SpringMVC Controller接收参数总结（将请求的参数绑定到controller的方法上）

问题背景：Spring项目框架，声明一个class为Controller，对外提供接口。如何将Ajax调用的http请求中的参数绑定到controller方法中的参数上。

基本数据类型

SpringMVC Controller各方法参数绑定首先支持Java所有基本类型（包括： byte、short、int、long、float、double、char、string、boolean），以及基本类型对应封装高级类（包括：StringBuilder、StringBuffer）。

代码示例如下所示（这里仅以int及Integer类型做例子，其他类型实现方式与此类同）：

@Controller
@RequestMapping("param")
public class ParamController {
    @RequestMapping(value="/int", method=RequestMethod.POST)
    @ResponseBody
    public String requestInt(int param) {
        return "Request successful. Post param : Int - " + param;
    }
    @RequestMapping(value="/integer", method=RequestMethod.POST)
    @ResponseBody
    public String requestInteger(Integer param) {
        return "Request successful. Post param : Integer - " + param;
    }
    //......
}

集合类型

• List

除了基本类型，Spring Controller各方法参数绑定还支持集合类型，这里拿常用的List和Map举例，如果直接拿集合类作为绑定参数，写法上与基本类型类似，不同的是需要在参数处增加注解@RequestParam()，具体代码示例如下所示：

@RequestMapping(value="/list", method=RequestMethod.POST)
@ResponseBody
public String requestList(@RequestParam("listParam[]") List<String> param) {
    return "Request successful. Post param : List<String> - " + param.toString();
}

对应Ajax的请求如下：

var strList = new Array();
strList.push("field1");
strList.push("field2");
function postList() {
    $.ajax({
        type:"POST",
        url:"http://localhost:8080/Learn-Spring-MVC/list",
        data:{"listParam" : strList},
        dataType:"json",
        success:function(result) {
            //......
        },
        error:function(result) {
            //......
        }
    });
}

• Map

Map类型作为参数，只需要使用@RequestParam注解即可，这里Map对应的key-value基本是String类型，value可以为Object，代码示例如下所示：

@RequestMapping(value="/map", method=RequestMethod.POST)
@ResponseBody
public String requestList(@RequestParam Map<String, Object> param) {
    return "Request successful. Post param : Map - " + param;
}

对应Ajax的请求如下：

function postMap() {
    $.ajax({
        type:"POST",
        url:"http://localhost:8080/Learn-Spring-MVC/map",
        data:{field1:"field1",field2:1},
        dataType:"json",
        success:function(result) {
            //......
        },
        error:function(result) {
            //......
        }
    });
}

Map作为参数的话，会把Ajax请求中的全部数据转换为key-value存入Map对应中，具体可参见Spring官方文档关于@RequestParam部分

自定义类型

自定义People类，具体类内容如下代码所示：

public class People implements Serializable{
    private static final long serialVersionUID = 1L;
    private String name;
    private short age;
    private Map<String, String> relationship;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public short getAge() {
        return age;
    }
    public void setAge(short age) {
        this.age = age;
    }
    public Map<String, String> getRelationship() {
        return relationship;
    }
    public void setRelationship(Map<String, String> relationship) {
        this.relationship = relationship;
    }
    @Override
    public String toString() {
        return "People [name=" + name + ", age=" + age + ", relationship=" + relationship + "]";
    }
}

对应Controller方法代码如下所示，主要的不同点就是需要在自定义类前添加@ModelAttribute注解：

@RequestMapping(value="/people", method=RequestMethod.POST)
@ResponseBody
public String requestPeople(@ModelAttribute People people) {
    return "Get request is successful. Post param : User Class - " + people.toString();
}

对应Ajax的请求如下：

  var people = {
    name:"Heacewalker",
    age:25,
    relationship:{"boss":"BigBoss"}
  }
  function postClick() {
    $.ajax({
      type:"POST",
      url:"http://localhost:8080/Learn-Spring-MVC/people",
      data:people,
      dataType:"json",
      success:function(result) {
          //......
      },
      error:function(result) {
          //......
      }
    });
  }

这里再说一下，如果自定义类中包含集合的话，要如何处理参数的问题，首先定义包含集合的类，具体代码如下所示：

public class Address {
    private String code;
    private String address;
    public String getCode() {
        return code;
    }
    public void setCode(String code) {
        this.code = code;
    }
    public String getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }
    @Override
    public String toString() {
        return "Address [code=" + code + ", address=" + address + "]";
    }
}

---

public class Link {
    private List<Address> address;
    public List<Address> getAddress() {
        return address;
    }
    public void setAddress(List<Address> address) {
        this.address = address;
    }
    @Override
    public String toString() {
        return "Link [address=" + address + "]";
    }
}

最后是Controller部分的代码，示例如下：

    @RequestMapping(value="/link", method=RequestMethod.POST)
    @ResponseBody
    public String requestLink(@ModelAttribute Link link) {
        return "Get request is successful. Post param : User Class - " + link.toString();
    }

对应Ajax的请求如下：

<form onsubmit="return PostData()">
    <input name="address[0].address" value="AKB"/>
    <input name="address[0].code" value="48"/>
    <input name="address[1].address" value="HKT"/>
    <input name="address[1].code" value="48"/>
    <input type="submit" value="提交"/>
</form>
......
function PostData() {
    $.ajax({
        type:"POST",
        url:"http://localhost:8080/Learn-Spring-MVC/link",
        data:'',
        success:function(result) {
            //......
        },
        error:function(result) {
            //......
        }
    });
}

最后，说一下用HttpServletRequest接收请求参数的方法，Controller代码如下所示，Controller接收到的参数值均为String类型：

@RequestMapping(value="/request", method=RequestMethod.POST)
@ResponseBody
public String request(HttpServletRequest arg0, HttpServletResponse arg1) {
    return "Get request is successful. Post param : param1 - " + arg0.getParameter("param1") +
           "; param2 - " + arg0.getParameter("param2") + 
           "; param3 - " + arg0.getParameter("param3");
}

对应Ajax请求：

  var idList = new Array();
  idList.push("1");
  idList.push("2");
  idList.push("3");
  function postTest() {
    $.ajax({
      type:"POST",
      url:"http://localhost:8080/Learn-Spring-MVC/request",
      data:{"param1":"test","param2":2,"param3":JSON.stringify(idList)},
      dataType:"json",
      success:function(result) {
        //......
      },
      error:function(result) {
          //......
      }
    });
  }

这里idList是集合类型，如果不是用JSON.stringify()进行转换的话，到Controller层接收到的参数值对应则为null。