SpringMVC注解-Annotated Controllers
目录：
1.简介
SpringMVC provides an annotation-based programming model where @Component and @RestContrller components use annotations to express request mappings, request input, exception handling,and more.Annotated controllers have flexible method signatures and do not have to extend
2.springmvc常用注解
@RequestParam
@RequestParam annotations to bind servlet request parameters (query paramters , form data) to a method argument in a controller.（key-value. form data(表单数据)也是以key-value传输的）
type conversion is automatically applied if the target method parameter type is not String.
when an @RequestParam annotation declared as a Map<String,String> or MultiValueMap<String,String> argument, the map is populated with all request parameters.
注意：@RequestParam适用于，请求Content-type:text/plan; 或者application/x-www.form-urlencoded。对于form表单来说，post提交会将key-value放在body体中。而get提交会将key-value放在url后面
@RequestParam注解用来处理Content-Type: 为 application/x-www-form-urlencoded编码的内容。提交方式为get或post。（Http协议中，form的enctype属性为编码方式，常用有两种：application/x-www-form-urlencoded和multipart/form-data，默认为application/x-www-form-urlencoded）；
@RequestParam注解实质是将Request.getParameter() 中的Key-Value参数Map利用Spring的转化机制ConversionService配置，转化成参数接收对象或字段， get方式中queryString的值，和post方式中body data的值都会被Servlet接受到并转化到Request.getParameter()参数集中，所以@RequestParam可以获取的到；
该注解有三个属性： value、required、defaultValue； value用来指定要传入值的id名称，required用来指示参数是否必录，defaultValue表示参数不传时候的默认值。
@Controller
@RequestMapping(value="/user",method={HttpRequestMethod.POST,HttpRequestMethod.GET})
public class UserController{
/**
* 获取单个请求参数
*/
@RequsetMapping(value="/getInfo")
@ResponseBody
public User getUser(@RequestParam("name")String name){
// service
return user;
}
}
@Controller
@RequestMapping(value="/user",method={HttpRequestMethod.POST,HttpRequestMethod.GET})
public class UserController{
/**
* 获取全部请求参数
*/
@RequsetMapping(value="/getInfo")
@ResponseBody
public User getUser(@RequestParam Map<String,String> params){
// service
return user;
}
}
@Controller
@RequestMapping(value="/user",method={HttpRequestMethod.POST,HttpRequestMethod.GET})
public class UserController{
/**
* POST
* content-type:application/x-www-urlencoded
* form表单单数与User字段属性对应
*/
@RequsetMapping(value="/addUser",method={RequestMethod.POST})
@ResponseBody
public User addUser(User user){
// service
return user;
}
}
@RequestBody
you can use the @RequestBody annotation to have the request body read and deserialized info an Object through HttpMessageConverter.
@Controller
@RequestMapping(value="/user",method={HttpRequestMethod.POST,HttpRequestMethod.GET})
public class UserController{
/**
* 请求参数转为对象
*/
@RequsetMapping(value="/add")
@ResponseBody
public HttpEntity<Boolean> addUser(@RequestBody User user){
return HttpEntity.success();
}
/**
* 前端请求参数为单个: 名称id
*/
@RequsetMapping(value="/add")
@ResponseBody
public HttpEntity<Boolean> addUser(@RequestBody Map<String,String> param){
String id = param.get("id");
return HttpEntity.success();
}
}
@RequestBody常用来处理Content-type:application/json格式的请求。
需要在pom.xml和springmvc-servlet.xml中配置
pom.xml
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>${jackson.version}</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>${jackson.version}</version>
</dependency>
springmvc-servlet.xml
<mvc:annotation-driven>
<!-- @ResponseBody 数据集合的转换-->
<mvc:message-converters>
<bean class="org.springframework.http.converter.StringHttpMessageConverter"/>
<bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"/>
</mvc:message-converters>
</mvc:annotation-driven>
@RequestHeader
获取Http请求头部信息
if the target method parameter is not String , type conversion is automatically applied.
@GetMapping("/demo")
public void handle(@RequestHeader("Accept-Encoding")String encoding,
@RequestHeader("keep-Alive")Long keepAlive){
//...
}
when an @RequestHeader annotation is used on a MapHttpHeaders,the map is populated with all header values.
Built-in support is avaliable for converting a comma-sperated string into an array or collection of strings or other types known to the type conversion system.For example, a method parameter annotated with @RequestHeader("Accept") can be of type String but also String[] or List<String>
@GetMapping("/demo")
public void handle(@RequestHeader("Accept")String[] accpet){
//...
}
@CookieValue
获取cookie值
@GetMapping("/demo")
public void handle(@CookieValue("JSESSIONID")String cookie){
//...
}