最近几年来，地理信息系统无论是在理论上还是应用上都处在一个飞速发展的阶段。 GIS被应用于多个领域的建模和决策支持，如城市管理、区划、环境整治等等，地理信息成为信息时代重要的组成部分之一； “数字地球”概念的提出，更进一步推动了作为其技术支撑的GIS的发展。 与此同时，一些学者致力于相关的理论研究，如空间感知、空间数据误差、空间关系的形式化等等。 这恰好说明了地理信息系统作为应用技术和学科的两个方面，并且这两个方面构成了相互促进的发展过程。
The MVC pattern stands for the Model-View-Controller (Model-View-Controller) pattern.
Model（模型） -the model represents an object or JAVA POJO that accesses data. It can also have logic to update the controller when the data changes.
View（视图） The view represents the visualization of the data contained in the model.
Controller（控制器） -controllers act on models and views. It controls the flow of data to model objects and updates the view when the data changes. It separates the view from the model.
As a model, we will create a Student Object. StudentView Is a view class that outputs student details to the console StudentController Is responsible for storing data to Student Object and update the view accordingly StudentView . MVCPatternDemo Our demo class uses the StudentController To demonstrate the use of MVC mode. Create a model. Create a view. Create a controller. Use StudentController Method to demonstrate the use of MVC design patterns. Execute the program and output the result:
6.28.1. Realize ¶
6.28.2. Step 1 ¶
Student.java ¶
publicclassStudent{privateStringrollNo;privateStringname;publicStringgetRollNo(){returnrollNo;}publicvoidsetRollNo(StringrollNo){this.rollNo=rollNo;}publicStringgetName(){returnname;}publicvoidsetName(Stringname){this.name=name;}}
6.28.3. Step 2 ¶
StudentView.java ¶
publicclassStudentView{publicvoidprintStudentDetails(StringstudentName,StringstudentRollNo){System.out.println("Student:");System.out.println("Name:"+studentName);System.out.println("Roll No:"+studentRollNo);}}
6.28.4. Step 3 ¶
StudentController.java ¶
publicclassStudentController{privateStudentmodel;privateStudentViewview;publicStudentController(Studentmodel,StudentViewview){this.model=model;this.view=view;}publicvoidsetStudentName(Stringname){model.setName(name);}publicStringgetStudentName(){returnmodel.getName();}publicvoidsetStudentRollNo(StringrollNo){model.setRollNo(rollNo);}publicStringgetStudentRollNo(){returnmodel.getRollNo();}publicvoidupdateView(){view.printStudentDetails(model.getName(),model.getRollNo());}}
6.28.5. Step 4 ¶
MVCPatternDemo.java ¶
publicclassMVCPatternDemo{publicstaticvoidmain(String[]args){//从数据库获取学生记录Studentmodel=retrieveStudentFromDatabase();//创建一个视图：把学生详细信息输出到控制台StudentViewview=newStudentView();StudentControllercontroller=newStudentController(model,view);controller.updateView();//更新模型数据controller.setStudentName("John");controller.updateView();}privatestaticStudentretrieveStudentFromDatabase(){Studentstudent=newStudent();student.setName("Robert");student.setRollNo("10");returnstudent;}} 6.28.6. Step 5 ¶
Student: Name: Robert Roll No: 10 Student: Name: John Roll No: 10