查询所有学生记录和查询S1年级以下的学生记录试题

　查询所有学生信息，年级信息以年级名称显示

　　一、DAO层搭建：

　　　　1.实体类：

　　　　　　Student

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package com.myschool.entity;   import java.io.Serializable; import java.util.Date;   public class Student implements Serializable {           private static final long serialVersionUID = 6439763802252472361L;           //定义实体属性     private int studentNo;     private String longinPwd;     private String studentName;     private int sex;     private grade grade;//把年级对象作为属性     private String phone;     private String address;     private Date bornDate;     private String email;     private String identityCard;               //封装     public int getStudentNo() {         return studentNo;     }     public void setStudentNo(int studentNo) {         this.studentNo = studentNo;     }     public String getLonginPwd() {         return longinPwd;     }     public void setLonginPwd(String longinPwd) {         this.longinPwd = longinPwd;     }     public String getStudentName() {         return studentName;     }     public void setStudentName(String studentName) {         this.studentName = studentName;     }     public int getSex() {         return sex;     }     public void setSex(int sex) {         this.sex = sex;     }     public grade getGrade() {         return grade;     }     public void setGrade(grade grades) {         this.grade = grades;     }     public String getPhone() {         return phone;     }     public void setPhone(String phone) {         this.phone = phone;     }     public String getAddress() {         return address;     }     public void setAddress(String address) {         this.address = address;     }     public Date getBornDate() {         return bornDate;     }     public void setBornDate(Date bornDate) {         this.bornDate = bornDate;     }     public String getEmail() {         return email;     }     public void setEmail(String email) {         this.email = email;     }     public String getIdentityCard() {         return identityCard;     }     public void setIdentityCard(String identityCard) {         this.identityCard = identityCard;     }              //有参构造     public Student(int studentNo, String longinPwd, String studentName,             int sex, grade gradeID, String phone, String address, Date bornDate,             String email, String identityCard) {         this.studentNo = studentNo;         this.longinPwd = longinPwd;         this.studentName = studentName;         this.sex = sex;         this.gradeID = gradeID;         this.phone = phone;         this.address = address;         this.bornDate = bornDate;         this.email = email;         this.identityCard = identityCard;     }       //无参构造     public Student() {               }

　　　　　Grade类：

package com.myschool.entity;

public class grade {
    private int gradeid;
    private String gradeName;
    public int getGradeid() {
        return gradeid;
    }
    public void setGradeid(int gradeid) {
        this.gradeid = gradeid;
    }
    public String getGradeName() {
        return gradeName;
    }
    public void setGradeName(String gradeName) {
        this.gradeName = gradeName;
    }
    public grade(int gradeid, String gradeName) {
        super();
        this.gradeid = gradeid;
        this.gradeName = gradeName;
    }
    public grade() {
        super();
        
    }
    
}

　　　　2.Daobase：

package com.myschool.dao;

import java.beans.Statement;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

public class baseDao {

    // 创建连接参数
    private final static String DRIVER = "com.mysql.jdbc.Driver";
    private final static String URL = "jdbc:mysql:///myschool";
    private final static String USER_NAME = "root";
    private final static String PASSWORD = "123";

    Connection con = null;
    PreparedStatement prestatement = null;
    ResultSet rs = null;

    // 获取连接
    private Connection getConnection() {
        try {
            Class.forName(DRIVER);
            if (con == null) {
                con = DriverManager.getConnection(URL, USER_NAME, PASSWORD);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        return con;
    }

    // 增删改
    public int executeUpdate(String sql, Object... obj) throws Exception {
        // 获取连接
        getConnection();

        // 获取prepareStatement对象
        prestatement = con.prepareStatement(sql);

        // 循环添加参数
        for (int i = 1; i <= obj.length; i++) {
            prestatement.setObject(i, obj[i - 1]);
        }
        // 执行SQL语句
        int count = prestatement.executeUpdate();
        return count;

    }

    // 查
    public ResultSet executeQuery(String sql, Object... obj) throws Exception {
        // 获取连接
        getConnection();

        // 获取prepareStatement对象
        prestatement = con.prepareStatement(sql);

        // 循环添加参数
        for (int i = 1; i <= obj.length; i++) {
            prestatement.setObject(i, obj[i - 1]);
        }
        // 执行SQL语句
        rs = prestatement.executeQuery();

        return rs;

    }
    
    //回收资源
    public void closeResouse() throws Exception
    {
        if (rs!=null) {
            rs.close();
        }
        if (prestatement!=null) {
            prestatement.close();
        }
        if (con!=null) {
            con.close();
        }
        
    }
 
}

　　　　3.DAO接口：

package com.myschool.dao;

import java.util.List;

import com.myschool.entity.Student;

public interface IStudentDao {

    /*
     * 查询所有学生记录,年级名称
     */
    public List<Student> Search() throws Exception;

    
}

　　　　　4.DAO接口实现类：

package com.mychool.dao.impl;

import java.sql.ResultSet;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.List;

import com.myschool.dao.IStudentDao;
import com.myschool.dao.baseDao;
import com.myschool.entity.Student;
import com.myschool.entity.grade;

public class IStudentDaoImpl extends baseDao implements IStudentDao {

    
    @Override
    public List<Student> Search() throws Exception {
        //创建student对象泛型集合
        List<Student> stus=new ArrayList<Student>();
        
        String sql="Select studentName,GradeName from Student,grade where Grade.gradeid=Student.gradeid ";

        //定义resultSet对象接收basedao的查询方法查出来的数据
        ResultSet rSet=executeQuery(sql);
        
        if (rSet!=null) {
            while (rSet.next()) {
                Student stu=new Student();
                grade grade=new grade();//创建年级对象
//                stu.setAddress(rSet.getString("address"));
//                stu.setEmail(rSet.getString("email"));
//                stu.setIdentityCard(rSet.getString("identityCard"));
//                stu.setLonginPwd(rSet.getString("longinPwd"));
//                stu.setPhone(rSet.getString("phone"));
//                stu.setSex(rSet.getInt("sex"));
                grade.setGradeName(rSet.getString("gradeName"));//给年级对象赋值
                stu.setStudentName(rSet.getString("studentName"));//给学生对象赋值
                stu.setGradeID(grade);
//                stu.setStudentNo(rSet.getInt("StudentNo"));
//                SimpleDateFormat sdFormat=new SimpleDateFormat("yyyy-MM-dd");
//                stu.setBornDate(sdFormat.parse(rSet.getString("bornDate")));
                stus.add(stu);//将学生对象添加到对象集合中
            }
            
        }
　　　　//回收释放资源
        closeResouse();
        return stus;
    }

    
}
为了简单明洁，部分属性不进行值查询

　　二、service层：

　　　　1.service接口：

package com.myschool.service;

import java.util.List;

import com.myschool.entity.Student;

public interface IService {
    
    public List<Student> Search() throws Exception;
}

　　　　2.service接口实现类：

package com.mychool.service.Impl;

import java.util.List;

import com.mychool.dao.impl.IStudentDaoImpl;
import com.myschool.dao.IStudentDao;
import com.myschool.entity.Student;
import com.myschool.service.IService;

public class IServiceImpl implements IService{

    IStudentDao isd=new IStudentDaoImpl();
    @Override
    public List<Student> Search() throws Exception {
        return isd.Search();
    }
    
}

　　三、UI层：

　　　　

package com.myschool.ui;

import java.util.List;

import com.mychool.service.Impl.IServiceImpl;
import com.myschool.entity.Student;
import com.myschool.service.IService;

public class test {    
    public static void main(String[] args) throws Exception {
　　　　　//创建service接口实现类的对象
        IService isv=new  IServiceImpl();
        List<Student> lsList=isv.Search();

        for (Student student : lsList) {
            System.out.println(student.getStudentName()+"	"+student.getGradeID().getGradeName());
        }
    }
}

　　　　DAO实现类写法：

　

 

package com.myschool.dao.impl;

import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

import com.myschool.dao.BaseDao;
import com.myschool.dao.IGradeDao;
import com.myschool.entity.Grade;
import com.myschool.entity.Student;

public class IGradeDaoImpl extends BaseDao implements IGradeDao{

    @Override
    public Grade getStudentByGrade(String gradeName) throws Exception {
        Grade grade=new Grade();
        String sql="SELECT * FROM Student,Grade WHERE Student.GradeId=Grade.GradeId AND GradeName=?";
        ResultSet rs = executeQuery(sql, gradeName);
        if(rs!=null){
            
            while (rs.next()) {
                
                //获取年级信息
                grade.setGradeName(rs.getString("gradeName"));
                //获取学生信息
                Student student=new Student();
                student.setGradeId(rs.getInt("gradeId"));
                student.setStudentName(rs.getString("StudentName"));
                student.setStudentNo(rs.getInt("studentNo"));
                //将查询出来的学生信息添加到集合当中
                grade.getStulist().add(student);
            }
            
        }
        return grade;
    }

}