MVC业务代表组合实体数据访问对象

Posted 2021-05-01 荆花知了窝

J2EE 模式 这些设计模式特别关注表示层。这些模式是由 Sun Java Center 鉴定的。

MVC 模式（MVC Pattern） 业务代表模式（Business Delegate Pattern） 组合实体模式（Composite Entity Pattern） 数据访问对象模式（Data Access Object Pattern） 前端控制器模式（Front Controller Pattern） 拦截过滤器模式（Intercepting Filter Pattern） 服务定位器模式（Service Locator Pattern） 传输对象模式（Transfer Object Pattern）

MVC模式

Student.java

public class Student {
   private String rollNo;
   private String name;
   public String getRollNo() {
      return rollNo;
   }
   public void setRollNo(String rollNo) {
      this.rollNo = rollNo;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
}

StudentView.java

public class StudentView {
   public void printStudentDetails(String studentName, String studentRollNo){
      System.out.println("Student: ");
      System.out.println("Name: " + studentName);
      System.out.println("Roll No: " + studentRollNo);
   }
}

StudentController.java

public class StudentController {
   private Student model;
   private StudentView view;

   public StudentController(Student model, StudentView view){
      this.model = model;
      this.view = view;
   }

   public void setStudentName(String name){
      model.setName(name);    
   }

   public String getStudentName(){
      return model.getName();     
   }

   public void setStudentRollNo(String rollNo){
      model.setRollNo(rollNo);    
   }

   public String getStudentRollNo(){
      return model.getRollNo();       
   }

   public void updateView(){            
      view.printStudentDetails(model.getName(), model.getRollNo());
   }   
}

MVCPatternDemo.java

public class MVCPatternDemo {
   public static void main(String[] args) {

      //从数据可获取学生记录
      Student model  = retriveStudentFromDatabase();

      //创建一个视图：把学生详细信息输出到控制台
      StudentView view = new StudentView();

      StudentController controller = new StudentController(model, view);

      controller.updateView();

      //更新模型数据
      controller.setStudentName("John");

      controller.updateView();
   }

   private static Student retriveStudentFromDatabase(){
      Student student = new Student();
      student.setName("Robert");
      student.setRollNo("10");
      return student;
   }
}

业务代表模式

BusinessService.java

public interface BusinessService {
   public void doProcessing();
}

EJBService.java

public class EJBService implements BusinessService {

   @Override
   public void doProcessing() {
      System.out.println("Processing task by invoking EJB Service");
   }
}

JMSService.java

public class JMSService implements BusinessService {

   @Override
   public void doProcessing() {
      System.out.println("Processing task by invoking JMS Service");
   }
}

BusinessLookUp.java

public class BusinessLookUp {
   public BusinessService getBusinessService(String serviceType){
      if(serviceType.equalsIgnoreCase("EJB")){
         return new EJBService();
      }else {
         return new JMSService();
      }
   }
}

BusinessDelegate.java

public class BusinessDelegate {
   private BusinessLookUp lookupService = new BusinessLookUp();
   private BusinessService businessService;
   private String serviceType;

   public void setServiceType(String serviceType){
      this.serviceType = serviceType;
   }

   public void doTask(){
      businessService = lookupService.getBusinessService(serviceType);
      businessService.doProcessing();     
   }
}

Client.java

public class Client {
   
   BusinessDelegate businessService;

   public Client(BusinessDelegate businessService){
      this.businessService  = businessService;
   }

   public void doTask(){      
      businessService.doTask();
   }
}

BusinessDelegatePatternDemo.java

public class BusinessDelegatePatternDemo {
   
   public static void main(String[] args) {

      BusinessDelegate businessDelegate = new BusinessDelegate();
      businessDelegate.setServiceType("EJB");

      Client client = new Client(businessDelegate);
      client.doTask();

      businessDelegate.setServiceType("JMS");
      client.doTask();
   }
}

组合实体模式

DependentObject1.java

public class DependentObject1 {
   
   private String data;

   public void setData(String data){
      this.data = data; 
   } 

   public String getData(){
      return data;
   }
}

DependentObject2.java

public class DependentObject2 {
   
   private String data;

   public void setData(String data){
      this.data = data; 
   } 

   public String getData(){
      return data;
   }
}

CoarseGrainedObject.java

public class CoarseGrainedObject {
   DependentObject1 do1 = new DependentObject1();
   DependentObject2 do2 = new DependentObject2();

   public void setData(String data1, String data2){
      do1.setData(data1);
      do2.setData(data2);
   }

   public String[] getData(){
      return new String[] {do1.getData(),do2.getData()};
   }
}

CompositeEntity.java

public class CompositeEntity {
   private CoarseGrainedObject cgo = new CoarseGrainedObject();

   public void setData(String data1, String data2){
      cgo.setData(data1, data2);
   }

   public String[] getData(){
      return cgo.getData();
   }
}

Client.java

public class Client {
   private CompositeEntity compositeEntity = new CompositeEntity();

   public void printData(){
      for (int i = 0; i < compositeEntity.getData().length; i++) {
         System.out.println("Data: " + compositeEntity.getData()[i]);
      }
   }

   public void setData(String data1, String data2){
      compositeEntity.setData(data1, data2);
   }
}

CompositeEntityPatternDemo.java

public class CompositeEntityPatternDemo {
   public static void main(String[] args) {
       Client client = new Client();
       client.setData("Test", "Data");
       client.printData();
       client.setData("Second Test", "Data1");
       client.printData();
   }
}

数据访问对象模式

Student.java

public class Student {
   private String name;
   private int rollNo;

   Student(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;
   }
}

StudentDao.java

import java.util.List;

public interface StudentDao {
   public List<Student> getAllStudents();
   public Student getStudent(int rollNo);
   public void updateStudent(Student student);
   public void deleteStudent(Student student);
}

StudentDaoImpl.java

import java.util.ArrayList;
import java.util.List;

public class StudentDaoImpl implements StudentDao {
   
   //列表是当作一个数据库
   List<Student> students;

   public StudentDaoImpl(){
      students = new ArrayList<Student>();
      Student student1 = new Student("Robert",0);
      Student student2 = new Student("John",1);
      students.add(student1);
      students.add(student2);     
   }
   @Override
   public void deleteStudent(Student student) {
      students.remove(student.getRollNo());
      System.out.println("Student: Roll No " + student.getRollNo() 
         +", deleted from database");
   }

   //从数据库中检索学生名单
   @Override
   public List<Student> getAllStudents() {
      return students;
   }

   @Override
   public Student getStudent(int rollNo) {
      return students.get(rollNo);
   }

   @Override
   public void updateStudent(Student student) {
      students.get(student.getRollNo()).setName(student.getName());
      System.out.println("Student: Roll No " + student.getRollNo() 
         +", updated in the database");
   }
}

DaoPatternDemo.java

public class DaoPatternDemo {
   public static void main(String[] args) {
      StudentDao studentDao = new StudentDaoImpl();

      //输出所有的学生
      for (Student student : studentDao.getAllStudents()) {
         System.out.println("Student: [RollNo : "
            +student.getRollNo()+", Name : "+student.getName()+" ]");
      }


      //更新学生
      Student student =studentDao.getAllStudents().get(0);
      student.setName("Michael");
      studentDao.updateStudent(student);

      //获取学生
      studentDao.getStudent(0);
      System.out.println("Student: [RollNo : "
         +student.getRollNo()+", Name : "+student.getName()+" ]");    
   }
}