Java DAO与Service层实现数据操作-优快云博客

本文链接：https://blog.youkuaiyun.com/aJiefy/article/details/84895058

这篇博客介绍了如何在Java中使用DAO和Service层来处理数据操作。它定义了一个CustomerDAO接口及其实现类CustomerDAOImpl，包含了插入、查询等数据库操作。同时，创建了CustomerService接口和实现类CustomerServiceImpl，它们调用了DAO层的方法来实现用户登录、注册等功能。

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建立一个dao接口，建立一个dao实现类

public interface CustomerDao {

//插入方法，传一个Customer对象进去
public void insert(Customer custname);

//根据名字查询
public Customer selectByName(String custname);

//根据用户名和密码查询
public Customer selectByNamePwd(String custname,String pwd);

//查询全部
List<Customer> selectAll();
}

建立一个dao实现类

public class CustomerDAOImpl implements CustomerDao{
   public void insert(Customer cust) {
       Connection conn = JDBCConnectionFactory.getConnection();
       String sql = "insert into customer values(?,?,?,?)";
       try {
           PreparedStatement ps= conn.prepareStatement(sql);
           ps.setString(1, cust.getCustname());
           ps.setString(2, cust.getPwd());
           ps.setInt(3,cust.getAge());
           ps.setString(4,cust.getAddress());
           ps.executeUpdate();
       } catch (SQLException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }finally{
           if(conn!=null){
               try {
                   conn.close();
               } catch (SQLException e) {
                   // TODO Auto-generated catch block
                   e.printStackTrace();
               }
           }
       }

   }

   public Customer selectByName(String custname) {
       Customer cust = null;
       Connection conn = JDBCConnectionFactory.getConnection();
       String sql = "select * from customer where custname=?";
       try {
           PreparedStatement ps = conn.prepareStatement(sql);
           ps.setString(1, custname);
           ResultSet rs = ps.executeQuery();
           if(rs.next()){
               cust = new Customer(rs.getString(1),rs.getString(2),rs.getInt(3),rs.getString(4));
           }
       } catch (SQLException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }if(conn!=null){
           try {
               conn.close();
           } catch (SQLException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
           }
       }
       return cust;
   }

   public Customer selectByNamePwd(String custname, String pwd) {
       // TODO Auto-generated method stub
       Customer cust = null;
       Connection conn = JDBCConnectionFactory.getConnection();
       String sql = "select * from customer where custname=? and pwd = ?";
       try {
           PreparedStatement ps = conn.prepareStatement(sql);
           ps.setString(1, custname);
           ps.setString(2, pwd);
           ResultSet rs = ps.executeQuery();
           if(rs.next()){
               cust = new Customer(rs.getString(1),rs.getString(2),rs.getInt(3),rs.getString(4));
           }
       } catch (SQLException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }finally{
           if(conn!=null){
               try {
                   conn.close();
               } catch (SQLException e) {
                   // TODO Auto-generated catch block
                   e.printStackTrace();
               }
           }
       }
       return cust;
   }

   public List<Customer> selectAll() {
       List<Customer> list = new ArrayList<Customer>();
       Connection conn = JDBCConnectionFactory.getConnection();
       String sql = "select custname,age,address from customer";
       try {
           Statement st = conn.createStatement();
           ResultSet rs = st.executeQuery(sql);
           while(rs.next()){
               list.add(new Customer(rs.getString(1),null,rs.getInt(2),rs.getString(3)));
           }
       } catch (SQLException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }finally{
           if(conn!=null){
               try {
                   conn.close();
               } catch (SQLException e) {
                   // TODO Auto-generated catch block
                   e.printStackTrace();
               }
           }
       }
       return list;
   }

}

建立一个service接口

public interface CustomerService {

//登录
public boolean login(String custname,String pwd);

//注册
public boolean register(Customer cust)throws RegisterException;

//查看个人信息
public Customer viewPersonal(String custname);
public List<Customer> viewAll();
}

建立一个service实现类

public class CustomerServiceImpl implements CustomerService{
   private CustomerDao dao;
   public boolean login(String custname, String pwd) {
       Customer cust = dao.selectByNamePwd(custname, pwd);
       if(cust!=null){
           return true;
       }else{
           return false;
       }
       // TODO Auto-generated method stub

   }

   public boolean register(Customer cust) throws RegisterException {
       // TODO Auto-generated method stub
       Customer c = dao.selectByName(cust.getCustname());
       if(c==null){
           dao.insert(cust);
           return true;
       }
       return false;
   }

   public Customer viewPersonal(String custname) {
       // TODO Auto-generated method stub
       return dao.selectByName(custname);

   }

   public List<Customer> viewAll() {
       // TODO Auto-generated method stub
       return dao.selectAll();
   }

}
service层调用dao层接口

dao接口写方法，接口实现类继承接口，写具体实现方法

service接口写方法，接口实现类的方法中调用dao层方法