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

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

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

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

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

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 此URL有inputStr值，则其值为myInput值

{inputStr=myInput}

访问URL:

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

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

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

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 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

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 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

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 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

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 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

@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";
}

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

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

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

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

返回结果：