作者:billy
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传输对象模式
传输对象模式(Transfer Object Pattern)用于从客户端向服务器一次性传递带有多个属性的数据。传输对象也被称为数值对象。传输对象是一个具有 getter/setter 方法的简单的 POJO 类,它是可序列化的,所以它可以通过网络传输。它没有任何的行为。服务器端的业务类通常从数据库读取数据,然后填充 POJO,并把它发送到客户端或按值传递它。对于客户端,传输对象是只读的。客户端可以创建自己的传输对象,并把它传递给服务器,以便一次性更新数据库中的数值。以下是这种设计模式的实体。
- 业务对象(Business Object) - 为传输对象填充数据的业务服务。
- 传输对象(Transfer Object) - 简单的 POJO,只有设置/获取属性的方法。
- 客户端(Client) - 客户端可以发送请求或者发送传输对象到业务对象。
UML结构图
代码实现
studentvo.h
创建传输对象
#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
创建业务对象
#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
实例应用 - 使用 StudentBO 来演示传输对象设计模式
#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;
}
运行结果:
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 ]