1-jdbc程序

mysql 數據庫驅動包 mysql-connector-java-x.x.x-bin.jar

pom文件
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.38</version>
</dependency>

        //數據庫連接
        Connection connection = null;
        //預編譯的Statement，使用預編譯的Statement提高數據庫性能
        PreparedStatement preparedStatement = null;
        //結果 集
        ResultSet resultSet = null;

        try {
            //加載數據庫驅動
            Class.forName("com.mysql.jdbc.Driver");
            //通過驅動管理類獲取數據庫鏈接
            connection =  DriverManager.getConnection("jdbc:mysql://localhost:3306/xiatest?characterEncoding=utf-8", "root", "root");
            //定義sql語句 ?表示佔位符
            String sql = "select * from user where username = ?";
            //獲取預處理statement
            preparedStatement = connection.prepareStatement(sql);
            //設置參數，第一個參數爲sql語句中參數的序號（從1開始），第二個參數爲設置的參數值
            preparedStatement.setString(1, "王五");
            //向數據庫發出sql執行查詢，查詢出結果集
            resultSet =  preparedStatement.executeQuery();
            //遍歷查詢結果集
            while(resultSet.next()){
                System.out.println(resultSet.getString("id")+"  "+resultSet.getString("username"));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            //釋放資源
            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();
                }
            }

        }