## 实现 我们将创建一个作为模型的*Student*对象。*StudentView*是一个把学生详细信息输出到控制台的视图类，*StudentController*是负责存储数据到*Student*对象中的控制器类，并相应地更新视图*StudentView*。 *MVCPatternDemo*，我们的演示类使用*StudentController*来演示 MVC 模式的用法。 ## 步骤 1 创建模型。 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; } } ``` ## 步骤 2 创建视图。 ## 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); } } ``` ## 步骤 3 创建控制器。 ## 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()); } } ``` ## 步骤 4 使用*StudentController*方法来演示 MVC 设计模式的用法。 ## MVCPatternDemo.java ``` public class MVCPatternDemo { public static void main(String[] args) { Student model = retrieveStudentFromDatabase(); //从数据库获取学生记录 StudentView view = new StudentView(); //创建一个视图：把学生详细信息输出到控制台 StudentController controller = new StudentController(model, view); controller.updateView(); controller.setStudentName("John"); //更新模型数据 controller.updateView(); } private static Student retrieveStudentFromDatabase(){ Student student = new Student(); student.setName("Robert"); student.setRollNo("10"); return student; } } ``` ## 步骤 5 执行程序，输出结果： ~~~ Student: Name: Robert Roll No: 10 Student: Name: John Roll No: 10 ~~~