增删改查

package fuxi;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

public class Dao {
    public int insert(Person person){
        Connection connection=null;
        PreparedStatement preparedStatement=null;
        String sql="insert into Preson (name,age,email,address) values(?,?,?,?)";
        try {
            connection=DBUtils.getConnection();
            preparedStatement=connection.prepareStatement(sql);
            preparedStatement.setString(1, person.getName());
            preparedStatement.setInt(2,person.getAge());
            preparedStatement.setString(3, person.getEmail());
            preparedStatement.setString(4, person.getAddress());
            int result=preparedStatement.executeUpdate();
            return result;
        } catch (SQLException e) {
            e.printStackTrace();
        }
        finally {
            DBUtils.closeAll(connection,preparedStatement,null);
        }
        return 0;}
    public int update(Person person){
        Connection connection=null;
        PreparedStatement preparedStatement=null;
        String sql="update Person set(name=?,age=?,email=?,address=?);";
        try {
            connection=DBUtils.getConnection();
            preparedStatement=connection.prepareStatement(sql);
            preparedStatement.setString(1, person.getName());
            preparedStatement.setInt(2,person.getAge());
            preparedStatement.setString(3, person.getEmail());
            preparedStatement.setString(4, person.address);
            int result=preparedStatement.executeUpdate();
            return result;
        } catch (SQLException e) {
            e.printStackTrace();
        }
        finally {
            DBUtils.closeAll(connection,preparedStatement,null);
        }
        return 0;}
    public int delete(int id){
        Connection connection=null;
        PreparedStatement preparedStatement=null;
        String sql="delete  from Person where id=?;";
        try {
            connection=DBUtils.getConnection();
            preparedStatement=connection.prepareStatement(sql);
            preparedStatement.setInt(1,id);
            int result=preparedStatement.executeUpdate();
            return  result;
        } catch (SQLException e) {
            e.printStackTrace();
        }
        finally {
            DBUtils.closeAll(connection,preparedStatement,null);
        }
        return 0;}
    public Person select(int id){
        Connection connection=null;
        PreparedStatement preparedStatement=null;
        ResultSet resultSet=null;
        Person person=null;
        String sql="select * from Person where id=?;";
        try {
            connection=DBUtils.getConnection();
            preparedStatement=connection.prepareStatement(sql);
            preparedStatement.setInt(1,id);
            resultSet= preparedStatement.executeQuery();

            if (resultSet.next()) {
                person=new Person();//
                int pid=resultSet.getInt("id");
                String name=resultSet.getString("name");
                int age=resultSet.getInt("age");
                String email=resultSet.getString("email");
                String address=resultSet.getString("address");
                person.setId(pid);
                person.setName(name);
                person.setAge(age);
                person.setEmail(email);
                person.setAddress(address);

            }
            return person;
        } catch (SQLException e) {
            e.printStackTrace();
        }
        finally {
            DBUtils.closeAll(connection,preparedStatement,resultSet);
        }

return null;
    }
    public List<Person> selectAll(){
        Connection connection=null;
        PreparedStatement preparedStatement=null;
        ResultSet resultSet=null;
        Person person=null;
        List<Person>personList=null;
        String sql="select * from Person;";
        try {
            person=new Person();
            connection=DBUtils.getConnection();
            preparedStatement=connection.prepareStatement(sql);
            resultSet= preparedStatement.executeQuery();
            while (resultSet.next()) {
                int pid=resultSet.getInt("id");
                String name=resultSet.getString("name");
                int age=resultSet.getInt("age");
                String email=resultSet.getString("email");
                String address=resultSet.getString("address");
//                person.setId(pid);
//                person.setName(name);
//                person.setAge(age);
//                person.setEmail(email);
//                person.setAddress(address);
//                personList.add(person);
                person=new Person(pid,name,age,email,address);
                personList.add(person);
            }
            return personList;
        } catch (SQLException e) {
            e.printStackTrace();
        }
        finally{
            DBUtils.closeAll(connection,preparedStatement,resultSet);
        }
        return null;
    }
}