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This article mainly introduces "SpringMVC @ RequestBody usage analysis". In the daily operation, I believe many people have doubts about the use and analysis of SpringMVC @ RequestBody. The editor consulted all kinds of data and sorted out simple and easy-to-use operation methods. I hope it will be helpful to answer the doubts of "SpringMVC @ RequestBody usage analysis"! Next, please follow the editor to study!

Use of SpringMVC @ RequestBody

Spring mvc is a very lightweight mvc framework, and annotations can greatly reduce configuration and make it easier to intercept requests. This time record the use of the @ RequestBody annotation receiving parameters, especially the array parameters.

There is no more to say about the configuration of the container, here is the sechme of spring-servlet.xml:

As long as you add a comment under the package name, you can scan the corresponding controller. Generally, @ Controller is used.

RequestBody receive basic type

@ Controllerpublic class TestController {/ / url request intercept @ RequestMapping ("test/test.do") @ ResponseBody / / the return parameter is JSON public void test (@ RequestBody String name) {System.out.println ("getParams:" + name);}! [write picture description here] (https://img-blog.csdn.net/20161114115809292)}

@ RequestBody only needs to receive data from the POST request Body.

By sending the request this way, you can print in the java console:

GetParams: {"name": "micro"}

@ RequestBody receives the basic array

Then we receive an array of primitive types:

@ RequestMapping ("test/test.do") @ ResponseBody public void test (@ RequestBody List nameList) {System.out.println ("getParams:" + nameList);}

In this way, you can get the parameters. Do not write {"nameList": ["name1", "name2"]} in the body. This will throw an exception.

@ RequestBody is the body,body of the corresponding POST request, that is, the obtained parameter. If you want to obtain it through the parameter, use the @ RequestParams annotation:

RequestMapping ("test/test.do") @ ResponseBody public void test (@ RequestParam ("name") String name) {System.out.println ("getParams:" + name);}

Note that it is a GET request, and the parameter is placed directly after the URL, so that you can use @ RequestParams to get the parameter value of the corresponding parameter name. If it's a complex object.

Use of @ RequestBody.

Define model:

Class Person {private Long id; private String name; / / setter getter}

@ RequestBody receives complex objects

How to receive parameters

@ RequestMapping ("test/test.do") @ ResponseBody public void test (@ RequestBody Person person) {System.out.println ("getParams:" + person.getId () + "," + person.getName ());}

You can get the parameters, and the parameters in body will automatically match the attributes of person and assign values.

Note that the name matches the property variable name of the object. Otherwise, you can't get the parameters, for example, you can't write {"I": 1, "name": "micro"} in body, so the id of getting person is null.

@ RequestBody receives an array of complex objects

If it is an array of complex objects:

@ RequestMapping ("test/test.do") @ ResponseBody public void test (@ RequestBody List personList) {for (Person p: personList) {System.out.println (p.getId () + "," + p.getName ());}}

The request method is as follows. Note that the format in body is [] array.

Console print:

1, micro

2, micro2

This completes the @ RequestBody receiving various types of parameters.

Some considerations for using @ RequestBody

As we all know, the @ RequestBody annotation in springmvc is a very practical function, which can help us parse the json data sent by clients (mobile devices, browsers, etc.) and encapsulate it into entity classes.

But what I'm going to talk about today is not how it works, but to document some of the problems encountered in using @ RequestBody annotations in some work, and to remind java developers to avoid similar problems.

Recently, there is a need to receive the json data sent by the customer's equipment, the customer's equipment can only modify the ip, and then send the data through the post mode of the http protocol. I naturally want to handle it at the login page, adding the @ RequestBody Kehu kehu parameter to the toLogin method, and the user parses and encapsulates the json data.

Don't talk too much nonsense, go to the code, as follows:

@ RequestMapping (value = "/ toLogin") public ModelAndView toLogin (HttpServletRequest request, @ RequestBody Kehu kehu) throws Exception {/ / receive json data if (kehu! = null & &! StringUtil.isEmpty (kehu.cmd)) {uploadData (kehu);} ModelAndView mv = new ModelAndView () PageData pageData = this.getPageData (request); pageData.put ("SYSNAME", Tools.readTxtFile (Const.SYSNAME)); / / read system name mv.setViewName ("base/login"); mv.addObject ("pd", pageData); return mv;}

Everything seems perfect. Test it on the browser and type localhost (my project has been set to the default project and the port number has been changed to 80)

I was dumbfounded and reported 400 mistakes. As shown in the following figure:

The request sent by the client was syntactically incorrect.

The request sent by the client is grammatically incorrect.

It's normal before you add @ RequestBody Kehu kehu. This must be the problem. I took a look at the source code of RequestBody:

Package org.springframework.web.bind.annotation; import java.lang.annotation.Documented;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target; import org.springframework.http.converter.HttpMessageConverter; / * * Annotation indicating a method parameter should be bound to the body of the web request. * The body of the request is passed through an {@ link HttpMessageConverter} to resolve the * method argument depending on the content type of the request. Optionally, automatic * validation can be applied by annotating the argument with {@ code @ Valid}. * *

Supported for annotated handler methods in Servlet environments. * * @ author Arjen Poutsma * @ since 3.0 * @ see RequestHeader * @ see ResponseBody * @ see org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter * @ see org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter * / @ Target (ElementType.PARAMETER) @ Retention (RetentionPolicy.RUNTIME) @ Documentedpublic @ interface RequestBody {/ * Whether body content is required. *

Default is {@ code true}, leading to an exception thrown in case * there is no body content. Switch this to {@ code false} if you prefer * {@ code null} to be passed when the body content is {@ code null}. * @ since 3.2 * / boolean required () default true;}

The default return value of the required method is true.

This makes it clear that when I asked for localhost, I didn't send json, so I reported a 400th error because the request sent by the client was syntactically incorrect.

Solution: add (required=false) after @ RequestBody. Indicates that the kehu object can not be passed in.

/ * access the login page * @ RequestBody (required=false) means that the kehu object can not be passed in. * be sure to add required=false, otherwise you will report a 400th error when logging in. Error code: * The request sent by the client was syntactically incorrect. * @ return * @ throws Exception * / @ RequestMapping (value = "/ toLogin") public ModelAndView toLogin (HttpServletRequest request, @ RequestBody (required=false) Kehu kehu) throws Exception {/ / receive json data if (kehu! = null & &! StringUtil.isEmpty (kehu.cmd)) {uploadData (kehu) } ModelAndView mv = new ModelAndView (); PageData pageData = this.getPageData (request); pageData.put ("SYSNAME", Tools.readTxtFile (Const.SYSNAME)); / / read system name mv.setViewName ("base/login"); mv.addObject ("pd", pageData); return mv At this point, the study of "SpringMVC @ RequestBody usage Analysis" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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