针对Student表的DAO设计实例

完整代码以及junit,mysql--connector包下载地址 : https://github.com/CasterWx/MyStudentDao

表信息:

代码:

dao包----impl包----StudentDAOImpl.java

package dao.impl;

import dao.IStudentDAO;
import domain.Student;

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

public class StudentDAOImpl implements IStudentDAO {
    public static Connection connection = null ;

    public void setConnection() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            System.out.println("连接成功");
        }catch (Exception e){
            System.out.println("连接失败");
        }
        try{
            connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/JavaJDBC","root","root");
        }catch (Exception e){
        }
    }

    public void shutdownConnection(){
        try {
            if(connection!=null){
                connection.close();
            }
        }catch (Exception e){
        }
    }
    @Override
    public void save(Student student) {
        setConnection();
        Statement statement = null ;
        try {
            statement = connection.createStatement();
            // sql语句:查询对应id
            String sql = "INSERT INTO t_student(id,name,age) VALUES(" + student.getId()+",'"+student.getName()+"',"+student.getAge()+")";
            statement.executeUpdate(sql);
        }catch (Exception e){
        }finally {
            try{
                if (statement!=null){
                    statement.close();
                }
            }catch (Exception e){
            }
        }
        shutdownConnection();
    }

    @Override
    public void delete(Student student) {
        Long id = student.getId() ;
        delete(id);
    }

    @Override
    public void delete(Long id) {
        setConnection();
        Statement statement = null ;
        try {
            statement = connection.createStatement();
            // sql语句:查询对应id
            String sql = "DELETE FROM t_student WHERE id="+id;
            statement.executeUpdate(sql);
        }catch (Exception e){
        }finally {
            try{
                if (statement!=null){
                    statement.close();
                }
            }catch (Exception e){
            }
        }
        shutdownConnection();
    }

    @Override
    public void update(Long id, Student student) {
        setConnection();
        Statement statement = null ;
        try {
            statement = connection.createStatement();
            // sql语句:查询对应id
            String sql = "UPDATE t_student SET name='"+ student.getName() +"',age="+student.getAge() +" WHERE id="+id;
            statement.executeUpdate(sql);
        }catch (Exception e){
        }finally {
            try{
                if (statement!=null){
                    statement.close();
                }
            }catch (Exception e){
            }
        }

        shutdownConnection();
    }

    @Override
    public void update(Student student) {
        Long id = student.getId() ;
        update(id,student);
    }

    @Override
    public Student get(Long id) {
        setConnection();
        Statement statement = null ;
        ResultSet resultSet = null ;
        Student student = null ;
        try {
            statement = connection.createStatement();
            // sql语句:查询对应id
            String sql = "SELECT * FROM t_student where id="+id ;
            resultSet = statement.executeQuery(sql);
            if(resultSet.next()){
                student = new Student() ;
                student.setId(resultSet.getLong("id"));
                student.setName(resultSet.getString("name"));
                student.setAge(resultSet.getLong("age"));
                return student ;
            }
        }catch (Exception e){
        }finally {
            try{
                if (statement!=null){
                    statement.close();
                }
            }catch (Exception e){
            }finally {
                try{
                    if(resultSet!=null){
                        resultSet.close();
                    }
                }catch (Exception e){
                }
            }
        }
        shutdownConnection();
        return null;
    }

    @Override
    public ArrayList<Student> list() {
        ArrayList<Student> list  = new ArrayList<Student>() ;
        setConnection();
        Statement statement = null ;
        ResultSet resultSet = null ;
        Student student = null ;
        try {
            statement = connection.createStatement();
            // sql语句:查询对应id
            String sql = "SELECT * FROM t_student" ;
            resultSet = statement.executeQuery(sql);

            while(resultSet.next()){
                student = new Student() ;
                student.setId(resultSet.getLong("id"));
                student.setName(resultSet.getString("name"));
                student.setAge(resultSet.getLong("age"));
                list.add(student) ;
            }
            return list ;
        }catch (Exception e){
        }finally {
            try{
                if (statement!=null){
                    statement.close();
                }
            }catch (Exception e){
            }finally {
                try{
                    if(resultSet!=null){
                        resultSet.close();
                    }
                }catch (Exception e){
                }
            }
        }
        shutdownConnection();
        return list;
    }

}

dao包----IStudentDAO接口

package dao;

import domain.Student;

import java.util.ArrayList;
import java.util.List;

/**
 *  Student对象的CRUD操作
 * */
public interface IStudentDAO {
    // ----------------------------------增--------------------------------------------

    /**
     * 保存学生对象
     * @param student
     * */
    void save(Student student);

    // ----------------------------------删--------------------------------------------

    /**
     *  根据删除指定学生
     *  @param student 学生对象
     * */

    void delete(Student student) ;
    /**
     *  根据主键删除指定学生
     *  @param id    学生对象主键
     * */
    void delete(Long id) ;

    // ----------------------------------改--------------------------------------------
    /**
     *  更新指定学生信息
     *  @param id  学生对象主键
     *  @param student  学生对象
     * */
    void update(Long id,Student student) ;
    /**
     *  根据主键删除指定学生
     *  @param student 学生对象
     * */
    void update(Student student);

    // ----------------------------------查--------------------------------------------

    /**
     *  查询指定id的学生对象
     *  @param id  学生对象主键
     *  @return Student if id存在,返回Student对象,否则返回null
     */
    Student get(Long id) ;
    /**
     *  查询所有学生对象
     *  @return 所有学生对象
     * */
    ArrayList<Student> list() ;
}

domain包-----Student.java

package domain;

public class Student {
    private long id ;
    private String name ;
    private long age ;
    public void getString(){
        System.out.println("Student(id="+id+",name="+name+",age="+age+")");
    }
    public void setId(long id){
        this.id = id ;
    }
    public void setName(String name){
        this.name = name ;
    }
    public void setAge(long age){
        this.age = age ;
    }

    public long getId() {
        return id;
    }

    public long getAge() {
        return age;
    }

    public String getName() {
        return name;
    }
}

test包----StudentDAOTest

package test;

import dao.IStudentDAO;
import dao.impl.StudentDAOImpl;
import domain.Student;
import org.junit.Test;

import java.util.ArrayList;
import java.util.List;

public class StudentDAOTest {
    IStudentDAO iStudentDAO = new StudentDAOImpl();
    @Test
    public void testSave() {
        Student student = new Student() ;
        student.setId(164L);
        student.setName("Wber");
        student.setAge(100L);
        iStudentDAO.save(student);
    }
    @Test
    public void testDelete() {
        iStudentDAO.delete(161L);
    }
    @Test
    public void testUpdate() {
        Student student = new Student() ;
        student.setId(161L);
        student.setName("wa");
        student.setAge(15L);
        iStudentDAO.update(161L,student);
    }
    @Test
    public void testGet() {
        iStudentDAO.get(162L).getString();
    }
    @Test
    public void testList() {
        ArrayList<Student> list = iStudentDAO.list() ;
        for(int i=0;i<list.size();i++){
            list.get(i).getString();
        }
    }
}