import java.util.Map;

import javax.validation.Valid;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.validation.Errors;
import org.springframework.validation.FieldError;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;

import com.atguigu.springmvc.crud.dao.DepartmentDao;
import com.atguigu.springmvc.crud.dao.EmployeeDao;
import com.atguigu.springmvc.crud.entities.Employee;

@Controller
public class EmployeeHandler {

	@Autowired
	private EmployeeDao employeeDao;
	
	@Autowired
	private DepartmentDao departmentDao;

	@ModelAttribute
	public void getEmployee(@RequestParam(value="id",required=false) Integer id,
			Map<String, Object> map){
		if(id != null){
			map.put("employee", employeeDao.get(id));
		}
	}
	
	@RequestMapping(value="/emp", method=RequestMethod.PUT)
	public String update(Employee employee){
		employeeDao.save(employee);
		
		return "redirect:/emps";
	}
	
	@RequestMapping(value="/emp/{id}", method=RequestMethod.GET)
	public String input(@PathVariable("id") Integer id, Map<String, Object> map){
		map.put("employee", employeeDao.get(id));
		map.put("departments", departmentDao.getDepartments());
		return "input";
	}
	
	@RequestMapping(value="/emp/{id}", method=RequestMethod.DELETE)
	public String delete(@PathVariable("id") Integer id){
		employeeDao.delete(id);
		return "redirect:/emps";
	}
	
	@RequestMapping(value="/emp", method=RequestMethod.POST)
	public String save(@Valid Employee employee, Errors result, 
			Map<String, Object> map){
		System.out.println("save: " + employee);
		
		if(result.getErrorCount() > 0){
			System.out.println("出错了!");
			
			for(FieldError error:result.getFieldErrors()){
				System.out.println(error.getField() + ":" + error.getDefaultMessage());
			}
			
			//若验证出错, 则转向定制的页面
			map.put("departments", departmentDao.getDepartments());
			return "input";
		}
		
		employeeDao.save(employee);
		return "redirect:/emps";
	}
	
	@RequestMapping(value="/emp", method=RequestMethod.GET)
	public String input(Map<String, Object> map){
		map.put("departments", departmentDao.getDepartments());
		map.put("employee", new Employee());
		return "input";
	}
	
	@RequestMapping("/emps")
	public String list(Map<String, Object> map){
		map.put("employees", employeeDao.getAll());
		return "list";
	}
	
//	@InitBinder
//	public void initBinder(WebDataBinder binder){
//		binder.setDisallowedFields("lastName");
//	}
	
}

拦截器

package com.atguigu.springmvc.interceptors;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

public class FirstInterceptor implements HandlerInterceptor{

	/**
	 * 该方法在目标方法之前被调用.
	 * 若返回值为 true, 则继续调用后续的拦截器和目标方法. 
	 * 若返回值为 false, 则不会再调用后续的拦截器和目标方法. 
	 * 
	 * 可以考虑做权限. 日志, 事务等. 
	 */
	@Override
	public boolean preHandle(HttpServletRequest request,
			HttpServletResponse response, Object handler) throws Exception {
		System.out.println("[FirstInterceptor] preHandle");
		return true;
	}

	/**
	 * 调用目标方法之后, 但渲染视图之前. 
	 * 可以对请求域中的属性或视图做出修改. 
	 */
	@Override
	public void postHandle(HttpServletRequest request,
			HttpServletResponse response, Object handler,
			ModelAndView modelAndView) throws Exception {
		System.out.println("[FirstInterceptor] postHandle");
	}

	/**
	 * 渲染视图之后被调用. 释放资源
	 */
	@Override
	public void afterCompletion(HttpServletRequest request,
			HttpServletResponse response, Object handler, Exception ex)
			throws Exception {
		System.out.println("[FirstInterceptor] afterCompletion");
	}

}