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();
         }
     }
 }