基础的JDBC查询数据代码
@Test
public void test2(){
Connection connection = null;
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
try {
//加载驱动
Class.forName("com.mysql.jdbc.Driver");
String url = "jdbc:mysql://localhost:3306/test";
String passWord = "123456";
String username = "root";
//通过url和数据库用户名密码获取连接
connection = DriverManager.getConnection(url, username, passWord);
//设置sql语句
String sql = "select * from `user` where id < ?";
//获取preparedStatement
preparedStatement = connection.prepareStatement(sql);
//设置预处理的值
preparedStatement.setInt(1,3);
//执行查询 返回结果集
resultSet = preparedStatement.executeQuery();
ResultSetmetaData metaData = resultSet.getmetaData();
if (resultSet.next()){
for (int i = 1; i <=metaData.getColumnCount(); i++) {
//获取列名和列值 注意下标要从1开始
System.out.print(metaData.getColumnName(i)+" ");
System.out.println(resultSet.getObject(i));
}
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally {
//关闭连接
try {
if (resultSet != null) {
resultSet.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (preparedStatement != null) {
preparedStatement.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (connection != null) {
connection.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
输出
id 1 username zhangsan password 123 name 张三
