Spring Boot系列九 spring mvc的@RequestMapping支持的方法参数类型和返回类型

亦凉 2021-06-24 15:57 459阅读 0赞

## 1. 概述 ##

本文介绍了spring mvc中使用@RequestMapping时，支持常用方法参数类型和返回类型。

常用的方法参数类型有：  
\- 1 PathVariable  
\- 2 RequestParam  
\- 3 RequestBody  
\- 4 HttpEntity  
\- 5 CookieValue  
\- 6 RequestHeader  
\- 7 自动封装form表单请求到对象中  
\- 8 HttpServletRequest HttpServletResponse  
\- 9 RequestMapping 参数配置params headers

常用的返回类型有：

*  1 返回一个页面的地址
 *  2 ResponseBody
 *  3 ResponseEntity
 *  4 ModelAndView

## 2. 前提条件 ##

代码工程名称：mvc

测试PO类  
**ModelAttributeVO**

public class ModelAttributeVO {
        private String name;
        private String value;
        private Date date;
        // set/get方法略
    }

**VO**

public class VO {
        private String name;
        private String value;
        private Date date;
        // set/get方法略
    }

## 3. @RequestMapping支持的方法参数类型 ##

### 3.1. RequestParameterController ###

以下代码都在RequestParameterController类中

@Controller: 表示此类对外提供url服务  
@RequestMapping：此注解不仅可以作用在方法上，也可以作用在类上。如果作用在类上，则表示此值是类中的所有@RequestMapping方法的URL的前缀

@Controller
    @RequestMapping(value = "/request") // 全局URL
    public class RequestParameterController {
        ....
    }

### 3.2. 使用的jsp ###

下面用到jsp的页面如下，都在META-INF\\resources\\WEB-INF\\page\\reqparameter目录下：  
**showInput.jsp**  
打印内容

<html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Request Parameter</title>
    </head>
    <body>
        ${map}
    </body>
    </html>

**formModel.jsp**  
测试form表单

<html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Insert title here</title>
    </head>
    <body>
    
        <form name="myform" method="post" action="formModel">
            <table>
                <tr>
                    <td>First Name:</td>
                    <td><input type="text" name="name" value="fisr name" /></td>
                </tr>
                <tr>
                    <td>Last Name:</td>
                    <td><input type="text" name="value" value="lastName" /></td>
                </tr>
                <tr>
                    <td colspan="2">
                        <input type="submit" value="Save Changes" />
                    </td>
                </tr>
            </table>
        </form>
    </body>
    </html>

**httpEntityForm.jsp**  
测试form表单

<html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Insert title here</title>
    </head>
    <body>
    
        <form name="myform" method="post" action="httpEntity">
            <table>
                <tr>
                    <td>First Name:</td>
                    <td><input type="text" value="name" /></td>
                </tr>
                <tr>
                    <td>Last Name:</td>
                    <td><input type="text" value="lastName" /></td>
                </tr>
                <tr>
                    <td colspan="2">
                        <input type="submit" value="Save Changes" />
                    </td>
                </tr>
            </table>
        </form>
    </body>
    </html>

### 3.3. @PathVariable ###

作用：可以注入URL中的变量值，可以注入一个或者多个

**单个 @PathVariable值**  
代码：

@RequestMapping(value="/path/{ownerId}")
    public String pathVariable(@PathVariable String ownerId, Model model){
        Map<String,Object> map = new HashMap<String,Object>();
        map.put("ownerId", ownerId);
        model.addAttribute("map", map);
        return "reqparameter/showInput";
    }

访问URL:  
[http://127.0.0.1:8080/request/path/1][http_127.0.0.1_8080_request_path_1]

返回结果：

{ownerId=1}

**多个 @PathVariable值**  
作用： 可以注入URL中的变量值，可以注入一个或者多个  
代码：

@RequestMapping(value="/path/{ownerId}/pet/{petId}")
        public String pathVariable2(@PathVariable String ownerId, @PathVariable String petId, Model model){
            Map<String,Object> map = new HashMap<String,Object>();
            map.put("ownerId", ownerId);
            map.put("petId", petId);
            model.addAttribute("map", map);
            return "reqparameter/showInput";
        }

访问URL:  
[http://127.0.0.1:8080/request/path/1/pet/1234][http_127.0.0.1_8080_request_path_1_pet_1234]

返回结果：

{petId=1234, ownerId=1}

### 3.4. @RequestParam ###

**通过@RequestParam注入单个值**  
作用：可以从请求参数中获取参数值  
代码：

@RequestMapping(value="/requestParam", method = RequestMethod.GET)
       public String requestParam(@RequestParam("ownerId") int ownerId, ModelMap model) {
        Map<String,Object> map = new HashMap<String,Object>();
        map.put("ownerId", ownerId);
    
        model.addAttribute("map", map);
        return "reqparameter/showInput";
       }

访问URL:  
[http://127.0.0.1:8080/request/requestParam?ownerId=223][http_127.0.0.1_8080_request_requestParam_ownerId_223]

返回结果：

{ownerId=223}

**通过@RequestParam注入多个值**  
作用： 可以从请求参数中获取多个参数值  
代码：

@RequestMapping(value="/requestParam2", method = RequestMethod.GET)
        public String requestParam2(@RequestParam Map<String,Object> map, ModelMap model) {
    // Map<String,Object> map = new HashMap<String,Object>();
    // map.put("ownerId", ownerId);
    
            model.addAttribute("map", map);
            return "reqparameter/showInput";
        }

访问URL:  
[http://127.0.0.1:8080/request/requestParam2?ownerId=223&a=4&c=5][http_127.0.0.1_8080_request_requestParam2_ownerId_223_a_4_c_5]

返回结果：

{ownerId=223, a=4, c=5}

**@RequestParam： required、defaultValue**  
作用：设置@RequestParam自定义参数：如设置默认值(defaultValue)，是否必须（required）等等  
代码：

@RequestMapping("/requestParam3")
    public String requestParam3(@RequestParam(value="inputStr", required=true, defaultValue="noInput") String inputStr,
                                ModelMap model) {
        Map<String,Object> map = new HashMap<String,Object>();
        map.put("inputStr",inputStr );
        model.addAttribute("map",map);
        return "reqparameter/showInput";
    }

访问URL:  
[http://127.0.0.1:8080/request/requestParam3?inputStr=myInput][http_127.0.0.1_8080_request_requestParam3_inputStr_myInput]  
此URL有inputStr值，则其值为myInput值

{inputStr=myInput}

访问URL:  
[http://127.0.0.1:8080/request/requestParam3][http_127.0.0.1_8080_request_requestParam3]  
此URL没有inputStr值，则其值为默认值，即noInput  
返回结果：

{inputStr=noInput}

### 3.5. @RequestBody ###

作用：@RequestBody: 获取请求的内容。请求内容为JSON，因为本工程设置请求为json，所以demo为：\{“a”:1\}  
代码：

@RequestMapping(value = "/requestBody", method = RequestMethod.POST)
    public String requestBody(@RequestBody String body, ModelMap model){
        Map<String,Object> map = new HashMap<String,Object>();
        map.put("body",body );
        model.addAttribute("map",map);
        return "reqparameter/showInput";
    }

访问URL：  
[http://127.0.0.1:8080/request/requestBody][http_127.0.0.1_8080_request_requestBody]  
内容为\{“a”:1\}  
此请求为POST，需要使用postman等模拟POST请求  
返回结果：

{
       body={
       "a":1}}

### 3.6. HttpEntity ###

作用：HttpEntity，可以操作更原始的请求方法  
代码：

@RequestMapping(value="/httpEntity", method = RequestMethod.GET)
    public String httpEntity(ModelMap model){
        return "reqparameter/httpEntityForm";
    }
    
    @RequestMapping("/httpEntity")
    public String httpEntity2(HttpEntity<byte[]> requestEntity, ModelMap model){
        // 获取header
        String acceptLanguage = requestEntity.getHeaders().getFirst("Accept-Language");
        // 获取内容：获取body的内容为空，暂时不知道原因
        byte[] requestBody = requestEntity.getBody();     
    
        Map<String,Object> map = new HashMap<String,Object>();
        map.put("acceptLanguage", acceptLanguage);
    // map.put("content", new String(requestBody));
    
        model.addAttribute("map", map);
        return "reqparameter/showInput";
    }

访问URL:  
[http://127.0.0.1:8080/request/httpEntity][http_127.0.0.1_8080_request_httpEntity]

返回结果：  
输入上面URL，进入form表单，填写内容后，会转到新的页面如下

{acceptLanguage=zh-CN,zh;q=0.9,zh-TW;q=0.8}

### 3.7. @CookieValue ###

作用：获取cookie里的值  
代码：

@RequestMapping("/cookieValue")
    public String cookieValue(@CookieValue("JSESSIONID") String cookie,ModelMap model) {
        Map<String,Object> map = new HashMap<String,Object>();
        map.put("cookie", cookie);
        model.addAttribute("map", map);
        return "reqparameter/showInput";
    }

访问URL:  
[http://127.0.0.1:8080/request/cookieValue][http_127.0.0.1_8080_request_cookieValue]

返回结果：

{cookie=38EDB55B71BB4CCA6EF1A2CDA7F1BCC0}

### 3.8. @RequestHeader ###

作用：操作http header的值  
**获取指定header里的值**  
代码：

@RequestMapping("/requestHeader")
    public String requestHeader (
            @RequestHeader ("User-Agent") String userAgent,
            @RequestHeader ("Host") String host,
            @RequestHeader ("Cache-Control") String cacheControl,
            ModelMap model) {
        Map<String,Object> map = new HashMap<String,Object>();
        map.put("User-Agent", userAgent);
        map.put("Host", host);
        map.put("Cache-Control", cacheControl);
    
        model.addAttribute("map", map);
        return "reqparameter/showInput";
    }

访问URL:  
[http://127.0.0.1:8080/request/requestHeader][http_127.0.0.1_8080_request_requestHeader]  
此请求刷新需求刷新多次

返回结果：

{
       Cache-Control=max-age=0, User-Agent=Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.62 Safari/537.36, Host=127.0.0.1:8080}

**获取所有header封装到Map**

代码：

@RequestMapping("/requestHeaderMap")
        public String requestHeaderMap (@RequestHeader Map<String,String> map,
                ModelMap model) {       
            model.addAttribute("map", map);
            return "reqparameter/showInput";
        }

访问URL:  
[http://127.0.0.1:8080/request/requestHeaderMap][http_127.0.0.1_8080_request_requestHeaderMap]

返回结果：

{host=127.0.0.1:8080, connection=keep-alive, user-agent=Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.62 Safari/537.36, upgrade-insecure-requests=1, accept=text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8, accept-encoding=gzip, deflate, br, accept-language=zh-CN,zh;q=0.9,zh-TW;q=0.8, cookie=JSESSIONID=38EDB55B71BB4CCA6EF1A2CDA7F1BCC0}

### 3.9. 自动封装form表单请求到对象中 ###

作用：  
代码：

@RequestMapping(value="/formModel", method = RequestMethod.GET)
    public String form(){
        return "reqparameter/formModel";
    }
    
    @RequestMapping("/formModel")
    public String formPost(VO vo, ModelMap model){
        Map<String,Object> map = new HashMap<String,Object>();
        map.put("name", vo.getName());
        map.put("value", vo.getValue());
        map.put("date", vo.getDate());
    
        model.addAttribute("map", map);
        return "reqparameter/showInput";
    }

访问URL:  
[http://127.0.0.1:8080/request/formModel][http_127.0.0.1_8080_request_formModel]  
此URL进入form表单，我们填写内容后，会提交到formPost方法，此时时会自动封装值到VO对象中，打印内容如下

返回结果：

{
       date=Sun Nov 12 22:11:22 CST 2017, name=fisr name, value=lastName}

### 3.10. HttpServletRequest + HttpServletResponse ###

作用：直接操作原始的HttpServletRequest 和 HttpServletResponse  
代码：

@RequestMapping("/httpServlet")
    public void formPost(HttpServletRequest request, HttpServletResponse response) throws IOException{      
        String userAgent = request.getHeader("User-Agent");
        String host = request.getHeader("Host");
        String cacheControl = request.getHeader("Cache-Control");
    
        PrintWriter pw = response.getWriter();
        pw.println("User-Agent :"+ userAgent);
        pw.println("Host :" + host);
        pw.println("Cache-Control :" + cacheControl);
    
    }

访问URL:  
[http://127.0.0.1:8080/request/httpServlet][http_127.0.0.1_8080_request_httpServlet]

返回结果：

User-Agent :Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.62 Safari/537.36
    Host :127.0.0.1:8080
    Cache-Control :null

### 3.11. @RequestMapping 参数配置params、headers ###

**@RequestMapping 参数配置params**   
作用：通过params过滤请求，如下面的代码，只有URL带上myParam=myValue才能进入  
代码：

@RequestMapping(value="/reqparameters/{ownerId}", method = RequestMethod.GET, params="myParam=myValue")
    public String reqParameters(@PathVariable String ownerId, Model model){
        Map<String,Object> map = new HashMap<String,Object>();
        map.put("ownerId", ownerId);
        model.addAttribute("map", map);
        return "reqparameter/showInput";
    t"; }

访问URL:[http://127.0.0.1:8080/request/reqparameters/1?myParam=myValue][http_127.0.0.1_8080_request_reqparameters_1_myParam_myValue] 可以进入到这个方法，  
但是以下URL无法进入这个方法：[http://127.0.0.1:8080/request/reqparameters/1][http_127.0.0.1_8080_request_reqparameters_1]

备注： 其他条件，也可以这样： “myParam”, “!myParam”, or “myParam=myValue”

**@RequestMapping 参数配置headers**  
作用：通过headers过滤请求，请求头里必须带上myParam，且值为myValue  
代码：

@RequestMapping(value="/reqparameters/{ownerId}", method = RequestMethod.GET, headers="myParam=myValue")
    public String headerParameters(@PathVariable String ownerId, Model model){
        Map<String,Object> map = new HashMap<String,Object>();
        map.put("ownerId", ownerId);
        model.addAttribute("map", map);
        return "reqparameter/showInput";
    }

访问URL:  
[http://127.0.0.1:8080/reqparameters/1][http_127.0.0.1_8080_reqparameters_1]  
如果使用POST请求，请使用postman，并在请求头里必须带上myParam，且值为myValue

## 4. @RequestMapping支持的返回类型 ##

### 4.1. ResponseParameterController ###

以下代码都在此类中

@Controller
    @RequestMapping(value = "/response")
    public class ResponseParameterController {
    ...
    }

### 4.2. 使用到JSP ###

下面用到jsp的页面如下，都在META-INF\\resources\\WEB-INF\\page\\resparameter目录下：

**showInput.jsp**

<html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Request Parameter</title>
    </head>
    <body>
        ${map}
    </body>
    </html>

### 4.3. 返回一个页面的地址 ###

默认情况下，返回一个字符串，表示转到一个指定页面，上面的demo都是这个模式

### 4.4. @ResponseBody ###

**@ResponseBody： 直接返回字符串内容**  
作用：此注解注解的方法返回字符串  
代码：

@RequestMapping(value = "/responseBody", method = RequestMethod.GET)
    @ResponseBody
    public String responseBodyString() {
        return "Hello World";
    }

访问URL:  
[http://127.0.0.1:8080/response/responseBody][http_127.0.0.1_8080_response_responseBody]

返回结果：

"Hello World"

**@ResponseBody：方法返回对象，系统自动转化为json**  
作用：方法返回对象，返回客户端时系统自动转化为json  
代码：

@RequestMapping(value = "/responseBodyMode", method = RequestMethod.GET)
    @ResponseBody
    public VO responseBodyMode() {
        return new VO();
    }

访问URL:  
[http://127.0.0.1:8080/response/responseBodyMode][http_127.0.0.1_8080_response_responseBodyMode]

返回结果：

{ "date":1510497345620, "name":"name", "value":"value" }

### 4.5. ResponseEntity ###

作用：返回一个ResponseEntity  
代码：

@RequestMapping("/responseEntity")
    public ResponseEntity<String> responseEntity(){
        // do something with request header and body
        HttpHeaders responseHeaders = new HttpHeaders();
        responseHeaders.set("MyResponseHeader", "MyValue");
        return new ResponseEntity<String>("Hello World", responseHeaders, HttpStatus.CREATED);
    }

访问URL:  
[http://127.0.0.1:8080/response/responseEntity][http_127.0.0.1_8080_response_responseEntity]

返回结果：

"Hello World"

### 4.6. ModelAndView ###

作用：返回ModelAndView  
代码：

public ModelAndView modelAndView(){
    
        Map<String,Object> map = new HashMap<String,Object>();
        map.put("ownerId", "1");
        map.put("petId", "23");
    
        ModelAndView modelAndView = new ModelAndView();
        modelAndView.setViewName("resparameter/showInput");
        modelAndView.addObject("map", map);
    
        return modelAndView;
    }

访问URL:  
[http://127.0.0.1:8080/response/modelAndView][http_127.0.0.1_8080_response_modelAndView]

返回结果：

{petId=23, ownerId=1}

## 5. 代码 ##

上文的详细代码[见github代码，请尽量使用tag v0.4，不要使用master，因为master一直在变，不能保证文章中代码和github上的代码一直相同][github_tag v0.4_master_master_github]

[http_127.0.0.1_8080_request_path_1]: http://127.0.0.1:8080/request/path/1
[http_127.0.0.1_8080_request_path_1_pet_1234]: http://127.0.0.1:8080/request/path/1/pet/1234
[http_127.0.0.1_8080_request_requestParam_ownerId_223]: http://127.0.0.1:8080/request/requestParam?ownerId=223
[http_127.0.0.1_8080_request_requestParam2_ownerId_223_a_4_c_5]: http://127.0.0.1:8080/request/requestParam2?ownerId=223&a=4&c=5
[http_127.0.0.1_8080_request_requestParam3_inputStr_myInput]: http://127.0.0.1:8080/request/requestParam3?inputStr=myInput
[http_127.0.0.1_8080_request_requestParam3]: http://127.0.0.1:8080/request/requestParam3
[http_127.0.0.1_8080_request_requestBody]: http://127.0.0.1:8080/request/requestBody
[http_127.0.0.1_8080_request_httpEntity]: http://127.0.0.1:8080/request/httpEntity
[http_127.0.0.1_8080_request_cookieValue]: http://127.0.0.1:8080/request/cookieValue
[http_127.0.0.1_8080_request_requestHeader]: http://127.0.0.1:8080/request/requestHeader
[http_127.0.0.1_8080_request_requestHeaderMap]: http://127.0.0.1:8080/request/requestHeaderMap
[http_127.0.0.1_8080_request_formModel]: http://127.0.0.1:8080/request/formModel
[http_127.0.0.1_8080_request_httpServlet]: http://127.0.0.1:8080/request/httpServlet
[http_127.0.0.1_8080_request_reqparameters_1_myParam_myValue]: http://127.0.0.1:8080/request/reqparameters/1?myParam=myValue
[http_127.0.0.1_8080_request_reqparameters_1]: http://127.0.0.1:8080/request/reqparameters/1
[http_127.0.0.1_8080_reqparameters_1]: http://127.0.0.1:8080/reqparameters/1
[http_127.0.0.1_8080_response_responseBody]: http://127.0.0.1:8080/response/responseBody
[http_127.0.0.1_8080_response_responseBodyMode]: http://127.0.0.1:8080/response/responseBodyMode
[http_127.0.0.1_8080_response_responseEntity]: http://127.0.0.1:8080/response/responseEntity
[http_127.0.0.1_8080_response_modelAndView]: http://127.0.0.1:8080/response/modelAndView
[github_tag v0.4_master_master_github]: https://github.com/hryou0922/spring_boot/tree/v0.4/mvc/src/main/java/com/hry/spring/mvc