邮寄收费系统 strategy模式运用

package calculator; import java.awt.*; import strategy.Context; import strategy.Mail; import strategy.RegisterdMail; import strategy.RegularMail; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.*; public class J_view extends JFrame implements ActionListener { JComboBox cb; JButton b; String d; double a1,b1,c1; JTextField [] t={new JTextField("重量:",3),new JTextField("",5), new JTextField("距离:",3),new JTextField("",5), new JTextField("金额:",3),new JTextField("",5), new JTextField("邮资:",3),new JTextField("",5),}; public J_view() { super("邮资的计算"); Container c=getContentPane(); c.setLayout(new FlowLayout()); String [] s={"邮寄类型","RegularMail","RegisterdMail"}; cb=new JComboBox(s); t[0].setEditable(false);//不可编辑 t[2].setEditable(false); t[4].setEditable(false); t[6].setEditable(false); b=new JButton("计算"); b.addActionListener(this); c.add(cb); for(int i=0;i<6;i++) { c.add(t[i]); } c.add(b); c.add(t[6]); c.add(t[7]); } public void actionPerformed(ActionEvent e) { String a = t[1].getText(); //System.out.println(a); String b = t[3].getText(); //System.out.println(b); String c = t[5].getText();//获得输入的a、b、c //System.out.println(c); a1 = Double.parseDouble(a); b1 = Double.parseDouble(b); c1 = Double.parseDouble(c);//将string类型转化成double类型进行计算 Context mail=new Context();//实例上下文对象 String m="strategy."+cb.getSelectedItem().toString(); try { mail.setMail((Mail)Class.forName(m).newInstance());//根据获得的参数来实例化类 } catch (InstantiationException | IllegalAccessException | ClassNotFoundException e1) { e1.printStackTrace(); } double calculate= mail.getCalculate(a1, b1, c1); String calculate1 = String.format("%.2f", calculate);//保留两位有效数字 t[7].setText(calculate1); } }