部署一个网站大概多少钱,稿定详情页设计模板,flash网站建设个人简介,宁夏快速自助制作网站#xff08;一#xff09;使用ModelAndView类用来存储处理完后的结果数据#xff0c;以及显示该数据的视图。从名字上看ModelAndView中的Model代表模型#xff0c;View代表视图#xff0c;这个名字就很好地解释了该类的作用。业务处理器调用模型层处理完用户请求后#x…一使用ModelAndView类用来存储处理完后的结果数据以及显示该数据的视图。从名字上看ModelAndView中的Model代表模型View代表视图这个名字就很好地解释了该类的作用。业务处理器调用模型层处理完用户请求后把结果数据存储在该类的model属性中把要返回的视图信息存储在该类的view属性中然后让该ModelAndView返回该Spring MVC框架。框架通过调用配置文件中定义的视图解析器对该对象进行解析最后把结果数据显示在指定的页面上。
具体作用
1、返回指定页面
ModelAndView构造方法可以指定返回的页面名称
也可以通过setViewName()方法跳转到指定的页面 ,
2、返回所需数值
使用addObject()设置需要返回的值addObject()有几个不同参数的方法可以默认和指定返回对象的名字。
1、【其源码】熟悉一个类的用法最好从其源码入手。
public class ModelAndView { /** View instance or view name String */ private Object view;//span stylecolor: rgb(0, 130, 0); font-family: Consolas, Courier New, Courier, mono, serif; line-height: 18px;该属性用来存储返回的视图信息/span /** Model Map */
private ModelMap model;//span stylecolor: rgb(0, 130, 0); font-family: Consolas, Courier New, Courier, mono, serif; line-height: 18px;该属性用来存储处理后的结果数据/span /** * 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 codeaddObject/code. * param viewName name of the View to render, to be resolved * by the DispatcherServlets 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 codeaddObject/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 DispatcherServlets ViewResolver * param model Map of model names (Strings) to model objects * (Objects). Model entries may not be codenull/code, but the * model Map may be codenull/code if there is no model data. */
public ModelAndView(String viewName, MapString, ? model) { this.view viewName; if (model ! null) { getModelMap().addAllAttributes(model); }
} /** * Creates new ModelAndView given a View object and a model. * emphasisNote: 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 codenull/code, but the * model Map may be codenull/code if there is no model data. */
public ModelAndView(View view, MapString, ? 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 DispatcherServlets 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 codenull/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 codenull/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 codeModelAndView/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. codetrue/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 codenull/code. * Called by DispatcherServlet for evaluation of the model. */
protected MapString, Object getModelInternal() { return this.model;
} /** * Return the underlying codeModelMap/code instance (never codenull/code). */
public ModelMap getModelMap() { if (this.model null) { this.model new ModelMap(); } return this.model;
} /** * Return the model map. Never returns codenull/code. * To be called by application code for modifying the model. */
public MapString, 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 codenull/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 codenull/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(MapString, ? modelMap) { getModelMap().addAllAttributes(modelMap); return this;
} /** * Clear the state of this ModelAndView object. * The object will be empty afterwards. * pCan be used to suppress rendering of a given ModelAndView object * in the codepostHandle/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. * pReturns codefalse/code if any additional state was added to the instance * strongafter/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();
} 在源码中有7个构造函数如何用是一个重点。构造ModelAndView对象当控制器处理完请求时通常会将包含视图名称或视图对象以及一些模型属性的ModelAndView对象
返回到DispatcherServlet。因此经常需要在控制器中构造ModelAndView对象。ModelAndView类提供了几个重载的构造器和一些方便的方法让你可以根据自己的喜好来构造ModelAndView对象。这些构造器和方法以类似的方式支持视图名称和视图对象。通过ModelAndView构造方法可以指定返回的页面名称也可以通过setViewName()方法跳转到指定的页面 , 使用addObject()设置需要返回的值addObject()有几个不同参数的方法可以默认和指定返回对象的名字。 1当你只有一个模型属性要返回时可以在构造器中指定该属性来构造ModelAndView对象
package com.apress.springrecipes.court.web;
...
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.AbstractController;
public class WelcomeController extends AbstractController{ public ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response)throws Exception{ Date today new Date(); return new ModelAndView(welcome,today,today); }
}
2如果有不止一个属性要返回可以先将它们传递到一个Map中再来构造ModelAndView对象。
package com.apress.springrecipes.court.web;
...
import org.springframework.web.servlet.ModelAndView;
import org. springframework.web.servlet.mvc.AbstractController;
public class ReservationQueryController extends AbstractController{ ... public ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response)throws Exception{ ... MapString,Object model new HashMapString,Object(); if(courtName ! null){ model.put(courtName,courtName); model.put(reservations,reservationService.query(courtName)); } return new ModelAndView(reservationQuery,model); }
}
Spring也提供了ModelMap,这是java.util.Map实现可以根据模型属性的具体类型自动生成模型属性的名称。
package com.apress.springrecipes.court.web;
...
import org.springframework.ui.ModelMap;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.AbstractController;
public class ReservationQueryController extends AbstractController{ ... public ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response)throws Exception{ ... ModelMap model new ModelMap(); if(courtName ! null){ model.addAttribute(courtName,courtName); model.addAttribute(reservations,reservationService.query(courtName)); } return new ModelAndView(reservationQuery,model); }
}
这里我又想多说一句
ModelMap对象主要用于传递控制方法处理数据到结果页面也就是说我们把结果页面上需要的数据放到ModelMap对象中即可他的作用类似于request对象的setAttribute方法的作用用来在一个请求过程中传递处理的数据。通过以下方法向页面传递参数 addAttribute(String key,Object value);
在页面上可以通过el变量方式$key或者bboss的一系列
数据展示标签
获取并展示modelmap中的数据。 modelmap本身不能设置页面跳转的url地址别名或者物理跳转地址那么我们可以通过控制器方法的返回值来设置跳转url地址别名或者物理跳转地址。 比如
public String xxxxmethod(String someparam,ModelMap model)
{ //省略方法处理逻辑若干 //将数据放置到ModelMap对象model中,第二个参数可以是任何java类型 model.addAttribute(key,someparam); ...... //返回跳转地址 return path:handleok;
} 在这些构造函数中最简单的ModelAndView是持有View的名称返回之后View名称被view resolver也就是实作org.springframework.web.servlet.View接口的实例解析例如 InternalResourceView或JstlView等等ModelAndView(String viewName)如果您要返回Model对象则可以使用Map来收集这些Model对象然后设定给ModelAndView使用下面这个版本的 ModelAndViewModelAndView(String viewName, Map model)Map对象中设定好key与value值之后可以在视图中取出如果您只是要返回一个Model对象则可以使用下面这个 ModelAndView版本ModelAndView(String viewName, String modelName, Object modelObject)其中modelName您可以在视图中取出Model并显示。
ModelAndView类别提供实作View接口的对象来作View的参数
ModelAndView(View view)
ModelAndView(View view, Map model)
ModelAndView(View view, String modelName, Object modelObject)
2【方法使用】给ModelAndView实例设置view的方法有两个setViewName(String viewName) 和 setView(View view)。前者是使用viewName后者是使用预先构造好的View对象。其中前者比较常用。事实上View是一个接口而不是一个可以构造的具体类我们只能通过其他途径来获取View的实例。对于viewName它既可以是jsp的名字也可以是tiles定义的名字取决于使用的ViewNameResolver如何理解这个view name。如何获取View的实例以后再研究。而对应如何给ModelAndView实例设置model则比较复杂。有三个方法可以使用addObject(Object modelObject);
addObject(String modelName, Object modelObject);addAllObjects(Map modelMap);
3【作用简介】
ModelAndView对象有两个作用 作用一 设置转向地址,如下所示这也是ModelAndView和ModelMap的主要区别 ModelAndView view new ModelAndView(path:ok); 作用二 用于传递控制方法处理结果数据到结果页面也就是说我们把需要在结果页面上需要的数据放到ModelAndView对象中即可他的作用类似于request对象的setAttribute方法的作用用来在一个请求过程中传递处理的数据。通过以下方法向页面传递参数
addObject(String key,Object value);
转载自https://blog.csdn.net/tongxinxiao/article/details/39502519#
