import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

public class JdbcTest {

    public static void main(String[] args) {

        Connection connection = null;

        //PreparedStatement是预编译的Statement，通过Statement发起数据库的操作

        //PreparedStatement防止sql注入，执行数据库效率高

        PreparedStatement preparedStatement = null;

        ResultSet resultSet = null;

        try {

            //加载数据库驱动

            Class.forName("com.mysql.jdbc.Driver");

            //通过驱动管理类获取数据库链接

            connection =  DriverManager.getConnection("jdbc:mysql://localhost:3306/test?characterEncoding=utf-8", "root", "QAZwsx123");

            //定义sql语句 ?表示占位符

            String sql = "select * from user where username = ?" ;

            //获取预处理statement

            preparedStatement = connection.prepareStatement(sql);

            //设置参数，第一个参数为sql语句中参数的序号（从1开始），第二个参数为设置的参数值

            preparedStatement.setString(, "张智");

            //向数据库发出sql执行查询，查询出结果集

            resultSet =  preparedStatement.executeQuery();

            //遍历查询结果集

            while(resultSet.next()){

                System.out.println(resultSet.getString("id")+"  "+resultSet.getString("username")+":"+resultSet.getString("address"));

            }

        } catch (Exception e) {

            e.printStackTrace();

        }finally{

            //释放资源

            if(resultSet!=null){

                try {

                    resultSet.close();

                } catch (SQLException e) {

                    // TODO Auto-generated catch block

                    e.printStackTrace();

                }

            }

            if(preparedStatement!=null){

                try {

                    preparedStatement.close();

                } catch (SQLException e) {

                    // TODO Auto-generated catch block

                    e.printStackTrace();

                }

            }

            if(connection!=null){

                try {

                    connection.close();

                } catch (SQLException e) {

                    // TODO Auto-generated catch block

                    e.printStackTrace();

                }

            }

        }

    }

}

CREATE TABLE `user` (

  `id` int() NOT NULL AUTO_INCREMENT,

  `username` varchar() DEFAULT NULL,

  `sex` varchar() DEFAULT NULL,

  `birthday` datetime DEFAULT NULL,

  `address` varchar() DEFAULT NULL,

  PRIMARY KEY (`id`)

) ENGINE=InnoDB AUTO_INCREMENT= DEFAULT CHARSET=utf8;