spring3 的restful API RequestMapping介绍

原文链接：http://www.javaarch.net/jiagoushi/694.htm

spring3 的restful API RequestMapping介绍

在spring mvc中 @RequestMapping是把web请求映射到controller的方法上。

1.RequestMapping Basic Example
  将http请求映射到controller方法的最直接方式
1.1 @RequestMapping  by Path
 
	@RequestMapping(value = "/foos")
	@ResponseBody
	public String getFoosBySimplePath() {
		return "Get some Foos";
	}
	
可以通过下面的方式测试： curl -i http://localhost:8080/springmvc/foos

1.2 @RequestMapping – the HTTP Method，我们可以加上http方法的限制

	@RequestMapping(value = "/foos", method = RequestMethod.POST)
	@ResponseBody
	public String postFoos() {
		return "Post some Foos";
	}
	
可以通过curl i -X POST http://localhost:8080/springmvc/foos测试。

2.RequestMapping 和http header

2.1 @RequestMapping with the headers attribute
  当request的header包含某个key value值时
	
	@RequestMapping(value = "/foos", headers = "key=val")
	@ResponseBody
	public String getFoosWithHeader() {
		return "Get some Foos with Header";
	}
	
  header多个字段满足条件时
  
	@RequestMapping(value = "/foos", headers = { "key1=val1", "key2=val2" })
	@ResponseBody
	public String getFoosWithHeaders() {
		return "Get some Foos with Header";
	}
	
通过curl -i -H "key:val" http://localhost:8080/springmvc/foos 测试。

2.2 @RequestMapping 和Accept头

	@RequestMapping(value = "/foos", method = RequestMethod.GET, headers = "Accept=application/json")
	@ResponseBody
	public String getFoosAsJsonFromBrowser() {
		return "Get some Foos with Header Old";
	}
支持accept头为json的请求，通过curl -H "Accept:application/json,text/html" http://localhost:8080/springmvc/foos测试

在spring3.1中@RequestMapping注解有produces和 consumes 两个属性来代替accept头

	@RequestMapping(value = "/foos", method = RequestMethod.GET, produces = "application/json")
	@ResponseBody
	public String getFoosAsJsonFromREST() {
		return "Get some Foos with Header New";
	}
同样可以通过curl -H "Accept:application/json" http://localhost:8080/springmvc/foos测试

produces可以支持多个

	@RequestMapping(value = "/foos", produces = { "application/json", "application/xml" })
	
当前不能有两个方法同时映射到同一个请求，要不然会出现下面这个异常

	Caused by: java.lang.IllegalStateException: Ambiguous mapping found. 
	Cannot map 'fooController' bean method
	public java.lang.String org.baeldung.spring.web.controller.FooController.getFoosAsJsonFromREST()
	to {[/foos],methods=[GET],params=[],headers=[],consumes=[],produces=[application/json],custom=[]}: 
	There is already 'fooController' bean method
	public java.lang.String org.baeldung.spring.web.controller.FooController.getFoosAsJsonFromBrowser() 
	mapped.
	
3.RequestMapping with Path Variables
3.1我们可以把@PathVariable把url映射到controller方法
	单个@PathVariable参数映射
	
	@RequestMapping(value = "/foos/{id}")
	@ResponseBody
	public String getFoosBySimplePathWithPathVariable(@PathVariable("id") long id) {
	   return "Get a specific Foo with id=" + id;
	}

通过curl http://localhost:8080/springmvc/foos/1试试
如果参数名跟url参数名一样，可以省略为

	@RequestMapping(value = "/foos/{id}")
	@ResponseBody
	public String getFoosBySimplePathWithPathVariable(@PathVariable String id) {
	   return "Get a specific Foo with id=" + id;
	}
3.2 多个@PathVariable
  
    @RequestMapping(value = "/foos/{fooid}/bar/{barid}")
	@ResponseBody
	public String getFoosBySimplePathWithPathVariables(@PathVariable long fooid, @PathVariable long barid) {
		return "Get a specific Bar with id=" + barid + " from a Foo with id=" + fooid;
	}
	
通过curl http://localhost:8080/springmvc/foos/1/bar/2测试。

3.3支持正则的@PathVariable 
  
    @RequestMapping(value = "/bars/{numericId:[\\d]+}")
	@ResponseBody
	public String getBarsBySimplePathWithPathVariable(@PathVariable final long numericId) {
		return "Get a specific Bar with id=" + numericId;
	}

这个url匹配：http://localhost:8080/springmvc/bars/1
不过这个不匹配：http://localhost:8080/springmvc/bars/abc

4.RequestMapping with Request Parameters

我们可以使用 @RequestParam注解把请求参数提取出来
比如url：http://localhost:8080/springmvc/bars?id=100

	@RequestMapping(value = "/bars")
	@ResponseBody
	public String getBarBySimplePathWithRequestParam(@RequestParam("id") long id) {
		return "Get a specific Bar with id=" + id;
	}
	
我们可以通过RequestMapping定义参数列表

	@RequestMapping(value = "/bars", params = "id")
	@ResponseBody
	public String getBarBySimplePathWithExplicitRequestParam(@RequestParam("id") long id) {
		return "Get a specific Bar with id=" + id;
	}
	
和

	@RequestMapping(value = "/bars", params = { "id", "second" })
	@ResponseBody
	public String getBarBySimplePathWithExplicitRequestParams(@RequestParam("id") long id) {
		return "Narrow Get a specific Bar with id=" + id;
	}
	
比如http://localhost:8080/springmvc/bars?id=100&second=something会匹配到最佳匹配的方法上，这里会映射到下面这个。

5.RequestMapping Corner Cases

5.1 @RequestMapping多个路径映射到同一个controller的同一个方法

	@RequestMapping(value = { "/advanced/bars", "/advanced/foos" })
	@ResponseBody
	public String getFoosOrBarsByPath() {
		return "Advanced - Get some Foos or Bars";
	}
	
下面这两个url会匹配到同一个方法

	curl -i http://localhost:8080/springmvc/advanced/foos
	curl -i http://localhost:8080/springmvc/advanced/bars
	
5.2@RequestMapping 多个http方法 映射到同一个controller的同一个方法

	@RequestMapping(value = "/foos/multiple", method = { RequestMethod.PUT, RequestMethod.POST })
	@ResponseBody
	public String putAndPostFoos() {
		return "Advanced - PUT and POST within single method";
	}
下面这两个url都会匹配到上面这个方法

	curl -i -X POST http://localhost:8080/springmvc/foos/multiple
	curl -i -X PUT http://localhost:8080/springmvc/foos/multiple
	
5.3@RequestMapping 匹配所有方法

	@RequestMapping(value = "*")
	@ResponseBody
	public String getFallback() {
		return "Fallback for GET Requests";
	}

匹配所有方法
	
	@RequestMapping(value = "*", method = { RequestMethod.GET, RequestMethod.POST ... })
	@ResponseBody
	public String allFallback() {
		return "Fallback for All Requests";
	}
	
6.Spring Configuration

controller的annotation

	@Controller
	public class FooController { ... }
	
spring3.1

	@Configuration
	@EnableWebMvc
	@ComponentScan({ "org.baeldung.spring.web.controller" })
	public class MvcConfig {
		//
	}
	
可以从这里看到所有的示例https://github.com/eugenp/tutorials/tree/master/springmvc