2、基础的查询方法（Statement）

package com.lsy.jdbc;



import java.lang.Thread.State;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Scanner;

import javax.management.RuntimeErrorException;
import javax.naming.spi.DirStateFactory.Result;

import org.junit.Test;



public class JDBCTest {
    
    @Test
    public void testGetStudnet(){
        //1.得到查询的类型
        int searchType = getSearchTypeFromConsole();
        
        //2.具体查询的学生信息
        Student student = searchStudent(searchType);
        //3.打印学生信息
        printStudent(student);
        
    }
    /**
     * 打印学生信息，若存在直接打印，不存在提示
     * @param student
     */
    private void printStudent(Student student) {
        if(student != null){
            System.out.println(student);
        }else{
            System.out.println("查无此人");
        }
        
    }
    /**
     * 
     * @param searchType
     * @return  1 / 2
     */
    private Student searchStudent(int searchType) {
        
        String sql = "select FlowID,type,IDCard,ExameCard,StudentName,Grade "
                + "from examestudent where ";
        
        Scanner sc = new Scanner(System.in);
         
        // 1.根据输入的 searchType 来提示用户输入
        // (1.如果输入 1 ，输入身份证号 ，输入 2 ，提示输入 准考证号
        // 2.根据 searchType 确定 SQL
        if(searchType == 1 ){
            System.out.println("请输入身份证号");
            String idCard = sc.next();
            sql = sql + "IDCard = "+idCard;
            System.out.println(sql);
        }else{
            System.out.println("请输入准考证号");
            String exameCard = sc.next();   
            sql = sql + "exameCard = "+exameCard;
            System.out.println(sql);
        }
        // 3.执行 查询
        Student student = getStudent(sql);
        // 4.r若存在结果，封装为 一个 Student 对象。
        return student;
    }
    /**
     * 根据传入的sql 语句，查询
     * @param sql
     * @return
     */
    private Student getStudent(String sql) {
        Student student = null;
        Connection connection = null;
        Statement statement = null;
        ResultSet resultSet = null;
        
        try {
            connection = JDBCTools.getConnection();
            statement = connection.createStatement();
            resultSet = statement.executeQuery(sql);
            
            if(resultSet.next()){
                student = new Student(resultSet.getInt(1), 
                        resultSet.getInt(2),resultSet.getString(3), 
                        resultSet.getString(4), resultSet.getString(5), 
                        resultSet.getInt(6));
            }
                    
        } catch (Exception e) {
            e.printStackTrace();
        } finally{
            JDBCTools.releaseDB(resultSet, statement, connection);
        }
        
        
        
        
        return student;
    }
    /**
     * 从控制台读入一个整数，确定要查询的类型
     * @return 1、身份证号码  2、准考证号
     * 其他无效，并提示用户重新输入
     */
    private int getSearchTypeFromConsole() {
        System.out.println("请输入查询类型:1、身份证号码  2、准考证号");
        Scanner sc = new Scanner(System.in);
        int type = sc.nextInt();
        if(type != 1 && type != 2){
            System.out.println("输入有误请重新输入");
//          throw new RuntimeException();
            getSearchTypeFromConsole();
        }
        
        return type;
    }


    @Test
    public void testAddStudent(){
        Student student = getStudentFromConsole();
        addStudent(student);
    }
    /**
     * 从控制台输入学生信息
     * @return
     */
    private Student getStudentFromConsole() {
        
        Scanner sc = new Scanner(System.in);
        Student student = new Student();
        
        System.out.print("FlowID:");
        student.setFlowID(sc.nextInt());
        
        System.out.print("type:");
        student.setType(sc.nextInt());
        
        System.out.print("IDCard:");
        student.setIDCard(sc.next());
        
        System.out.print("ExameCard:");
        student.setExameCard(sc.next());
        
        System.out.print("StudentName:");
        student.setStudentName(sc.next());
        
        System.out.print("Grade:");
        student.setGrade(sc.nextInt());
        
        return student;
    }

    public void addStudent(Student student){
        //1.准备数据sql 语句
//      String sql = "insert into examestudent values(0,4,'123456','123','小明',100);";
                      
        String sql = "insert into examestudent" 
                +" values("+student.getFlowID()
                +","+student.getType()
                +",'"+student.getIDCard()
                +"','"+student.getExameCard()
                +"','"+student.getStudentName()
                +"',"+student.getGrade()
                +");";
        System.out.println(sql);
        //2.调用 JDBCTools 中的 update(String sql)方法
        JDBCTools.update(sql);
    }
    
}