黑猴子的家：JDBC -> PreparedStateme

1、需求

在eclipse中建立java 程序，输入身份证号或准考证号可以查询到学生的基本信息

2、code

package com.yinggu.demo3;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.Scanner;
import org.junit.Test;
import com.yinggu.utils.JDBCUtils;

 * 使用PreparedStatement实现增删改查
 * 
 * @author:黑猴子的家
 * @博客 :https://www.jianshu.com/u/37fd8e2dff4c

public class TestPreparedStatement {
    Scanner input = new Scanner(System.in);
    @Test
    public void testSelect() {
        System.out.println("请选择要输入的类型");
        System.out.print("a、身份证号");
        System.out.print("b、准考证号");
        char key = input.next().charAt(0);
        switch (key) {
        case 'a':
            // 按身份证号查询
            selectByIdCard();
            break;
        case 'b':
            // 按准考证查询
            selectByExamCard();
            break;
        default:
            break;
        }
    }

    /**
     * 按准考证查询
     */
    private void selectByExamCard() {
        System.out.println("请输入准考证号：");
        String examCard = input.next();
        // ------------------------以下为连接数据库的步骤-------------------
        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet set = null;
        try {
            // 1.获取连接
            connection = JDBCUtils.getConnection();
            // 2.获取命令并执行增删改查
            // 2-1 获取命令对象
            statement = connection.prepareStatement(
                "select * from examstudent where examCard=?");
            // 2-2 设置占位符
            statement.setString(1, examCard);
            // 2-3 执行
            set = statement.executeQuery();
            if (set.next()) {
                int flowId = set.getInt(1);
                int type = set.getInt(2);
                String idCard = set.getString(3);
                String studentName = set.getString(5);
                String location = set.getString(6);
                int grade = set.getInt(7);
                System.out.println(flowId);
                System.out.println(type);
                System.out.println(idCard);
                System.out.println(examCard);
                System.out.println(studentName);
                System.out.println(location);
                System.out.println(grade);
            } else {
                System.out.println("查无此人");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {

            try {
                JDBCUtils.closeConnection(set, statement, connection);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 按身份证号查询
     */
    private void selectByIdCard() {
        System.out.println("请输入身份证号：");
        String idCard = input.next();
        // ------------------------以下为连接数据库的步骤-------------------
        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet set = null;
        try {
            // 1.获取连接
            connection = JDBCUtils.getConnection();
            // 2.获取命令并执行增删改查
            // 2-1 获取命令对象
            statement = connection.prepareStatement(
                "select * from examstudent where idcard=?");
            // 2-2 设置占位符
            statement.setString(1, idCard);
            // 2-3 执行
            set = statement.executeQuery();
            if (set.next()) {
                int flowId = set.getInt(1);
                int type = set.getInt(2);
                String examCard = set.getString(4);
                String studentName = set.getString(5);
                String location = set.getString(6);
                int grade = set.getInt(7);
                System.out.println(flowId);
                System.out.println(type);
                System.out.println(idCard);
                System.out.println(examCard);
                System.out.println(studentName);
                System.out.println(location);
                System.out.println(grade);
            } else {
                System.out.println("查无此人");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {

            try {
                JDBCUtils.closeConnection(set, statement, connection);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}