SpringMVC（四）:接收参数的方式

一.SpringMVC参数接收思维导图

 

二.接收参数实例

1.普通方式接受参数

1.1.控制端代码

@Controller
@RequestMapping("requestParam")
public class RequestParamsController {

    @RequestMapping("requestParam")
    public ModelAndView requestParams( String user_id){
        System.out.println("user_id:"+userId);
        ModelAndView mv = new ModelAndView();
        mv.setViewName("/springMVC/paramRequest/RequestParams");
        return mv;
    }
}

1.2.前端jsp代码

<form action="<%=path%>/param/commonParam">
    <input type="text" name="user_id">
    <input type="text" name="user_password">
    <input type="submit" value="提交">
</form>

1.3.提交之后便会看到结果输出，两端参数名字相同才能接收，view端name为h5中input的name属性。

2.RequestParam接收参数

2.1.控制端代码

@Controller
@RequestMapping("requestParam")
public class RequestParamsController {

    @RequestMapping("requestParam")
    public ModelAndView requestParams(@RequestParam(value = "user_id",required = false) String userId){
        System.out.println("user_id:"+userId);
        ModelAndView mv = new ModelAndView();
        mv.setViewName("/springMVC/paramRequest/RequestParams");
        return mv;
    }
}

2.2.前端jsp代码

<form action="<%=path%>/requestParam/requestParam">
    <input type="text" name="user_id">
    <input type="text" name="user_password">
    <input type="submit" value="提交">
</form>

2.3.view端name为h5中input的name属性，@RequestParam默认参数不为空，否则会出现400异常，需要为空，则设置:@RequestParam(value = "user_id",required = false)

3.使用URL传递参数

3.1.控制端代码

@Controller
@RequestMapping("urlParam")
public class UrlParamsController {

    @RequestMapping("/urlParam/{id}")
    public ModelAndView urlParams(@PathVariable("id") int id){
        User user = new User();
        user.setUserId(String.valueOf(id));
        ModelAndView mv = new ModelAndView();
        mv.addObject(user);
        mv.setView(new MappingJackson2JsonView());
        return mv;

    }
}

3.2.前端没有代码，直接使用new MappingJackson2JsonView()显示数据，注意其只能返回显示对象类型数据，该方法在org.springframework.web.servlet.view.json.MappingJackson2JsonView包下；@PathVariable表示从URL请求地址中获取的参数，允许为空。

4.传递JSON数据

4.1.前端代码,引入JQ.

<script>
        $(document).ready(function () {
            $("#start").click(function () {
                alert("点击了");
                var user={
                        userId: "e",
                        userNickName: "hly",
                        userPassword: "qq",

                    }
                $.ajax({
                    url:"<%=path%>/jsonParam/jsonParam/",
                    type : "POST",
                    data:JSON.stringify(user),
                    contentType:'application/json',
                    dataType : 'json',
                    beforeSend : function () {
                        console.log(user);
                    },
                    success:function () {
                        alert("传递成功");
                    },
                    error:function () {
                        alert("错误了");
                    }
                });
            });
        });
    </script>

1.contentType:发送什么类型的数据到服务器,dataType:服务器返回的是什么类型的数据。

2.可能会出现的错误:

2.1.400错误:前端传递过来的属性和后端不一致.

2.2.414错误:

2.2.1.前端JSON属性必须和传递的pojo的属性对应，顺序无所谓，属性名字一直就行.

2.2.2.前端ajax里的关键字区分大小写（重点），否则也会出现404错误.

2.2.3.需要添加相关的JSONjar.

4.2.后端代码

@RequestMapping("jsonParam")
    public ModelAndView jsonParam(@RequestBody User user) {

        System.out.println(user.toString());
        ModelAndView mv = new ModelAndView();
        //mv.addObject(json);
        mv.setView(new MappingJackson2JsonView());
        return mv;
    }

4.3.pojo的属性

public class User {
    private String userId;
    private String userNickName;
    private String userPassword;
    }

4.4.springMVC的配置

    <!--使用注解驱动,没有就不能扫描@Controller,就会出现404-->
    <!-- 一个配置节解决映射器和适配器的配置注解配置 -->
    <mvc:annotation-driven></mvc:annotation-driven>

    <!--是用于**那些已经在spring容器里注册过的bean-->
    <context:annotation-config />

    <!--定义扫描装载的包-->
    <!--具有<context:annotation-config>的功能-->
    <context:component-scan base-package="com.*"></context:component-scan>

4.5.JSON的maven依赖，spring版本是4.0

<dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.2.3</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.2.3</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>2.2.3</version>
        </dependency>

        <!-- 各种json 配置开始 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.7</version>
        </dependency>
        <dependency>
            <groupId>org.json</groupId>
            <artifactId>json</artifactId>
            <version>20150729</version>
        </dependency>
        <dependency>
            <groupId>org.codehaus.jackson</groupId>
            <artifactId>jackson-mapper-asl</artifactId>
            <version>1.9.13</version>
        </dependency>

5.接收列表和表单数据

5.1.前端代码

<form id="form">
    <input type="text" name="userId">
    <input type="text" name="userPassword">
    <input type="submit" name="submit" id="submit">
    </form>

将表单数据转化为字符串传递给后端

$("#submit").click(function () {
                var str = $("form").serialize();
                $.ajax({
                    url: "<%=path%>/listParam/formParam/",
                    type: "POST",
                    data: str,
                });
            });

5.2.后端代码

@RequestMapping("formParam")
    public ModelAndView formParams(String userId,String userPassword){
        System.out.println(userId+" "+userPassword);
        ModelAndView mv = new ModelAndView();
        return mv;

    }

前后端传递的标识符保持一致

完整代码请在笔者github中查看