JDBC 查询返回List

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String JDBC_URL = "jdbc:mysql://localhost:3306/test";
String JDBC_USER = "root";
String JDBC_PASS = "root";

Connection conn = DriverManager.getConnection(JDBC_URL, JDBC_USER, JDBC_PASS);
PreparedStatement ps = conn.prepareStatement("select * from user where username = ?");
ps.setObject(1, "test");

// PreparedStatement ps = conn.prepareStatement("select count(1) as num from user");

ResultSet rs = ps.executeQuery();
// 取得数据库的列名
ResultSetMetaData rsmd = rs.getMetaData();
// 列数
int numberOfColumns = rsmd.getColumnCount();

ArrayList<Map<String, Object>> rsList = new ArrayList<Map<String, Object>>();
Map<String, Object> rsMap = null;

while (rs.next()) {
	rsMap = new HashMap<String, Object>(numberOfColumns);
	for (int i = 1; i < numberOfColumns + 1; i++) {
		rsMap.put(rsmd.getColumnName(i), rs.getObject(i));
	}
	rsList.add(rsMap);
}

conn.close();

System.out.println(rsList);