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：

@RequestMapping("/testPathVariable")
@Controller
public class TestPathVariable {

    /*
    * 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
    *
    * 若请求为 testPathVariable/user/29，则uid=29，输出29
    *
    * */
    @RequestMapping("/user/{id}")
    public String testPathVariable(@PathVariable("id") Integer uid) {
        System.out.println(uid);
        return "success";
    }

}

URL:

<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：

@RequestMapping("/testPathVariable")
@Controller
public class TestPathVariable {

    @RequestMapping("/user/{uid}/book/{bid}")
    public String testMultiplePathVariable(@PathVariable("uid") Integer uid,@PathVariable("bid") Integer bid) {
        System.out.println(uid);
        System.out.println(bid);
        return "success";
    }

}

URL:

<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：

@RequestMapping("/testPathVariable/user/{uid}")
@Controller
public class TestPathVariable {

    @RequestMapping("/book/{bid}")
    public String testMultiplePathVariable(@PathVariable("uid") Integer uid, @PathVariable("bid") Integer bid) {

        System.out.println(uid);
        System.out.println(bid);
        return "success";
    }

}

URL:

<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：

@RequestMapping("/testPathVariable/user/{uid}")
@Controller
public class TestPathVariable {

    @RequestMapping("/book/{bid}")
    public String testMultiplePathVariable_Map(@PathVariable Map<String, String> map) {
        System.out.println(map.get("uid"));
        System.out.println(map.get("bid"));
        return "success";
    }

}

URL：

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

applicationContext.xml

<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：

@RequestMapping("/testPathVariable/user/{uid}")
@Controller
public class TestPathVariable {

    /*
    *获取某用户的所有订单
    * */
    @RequestMapping(value = "/order", method = RequestMethod.GET)
    public String testGET(@PathVariable Integer uid) {
        System.out.println("GET: " + " user-" + uid);
        return "success";
    }

    /*
    * 获取某用户的某个订单详情
    * */
    @RequestMapping(value = "/order/{oid}", method = RequestMethod.GET)
    public String testGET_OID(@PathVariable Integer uid, @PathVariable Integer oid) {
        System.out.println("GET_OID: " + " user-" + uid + " order-" + oid);
        return "success";
    }

    /*
    * 修改某用户的某个订单的总价
    * params = {"total"}
    *   若加params，则请求中必须有该变量,没有会报错。
    *   如果不加params，则请求中不强制要求包含该变量
    *   不包含时，则parameter中的对应变量值为为Null，
    *       如请求/testPathVariable/user/29/order/101
    *       则total=null
    *   包含，则parameter中的对应变量值为请求中的值
    *       如请求/testPathVariable/user/29/order/101?total=1000
    *       则total=1000
    * */
    @RequestMapping(value = "/order/{oid}", method = RequestMethod.PUT, params = {"total"})
    public String testPUT(@PathVariable Integer uid, @PathVariable Integer oid, Integer total) {
        System.out.println("PUT: " + " user-" + uid + " order-" + oid);
        System.out.println(total);
        return "success";
    }

    /*
    * 新增某用户的订单,变量略
    * */
    @RequestMapping(value = "/order", method = RequestMethod.POST)
    public String testPOST_(@PathVariable Integer uid) {
        System.out.println("POST: " + " user-" + uid + " order：订单信息");
        return "success";
    }

    /*
    * 删除某用户的某个订单
    * */
    @RequestMapping(value = "/order/{oid}", method = RequestMethod.DELETE)
    public String testDELETE(@PathVariable Integer uid, @PathVariable Integer oid) {
        System.out.println("GET: " + " user-" + uid + " order-" + oid);
        return "success";
    }
}

index.jsp:

<form action="testPathVariable/user/29/order/101" method="post">
    <input type="hidden" name="_method" value="DELETE"/><br/>
    <input type="submit" value="删除ID为29用户的ID为101的订单"/>
</form>

<br/><br/>
<form action="testPathVariable/user/29/order" method="post">
    输入订单信息....<br/>
    <input type="submit" value="ID为29用户新增订单"/>
</form>

<br/><br/>

<form action="testPathVariable/user/29/order/101" method="post">
    <input type="hidden" name="_method" value="put"/><br/>
    <input type="text" name="total"/><br/>
    <input type="submit" value="修改ID为29用户，ID为101订单的总价"/>
</form>

<br/><br/>


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

<br/><br/>

<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>

<br/><br/>

在web.xml中配置HiddenHttpMethodFilter：

<filter>
    <filter-name>hiddenHttpMethodFilter</filter-name>
    <filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>hiddenHttpMethodFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>