有谁知道视图层具体实现如何修改的功能，关于字段为Null时，该怎么修改？
package view;
import java.io.*;
import java.sql.SQLException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.*;
import action.GodessAction;
import model.Godess;
public class View {
private static final String CONTEXT="欢迎来到女神禁区：\n" +
"下面是女神禁区的功能列表：\n" +
"[MAIN/M]:主菜单\n" +
"[QUERY/Q]:查看全部女神的信息\n" +
"[GET/G]:查看某位女神的详细信息\n" +
"[ADD/A]:添加女神信息\n" +
"[UPDATE/U]:更新女神信息\n" +
"[DELETE/D]:删除女神信息\n" +
"[SEARCH/S]:查询女神信息(根据姓名、手机号来查询)\n" +
"[EXIT/E]:退出女神禁区\n" +
"[BREAK/B]:退出当前功能，返回主菜单";
private static final String OPERATION_MAIN="MAIN";
private static final String OPERATION_QUERY="QUERY";
private static final String OPERATION_GET="GET";
private static final String OPERATION_ADD="ADD";
private static final String OPERATION_UPDATE="UPDATE";
private static final String OPERATION_DELETE="DELETE";
private static final String OPERATION_SEARCH="SEARCH";
private static final String OPERATION_EXIT="EXIT";
private static final String OPERATION_BREAK="BREAK";
public static void main(String[] args) {
System.out.println(CONTEXT);
Scanner scan = new Scanner(System.in);
Godess g = new Godess();
GodessAction ga = new GodessAction();
String previous = null;
Integer step=1;
while(scan.hasNext()) {
String input = scan.next().toString();
System.out.println("你输入的值为："+input);
if(OPERATION_EXIT.equals(input.toUpperCase())||OPERATION_EXIT.substring(0, 1).equals(input.toUpperCase())) {
System.out.println("你已成功退出！");
break;
}else if(OPERATION_UPDATE.equals(input.toUpperCase())||OPERATION_UPDATE.substring(0, 1).equals(input.toUpperCase())) {
Godess gu= new Godess();
gu.setUser_name("小兰");
gu.setAge(30);
gu.setSex(0);
gu.setBirthday(new Date());
gu.setMobile("15648790987");
gu.setEmail("xiaolan@163.com");
gu.setIsdel(1);
gu.setId(3);
try {
ga.update(gu);
System.out.println("你已成功修改！");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}else if(OPERATION_DELETE.equals(input.toUpperCase())||OPERATION_DELETE.substring(0, 1).equals(input.toUpperCase())) {
System.out.println("输入要删除的女神id:");
Integer id = scan.nextInt();
try {
ga.delete(id);
System.out.println("你已成功删除！");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}else if(OPERATION_QUERY.equals(input.toUpperCase())||OPERATION_QUERY.substring(0, 1).equals(input.toUpperCase())) {
try {
List<Godess> gds = ga.queryAll();
System.out.println("查询成功，查询结果如下：");
for(Godess gd:gds) {
System.out.println("姓名:"+gd.getUser_name()+" "+"年龄:"+gd.getAge());
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println("查询失败");
}
}else if(OPERATION_ADD.equals(input.toUpperCase())||
OPERATION_ADD.substring(0, 1).equals(input.toUpperCase())||OPERATION_ADD.equals(previous)) {
previous = "ADD";
if(step==1) {
System.out.println("请输入女神的[姓名]");
}else if(step==2) {
g.setUser_name(input);
System.out.println("请输入女神的[年龄]");
}else if(step==3) {
g.setAge(Integer.valueOf(input));
System.out.println("请输入女神的[性别]");
}else if(step==4) {
g.setSex(Integer.valueOf(input));
System.out.println("请输入女神的[生日] 格式为yyyy-mm-dd");
}else if(step==5) {
SimpleDateFormat sd = new SimpleDateFormat("yyyy-mm-dd");
Date birthday = null;
try {
birthday = sd.parse(input);
g.setBirthday(birthday);
System.out.println("请输入女神的[邮箱]");
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println("你输入的生日格式有误，请重新输入");
step = 4;
}
g.setBirthday(birthday);
}else if(step == 6) {
g.setEmail(input);
System.out.println("请输入女神的[手机号]");
}else if(step==7){
g.setMobile(input);
System.out.println("请输入女神的[是否删除标志]");
}else {
g.setIsdel(Integer.valueOf(input));
try {
ga.add(g);
System.out.println("新增女神成功");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println("新增女神失败");
}
}
step++;
}else{
System.out.println("新增女神失败");
}
}
}
}