public static void main(String[] args) {
		String url = "jdbc:mysql://localhost/sql_test";
		String userName = "root";
		String password = "root";
		Connection conn = null;
		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch(ClassNotFoundException e) {
			System.out.println("加载驱动器类时出现异常");
		}
		
		try {
			conn = DriverManager.getConnection(url, userName, password);
			Statement stmt = conn.createStatement();			
			ResultSet rs = stmt.executeQuery(
					"SELECT * FROM student ORDER BY stu_id");
			
			//使用ResultSet的getMetaData方法获得结果集元数据
			ResultSetMetaData rsmd = rs.getMetaData();
			
			//使用getColumnCount方法获得结果集列数目
			int columnCount = rsmd.getColumnCount();
			System.out.println("");
			
			for (int i=1; i<=columnCount; i++) {
				//使用getColumnName方法获得列名称
				String name = rsmd.getColumnName(i);
				System.out.println("第 " + i + " 列名称为：" + name);
			}
			System.out.println("");
			
			String labelLine = "";
			for (int i=1; i<=columnCount; i++) {	
				//使用getColumnLabel方法获得列标签
				String label = rsmd.getColumnLabel(i);
				labelLine = labelLine + label + "   ";
			}
			System.out.println(labelLine);
			
			//显示返回的结果集
			while (rs.next()) {
				String line = "";
				String field = "";
				
				//根据结果集元数据提供的列数目检索所有列值
				for (int i=1; i<=columnCount; i++) {
					field = rs.getString(i);
					line = line + field + "   ";
				}						
				System.out.println(line);
			}
			
			rs.close();
			stmt.close();
			
		} catch(SQLException e) {
			System.out.println("出现SQLException异常");
		} finally {
			//关闭语句和数据库连接
			try {
				if (conn != null) conn.close();
			} catch(SQLException e) {
				System.out.println("关闭数据库连接时出现异常");
			}		
		}
		
	}
}