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测试第一个仓库

用java链接mysql数据库实现对数据库的增删改查，并输出到控制台，做题判分 1. examclass类{定义一个试题类，以试题类为单位进行存储，属性分别为： （id，tatil，optionA,optionB,optionC,optionD,answer,score, delflag[这里的delflag属性设为int类型，0表示不删除状态，默认为0，非0表示删除状态]） 并重写tostring方法}：

代码如下：

public class examclass {
    private String id;
    private String tatil;
    private String optionA;
    private String optionB;
    private String optionC;
    private String optionD;
    private String answer;
    private int score;
    private int delflag;
        //试题类的空参构造器和有参构造器
    public examclass(){
        super();
        }
    public  examclass(String id,String tatil,String optionA,String optionB,
        String optionC,String optionD,String answer,int score,int delflag){
        super();
        this.id=id;
        this.answer=answer;
        this.optionA=optionA;
        this.optionB=optionB;
        this.optionC=optionC;
        this.optionD=optionD;
        this.tatil=tatil;
        this.score=score;
        this.delflag=delflag;
         }

public int getDelflag() {
    return delflag;
}

public void setDelflag(int delflag) {
    this.delflag = delflag;
}

public String getId() {
    return id;
}

public void setId(String id) {
    this.id = id;
}

public String getTatil() {
    return tatil;
}

public void setTatil(String tatil) {
    this.tatil = tatil;
}

public String getOptionA() {
    return optionA;
}

public void setOptionA(String optionA) {
    this.optionA = optionA;
}

public String getOptionB() {
    return optionB;
}

public void setOptionB(String optionB) {
    this.optionB = optionB;
}

public String getOptionC() {
    return optionC;
}

public void setOptionC(String optionC) {
    this.optionC = optionC;
}

public String getOptionD() {
    return optionD;
}

public void setOptionD(String optionD) {
    this.optionD = optionD;
}

public String getAnswer() {
    return answer;
}

public void setAnswer(String answer) {
    this.answer = answer;
}

public int getScore() {
    return score;
}

public void setScore(int score) {
    this.score = score;
}

@Override
public String toString() {
    return
            "第'" + id + "题:\t\n" +
            tatil + "\t\n" +
            "A:" + optionA +"\t\n" +
            "B:" + optionB + "\t\n"+
            "C:" + optionC +"\t\n"+
            "D:" + optionD + "\t\n"
           ;
    }
}

定义sysexam类，实现用jdbc对数据库的链接，并将sql查询结果放入Resultset集保存， 用Resultset.getXXX()方法将数据赋值给变量，并利用变量进行创建试题类对象存放在 数据结构ArrayList（注意泛型）存储：

代码如下：

    import java.sql.*;
    import java.util.ArrayList;

    public class sysexam {

        public ArrayList<examclass> getQuestion() {
        //选择数据结构ArrayList作为存储试题的集合
        ArrayList<examclass> list=new ArrayList<>();
        /*
        *jdbc进行链接数据库操作
        *1.注册Driver驱动：使用Class.forName("com.mysql.jdbc.Driver")进行注册
        *2.链接mysql库：Connection conn=DriverManager.getConnection("url","user","pwd")
        *3.创建Statement类的对象：使用链接库的对象的createStatement()方法创建
        *4.使用Statement对象的execute方法进行sql操作
        *5.关闭资源
        */
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection conn= DriverManager.getConnection("jdbc:mysql://localhost:3306/sys","root","root");
            Statement state= conn.createStatement();
            ResultSet res= state.executeQuery("select * from exam");
            while(res.next()){
                String id =res.getString(1);
                String tatil =res.getString(2);
                String a =res.getString(3);
                String b =res.getString(4);
                String c =res.getString(5);
                String d =res.getString(6);
                String anw =res.getString(7);
                int score =res.getInt(8);
                list.add(new examclass(id,tatil,a,b,c,d,anw,score,0));
                }

                res.close();
                state.close();
                conn.close();
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }
            return list;
        }
    }

定义exammanage类，实现对题库的增、删、改、查操作： 代码如下：

    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.SQLException;
    import java.sql.Statement;
    import java.util.ArrayList;
    import java.util.Random;
    import java.util.Scanner;

    import com.mysql.jdbc.ResultSet;

    public class exammanage {

    public ArrayList<examclass> printexam(ArrayList<examclass> list, int total) {

        ArrayList<examclass> listb=new ArrayList<examclass>();
        ArrayList<Integer> listNumber=new ArrayList<Integer>();
        sysexam sy=new sysexam();
        Random ran=new Random();
        int i=-1;
        while(listNumber.size()<total){
            i=ran.nextInt(list.size());
            if(!listNumber.contains(i)&&list.get(i).getDelflag()==0){
                listNumber.add(i);
            }
        }
        for (Integer n:listNumber){
            listb.add(list.get(n));
        }
        return listb;

    }
    public Integer doexam(ArrayList<examclass> listb) {
        int score=0;
        for(examclass q:listb){
            System.out.println(q);
            Scanner scan=new Scanner(System.in);
            System.out.println("-----------");
            System.out.println("--请输入您的答案：");
            String youranswer=scan.next();
            if(youranswer.equals(q.getAnswer())){
                System.out.println("恭喜回答正确");
                score=score+10;
            }else{
                System.out.println("对不起回答错误");
            }

        }
        return score;

    }

    public void addexam(String labname, String user, String pwd) {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection conn = DriverManager.getConnection(
                    "jdbc:mysql://localhost:3306/" + labname, user, pwd);
            Statement state = conn.createStatement();
            ResultSet result = (ResultSet) state
                    .executeQuery("select * from exam");
            Scanner scan=new Scanner(System.in);
            System.out.println("--请输入题号(4位)：");
            int id=scan.nextInt();
            System.out.println("--请输入题干：");
            String title=scan.next();
            System.out.println("--请输入选项A：");
            String opA=scan.next();
            System.out.println("--请输入选项B：");
            String opB=scan.next();
            System.out.println("--请输入选项C：");
            String opC=scan.next();
            System.out.println("--请输入选项D：");
            String opD=scan.next();
            System.out.println("--请输入标准答案：");
            String answer=scan.next();
            int delflag=0;
            String s="insert into exam values('"+id+"','"+title+"','"+opA
                    +"','"+opB+"','"+opC+"','"+opD+"','"+answer+"','"+delflag+"')";

            state.executeUpdate(s);

            result.close();
            state.close();
            conn.close();

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }

    }
    public void changeexam(String labname, String user, String pwd) {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection conn = DriverManager.getConnection(
                "jdbc:mysql://localhost:3306/" + labname, user, pwd);
            Statement state = conn.createStatement();
            ResultSet result = (ResultSet) state
                .executeQuery("select * from exam");
            Scanner scan=new Scanner(System.in);
            System.out.println("请输入要修改的题号(4位)：");
            int id=scan.nextInt();
            System.out.println("请输入选择修改的选项：");
            System.out.println("1题干，2选项A,3选项B,4选项C,5选项D,6答案");
            int option=scan.nextInt();
            String changer=null;
            switch (option){
                case 1:changer="tatil";break;
                case 2:changer="optionA";break;
                case 3:changer="optionB";break;
                case 4:changer="optionC";break;
                case 5:changer="optionD";break;
                case 6:changer="answer";break;
                default:System.out.println("输入错误");
            }
            System.out.println("请修改：");
            String changefinal=scan.next();
            String s="update exam set "+changer+ "='" +changefinal+ "' where(id='" +id+ "')";

            state.executeUpdate(s);

            result.close();
            state.close();
            conn.close();

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }

    }
    public void selexam (String labname, String user, String pwd) {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection conn = DriverManager.getConnection(
                "jdbc:mysql://localhost:3306/" + labname, user, pwd);
            Statement state = conn.createStatement();
            Scanner scan=new Scanner(System.in);
            System.out.println("请输入要查找的题号(4位)：");
            int id=scan.nextInt();
            String s="select * from exam where(id='"+id+"')";
            ResultSet result=(ResultSet) state.executeQuery(s);
            while(result.next()){
                System.out.println( "第'" + id + "题:\t\n" +
                            result.getString(2) + "\t\n" +
                            "A:" + result.getString(3) +"\t\n" +
                            "B:" + result.getString(4)+ "\t\n"+
                            "C:" + result.getString(5)+"\t\n"+
                            "D:" + result.getString(6)+ "\t\n"+
                            "答案："+result.getString(7));
            }

        result.close();
        state.close();
        conn.close();

    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    } catch (SQLException e) {
        e.printStackTrace();
    }

}
public void delexam (ArrayList<examclass> list){
    Scanner scan=new Scanner(System.in);
    System.out.println("请输入要删除的题号(4位)：");
    String id=scan.next();

    list.forEach(h->{
        if (h.getId().equals(id)){
            h.setDelflag(1);
            System.out.println("删除成功");
        }
    });
    System.out.println("试题不存在");

}
public void meau(ArrayList<examclass> list){
    System.out.println("1.增加试题，2.修改试题，3.删除试题，4.查找试题");
    Scanner scan=new Scanner(System.in);
    int option=scan.nextInt();
    switch (option){
        case 1:addexam("sys","root","root");break;
        case 2:changeexam("sys","root","root");break;
        case 3:delexam(list);break;
        case 4:selexam("sys","root","root");break;
        }
    }
}

定义text类，进行对程序的测试运行： 代码如下：

import java.util.ArrayList;
import java.util.Scanner;

public class text {
    public static void main(String[] args) {
        int userscore=0;
        int examnum=0;
        exammanage em=new exammanage();
        sysexam sy=new sysexam();
        ArrayList<examclass> list=new ArrayList<>(sy.getQuestion());
        Scanner scan=new Scanner(System.in);
        System.out.println("**********考试系统************");
        while(true) {
            System.out.println("1考试，2试题管理，3退出");
            int option = scan.nextInt();
            switch (option) {
                case 1:
                    while (true) {
                        System.out.println("请输入题量:");
                        examnum = scan.nextInt();
                        userscore = em.doexam(em.printexam(list, examnum));
                        System.out.println("你的总分为:" + userscore);
                        System.out.println("1.返回上一级菜单，2.继续答题");
                        int opt = scan.nextInt();
                        if (opt == 1) {
                            break;
                        } else if (opt == 2) {
                            continue;
                        } else {
                            System.out.println("输入错误");
                            break;
                        }

                    }break;
                case 2:
                    em.meau(list);
                    break;
                case 3:
                    System.exit(0);
                    break;
                default:
                    System.out.println("输入错误");
                    System.exit(0);
            }

        }
    }
}