SpringMVC（三）@PathVariable

使用@PathVariable可以快速的访问，URL中的部分内容。

①. 在@RequestMapping的value中使用URI template（{变量名}），然后在@RequestMapping注解方法的需要绑定的参数前，使用@PathVariable指定变量名（如果变量名和参数名一致也可以不指定），从而将URL中的值绑定到参数上。

代码：

   1: @RequestMapping("/testPathVariable")

   2: @Controller

   3: public class TestPathVariable {

   4:  

   5:     /*

   6:     * URI模板指定了一个变量名为id的变量，当控制器处理请求时会将 id 替换为正确的值

   7:     *

   8:     * 若请求为 testPathVariable/user/29，则uid=29，输出29

   9:     *

  10:     * */

  11:     @RequestMapping("/user/{id}")

  12:     public String testPathVariable(@PathVariable("id") Integer uid) {

  13:         System.out.println(uid);

  14:         return "success";

  15:     }

  16:  

  17: }

URL:

   1: <a href="testPathVariable/user/29">testPathVariable user 29</a>

②. 一个方法可以有多个@PathVriable注解

URI template 可以这样，全部在方法上

代码：

   1: @RequestMapping("/testPathVariable")

   2: @Controller

   3: public class TestPathVariable {

   4:  

   5:     @RequestMapping("/user/{uid}/book/{bid}")

   6:     public String testMultiplePathVariable(@PathVariable("uid") Integer uid,@PathVariable("bid") Integer bid) {

   7:         System.out.println(uid);

   8:         System.out.println(bid);

   9:         return "success";

  10:     }

  11:  

  12: }

URL:

   1: <a href="testPathVariable/user/29/book/101">testPathVariable user 29 book 101</a>

URI template还可以这样， 加在类和方法上

代码：

   1: @RequestMapping("/testPathVariable/user/{uid}")

   2: @Controller

   3: public class TestPathVariable {

   4:  

   5:     @RequestMapping("/book/{bid}")

   6:     public String testMultiplePathVariable(@PathVariable("uid") Integer uid, @PathVariable("bid") Integer bid) {

   7:  

   8:         System.out.println(uid);

   9:         System.out.println(bid);

  10:         return "success";

  11:     }

  12:  

  13: }

URL:

   1: <a href="testPathVariable/user/29/book/101">testPathVariable user 29 book 101</a>

③. @PathVariable 还可以使用在 map 参数上，但是必须配置<mvc:annotation-driven />

代码：

   1: @RequestMapping("/testPathVariable/user/{uid}")

   2: @Controller

   3: public class TestPathVariable {

   4:  

   5:     @RequestMapping("/book/{bid}")

   6:     public String testMultiplePathVariable_Map(@PathVariable Map<String, String> map) {

   7:         System.out.println(map.get("uid"));

   8:         System.out.println(map.get("bid"));

   9:         return "success";

  10:     }

  11:     

  12: }

URL：

   1: <a href="testPathVariable/user/29/book/101">testPathVariable user 29 book 101</a>

applicationContext.xml

   1: <mvc:annotation-driven></mvc:annotation-driven>

④. URI template 还支持正则表达式 。具体请看API

⑤. 使用@PathVariable可以让我们进行REST风格的编程，简单理解REST：对网络中某一资源的操作使用一个URI进行表示，然后使用状态来（GET、POST、PUT、DELETE）表示某种操作

原来对user进行CURD	使用了@PathVariable之后的CRUD
/user/get?id=10 /user/post?… /user/update?id=10… /user/delete?id=10	/user/id=10                RequestMethod.GET /user/…                       RequestMethod.POST /user/id=10…            RequestMethod.PUT /user/id=10               RequestMethod.DELETE

为了使普通表单支持PUT、DELETE请求，可以在POST请求下添加一个隐藏域（<input type="hidden" name="_method" value="PUT、DELETE"/>），然后在web.xml中配置HiddenHttpMethodFilter

对某用户的订单进行CRUD，代码：

   1: @RequestMapping("/testPathVariable/user/{uid}")

   2: @Controller

   3: public class TestPathVariable {

   4:  

   5:     /*

   6:     *获取某用户的所有订单

   7:     * */

   8:     @RequestMapping(value = "/order", method = RequestMethod.GET)

   9:     public String testGET(@PathVariable Integer uid) {

  10:         System.out.println("GET: " + " user-" + uid);

  11:         return "success";

  12:     }

  13:  

  14:     /*

  15:     * 获取某用户的某个订单详情

  16:     * */

  17:     @RequestMapping(value = "/order/{oid}", method = RequestMethod.GET)

  18:     public String testGET_OID(@PathVariable Integer uid, @PathVariable Integer oid) {

  19:         System.out.println("GET_OID: " + " user-" + uid + " order-" + oid);

  20:         return "success";

  21:     }

  22:  

  23:     /*

  24:     * 修改某用户的某个订单的总价

  25:     * params = {"total"}

  26:     *   若加params，则请求中必须有该变量,没有会报错。

  27:     *   如果不加params，则请求中不强制要求包含该变量

  28:     *   不包含时，则parameter中的对应变量值为为Null，

  29:     *       如请求/testPathVariable/user/29/order/101    

  30:     *       则total=null

  31:     *   包含，则parameter中的对应变量值为请求中的值

  32:     *       如请求/testPathVariable/user/29/order/101?total=1000   

  33:     *       则total=1000

  34:     * */

  35:     @RequestMapping(value = "/order/{oid}", method = RequestMethod.PUT, params = {"total"})

  36:     public String testPUT(@PathVariable Integer uid, @PathVariable Integer oid, Integer total) {

  37:         System.out.println("PUT: " + " user-" + uid + " order-" + oid);

  38:         System.out.println(total);

  39:         return "success";

  40:     }

  41:  

  42:     /*

  43:     * 新增某用户的订单,变量略

  44:     * */

  45:     @RequestMapping(value = "/order", method = RequestMethod.POST)

  46:     public String testPOST_(@PathVariable Integer uid) {

  47:         System.out.println("POST: " + " user-" + uid + " order：订单信息");

  48:         return "success";

  49:     }

  50:  

  51:     /*

  52:     * 删除某用户的某个订单

  53:     * */

  54:     @RequestMapping(value = "/order/{oid}", method = RequestMethod.DELETE)

  55:     public String testDELETE(@PathVariable Integer uid, @PathVariable Integer oid) {

  56:         System.out.println("GET: " + " user-" + uid + " order-" + oid);

  57:         return "success";

  58:     }

  59: }

index.jsp:

   1:  

   2: <form action="testPathVariable/user/29/order/101" method="post">

   3:     <input type="hidden" name="_method" value="DELETE"/><br/>

   4:     <input type="submit" value="删除ID为29用户的ID为101的订单"/>

   5: </form>

   6:  

   7: <br/><br/>

   8: <form action="testPathVariable/user/29/order" method="post">

   9:     输入订单信息....<br/>

  10:     <input type="submit" value="ID为29用户新增订单"/>

  11: </form>

  12:  

  13: <br/><br/>

  14:  

  15: <form action="testPathVariable/user/29/order/101" method="post">

  16:     <input type="hidden" name="_method" value="put"/><br/>

  17:     <input type="text" name="total"/><br/>

  18:     <input type="submit" value="修改ID为29用户，ID为101订单的总价"/>

  19: </form>

  20:  

  21: <br/><br/>

  22:  

  23:  

  24: <a href="testPathVariable/user/29/order">获取ID为29用户的所有订单</a>

  25:  

  26: <br/><br/>

  27:  

  28: <a href="testPathVariable/user/29/order/101">获取ID为29的用户，ID为101的订单的详情</a>

  29:  

  30: <br/><br/>

  31:  

在web.xml中配置HiddenHttpMethodFilter：

   1: <filter>

   2:     <filter-name>hiddenHttpMethodFilter</filter-name>

   3:     <filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filter-class>

   4: </filter>

   5: <filter-mapping>

   6:     <filter-name>hiddenHttpMethodFilter</filter-name>

   7:     <url-pattern>/*</url-pattern>

   8: </filter-mapping>