SpringMVC（5）：MVC的参数传递详解与示例（简单类型数据、ModelAndView、Model 、 POJO 以及 Map）
2018/1/7
SpringMVC是一个以模型数据为核心的开源框架，将前后端松耦合的管理，最重要的就是数据的传递。
下面给大家介绍的是把参数值传递，包括使用简单类型数据、ModelAndView、Model 、POJO 以及 Map。
一、（View to Conotroller） URL传值--@RequestMapping
【1】修改IndexController.java：
package com.smbms.controller;
import org.apache.log4j.Logger;
import org.apache.log4j.PropertyConfigurator;
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.servlet.ModelAndView;
@Controller
@RequestMapping("/a")
public class IndexController {
private Logger log = Logger.getLogger(IndexController.class.getName());
@RequestMapping(value="/hello",method=RequestMethod.POST,params="username")
public String hello(@RequestParam String username){
log.info("welcome username1 ,"+username);
return "hello";
}
} 【2】在index.html 修改：
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
Insert title here
click
hello
解释：（1）@RequestMapping 负责将不同的请求映射到对应的控制器方法上；
（2）@RequestMapping 的请求信息必须保持全局唯一，处理修饰方法，也可以修饰类；
（3）@RequestMapping 除了URL 映射请求，还可以使用请求参数、请求方法来映射请求，多条件可以让请求更加精确，匹配顺序为：首先value，然后method，最后参数；
输出结果：
18/01/07 11:08:17 INFO controller.IndexController: welcome username ,mmb二、（View to Conotroller） URL传值--@RequestParam
【1】修改IndexController.java：
package com.smbms.controller;
import org.apache.log4j.Logger;
import org.apache.log4j.PropertyConfigurator;
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.servlet.ModelAndView;
@Controller
@RequestMapping("/a")
public class IndexController {
private Logger log = Logger.getLogger(IndexController.class.getName());
//@RequestParam
@RequestMapping(value="/hello")
public String hello2(@RequestParam(value="username" ,required=false) String username){
log.info("welcome username2 ,"+username);
return "hello";
}
} 【2】输出结果：
18/01/07 11:12:46 INFO controller.IndexController: welcome username2 ,mmb解释：（1）@RequestParam 注解指定对应的请求参数。@RequestParam 有以三个参数：value（参数名）、required（参数是否必须）、defaultValue（不推荐）；
三、（Conotroller to View ）
对于mvc，模型数据最重要，Controller产生了Model，View最终也是为了渲染模型数据并进行输出：
1、ModelAndView
既包含视图信息，也包含模型数据。IndexController.java 做修改，将前端URL传参，在控制台输出参数值，并在视图层输出username；
【1】IndexController.java：
package com.smbms.controller;
import org.apache.log4j.Logger;
import org.apache.log4j.PropertyConfigurator;
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.servlet.ModelAndView;
@Controller
@RequestMapping("/a")
public class IndexController {
private Logger log = Logger.getLogger(IndexController.class.getName());
//ModelAndView
@RequestMapping(value="/hello")
public ModelAndView hello3(@RequestParam(value="username3" ,required=true) String username3){
log.info("welcome username3 ,"+username3);
ModelAndView mView = new ModelAndView();
mView.addObject("username",username3);
mView.setViewName("hello");
return mView;
}
} 【2】在index.html 修改：
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
Insert title here
click
hello-username
hello-usernameA
【3】输出结果：
18/01/07 11:29:24 INFO controller.IndexController: welcome usernameA ,mmb
解释：（1）ModelAndView 对象介绍（官方文档）：
org.springframework.web.servlet
Class ModelAndView
java.lang.Object org.springframework.web.servlet.ModelAndView
public class ModelAndViewextends Object
| Constructor Summary | |
|---|---|
ModelAndView() Default constructor for bean-style usage: populating bean properties instead of passing in constructor arguments. |
|
ModelAndView(String viewName) Convenient constructor when there is no model data to expose. |
|
ModelAndView(String viewName, Map Creates new ModelAndView given a view name and a model. |
|
ModelAndView(String viewName, String modelName, Object modelObject) Convenient constructor to take a single model object. |
|
ModelAndView(View view) Convenient constructor when there is no model data to expose. |
|
ModelAndView(View view, Map Creates new ModelAndView given a View object and a model. |
|
ModelAndView(View view, String modelName, Object modelObject) Convenient constructor to take a single model object. |
|
| Method Summary | |
|---|---|
ModelAndView |
addAllObjects(Map Add all attributes contained in the provided Map to the model. |
ModelAndView |
addObject(Object attributeValue) Add an attribute to the model using parameter name generation. |
ModelAndView |
addObject(String attributeName, Object attributeValue) Add an attribute to the model. |
void |
clear() Clear the state of this ModelAndView object. |
Map |
getModel() Return the model map. |
protected Map |
getModelInternal() Return the model map. |
ModelMap |
getModelMap() Return the underlying ModelMap instance (never null). |
View |
getView() Return the View object, or null if we are using a view name to be resolved by the DispatcherServlet via a ViewResolver. |
String |
getViewName() Return the view name to be resolved by the DispatcherServlet via a ViewResolver, or null if we are using a View object. |
boolean |
hasView() Indicate whether or not this ModelAndView has a view, either as a view name or as a direct View instance. |
boolean |
isEmpty() Return whether this ModelAndView object is empty, i.e. |
boolean |
isReference() Return whether we use a view reference, i.e. |
void |
setView(View view) Set a View object for this ModelAndView. |
void |
setViewName(String viewName) Set a view name for this ModelAndView, to be resolved by the DispatcherServlet via a ViewResolver. |
String |
toString() Return diagnostic information about this model and view. |
boolean |
wasCleared() Return whether this ModelAndView object is empty as a result of a call to clear() i.e. |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
2、Model 对象模型的使用
还可以使用Model对象完成模型数据的传递。
【1】修改IndexController.java：
package com.smbms.controller;
import org.apache.log4j.Logger;
import org.apache.log4j.PropertyConfigurator;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.servlet.ModelAndView;
@Controller
@RequestMapping("/a")
public class IndexController {
private Logger log = Logger.getLogger(IndexController.class.getName());
//Model
@RequestMapping(value="/helloB")
public String hello4(String usernameB ,Model model){
log.info("welcome usernameB ,"+usernameB);
model.addAttribute("usernameB",usernameB);
return "helloB";
}
} 【2】在index.jsp 修改：
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
Insert title here
click
hello-username
hello-usernameA
hello-usernameB
【3】helloB.jsp：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
Insert title here
bb
usernameB(key:usernameB) --> ${usernameB}
【4】输出结果：
18/01/07 11:52:33 INFO controller.IndexController: welcome usernameB ,mmb
解释：（1）Model对象介绍（官方文档）：
org.springframework.ui
Interface Model
- All Known Subinterfaces:
- RedirectAttributes
- All Known Implementing Classes:
- BindingAwareModelMap, ExtendedModelMap, RedirectAttributesModelMap
public interface Model
| Method Summary | |
|---|---|
Model |
addAllAttributes(Collection attributeValues) Copy all attributes in the supplied Collection into this Map, using attribute name generation for each element. |
Model |
addAllAttributes(Map Copy all attributes in the supplied Map into this Map. |
Model |
addAttribute(Object attributeValue) Add the supplied attribute to this Map using a generated name. |
Model |
addAttribute(String attributeName, Object attributeValue) Add the supplied attribute under the supplied name. |
Map |
asMap() Return the current set of model attributes as a Map. |
boolean |
containsAttribute(String attributeName) Does this model contain an attribute of the given name? |
Model |
mergeAttributes(Map Copy all attributes in the supplied Map into this Map, with existing objects of the same name taking precedence (i.e. |
（2）其实springmvc 在调用方法前，就会创建一个隐含的模型对象（隐含模型）Model，作为数据的存储容器。那么，若处理方法的入参为Model模型，springmvc就会将隐含模型的引用传递给这些入参；简单说，开发者可以通过一个Model类型的入参对象，访问到模型的所有数据，当然也可以添加新的属性数据！
【4】添加无key值的属性，修改IndexController.java：：
package com.smbms.controller;
import org.apache.log4j.Logger;
import org.apache.log4j.PropertyConfigurator;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.servlet.ModelAndView;
@Controller
@RequestMapping("/a")
public class IndexController {
private Logger log = Logger.getLogger(IndexController.class.getName());
//Model
@RequestMapping(value="/hello")
public String hello4(String usernameB ,Model model){
Integer value = 110;
log.info("welcome usernameB ,"+usernameB);
model.addAttribute("usernameB",usernameB);
model.addAttribute(usernameB);
model.addAttribute(value);
return "helloB";
}
} 输出结果：
18/01/07 12:07:39 INFO controller.IndexController: welcome usernameB ,mmb是否包含string :true是否包含integer:true
解释：（3）Model对象使用无参属性是，参数的类型名称会成为其默认的key！！大家可以自主探究：对于使用多个相同类型的无key参数，调用会出错吗？参数的key区分大小写吗？（答案：区分大小写！多个参数时，若是没有通过变量赋值，是取不出来的！）
3、POJO 对象模型的使用
【0】在工程新建一个包，新建一个JavaBean，这里举例User.java：
package com.smbms.entities;
import java.util.Date;
import java.util.List;
public class User {
private Integer id;
private String userCode;
private String userName;
private String userPassword;
private Integer gender;
private Date birthday;
private String phone;
private String address ;
private Integer userRole;
private Integer createdBy;
private Date creationDate;
private Integer modifyBy;
private Date modifyDate;
private String userRoleName;
public String getUserRoleName() {
return userRoleName;
}
public void setUserRoleName(String userRoleName) {
this.userRoleName = userRoleName;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUserCode() {
return userCode;
}
public void setUserCode(String userCode) {
this.userCode = userCode;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getUserPassword() {
return userPassword;
}
public void setUserPassword(String userPassword) {
this.userPassword = userPassword;
}
public Integer getGender() {
return gender;
}
public void setGender(Integer gender) {
this.gender = gender;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public Integer getUserRole() {
return userRole;
}
public void setUserRole(Integer userRole) {
this.userRole = userRole;
}
public Integer getCreatedBy() {
return createdBy;
}
public void setCreatedBy(Integer createdBy) {
this.createdBy = createdBy;
}
public Date getCreationDate() {
return creationDate;
}
public void setCreationDate(Date creationDate) {
this.creationDate = creationDate;
}
public Integer getModifyBy() {
return modifyBy;
}
public void setModifyBy(Integer modifyBy) {
this.modifyBy = modifyBy;
}
public Date getModifyDate() {
return modifyDate;
}
public void setModifyDate(Date modifyDate) {
this.modifyDate = modifyDate;
}
public User(Integer id, String userCode, String userName, String userPassword, Integer gender, Date birthday,
String phone, String address, Integer userRole, Integer createdBy, Date creationDate, Integer modifyBy,
Date modifyDate) {
super();
this.id = id;
this.userCode = userCode;
this.userName = userName;
this.userPassword = userPassword;
this.gender = gender;
this.birthday = birthday;
this.phone = phone;
this.address = address;
this.userRole = userRole;
this.createdBy = createdBy;
this.creationDate = creationDate;
this.modifyBy = modifyBy;
this.modifyDate = modifyDate;
}
public User() {
super();
// TODO 自动生成的构造函数存根
}
@Override
public String toString() {
return "User [id=" + id + ", userCode=" + userCode + ", userName=" + userName + ", userPassword=" + userPassword
+ ", gender=" + gender + ", birthday=" + birthday + ", phone=" + phone + ", address=" + address
+ ", userRole=" + userRole + ", createdBy=" + createdBy + ", creationDate=" + creationDate
+ ", modifyBy=" + modifyBy + ", modifyDate=" + modifyDate + "]";
}
}
【1】修改IndexController.java：
package com.smbms.controller;
import org.apache.log4j.Logger;
import org.apache.log4j.PropertyConfigurator;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.servlet.ModelAndView;
import com.smbms.entities.User;
@Controller
@RequestMapping("/a")
public class IndexController {
private Logger log = Logger.getLogger(IndexController.class.getName());
//POJO+Model
@RequestMapping(value="/hello")
public String hello5(String usernameB ,Model model){
model.addAttribute("usernameB",usernameB);
model.addAttribute(usernameB);
User user = new User();
user.setUserName(usernameB);
model.addAttribute("currentUser", user);
model.addAttribute(user);
return "helloB";
}
} 【2】index.jsp 不作修改；
【3】helloB.jsp：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
Insert title here
bb
usernameB(key:usernameB) --> ${usernameB}
无key值(key:string) --> ${string}
无key值(key:integer) --> ${integer}
有key值(key:currentUser.userName) --> ${currentUser.userName}
无key值(key:user.userName) --> ${user.userName}
【4】输出结果：
解释：还是使用“.”进行属性值的访问。
4、Map 对象模型的使用
不难发现，其实Model也是一个Map 的数据结构，所以，我们使用Map 作为处理方法入参也是可以的。
【1】修改IndexController.java：
package com.smbms.controller;
import java.util.Map;
import org.apache.log4j.Logger;
import org.apache.log4j.PropertyConfigurator;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.servlet.ModelAndView;
import com.smbms.entities.User;
@Controller
@RequestMapping("/a")
public class IndexController {
private Logger log = Logger.getLogger(IndexController.class.getName());
//Map
@RequestMapping(value="/hello")
public String index(String username,Mapmodel){
log.info("hello springmvc!username:"+username);
model.put("usernameKK", username);
return "helloC";
}
} 【2】 index.jsp 不作修改；
【3】新建helloC.jsp：
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
Insert title here
hello springmvc!
username(key:username) --> ${username}
username(key:usernameKK) --> ${usernameKK}
【4】输出结果：
18/01/07 12:49:20 INFO controller.IndexController: hello springmvc!username:mmb
4、@ModelAttribute 对象模型的注解使用：
若希望将入参的数据对象放入数据模型，可以在相应的参数入参前使用该注解。后续做跟进。
5、@ModelAttributes 对象模型的注解使用：
此注解可以将模型的属性存入HttpSession中，以便多个请求之间共享该属性。后续做跟进。