spring mvc中的控制器返回方式集合

第一次自己写文章，参考了很多前人的作品，整理并加入了一些自己的见解，写的不好请多谅解

对于springMVC处理方法支持支持一系列的返回方式（可能有更多目前仅了解到这些）：

1.ModelAndView

2.Model

3.ModelMap

4.Map

5.View

6.String

7.ResponseEntity

 -----------------------------------------------------------------------------------------------------------

一.ModelAndView

 

@RequestMapping("/test")
public ModelAndView list(@ModelAttribute("id") String id,HttpServletRequest request) {
             ModelAndView mv = new ModelAndView();
           //ModelAndView mv = new ModelAndView("test");
             mv.addObject("name", "test");
             mv.setViewName("test");//如用上面注释的可去掉这句
             return mv;
}

 ModelAndView构造函数可以指定返回页面的名称，也可以通过setViewName方法来设置所需要跳转的页面，并且返回的是一个包含模型和视图的ModelAndView对象；

 

 

二.Model

Model是一个接口，并不能直接返回，作用是作为一个模型对象包含了封装好的Model和modelMap,以及java.util.Map，当没有视图返回的时候视图名称将由requestToViewNameTranslator决定；

本人水平有限，可能描述的不够到位，附上spring里这个类的源码

 

/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.ui;

import java.util.Collection;
import java.util.Map;

/**
 * Java-5-specific interface that defines a holder for model attributes.
 * Primarily designed for adding attributes to the model.
 * Allows for accessing the overall model as a {@code java.util.Map}.
 *
 * @author Juergen Hoeller
 * @since 2.5.1
 */
public interface Model {

	/**
	 * Add the supplied attribute under the supplied name.
	 * @param attributeName the name of the model attribute (never {@code null})
	 * @param attributeValue the model attribute value (can be {@code null})
	 */
	Model addAttribute(String attributeName, Object attributeValue);

	/**
	 * Add the supplied attribute to this {@code Map} using a
	 * {@link org.springframework.core.Conventions#getVariableName generated name}.
	 * <p><emphasis>Note: Empty {@link java.util.Collection Collections} are not added to
	 * the model when using this method because we cannot correctly determine
	 * the true convention name. View code should check for {@code null} rather
	 * than for empty collections as is already done by JSTL tags.</emphasis>
	 * @param attributeValue the model attribute value (never {@code null})
	 */
	Model addAttribute(Object attributeValue);

	/**
	 * Copy all attributes in the supplied {@code Collection} into this
	 * {@code Map}, using attribute name generation for each element.
	 * @see #addAttribute(Object)
	 */
	Model addAllAttributes(Collection<?> attributeValues);

	/**
	 * Copy all attributes in the supplied {@code Map} into this {@code Map}.
	 * @see #addAttribute(String, Object)
	 */
	Model addAllAttributes(Map<String, ?> attributes);

	/**
	 * Copy all attributes in the supplied {@code Map} into this {@code Map},
	 * with existing objects of the same name taking precedence (i.e. not getting
	 * replaced).
	 */
	Model mergeAttributes(Map<String, ?> attributes);

	/**
	 * Does this model contain an attribute of the given name?
	 * @param attributeName the name of the model attribute (never {@code null})
	 * @return whether this model contains a corresponding attribute
	 */
	boolean containsAttribute(String attributeName);

	/**
	 * Return the current set of model attributes as a Map.
	 */
	Map<String, Object> asMap();

}

 

 

 三.ModelMap

在spring mvc中可以通过ModelMap对象传递模型参数到视图进行处理。在Controller方法中声明一个ModelMap参数，spring会创建一个ModelMap对象，并传入方法，方法处理完成后自动传递到视图进行处理。

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。

 

@RequestMapping("/test")
	public String testmethod(String someparam,ModelMap model)
	{
	      model.addAttribute("test","test");
		// 返回跳转地址
	      return "path:handleok";
	}

 PS：建议使用ModelAndView

 

四.Map

这个个人感觉没什么可以介绍的，直接上代码

 

@RequestMapping(value = "/test")
	public Map<String, String> index() {
		Map<String, String> map = new HashMap<String, String>();
		map.put("test", "test");
		// map.put相当于request.setAttribute方法
		return map;

	}

 

 

五.View

View同Model一样也是一个接口，了解不多，上源码，欢迎补充

 

/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.servlet;

import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.http.MediaType;

/**
 * MVC View for a web interaction. Implementations are responsible for rendering
 * content, and exposing the model. A single view exposes multiple model attributes.
 *
 * <p>This class and the MVC approach associated with it is discussed in Chapter 12 of
 * <a href="http://www.amazon.com/exec/obidos/tg/detail/-/0764543857/">Expert One-On-One J2EE Design and Development</a>
 * by Rod Johnson (Wrox, 2002).
 *
 * <p>View implementations may differ widely. An obvious implementation would be
 * JSP-based. Other implementations might be XSLT-based, or use an HTML generation library.
 * This interface is designed to avoid restricting the range of possible implementations.
 *
 * <p>Views should be beans. They are likely to be instantiated as beans by a ViewResolver.
 * As this interface is stateless, view implementations should be thread-safe.
 *
 * @author Rod Johnson
 * @author Arjen Poutsma
 * @see org.springframework.web.servlet.view.AbstractView
 * @see org.springframework.web.servlet.view.InternalResourceView
 */
public interface View {

	/**
	 * Name of the {@link HttpServletRequest} attribute that contains the response status code.
	 * <p>Note: This attribute is not required to be supported by all View implementations.
	 */
	String RESPONSE_STATUS_ATTRIBUTE = View.class.getName() + ".responseStatus";

	/**
	 * Name of the {@link HttpServletRequest} attribute that contains a Map with path variables.
	 * The map consists of String-based URI template variable names as keys and their corresponding
	 * Object-based values -- extracted from segments of the URL and type converted.
	 *
	 * <p>Note: This attribute is not required to be supported by all View implementations.
	 */
	String PATH_VARIABLES = View.class.getName() + ".pathVariables";

	/**
	 * The {@link MediaType} selected during content negotiation, which may be
	 * more specific than the one the View is configured with. For example:
	 * "application/vnd.example-v1+xml" vs "application/*+xml".
	 */
	String SELECTED_CONTENT_TYPE = View.class.getName() + ".selectedContentType";

	/**
	 * Return the content type of the view, if predetermined.
	 * <p>Can be used to check the content type upfront,
	 * before the actual rendering process.
	 * @return the content type String (optionally including a character set),
	 * or {@code null} if not predetermined.
	 */
	String getContentType();

	/**
	 * Render the view given the specified model.
	 * <p>The first step will be preparing the request: In the JSP case,
	 * this would mean setting model objects as request attributes.
	 * The second step will be the actual rendering of the view,
	 * for example including the JSP via a RequestDispatcher.
	 * @param model Map with name Strings as keys and corresponding model
	 * objects as values (Map can also be {@code null} in case of empty model)
	 * @param request current HTTP request
	 * @param response HTTP response we are building
	 * @throws Exception if rendering failed
	 */
	void render(Map<String, ?> model, HttpServletRequest request, HttpServletResponse response) throws Exception;

}

 

六.String

有2种返回方式：

String 指定返回的视图页面名称，结合设置的返回地址路径加上页面名称后缀即可访问到。

 

@RequestMapping("/test") 
	public String welcomeHandler() { 
	  return "index"; 
	}

 简单粗暴，对应的逻辑视图名为“index”，URL= prefix前缀+视图名称 +suffix后缀。

第2种返回字符串

 

@RequestMapping(value = "/test")
	@ResponseBody
	public String lista(HttpServletRequest request) {
		return "test";
	}

 

七.ResponseEntity

ResponseEntity作用比较强大,可以返回文件，字符串等

字符串的demo：

 

@RequestMapping(value = "/test", method = RequestMethod.POST, produces = "text/plain;charset=UTF-8;")
	public ResponseEntity<String> test(HttpServletResponse response) {
		return new ResponseEntity<String>("这是测试", HttpStatus.OK);
	}

 文件的demo：

@RequestMapping("download")
	public ResponseEntity<byte[]> download(String filepath) throws IOException {
		HttpHeaders headers = new HttpHeaders();
		headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
		headers.setContentDispositionFormData("attachment", "filename.suffix");
		File file = new File(filepath);
		return new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(file),
				headers, HttpStatus.CREATED);
	}

 PS:使用ResponseEntity需要正确配置AnnotationMethodHandlerAdapter，messageConverters中的list是有顺序的，这点很重要！