傳輸對(duì)象模式
傳輸對(duì)象模式(Transfer Object Pattern)用于從客戶端向服務(wù)器一次性傳遞帶有多個(gè)屬性的數(shù)據(jù)。傳輸對(duì)象也被稱為數(shù)值對(duì)象。傳輸對(duì)象是一個(gè)具有 getter/setter 方法的簡(jiǎn)單的 POJO 類,它是可序列化的,所以它可以通過(guò)網(wǎng)絡(luò)傳輸。它沒有任何的行為。服務(wù)器端的業(yè)務(wù)類通常從數(shù)據(jù)庫(kù)讀取數(shù)據(jù),然后填充 POJO,并把它發(fā)送到客戶端或按值傳遞它。對(duì)于客戶端,傳輸對(duì)象是只讀的??蛻舳丝梢詣?chuàng)建自己的傳輸對(duì)象,并把它傳遞給服務(wù)器,以便一次性更新數(shù)據(jù)庫(kù)中的數(shù)值。以下是這種設(shè)計(jì)模式的實(shí)體。
業(yè)務(wù)對(duì)象(Business Object) - 為傳輸對(duì)象填充數(shù)據(jù)的業(yè)務(wù)服務(wù)。
傳輸對(duì)象(Transfer Object) - 簡(jiǎn)單的 POJO,只有設(shè)置/獲取屬性的方法。
客戶端(Client) - 客戶端可以發(fā)送請(qǐng)求或者發(fā)送傳輸對(duì)象到業(yè)務(wù)對(duì)象。
實(shí)現(xiàn)
我們將創(chuàng)建一個(gè)作為業(yè)務(wù)對(duì)象的 StudentBO 和作為傳輸對(duì)象的 StudentVO,它們都代表了我們的實(shí)體。
TransferObjectPatternDemo,我們的演示類在這里是作為一個(gè)客戶端,將使用 StudentBO 和 Student 來(lái)演示傳輸對(duì)象設(shè)計(jì)模式。

步驟 1
創(chuàng)建傳輸對(duì)象。
StudentVO.java
public class StudentVO { private String name; private int rollNo; StudentVO(String name, int rollNo){ this.name = name; this.rollNo = rollNo; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getRollNo() { return rollNo; } public void setRollNo(int rollNo) { this.rollNo = rollNo; } }
步驟 2
創(chuàng)建業(yè)務(wù)對(duì)象。
StudentBO.java
import java.util.ArrayList; import java.util.List; public class StudentBO { //列表是當(dāng)作一個(gè)數(shù)據(jù)庫(kù) List<StudentVO> students; public StudentBO(){ students = new ArrayList<StudentVO>(); StudentVO student1 = new StudentVO("Robert",0); StudentVO student2 = new StudentVO("John",1); students.add(student1); students.add(student2); } public void deleteStudent(StudentVO student) { students.remove(student.getRollNo()); System.out.println("Student: Roll No " + student.getRollNo() +", deleted from database"); } //從數(shù)據(jù)庫(kù)中檢索學(xué)生名單 public List<StudentVO> getAllStudents() { return students; } public StudentVO getStudent(int rollNo) { return students.get(rollNo); } public void updateStudent(StudentVO student) { students.get(student.getRollNo()).setName(student.getName()); System.out.println("Student: Roll No " + student.getRollNo() +", updated in the database"); } }
步驟 3
使用 StudentBO 來(lái)演示傳輸對(duì)象設(shè)計(jì)模式。
TransferObjectPatternDemo.java
public class TransferObjectPatternDemo { public static void main(String[] args) { StudentBO studentBusinessObject = new StudentBO(); //輸出所有的學(xué)生 for (StudentVO student : studentBusinessObject.getAllStudents()) { System.out.println("Student: [RollNo : " +student.getRollNo()+", Name : "+student.getName()+" ]"); } //更新學(xué)生 StudentVO student =studentBusinessObject.getAllStudents().get(0); student.setName("Michael"); studentBusinessObject.updateStudent(student); //獲取學(xué)生 studentBusinessObject.getStudent(0); System.out.println("Student: [RollNo : " +student.getRollNo()+", Name : "+student.getName()+" ]"); } }
步驟 4
驗(yàn)證輸出。
Student: [RollNo : 0, Name : Robert ] Student: [RollNo : 1, Name : John ] Student: Roll No 0, updated in the database Student: [RollNo : 0, Name : Michael ]