作者:billy
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傳輸對象模式
傳輸對象模式(Transfer Object Pattern)用於從客戶端向服務器一次性傳遞帶有多個屬性的數據。傳輸對象也被稱爲數值對象。傳輸對象是一個具有 getter/setter 方法的簡單的 POJO 類,它是可序列化的,所以它可以通過網絡傳輸。它沒有任何的行爲。服務器端的業務類通常從數據庫讀取數據,然後填充 POJO,並把它發送到客戶端或按值傳遞它。對於客戶端,傳輸對象是隻讀的。客戶端可以創建自己的傳輸對象,並把它傳遞給服務器,以便一次性更新數據庫中的數值。以下是這種設計模式的實體。
- 業務對象(Business Object) - 爲傳輸對象填充數據的業務服務。
- 傳輸對象(Transfer Object) - 簡單的 POJO,只有設置/獲取屬性的方法。
- 客戶端(Client) - 客戶端可以發送請求或者發送傳輸對象到業務對象。
UML結構圖
代碼實現
studentvo.h
創建傳輸對象
#include <string>
using namespace std;
class StudentVO
{
public:
StudentVO(string name, int rollNo)
{
this->name = name;
this->rollNo = rollNo;
}
string getName()
{
return name;
}
void setName(string name)
{
this->name = name;
}
int getRollNo()
{
return rollNo;
}
void setRollNo(int rollNo)
{
this->rollNo = rollNo;
}
private:
string name;
int rollNo;
};
studentbo.h
創建業務對象
#include "studentvo.h"
#include <iostream>
#include <vector>
class StudentBO {
public:
StudentBO()
{
StudentVO *student1 = new StudentVO("Robert",0);
StudentVO *student2 = new StudentVO("John",1);
students.push_back(student1);
students.push_back(student2);
}
void deleteStudent(StudentVO *student)
{
auto it = std::find(std::begin(students), std::end(students), student);
if (it != std::end(students))
{
students.erase(it);
cout << "Student: Roll No " << student->getRollNo() << ", deleted from database" << endl;
}
else
{
cout << "Student: Roll No " << student->getRollNo() << ", not found in database" << endl;
}
}
void getAllStudents()
{
for (auto it : students)
{
cout << "Student name: " + it->getName() <<
", Student rollNo: " + std::to_string(it->getRollNo()) << endl;
}
}
StudentVO * getStudent(int rollNo)
{
for (auto it : students)
{
if (rollNo == it->getRollNo())
{
return it;
}
}
return nullptr;
}
void updateStudent(StudentVO *student)
{
for (auto it : students)
{
if (student->getRollNo() == it->getRollNo())
{
it->setName(student->getName());
cout << "Student: Roll No " << student->getRollNo() <<
", updated in the database" << endl;
}
}
}
private:
vector<StudentVO *> students;
};
main.cpp
實例應用 - 使用 StudentBO 來演示傳輸對象設計模式
#include "studentbo.h"
int main()
{
StudentBO *studentBusinessObject = new StudentBO();
studentBusinessObject->getAllStudents();
cout << endl;
StudentVO *student = studentBusinessObject->getStudent(0);
student->setName("Michael");
studentBusinessObject->updateStudent(student);
studentBusinessObject->getStudent(0);
cout << "Student: [RollNo : " << student->getRollNo() <<
", Name : " + student->getName()+" ]" << endl;
return 0;
}
運行結果:
Student name: Robert, Student rollNo: 0
Student name: John, Student rollNo: 1
Student: Roll No 0, updated in the database
Student: [RollNo : 0, Name : Michael ]