SpringMVC轻松学习-其他常用(四)
Spring MVC 3.0 深入
核心原理
1. 用户发送请求给服务器。url:user.do
2. 服务器收到请求。发现DispatchServlet可以处理。于是调用DispatchServlet。
3. DispatchServlet内部,通过HandleMapping检查这个url有没有对应的Controller。如果有,则调用Controller。
4. Controller开始执行。
5. Controller执行完毕后,如果返回字符串,则ViewResolver将字符串转化成相应的视图对象;如果返回ModelAndView对象,该对象本身就包含了视图对象信息。
6. DispatchServlet将执视图对象中的数据,输出给服务器。
7. 服务器将数据输出给客户端。
spring3.0中相关jar包的含义
org.springframework.aop-3.0.3.RELEASE.jar |
spring的aop面向切面编程 |
org.springframework.asm-3.0.3.RELEASE.jar |
spring独立的asm字节码生成程序 |
org.springframework.beans-3.0.3.RELEASE.jar |
IOC的基础实现 |
org.springframework.context-3.0.3.RELEASE.jar |
IOC基础上的扩展服务 |
org.springframework.core-3.0.3.RELEASE.jar |
spring的核心包 |
org.springframework.expression-3.0.3.RELEASE.jar |
spring的表达式语言 |
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 3.0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.sxt.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.sxt.web; import javax.annotation.Resource; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import com.sxt.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。
@SessionAttributes
将ModelMap中指定的属性放到session中。示例代码如下:
@Controller @RequestMapping("/user.do") @SessionAttributes({"u","a"}) //将ModelMap中属性名字为u、a的再放入session中。这样,request和session中都有了。 public class UserController { @RequestMapping(params="method=reg4") public String reg4(ModelMap map) { System.out.println("HelloController.handleRequest()"); map.addAttribute("u","uuuu"); //将u放入request作用域中,这样转发页面也可以取到这个数据。 return "index"; } } |
<body> <h1>**********${requestScope.u.uname}</h1> <h1>**********${sessionScope.u.uname}</h1> </body> |
注:名字为”user”的属性再结合使用注解@SessionAttributes可能会报错。
@ModelAttribute
这个注解可以跟@SessionAttributes配合在一起用。可以将ModelMap中属性的值通过该注解自动赋给指定变量。
示例代码如下:
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"}) public class UserController { @RequestMapping(params="method=reg4") public String reg4(ModelMap map) { System.out.println("HelloController.handleRequest()"); map.addAttribute("u","尚学堂高淇"); return "index"; } @RequestMapping(params="method=reg5") public String reg5(@ModelAttribute("u")String uname[微软用户1] ,ModelMap map) { System.out.println("HelloController.handleRequest()"); System.out.println(uname); return "index"; } } |
先调用reg4方法,再调用reg5方法。我们发现控制台打印出来:尚学堂高淇
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.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") 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.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") 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> <head></head> <body> <h1>${requestScope.a}</h1> <c:out value="${requestScope.a}"></c:out> </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.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: |
基于spring 3.0mvc 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:
<!--处理文件上传 --> <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver" > <property name="defaultEncoding" value="gbk"/> <!-- 默认编码 (ISO-8859-1) --> <property name="maxInMemorySize" value="10240"/> <!-- 最大内存大小 (10240)--> <property name="uploadTempDir" value="/upload/"/> <!-- 上传后的目录名 (WebUtils#TEMP_DIR_CONTEXT_ATTRIBUTE) --> <property name="maxUploadSize" value="-1"/> <!-- 最大文件大小,-1为无限止(-1) --> </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 action="upload.do" method="post" enctype="multipart/form-data"> <input type="text" name="name" /> <input type="file" name="file" /> <input type="submit" /> </form> </body> </html> |
4. 建立控制器,代码如下:
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")[微软用户2] 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> <h1>上传成功!</h1> </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> <h1>上传失败!</h1> </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:
处理ajax请求
spring使用了jackson类库,帮助我们在java对象和json、xml数据之间的互相转换。他可以将控制器返回的对象直接转换成json数据,供客户端使用。客户端也可以传送json数据到服务器进行直接转换。使用步骤如下:
1. 项目中需要引入如下两个jar包:
jackson-core-asl-1.7.2jar
jackson-mapper-asl-1.7.2jar
2. spring配置文件中修改:
<mvc:annotation-driven /> <!-- 支持spring3.0新的mvc注解 --> <!-- 启动Spring MVC的注解功能,完成请求和注解POJO的映射 --> <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"> <property name="cacheSeconds" value="0" /> <property name="messageConverters"> <list> <bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"></bean> </list> </property> </bean> |
3. 客户端代码a.jsp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> <base href="<%=basePath%>"> <title>My JSP 'index.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <script> function createAjaxObj(){ var req; if(window.XMLHttpRequest){ req = new XMLHttpRequest(); }else{ req = new ActiveXObject("Msxml2.XMLHTTP"); //ie } return req; } function sendAjaxReq(){ var req = createAjaxObj(); req.open("get","myajax.do?method=test2&uname=张三"); req.setRequestHeader("accept","application/json"); req.onreadystatechange = function(){ eval("var result="+req.responseText); document.getElementById("div1").innerHTML=result[0].uname; } req.send(null); } </script> </head> <body> <a href="javascript:void(0);" onclick="sendAjaxReq();">测试</a> <div id="div1"></div> </body> </html> |
4. 服务器端代码如下:
import java.io.UnsupportedEncodingException; import java.util.ArrayList; import java.util.List; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestBody; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.bind.annotation.ResponseBody; import com.sxt.po.User; @Controller @RequestMapping("myajax.do") public class MyAjaxController { @RequestMapping(params="method=test1",method=RequestMethod.GET) public @ResponseBody List<User> test1(String uname) throws Exception{ String uname2 = new String(uname.getBytes("iso8859-1"),"gbk"); System.out.println(uname2); System.out.println("MyAjaxController.test1()"); List<User> list = new ArrayList<User>(); list.add(new User("高淇","123")); list.add(new User("马士兵","456")); return list; } } |
5. 测试。
a) 启动服务器。输入:http://localhost:8080/springmvc03/a.jsp
Spring中的拦截器
定义spring拦截器两种基本方式
1. 实现接口:org.springframework.web.servlet.HandlerInterceptor。
接口中有如下方法需要重写:
注意:参数中的Object handler是下一个拦截器。
a) public boolean preHandle
(HttpServletRequest request,HttpServletResponse response,
Object handler) throws Exception
该方法在action执行前执行,可以实现对数据的预处理,比如:编码、安全控制等。
如果方法返回true,则继续执行action。
b) public void postHandle
(HttpServletRequest request,HttpServletResponse response,
Object handler, ModelAndViewmodelAndView) throws Exception
该方法在action执行后,生成视图前执行。在这里,我们有机会修改视图层数据。
c) public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler,Exception ex) throws Exception
最后执行,通常用于释放资源,处理异常。我们可以根据ex是否为空,来进行相关的异常处理。因为我们在平时处理异常时,都是从底层向上抛出异常,最后到了spring框架从而到了这个方法中。
2. 继承适配器:
org.springframework.web.servlet.handler.HandlerInterceptorAdapter
这个适配器实现了HandlerInterceptor接口。提供了这个接口中所有方法的空实现。
如下我们写出两个拦截器的示例代码,仅供大家参考:
package com.sxt.interceptor; import javax.interceptor.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 MyInterceptor implements HandlerInterceptor { @Override public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { System.out.println("最后执行!!!一般用于释放资源!!"); } @Override public void postHandle(HttpServletRequest request,HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { System.out.println("Action执行之后,生成视图之前执行!!"); } @Override public boolean preHandle(HttpServletRequest request,HttpServletResponse response, Object handler) throws Exception { System.out.println("action之前执行!!!"); return true; //继续执行action } } |
package com.sxt.interceptor; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.springframework.web.servlet.handler.HandlerInterceptorAdapter; public class MyInterceptor2 extends HandlerInterceptorAdapter { @Override public boolean preHandle(HttpServletRequest request,HttpServletResponse response, Object handler) throws Exception { System.out.println("MyInterceptor2.preHandle()"); return true; //继续执行action } } |
3. XML中如何配置。如下为示例代码:
<mvc:interceptors> <bean class="com.sxt.interceptor.MyInterceptor"></bean> <!-- 拦截所有springmvc的url! --> <mvc:interceptor> <mvc:mapping path="/user.do" /> <!--<mvc:mapping path="/test/*" />--> <bean class="com.sxt.interceptor.MyInterceptor2"></bean> </mvc:interceptor> </mvc:interceptors> |
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