1. 用戶發送請求給服務器。url:user.dohtml
2. 服務器收到請求。發現Dispatchservlet能夠處理。因而調用DispatchServlet。java
3. DispatchServlet內部,經過HandleMapping檢查這個url有沒有對應的Controller。若是有,則調用Controller。web
四、 Control開始執行spring
5. Controller執行完畢後,若是返回字符串,則ViewResolver將字符串轉化成相應的視圖對象;若是返回ModelAndView對象,該對象自己就包含了視圖對象信息。express
6. DispatchServlet將執視圖對象中的數據,輸出給服務器。編程
7. 服務器將數據輸出給客戶端。服務器
org.springframework.aop-3.0.3.RELEASE.jarsession |
spring的aop面向切面編程mvc |
org.springframework.asm-3.0.3.RELEASE.jarapp |
spring獨立的asm字節碼生成程序 |
org.springframework.beans-3.0.3.RELEASE.jar |
IOC的基礎實現 |
org.springframework.context-3.0.3.RELEASE.jar |
IOC基礎上的擴展服務 |
org.springframework.core-3.0.3.RELEASE.jar |
spring的核心包 |
org.springframework.expression-3.0.3.RELEASE.jar |
spring的表達式語言 |
org.springframework.web-3.0.3.RELEASE.jar |
web工具包 |
org.springframework.web.servlet-3.0.3.RELEASE.jar |
mvc工具包 |
和Struts1同樣,Spring的Controller是Singleton的。這就意味着會被多個請求線程共享。所以,咱們將控制器設計成無狀態類。
在spring 3.0中,經過@controller標註便可將class定義爲一個controller類。爲使spring能找到定義爲controller的bean,須要在spring-context配置文件中增長以下定義:
<context:component-scan base-package="com.sxt.web"/> |
注:實際上,使用@component,也能夠起到@Controller一樣的做用。
在類前面定義,則將url和類綁定。
在方法前面定義,則將url和類的方法綁定
通常用於將指定的請求參數付給方法中形參。示例代碼以下:
@RequestMapping(params="method=reg5") public String reg5(@RequestParam("name")String uname,ModelMap map) { System.out.println("HelloController.handleRequest()"); System.out.println(uname); return"index"; } |
這樣,就會將name參數的值付給uname。固然,若是請求參數名稱和形參名稱保持一致,則不須要這種寫法。
將ModelMap中指定的屬性放到session中。示例代碼以下:
@Controller @RequestMapping("/user.do") @SessionAttributes({"u","a"}) //將ModelMap中屬性名字爲u、a的再放入session中。這樣,request和session中都有了。 publicclass UserController { @RequestMapping(params="method=reg4") public String reg4(ModelMap map) { System.out.println("HelloController.handleRequest()"); map.addAttribute("u","uuuu"); //將u放入request做用域中,這樣轉發頁面也能夠取到這個數據。 return"index"; } } |
<body> <h1>**********${requestScope.u.uname}</h1> <h1>**********${sessionScope.u.uname}</h1> </body> |
注:名字爲」user」的屬性再結合使用註解@SessionAttributes可能會報錯。
這個註解能夠跟@SessionAttributes配合在一塊兒用。能夠將ModelMap中屬性的值經過該註解自動賦給指定變量。
示例代碼以下:
package com.sxt.web; import javax.annotation.Resource; import org.springframework.stereotype.Controller; import org.springframework.ui.ModelMap; import org.springframework.web.bind.annotation.ModelAttribute; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.SessionAttributes; @Controller @RequestMapping("/user.do") @SessionAttributes({"u","a"}) publicclass UserController {
@RequestMapping(params="method=reg4") public String reg4(ModelMap map) { System.out.println("HelloController.handleRequest()"); map.addAttribute("u","尚學堂高淇"); return"index"; }
@RequestMapping(params="method=reg5") public String reg5(@ModelAttribute("u")String uname ,ModelMap map) { System.out.println("HelloController.handleRequest()"); System.out.println(uname); return"index"; }
} |
先調用reg4方法,再調用reg5方法。
1. 返回string(建議)
a) 根據返回值找對應的顯示頁面。路徑規則爲:prefix前綴+返回值+suffix後綴組成
b) 代碼以下:
@RequestMapping(params="method=reg4") public String reg4(ModelMap map) { System.out.println("HelloController.handleRequest()"); return"index"; } |
前綴爲:/WEB-INF/jsp/ 後綴是:.jsp 在轉發到:/WEB-INF/jsp/index.jsp |
2. 也能夠返回ModelMap、ModelAndView、map、List、Set、Object、無返回值。通常建議返回字符串!
代碼示例:
package com.sxt.web;
import javax.annotation.Resource; import org.springframework.stereotype.Controller; import org.springframework.ui.ModelMap; import org.springframework.web.bind.annotation.ModelAttribute; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.SessionAttributes;
@Controller @RequestMapping("/user.do") publicclass UserController {
@RequestMapping(params="method=reg4") public String reg4(ModelMap map) { System.out.println("HelloController.handleRequest()"); // return "forward:index.jsp"; // return "forward:user.do?method=reg5"; //轉發 // return "redirect:user.do?method=reg5"; //重定向 return"redirect:http://www.baidu.com"; //重定向 }
@RequestMapping(params="method=reg5") public String reg5(String uname,ModelMap map) { System.out.println("HelloController.handleRequest()"); System.out.println(uname); return"index"; }
} |
訪問reg4方法,既能夠看到效果。
普通的Controller類,示例代碼以下:
@Controller @RequestMapping("/user.do") publicclass UserController {
@RequestMapping(params="method=reg2") public String reg2(String uname,HttpServletRequest req,ModelMap map){ req.setAttribute("a", "aa"); req.getSession().setAttribute("b", "bb"); return"index"; } } |
是map的實現,能夠在其中存放屬性,做用域同request。下面這個示例,咱們能夠在modelMap中放入數據,而後在forward的頁面上顯示這些數據。經過el表達式、JSTL、Java代碼都可。代碼以下:
package com.sxt.web;
import org.springframework.stereotype.Controller; import org.springframework.ui.ModelMap; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.servlet.mvc.multiaction.MultiActionController;
@Controller @RequestMapping("/user.do") publicclass UserController extends MultiActionController {
@RequestMapping(params="method=reg") public String reg(String uname,ModelMap map){ map.put("a", "aaa"); return"index"; } } |
<%@ page language="java" import="java.util.*" pageEncoding="gbk"%> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head></head> <body> <h1>${requestScope.a}</h1> <c:out value="${requestScope.a}"></c:out> </body> </html> |
將屬性u的值賦給形參uname
見名知意,從名字上咱們能夠知道ModelAndView中的Model表明模型,View表明視圖。即,這個類把要顯示的數據存儲到了Model屬性中,要跳轉的視圖信息存儲到了view屬性。咱們看一下ModelAndView的部分源碼,便可知其中關係:
[java] view plain copy
public class ModelAndView { /** View instance or view name String */ private Object view; /** Model Map */ private ModelMap model; /** * Indicates whether or not this instance has been cleared with a call to {@link #clear()}. */ private boolean cleared = false; /** * Default constructor for bean-style usage: populating bean * properties instead of passing in constructor arguments. * @see #setView(View) * @see #setViewName(String) */ public ModelAndView() { } /** * Convenient constructor when there is no model data to expose. * Can also be used in conjunction with <code>addObject</code>. * @param viewName name of the View to render, to be resolved * by the DispatcherServlet's ViewResolver * @see #addObject */ public ModelAndView(String viewName) { this.view = viewName; } /** * Convenient constructor when there is no model data to expose. * Can also be used in conjunction with <code>addObject</code>. * @param view View object to render * @see #addObject */ public ModelAndView(View view) { this.view = view; } /** * Creates new ModelAndView given a view name and a model. * @param viewName name of the View to render, to be resolved * by the DispatcherServlet's ViewResolver * @param model Map of model names (Strings) to model objects * (Objects). Model entries may not be <code>null</code>, but the * model Map may be <code>null</code> if there is no model data. */ public ModelAndView(String viewName, Map<String, ?> model) { this.view = viewName; if (model != null) { getModelMap().addAllAttributes(model); } } /** * Creates new ModelAndView given a View object and a model. * <emphasis>Note: the supplied model data is copied into the internal * storage of this class. You should not consider to modify the supplied * Map after supplying it to this class</emphasis> * @param view View object to render * @param model Map of model names (Strings) to model objects * (Objects). Model entries may not be <code>null</code>, but the * model Map may be <code>null</code> if there is no model data. */ public ModelAndView(View view, Map<String, ?> model) { this.view = view; if (model != null) { getModelMap().addAllAttributes(model); } } /** * Convenient constructor to take a single model object. * @param viewName name of the View to render, to be resolved * by the DispatcherServlet's ViewResolver * @param modelName name of the single entry in the model * @param modelObject the single model object */ public ModelAndView(String viewName, String modelName, Object modelObject) { this.view = viewName; addObject(modelName, modelObject); } /** * Convenient constructor to take a single model object. * @param view View object to render * @param modelName name of the single entry in the model * @param modelObject the single model object */ public ModelAndView(View view, String modelName, Object modelObject) { this.view = view; addObject(modelName, modelObject); } /** * Set a view name for this ModelAndView, to be resolved by the * DispatcherServlet via a ViewResolver. Will override any * pre-existing view name or View. */ public void setViewName(String viewName) { this.view = viewName; } /** * Return the view name to be resolved by the DispatcherServlet * via a ViewResolver, or <code>null</code> if we are using a View object. */ public String getViewName() { return (this.view instanceof String ? (String) this.view : null); } /** * Set a View object for this ModelAndView. Will override any * pre-existing view name or View. */ public void setView(View view) { this.view = view; } /** * Return the View object, or <code>null</code> if we are using a view name * to be resolved by the DispatcherServlet via a ViewResolver. */ public View getView() { return (this.view instanceof View ? (View) this.view : null); } /** * Indicate whether or not this <code>ModelAndView</code> has a view, either * as a view name or as a direct {@link View} instance. */ public boolean hasView() { return (this.view != null); } /** * Return whether we use a view reference, i.e. <code>true</code> * if the view has been specified via a name to be resolved by the * DispatcherServlet via a ViewResolver. */ public boolean isReference() { return (this.view instanceof String); } /** * Return the model map. May return <code>null</code>. * Called by DispatcherServlet for evaluation of the model. */ protected Map<String, Object> getModelInternal() { return this.model; } /** * Return the underlying <code>ModelMap</code> instance (never <code>null</code>). */ public ModelMap getModelMap() { if (this.model == null) { this.model = new ModelMap(); } return this.model; } /** * Return the model map. Never returns <code>null</code>. * To be called by application code for modifying the model. */ public Map<String, Object> getModel() { return getModelMap(); } /** * Add an attribute to the model. * @param attributeName name of the object to add to the model * @param attributeValue object to add to the model (never <code>null</code>) * @see ModelMap#addAttribute(String, Object) * @see #getModelMap() */ public ModelAndView addObject(String attributeName, Object attributeValue) { getModelMap().addAttribute(attributeName, attributeValue); return this; } /** * Add an attribute to the model using parameter name generation. * @param attributeValue the object to add to the model (never <code>null</code>) * @see ModelMap#addAttribute(Object) * @see #getModelMap() */ public ModelAndView addObject(Object attributeValue) { getModelMap().addAttribute(attributeValue); return this; } /** * Add all attributes contained in the provided Map to the model. * @param modelMap a Map of attributeName -> attributeValue pairs * @see ModelMap#addAllAttributes(Map) * @see #getModelMap() */ public ModelAndView addAllObjects(Map<String, ?> modelMap) { getModelMap().addAllAttributes(modelMap); return this; } /** * Clear the state of this ModelAndView object. * The object will be empty afterwards. * <p>Can be used to suppress rendering of a given ModelAndView object * in the <code>postHandle</code> method of a HandlerInterceptor. * @see #isEmpty() * @see HandlerInterceptor#postHandle */ public void clear() { this.view = null; this.model = null; this.cleared = true; } /** * Return whether this ModelAndView object is empty, * i.e. whether it does not hold any view and does not contain a model. */ public boolean isEmpty() { return (this.view == null && CollectionUtils.isEmpty(this.model)); } /** * Return whether this ModelAndView object is empty as a result of a call to {@link #clear} * i.e. whether it does not hold any view and does not contain a model. * <p>Returns <code>false</code> if any additional state was added to the instance * <strong>after</strong> the call to {@link #clear}. * @see #clear() */ public boolean wasCleared() { return (this.cleared && isEmpty()); } /** * Return diagnostic information about this model and view. */ @Override public String toString() { StringBuilder sb = new StringBuilder("ModelAndView: "); if (isReference()) { sb.append("reference to view with name '").append(this.view).append("'"); } else { sb.append("materialized View is [").append(this.view).append(']'); } sb.append("; model is ").append(this.model); return sb.toString(); } }
[java] view plain copy
import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.servlet.ModelAndView; import org.springframework.web.servlet.mvc.multiaction.MultiActionController; import com.sxt.po.User; @Controller @RequestMapping("/user.do") public class UserController extends MultiActionController { @RequestMapping(params="method=reg") public ModelAndView reg(String uname){ ModelAndView mv = new ModelAndView(); mv.setViewName("index"); // mv.setView(new RedirectView("index")); User u = new User(); u.setUname("高淇"); mv.addObject(u); //查看源代碼,得知,直接放入對象。屬性名爲」首字母小寫的類名」。 通常建議手動增長屬性名稱。 mv.addObject("a", "aaaa"); return mv; } }
<%@ page language="java" import="java.util.*" pageEncoding="gbk"%> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> </head> <body> <h1>${requestScope.a}</h1> <h1>${requestScope.user.uname}</h1> </body> </html>
地址欄輸入:http://localhost:8080/springmvc03/user.do?method=reg