REST and a RESTful:
REST: presentation layer state transition, resource state transition in the network in some form.
RESTful REST is a style of development based on the concept, the development of specific rules.
Server returns only data, or to json xml format.
RESTful development specifications:
• Use a URL as user interaction entrance
• explicit semantic specification (GET | POST | PUT | DELETE)
• returns only the data (JSON | XML), contains no show
RESTful naming requirements:
1. The first RESTful application
@Controller @RequestMapping ( "/ RESTful") // the URL is all nouns public class RestfulController { @GetMapping (value = "/ Request", Produces = "file application / JSON; charset = UTF-. 8" ) @ResponseBody public doGetRequest String () { return "{\" Message \ ": \" test \ "}"; // use \ output Yoshito } }
2. To achieve RESTful laboratory
General PC and mobile terminal can call API interface, the following analog PC end calls, use Ajax:
Send page via ajax request:
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>RESTful</title> <script src="jquery-3.4.1.min.js"></script> <script> $(function () { $("#btnGet").click(function () { $.ajax({ url : "/restful/request", type : "get", dataType : "json", success : function (json) { $("#message").text(json.message) } }) }) }) </script> </head> <body> <input type="button" id="btnGet" value="发送Get请求"> <h2 id="message"></h2> </body> </html>
Because the definition of the root directory of the webapp as static files, so client.html can be accessed directly.
Actually produced a garbled view the request header found the use of incorrect character set.
<mvc:annotation-driven> <mvc:message-converters> <bean class="org.springframework.http.converter.StringHttpMessageConverter"> <property name="supportedMediaTypes"> <list> <value>test/html;charset=utf-8</value> <!--通知浏览器以这种格式加载数据--> <value>application/json;charset=utf-8</value> </list> </property> </bean> </mvc:message-converters> </mvc:annotation-driven>
Add the above configuration on it. (Ajax can only solve the garbage problem)
3.RestController Notes and path variables
（1）RestController
@Controller @RequestMapping ( "/ RESTful") // the URL is all nouns public class RestfulController { @GetMapping (value = "/ Request", Produces = "file application / JSON; charset = UTF-. 8" ) @ResponseBody public doGetRequest String () { return "{\" Message \ ": \" test \ "}"; // use \ output Yoshito } }
If we want to return the plain text data, we must use @ResponseBody this comment.
If we use @RestController this annotation, then the following methods are all class returns plain text data.
@RestController @RequestMapping ( "/ RESTful") // the URL is all nouns public class RestfulController { @GetMapping (value = "/ Request", Produces = "file application / JSON; charset = UTF-. 8" ) public String doGetRequest () { return "{\" Message \ ": \" test \ "}"; // use \ output Yoshito } }
@RestController can help us simplify development.
(2) Path Variable
/ Request / 1 for variables in the URL we can call path variable. So how do you value it?
@RestController @RequestMapping("/restful") //URL中所有的都是名词 public class RestfulController { @GetMapping(value = "/request/{rid}",produces = "application/json;charset=utf-8") public String doGetRequest(@PathVariable("rid") Integer requestId){ System.out.println(requestId); return "{\"message\":\"测试\"}"; //使用\原义输出 } }
Annotations using @PathVariable receive path variable, and then assigned to the parameter method.
4.JSON serialization
(1) the step of introducing
Introducing dependencies:
< Dependency > < groupId > com.fasterxml.jackson.core </ groupId > < artifactId > jackson-Core </ artifactId > <-! Be sure to use later versions 2.9.9, or there will be security issues -> < Version > 2.9.9 </ Version > </ dependency > <-! root causes jackson interact with the target object -> < dependency > < groupId > com.fasterxml.jackson.core </ groupId > <artifactId>jackson-databind</artifactId> <version>2.9.9</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <version>2.9.9</version> </dependency>
spring is smart, as long as the check jackson-core and jackson-databind these two dependencies.
Jackson is automatically enabled us to provide json serialization services.
Create entity classes:
public class Person { private String name; private String address; }
Write controller:
@GetMapping ( "/ Person / PID {}" )
public the Person findByPersonId (@PathVariable ( "PID" ) Integer the personId) {
the Person Person = new new the Person ();
IF (the personId ==. 1 ) {
person.setName ( "Kobe" );
person.setAddress ( "Luotian" );
} the else IF (the personId == 2 ) {
person.setName ( "Yeh" );
person.setAddress ( "Hubei Anlu" );
} the else {
person.setName ( "Anonymous" );
}
return person;
}
If we return to a solid object, and configure the @RestController or @ResponseBody, then jackson will automatically provide serialization services.
access:
(2) a plurality of objects Returns
If a return multiple objects, we can List collection:
@GetMapping("/persons")
public List<Person> findPersons(){
List list = new ArrayList();
Person p1 = new Person();
p1.setName("科比");
p1.setAddress("湖北罗田");
Person p2 = new Person();
p2.setName("科比");
p2.setAddress("湖北罗田");
list.add(p1);
list.add(p2);
return list;
}
In the front end, we will receive the following data:
In the page, we can extract the following manner:
$(function () { $("#btnPersons").click(function () { $.ajax({ url : "/restful/persons", type : "get", datatype : "json", success : function (json) { console.info(json) for(var i=0;i<json.length;i++){ var p = json[i]; $("#divPersons").append("<h2>" + p.name + "-" + p.address + "</h2>") } } }) }) })
(3) Processing time
Note that, jackson not friendly to time to deal with:
Add an event attribute:
Private a Date Birthday;
if not treated, is the direct return in the form of stamp events.
We only need to add the corresponding time annotations:
@JsonFormat (pattern = "the MM-dd-YYYY HH: mm: SS")
Private a Date Birthday;
normal output of:
Note that there is time to use the default Green, specify the time zone:
@JsonFormat (pattern = "the MM-dd-YYYY HH: mm: SS", TimeZone = "GMT +. 8")
Private a Date Birthday;
5. The browser's same-origin policy
Origin policy: to prevent access to resources on another domain from a domain script loaded.
Two different domain websites can not be accessed by Ajax, this is due to security considerations.
For example, the following two addresses, although essentially a page, but it belongs to a different source.
As long as the protocol, domain name, port any different, are as different domains.
Browser Console see Access-Control-Allow-Origin represents a cross-domain.
HTML tags allowed cross-domain:
<IMG> explicit remote image
<script> Remote loading the JS
<Link> Remote loading CSS
6.SpringMVC solve cross-domain
CORS is a mechanism to use additional HTTP header tells the browser to access other domains.
URL response header included in Access-Control- * allowed cross-domain request specified.
(1) @CrossOrigin - Controller across domains comment
@RestController @RequestMapping("/restful") @CrossOrigin(origins = {"*"}) public class RestfulController { @GetMapping(value = "/request/{rid}",produces = "application/json;charset=utf-8") public String doGetRequest(@PathVariable("rid") Integer requestId){ System.out.println(requestId); return "{\"message\":\"测试\"}"; } }
(2) <mvc: cors> Spring MVC Global cross-domain configuration
<MVC: CORS>
<- path which path to allow cross-domain access -!>
<- who is allowed allowed Origins-domain access -!>
<- - Age-set buffer time max!>
< MVC: Mapping path = "*" allowed-Origins = "*" />
</ MVC: CORS>