java----MVC

package shiyan15;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Test {
	public static void main(String args[]){
		WindowTriangle win=new WindowTriangle();
		
		win.setTitle("使用MVC结构");
		win.setBounds(100,100,420,260);
	}

}
class WindowTriangle extends JFrame implements ActionListener{
	Triangle triangle;
	JTextField textA,textB,textC;
	JTextArea showArea;
	JButton controlButton;
	WindowTriangle(){
		init();
		setVisible(true);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
	}
	void init(){
		triangle=new Triangle();
		textA=new JTextField(5);
		textB=new JTextField(5);
		textC=new JTextField(5);
		showArea=new JTextArea();
		controlButton=new JButton("计算面积");
		JPanel pNorth=new JPanel();
		pNorth.add(new JLabel("边A："));
		pNorth.add(textA);
		pNorth.add(new JLabel("边B："));
		pNorth.add(textB);
		pNorth.add(new JLabel("边C："));
		pNorth.add(textC);
		pNorth.add(controlButton);
		controlButton.addActionListener(this);

		add(pNorth,BorderLayout.NORTH);
		add(new JScrollPane(showArea),BorderLayout.CENTER);
		
	}
	public void actionPerformed(ActionEvent e){
		try{
			double a=Double.parseDouble(textA.getText().trim());
			double b=Double.parseDouble(textB.getText().trim());
			double c=Double.parseDouble(textC.getText().trim());
			triangle.setA(a);
			triangle.setB(b);
			triangle.setC(c);
			String area=triangle.getArea();
			showArea.append("三角形"+a+","+b+","+c+"的面积：");
			showArea.append(area+"\n");
		}
		catch(Exception ex){
			showArea.append("\n"+ex+"\n");
		}
	}


	
}
class Triangle{
	double sideA,sideB,sideC,area;
	boolean isTriange;
	public String getArea(){
		if(isTriange){
			double p=(sideA+sideB+sideC)/2.0;
			area=Math.sqrt(p*(p-sideA)*(p-sideB)*(p-sideC));
			return String.valueOf(area);
		}
		else{
			return "无法计算面积";
		}
	}
	public void setA(double a){
		sideA=a;
		if(sideA+sideB>sideC&&sideA+sideC>sideB&&sideC+sideB>sideA)
			isTriange=true;
		else
			isTriange=false;
	}
	public void setB(double b){
		sideB=b;
		if(sideA+sideB>sideC&&sideA+sideC>sideB&&sideC+sideB>sideA)
			isTriange=true;
		else
			isTriange=false;
	}
	public void setC(double c){
		sideC=c;
		if(sideA+sideB>sideC&&sideA+sideC>sideB&&sideC+sideB>sideA)
			isTriange=true;
		else
			isTriange=false;
	}
}