Spring MVC 3.0 深入及對(duì)注解的詳細(xì)講解

發(fā)布時(shí)間：2020-06-26 20:56:32 來(lái)源：網(wǎng)絡(luò) 閱讀：294 作者：沙漏半杯欄目：編程語(yǔ)言

核心原理

1.? ? ? ?用戶發(fā)送請(qǐng)求給服務(wù)器。url：user.do

2.? ? ? ?服務(wù)器收到請(qǐng)求。發(fā)現(xiàn)Dispatchservlet可以處理。于是調(diào)用DispatchServlet。

3.? ? ? DispatchServlet內(nèi)部，通過(guò)HandleMapping檢查這個(gè)url有沒(méi)有對(duì)應(yīng)的Controller。如果有，則調(diào)用Controller。

4、? ? Control開(kāi)始執(zhí)行

5.? ? ? Controller執(zhí)行完畢后，如果返回字符串，則ViewResolver將字符串轉(zhuǎn)化成相應(yīng)的視圖對(duì)象；如果返回ModelAndView對(duì)象，該對(duì)象本身就包含了視圖對(duì)象信息。

6.? ? ? DispatchServlet將執(zhí)視圖對(duì)象中的數(shù)據(jù)，輸出給服務(wù)器。

7.? ? ? 服務(wù)器將數(shù)據(jù)輸出給客戶端。

spring3.0中相關(guān)jar包的含義

org.springframework.aop-3.0.3.RELEASE.jar

spring的aop面向切面編程

org.springframework.asm-3.0.3.RELEASE.jar

spring獨(dú)立的asm字節(jié)碼生成程序

org.springframework.beans-3.0.3.RELEASE.jar

IOC的基礎(chǔ)實(shí)現(xiàn)

org.springframework.context-3.0.3.RELEASE.jar

IOC基礎(chǔ)上的擴(kuò)展服務(wù)

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(dá)式語(yǔ)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

@Controller控制器定義

和Struts1一樣，Spring的Controller是Singleton的。這就意味著會(huì)被多個(gè)請(qǐng)求線程共享。因此，我們將控制器設(shè)計(jì)成無(wú)狀態(tài)類。

在spring 3.0中，通過(guò)@controller標(biāo)注即可將class定義為一個(gè)controller類。為使spring能找到定義為controller的bean,需要在spring-context配置文件中增加如下定義：

<context:component-scan base-package="com.sxt.web"/>

? ? ? ? 注：實(shí)際上，使用@component，也可以起到@Controller同樣的作用。

@RequestMapping

? ? 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

@RequestParam

? ? ? ? ?一般用于將指定的請(qǐng)求參數(shù)付給方法中形參。示例代碼如下：

? ? ? ??

@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(huì)將name參數(shù)的值付給uname。當(dāng)然，如果請(qǐng)求參數(shù)名稱和形參名稱保持一致，則不需要這種寫(xiě)法。

@SessionAttributes

? ? 將ModelMap中指定的屬性放到session中。示例代碼如下：

? ?

@Controller

@RequestMapping("/user.do")

@SessionAttributes({"u","a"})? //將ModelMap中屬性名字為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作用域中，這樣轉(zhuǎn)發(fā)頁(yè)面也可以取到這個(gè)數(shù)據(jù)。

? ? ? ?return"index";

? ? }

}

? <body>

? ?<h2>**********${requestScope.u.uname}</h2>

? ?<h2>**********${sessionScope.u.uname}</h2>

? </body>

? ?

? ? 注：名字為”user”的屬性再結(jié)合使用注解@SessionAttributes可能會(huì)報(bào)錯(cuò)。

@ModelAttribute

? ? ?這個(gè)注解可以跟@SessionAttributes配合在一起用?？梢詫odelMap中屬性的值通過(guò)該注解自動(dòng)賦給指定變量。

? ? 示例代碼如下：

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(xué)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(diào)用reg4方法，再調(diào)用reg5方法。?

Controller類中方法參數(shù)的處理

Controller類中方法返回值的處理

1.? ? ? ?返回string(建議)

a)? ? ? ? ?根據(jù)返回值找對(duì)應(yīng)的顯示頁(yè)面。路徑規(guī)則為：prefix前綴+返回值+suffix后綴組成

b)? ? ? ? ?代碼如下：

@RequestMapping(params="method=reg4")

? ? public String reg4(ModelMap map) {

? ? ? ?System.out.println("HelloController.handleRequest()");

? ? ? ?return"index";

? ? }

前綴為：/WEB-INF/jsp/? ?后綴是：.jsp

在轉(zhuǎn)發(fā)到：/WEB-INF/jsp/index.jsp

2.? ? ? ?也可以返回ModelMap、ModelAndView、map、List、Set、Object、無(wú)返回值。一般建議返回字符串！

請(qǐng)求轉(zhuǎn)發(fā)和重定向

? ? ? ? ?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(zhuǎn)發(fā)

//? ? ?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(wèn)reg4方法，既可以看到效果。

獲得request對(duì)象、session對(duì)象

普通的Controller類，示例代碼如下：

@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";

? ? }

}

ModelMap

? ? ? ? ?是map的實(shí)現(xiàn)，可以在其中存放屬性，作用域同request。下面這個(gè)示例，我們可以在modelMap中放入數(shù)據(jù)，然后在forward的頁(yè)面上顯示這些數(shù)據(jù)。通過(guò)el表達(dá)式、JSTL、java代碼均可。代碼如下：

? ? ? ??

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 UserControllerextends 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"%>

<!DOCTYPEHTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

? <head></head>

? <body>

? ? ? ?<h2>${requestScope.a}</h2>

? ? ? ?<c:out value="${requestScope.a}"></c:out>

? </body>

</html>

將屬性u(píng)的值賦給形參uname

ModelAndView模型視圖類

見(jiàn)名知意，從名字上我們可以知道ModelAndView中的Model代表模型，View代表視圖。即，這個(gè)類把要顯示的數(shù)據(jù)存儲(chǔ)到了Model屬性中，要跳轉(zhuǎn)的視圖信息存儲(chǔ)到了view屬性。我們看一下ModelAndView的部分源碼，即可知其中關(guān)系：

[java] view plaincopy

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 plaincopy

測(cè)試代碼如下：??

package com.sxt.web;??

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(duì)象。屬性名為”首字母小寫(xiě)的類名”。一般建議手動(dòng)增加屬性名稱。??

? ? ? ? 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>??

? ? ? ?<h2>${requestScope.a}</h2>??

? ? ? ?<h2>${requestScope.user.uname}</h2>??

? </body>??

</html>??

地址欄輸入：http://localhost:8080/springmvc03/user.do?method=reg??

? ? ?

-----------

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Spring MVC 3.0 深入及對(duì)注解的詳細(xì)講解

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