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