Spring MVC框架学习与使用

java无忧网 · 发表于 2016-5-28 16:54:57

Spring MVC 背景介绍

Spring 框架提供了构建 Web 应用程序的全功能 MVC 模块。使用 Spring 可插入的 MVC 架构，可以选择是使用内置的 Spring Web 框架还是 Struts 这样的 Web 框架。通过策略接口，Spring 框架是高度可配置的，而且包含多种视图技术，例如 JavaServer Pages（JSP）技术、Velocity、Tiles、iText 和 POI。Spring MVC 框架并不知道使用的视图，所以不会强迫您只使用 JSP 技术。Spring MVC 分离了控制器、模型对象、分派器以及处理程序对象的角色，这种分离让它们更容易进行定制。

常见MVC框架比较

运行性能上：

Jsp+servlet>struts1>spring mvc>struts2+freemarker>>struts2,ognl,值栈。

开发效率上,基本正好相反。值得强调的是，spring mvc开发效率和struts2不相上下。

Struts2的性能低的原因是因为OGNL和值栈造成的。所以，如果你的系统并发量高，可以使用freemaker进行显示，而不是采用OGNL和值栈。这样，在性能上会有相当大得提高。

基于spring2.5注解实现的spring MVC项目

我们采用sprng MVC开发项目时，通常都会采用注解的方式，这样可以大大提高我们的开发效率。实现零配置。下面我们从零开始重新做一个spring MVC的配置。这个项目完全采用注解的方式开发。同时，我们以后的spring MVC项目也都会采用注解的方式。

1. 建立web项目

2. 导入jar包(spring.jar, spring-webmvc.jar, commons-logging.jar。其他jar包为hibernate相关jar包)

3. 修改web.xml，文件内容如下：

<?xml version="1.0" encoding="UTF-8"?>

<web-app version="2.5"

xmlns="http://java.sun.com/xml/ns/javaee"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://java.sun.com/xml/ns/javaee

http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

<servlet-name>springmvc</servlet-name>

<servlet-class>

org.springframework.web.servlet.DispatcherServlet

</servlet-class>

<init-param>

<param-name>contextConfigLocation</param-name>

<param-value>/WEB-INF/springmvc-servlet.xml</param-value>

</init-param>

<load-on-startup>1</load-on-startup>

</servlet>

<servlet-mapping>

<servlet-name>springmvc</servlet-name>

<url-pattern>*.do</url-pattern>

</servlet-mapping>

</web-app>

4. springmvc-servlet.xml配置内容如下：

<?xml version="1.0" encoding="UTF-8"?>

<beans

xmlns="http://www.springframework.org/schema/beans"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xmlns:p="http://www.springframework.org/schema/p"

xmlns:tx="http://www.springframework.org/schema/tx"

xmlns:context="http://www.springframework.org/schema/context"

xsi:schemaLocation="http://www.springframework.org/schema/beans

http://www.springframework.org/schema/beans/spring-beans-2.5.xsd

http://www.springframework.org/schema/context

http://www.springframework.org/s ... ing-context-2.5.xsd

http://www.springframework.org/schema/tx

http://www.springframework.org/schema/tx/spring-tx-2.5.xsd

">

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

<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" p:prefix="/WEB-INF/jsp/"

p:suffix=".jsp"/>

<list>

<value>/WEB-INF/properties/jdbc.properties</value>

</list>

</property>

</bean>

<bean id="dataSource"

class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">

<property name="driverClassName"

value="${driverClassName}">

</property>

</property>

</bean>

<bean id="sessionFactory"

class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">

</property>

<list>

</list>

</property>

<value>

hibernate.dialect=org.hibernate.dialect.MySQL5Dialect

hibernate.hbm2ddl.auto=update

hibernate.show_sql=true

hibernate.format_sql=false

hibernate.cache.use_second_level_cache=true

hibernate.cache.provider_class=org.hibernate.cache.EhCacheProvider

hibernate.cache.use_query_cache=false

</value>

</property>

</bean>

</bean>

<tx:annotation-driven transaction-manager="txManager"/>

</bean>

</beans>

5. WEB-INF下建立jsp文件夹，并且将index.jsp放入该文件夹下。Index.jsp的内容如下：

<%@ page language="java" import="java.util.*" pageEncoding="gbk"%>

<%

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

%>

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

<html>

<head>

<title>My JSP 'index.jsp' starting page</title>

<!--

-->

</head>

<body>

<h1>**********${params.uname}</h1>

<h1>**********${requestScope.u}</h1>

<h1>**********${requestScope.user}</h1>

</body>

</html>

6. 建立整个项目的包结构和相关类。如下图所示：

7. User、UserDao、UserService、UserController类的代码如下：

package com.xz.po;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.GenerationType;

import javax.persistence.Id;

@Entity

public class User {

@Id

@GeneratedValue(strategy=GenerationType.AUTO)

private int id;

private String uname;

private String pwd;

public String getPwd() {

return pwd;

}

public void setPwd(String pwd) {

this.pwd = pwd;

}

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public String getUname() {

return uname;

}

public void setUname(String uname) {

this.uname = uname;

}

package com.xz.dao;

import javax.annotation.Resource;

import org.springframework.orm.hibernate3.HibernateTemplate;

import org.springframework.stereotype.Repository;

import com.xz.po.User;

@Repository("userDao")

public class UserDao {

@Resource

private HibernateTemplate hibernateTemplate;

public void add(User u){

System.out.println("UserDao.add()");

hibernateTemplate.save(u);

}

public HibernateTemplate getHibernateTemplate() {

return hibernateTemplate;

}

public void setHibernateTemplate(HibernateTemplate hibernateTemplate) {

this.hibernateTemplate = hibernateTemplate;

}

package com.xz.service;

import javax.annotation.Resource;

import org.springframework.stereotype.Service;

import com.xz.dao.UserDao;

import com.xz.po.User;

@Service("userService")

public class UserService {

@Resource

private UserDao userDao;

public void add(String uname){

System.out.println("UserService.add()");

User u = new User();

u.setUname(uname);

userDao.add(u);

}

public UserDao getUserDao() {

return userDao;

}

public void setUserDao(UserDao userDao) {

this.userDao = userDao;

}

package com.xz.web;

import javax.annotation.Resource;

import org.springframework.stereotype.Controller;

import org.springframework.ui.ModelMap;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestParam;

import org.springframework.web.bind.annotation.SessionAttributes;

import com.xz.po.User;

import com.xz.service.UserService;

@Controller("userController")

@RequestMapping("/user.do")

public class UserController {

@Resource

private UserService userService;

@RequestMapping(params="method=reg")

public String reg(String uname) {

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

userService.add(uname);

return "index";

}

public UserService getUserService() {

return userService;

}

public void setUserService(UserService userService) {

this.userService = userService;

}

8. 运行测试：

http://pc-201110291327:8080/springmvc02/user.do?method=reg&uname=gaoqi

则会调用userController的reg方法，从而将数据内容插入到数据库中。

@Controller控制器定义

和Struts1一样，Spring的Controller是Singleton的。这就意味着会被多个请求线程共享。因此，我们将控制器设计成无状态类。

在spring 中，通过@controller标注即可将class定义为一个controller类。为使spring能找到定义为controller的bean,需要在spring-context配置文件中增加如下定义：

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

注：实际上，使用@component，也可以起到@Controller同样的作用。

@RequestMapping

在类前面定义，则将url和类绑定。

在方法前面定义，则将url和类的方法绑定，如下所示：

package com.xz.web;

import javax.annotation.Resource;

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.RequestMapping;

import com.xz.service.UserService;

@Controller

@RequestMapping("/user.do")

public class UserController {

@Resource

private UserService userService;

//http://localhost:8080/springmvc02/user.do?method=reg&uname=zzzz

@RequestMapping(params="method=reg")

public String reg(String uname) {

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

userService.add(uname);

return "index";

}

public UserService getUserService() {

return userService;

}

public void setUserService(UserService userService) {

this.userService = userService;

}

@RequestParam

一般用于将指定的请求参数付给方法中形参。示例代码如下：

@RequestMapping(params="method=reg5")

public String reg5(@RequestParam("name")String uname,ModelMap map) {

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

System.out.println(uname);

return "index";

}

这样，就会将name参数的值付给uname。当然，如果请求参数名称和形参名称保持一致，则不需要这种写法。

Controller类中方法参数的处理

Controller类中方法返回值的处理

1. 返回string(建议)

a) 根据返回值找对应的显示页面。路径规则为：prefix前缀+返回值+suffix后缀组成

b) 代码如下：

@RequestMapping(params="method=reg4")

public String reg4(ModelMap map) {

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

return "index";

}

前缀为：/WEB-INF/jsp/ 后缀是：.jsp

在转发到：/WEB-INF/jsp/index.jsp

2. 也可以返回ModelMap、ModelAndView、map、List、Set、Object、无返回值。 一般建议返回字符串！

请求转发和重定向

代码示例：

package com.xz.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")

public class 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"; //转发

// 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";

}

访问reg4方法，既可以看到效果。

获得request对象、session对象

普通的Controller类，示例代码如下：

@Controller

@RequestMapping("/user.do")

public class 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的实现，可以在其中存放属性，作用域同request。下面这个示例，我们可以在modelMap中放入数据，然后在forward的页面上显示这些数据。通过el表达式、JSTL、java代码均可。代码如下：

package com.xz.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")

public class 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>

<body>

<h1>${requestScope.a}</h1>

<c

ut value="${requestScope.a}"></c

ut>

</body>

</html>

ModelAndView模型视图类

见名知意，从名字上我们可以知道ModelAndView中的Model代表模型，View代表视图。即，这个类把要显示的数据存储到了Model属性中，要跳转的视图信息存储到了view属性。我们看一下ModelAndView的部分源码，即可知其中关系：

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();

}

测试代码如下：

package com.xz.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.xz.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); //查看源代码，得知，直接放入对象。属性名为”首字母小写的类名”。一般建议手动增加属性名称。

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>

地址栏输入：http://localhost:8080/springmvc03/user.do?method=reg

结果为：

file:///C:\Users\ADMINI~1\AppData\Local\Temp\ksohtml\wps7E5F.tmp.jpg

基于spring mvc 框架的文件上传实现

1. spring使用了apache-commons下得上传组件，因此，我们需要引入两个jar包：

1. apache-commons-fileupload.jar

2. apache-commons-io.jar

2. 在springmvc-servlet.xml配置文件中，增加CommonsMultipartResoler配置：

<bean id="multipartResolver"

class="org.springframework.web.multipart.commons.CommonsMultipartResolver" >

</bean>

3. 建立upload.jsp页面，内容如下：

<%@ page language="java" import="java.util.*" pageEncoding="gbk"%>

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

<html>

<head>

<title>测试springmvc中上传的实现</title>

</head>

<body>

</form>

</body>

</html>

4. 建立控制器，代码如下：

package com.xz.web;

import java.io.File;

import java.util.Date;

import javax.servlet.ServletContext;

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.RequestParam;

import org.springframework.web.context.ServletContextAware;

import org.springframework.web.multipart.commons.CommonsMultipartFile;

@Controller

public class FileUploadController implements ServletContextAware {

private ServletContext servletContext;

@Override

public void setServletContext(ServletContext context) {

this.servletContext = context;

}

@RequestMapping(value="/upload.do", method = RequestMethod.POST)

public String handleUploadData(String name,@RequestParam("file")CommonsMultipartFile file){

if (!file.isEmpty()) {

String path = this.servletContext.getRealPath("/tmp/"); //获取本地存储路径

System.out.println(path);

String fileName = file.getOriginalFilename();

String fileType = fileName.substring(fileName.lastIndexOf("."));

System.out.println(fileType);

File file2 = new File(path,new Date().getTime() + fileType); //新建一个文件

try {

file.getFileItem().write(file2); //将上传的文件写入新建的文件中

} catch (Exception e) {

e.printStackTrace();

}

return "redirect:upload_ok.jsp";

}else{

return "redirect:upload_error.jsp";

}

5. 建立upload_ok.jsp页面

<%@ page language="java" import="java.util.*" pageEncoding="gbk"%>

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

<html>

<head>

</head>

<body>

</body>

</html>

6. 建立upload_error.jsp页面

<%@ page language="java" import="java.util.*" pageEncoding="gbk"%>

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

<html>

<head>

</head>

<body>

</body>

</html>

1. 发布项目，运行测试：http://localhost:8080/springmvc03/upload.jsp

进入项目发布后的目录，发现文件上传成功：

Spring MVC框架学习与使用

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