Spring chapter--04 Spring MVC reads request parameter values, passes values to pages and redirects

1. Read the request parameter value

1. Through the request object

Note: The request object can be used as the input parameter of the method

@RequestMapping("/login1.do")
	public String login1(HttpServletRequest request) {
		System.out.println("login1()");
		String adminCode=request.getParameter("adminCode");
		String pwd = request.getParameter("pwd");
		System.out.println(adminCode+":"+pwd);
		return "index";
	}

2. Use an annotation @RequestParam annotation

Note: Add this annotation to the front of the formal parameters of the method

@RequestMapping("/login2.do")
	//The second way to read the request parameter value
	//Annotate with @RequestParam
	public String login2(String adminCode,@RequestParam("pwd")String password) {
		System.out.println("login2()");
		System.out.println("adminCode:"+adminCode+"pwd:"+password);
		return "index";
	}

3. Use javabean to encapsulate request parameter values

step1: Write a Java class that requires corresponding get/set methods

step2: use the javabean as a formal parameter of the method

@RequestMapping("/login3.do")
	//The third way to read the request parameter value
	// encapsulate into a javabean
	public String login3(AdminParam ap) {
		System.out.println("login3()");
		System.out.println(ap.getAdminCode()+" "+ap.getPwd());
		return "index";
	}
	

2. Passing values ​​to the page

1. Use request

Bind the data to the request and forward it to a jsp.

Note: springmvc uses forwarding by default

	@RequestMapping("/login4.do")
	//The first way to pass values ​​to the page
	// use request
	public String login4(AdminParam ap,HttpServletRequest request) {
		System.out.println("login5()");
		String adminCode=ap.getAdminCode();
		System.out.println(adminCode);
		//bind the data to the request
		request.setAttribute("adminCode", adminCode);
		//springmvc uses forwarding by default
		return "index";
	}

2. Use ModelAndView

Encapsulate the data into the ModelAndView object first, and then use the object as the return value of the method

@RequestMapping("/login5.do")
	//The second way to pass values ​​to the page
	// use ModelAndView
	public ModelAndView login5(AdminParam ap) {
		System.out.println("login5()");
		String adminCode = ap.getAdminCode();
		System.out.println(adminCode);
		Map<String, Object> data=new HashMap<String, Object>();
		//equivalent to request.setAttribute("adminCode",adminCode);
		data.put("adminCode", adminCode);
		//Construct ModelAndView object
		ModelAndView modelAndView = new ModelAndView("index",data);
		return modelAndView;
	}

3. Use ModelMap

Take that object as a parameter to the method and then bind data to that object

	@RequestMapping("/login6.do")
	//The third way to pass values ​​to the page
	public String login6(AdminParam ap,ModelMap mm) {
		System.out.println("login6()");
		String adminCode = ap.getAdminCode();
		System.out.println(adminCode);
		mm.addAttribute("adminCode", adminCode);
		return "index";
	}

4. Use session

@RequestMapping("/login7.do")
	//The fourth way to pass values ​​to the page
	// use session
	public String login7(AdminParam ap,HttpSession session) {
		System.out.println("login7()");
		String adminCode = ap.getAdminCode();
		System.out.println(adminCode);
		session.setAttribute("adminCode", adminCode);
		return "index";
	}

3. Redirect

1. If the return value of the method is String;

Add " redirect :" before the redirect address

@RequestMapping("/login8.do")
	public String login8() {
		System.out.println("login8()");
		return "redirect:toIndex.do";
	}

2. If the return value of the method is ModelAndView

 

@RequestMapping("/login9.do")
	public ModelAndView login9() {
		System.out.println("login9()");
		RedirectView rv=new RedirectView("toIndex.do");
		return new ModelAndView(rv);
	}