Spring MVC自定义数据绑定--HandlerMethodArgumentResolver

参考资料：http://blog.csdn.net/linuu/article/details/51065476
自己实现的自定义annotation绑定一个数据的例子：
1、创建一个annotation–ManyUser，默认只能注解参数，切运行时有效：

package com.data.custom;

import java.lang.annotation.*;

@Target({ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface ManyUser {
    String value() default "";
}

2、自定义一个ManyUserHandlerMethodArgumentResolver实现HandlerMethodArgumentResolver，所有的自定义数据绑定的区别就在resolveArgument方法中。客户端用不同的方式传来数据，则在resolveArgument方法中用不同的方式接受数据，比如：1、通过@ModelAttribute方式注入参数，则用webRequest.getAttribute获取参数数据；2、通过”URL？参数1=value1”的方式注入参数，则用webRequest.getParameter方式获取参数数据。然后需要返回的数据则是resolveArgument处理后返回（应该好好研究下参数传递方式，如：webRequest等）。
方式1的示例代码：

package com.data.custom;

import org.springframework.core.MethodParameter;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;

import java.util.ArrayList;
import java.util.List;

public class ManyUserHandlerMethodArgumentResolver implements HandlerMethodArgumentResolver {
//    public boolean supportsParameter(MethodParameter parameter) {
//        return parameter.hasParameterAnnotation(ManyUser.class);
//    }
    public boolean supportsParameter(MethodParameter parameter) {
        return parameter.getParameterAnnotation(ManyUser.class) != null;
    }
    public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest,
                                  WebDataBinderFactory binderFactory) throws Exception{
        List<User> users = new ArrayList<User>();
        ManyUser attr = parameter.getParameterAnnotation(ManyUser.class);
        String names=webRequest.getAttribute("names", 
                     WebRequest.SCOPE_REQUEST).toString();
        String ids=webRequest.getAttribute("ids", 
                     WebRequest.SCOPE_REQUEST).toString();
        System.out.println("names = "+names+" ids = "+ids);
        if(names !=null && ids !=null) {
            String[] nameStrs = names.trim().split(",");
            String[] idStrs = ids.trim().split(",");
            for(int i=0;i<nameStrs.length;i++){
                User u = new User(Integer.parseInt(idStrs[i]),nameStrs[i]);
                users.add(u);
            }
        }
        return users;
    }
}

方式2的示例代码：

package com.data.custom;

import org.springframework.core.MethodParameter;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;

import java.util.ArrayList;
import java.util.List;

public class ManyUserHandlerMethodArgumentResolver implements HandlerMethodArgumentResolver {
    public boolean supportsParameter(MethodParameter parameter) {
        return parameter.getParameterAnnotation(ManyUser.class) != null;
    }
    public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest,
                                  WebDataBinderFactory binderFactory) throws Exception{

        List<User> users = new ArrayList<User>();
        String names = (String) webRequest.getParameter("names");
        String ids = (String) webRequest.getParameter("ids");
        if(names !=null && ids !=null) {
            String[] nameStrs = names.trim().split(",");
            String[] idStrs = ids.trim().split(",");
            for(int i=0;i<nameStrs.length;i++){
                User u = new User(Integer.parseInt(idStrs[i]),nameStrs[i]);
                users.add(u);
            }
        }
        return users;
    }
}

写controller来测试一下（一定不要搞忘了在前面加@ResponseBody注解，不加的话Spring会调用视图解析器去找返回值对应的jsp页面，而不是给调用页面返回一个字符串）：
方式1的controller示例代码：

package com.data.custom;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

import javax.servlet.http.HttpServletRequest;
import java.util.Iterator;
import java.util.List;

@Controller
public class ManyUserHandlerMethodArgumentController {
    @ModelAttribute
    public void beforeInvokingHandlerMethod(HttpServletRequest request){
        request.setAttribute("names","lyncc,fly,ted");
        request.setAttribute("ids","1,2,3");
    }
    @RequestMapping(value = "/data/manyUser",method = RequestMethod.GET)
    public @ResponseBody String manyUser(@ManyUser List<User> users){
        System.out.println("tsuhlfsfbnm,.'/" +
                "");
        String usrStr = "feikong";
        //java中遍历ArrayList的三种方式。
        for(int i=0 ;i<users.size();i++){
            usrStr += users.get(i).toString();
        }
//        for(User u: users){
//            usrStr += u.toString();
//        }
//        for(Iterator<User> it = users.iterator(); it.hasNext(); ){
//            usrStr +=it.next().toString();
//        }
        return usrStr;
    }
}

方式2的controller示例代码：

package com.data.custom;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

import javax.servlet.http.HttpServletRequest;
import java.util.Iterator;
import java.util.List;

@Controller
public class ManyUserHandlerMethodArgumentController {
    @RequestMapping(value = "/data/manyUser",method = RequestMethod.GET)
    public @ResponseBody String manyUser(@ManyUser List<User> users){
        System.out.println("tsuhlfsfbnm,.'/" +
                "");
        String usrStr = "feikong";
        //java中遍历ArrayList的三种方式。
        for(int i=0 ;i<users.size();i++){
            usrStr += users.get(i).toString();
        }
//        for(User u: users){
//            usrStr += u.toString();
//        }
//        for(Iterator<User> it = users.iterator(); it.hasNext(); ){
//            usrStr +=it.next().toString();
//        }
        return usrStr;
    }
}

方式1的GET请求示例代码：

<a id="manyUser" class="textLink" href="<c:url value="/data/manyUser" />">ManyUser</a>

方式2的GET请求示例代码：

<a id="manyUser" class="textLink" href="<c:url value="/data/manyUser?names=lyncc,fly,ted&ids=1,2,3" />">ManyUser</a>

写完之后还要进行配置：

    <!--SpirngMVC配置文件-->
    <mvc:annotation-driven enable-matrix-variables="true">
        <mvc:argument-resolvers>
            <bean class="com.data.custom.ManyUserHandlerMethodArgumentResolver"/>
        </mvc:argument-resolvers>
    </mvc:annotation-driven>