SpringMVC在对应绑定不同实体,但具有相同属性名的解决方案....

在springmvc中,可以对前台传递过来的参数进行与后台实体绑定(第二种方式相对较好).

比如:

前台页面:

 <form action="${pageContext.request.contextPath}/test/test" method="POST">
         用户名:<input type="text" name="name"><br/>
         <input type="submit" value="提交">
 </form>

实体类:

 package com.yemaozi.rms.domain;

 public class Student {
     private Integer id;
     private String name;
     public Integer getId() {
         return id;
     }
     public void setId(Integer id) {
         this.id = id;
     }
     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }
 }

对应的Controller:

 @Controller
 @Scope(value="prototype")
 @RequestMapping("/test")
 public class TestController {
     @RequestMapping("/test")
     public String test(Student stu){
         System.out.println(stu.getName());
         return "success";
     }
 }

这样,在Controller是可以进行绑定的....

但是,若是,要对多个实体数据进行绑定,而且这些实体有同名的属性....

前台页面:

<form action="${pageContext.request.contextPath}/test/test" method="POST">
        学生姓名:<input type="text" name="name"><br/>
        老师姓名:<input type="text" name="name"><br/>
        <input type="submit" value="提交">
</form>

实体类:

 public class Teacher {
     private Integer id;
     private String name;
     public Integer getId() {
         return id;
     }
     public void setId(Integer id) {
         this.id = id;
     }
     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }
 }

Controller:

 @RequestMapping("/test")
 public String test(Student stu, Teacher teacher){
     System.out.println(stu.getName() + teacher.getName());
     return "success";
5 }

这样,就会明白,name并不是唯一标识了,所以,在后台不能精确的绑定,其实,若是将该表单进行提交,则会将这两个name属性分别都添加到stu 和teacher这两个对象中..

因为springmvc中,是根据属性来进行数据绑定的,不像struts2是基于ognl的数据绑定机制.

要解决现在这样问题的方案一:

复合实体:  

即:

 public class StuTeacher {
     private Student stu;
     private Teacher teacher;
     public Student getStu() {
         return stu;
     }
     public void setStu(Student stu) {
         this.stu = stu;
     }
     public Teacher getTeacher() {
         return teacher;
     }
     public void setTeacher(Teacher teacher) {
         this.teacher = teacher;
     }
 }

创建一个拥有stu和teacher这两个实体对象的类StuTeacher.....

这样我们就可以再前台这样书写.

 <form action="${pageContext.request.contextPath}/test/test1" method="POST">
     学生姓名:<input type="text" name="stu.name"><br/>
     老师姓名:<input type="text" name="teacher.name"><br/>
     <input type="submit" value="提交">
 </form>

就可以根据复合实体中的属性通过.进行导航绑定数据

在Controller中的代码:

 @RequestMapping("/test1")
 public String test1(StuTeacher stuTeacher){
     System.out.println(stuTeacher);
     return "success";
 }

这种方法可以简单的处理这种数据绑定问题,好处是不需要添加任何插件代码,缺点是 扩展性不好,后期可能使得代码臃肿.

所以可以在springmvc中可以进行自定义ModelAttributeProcessor来进行数据绑定的扩展.

1,自定义注解:

 import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;

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

2,继承ServletModelAttributeMethodProcessor类,实现自己的数据绑定模式.

 import javax.servlet.ServletRequest;

 import org.springframework.core.MethodParameter;
 import org.springframework.web.bind.ServletRequestDataBinder;
 import org.springframework.web.bind.WebDataBinder;
 import org.springframework.web.context.request.NativeWebRequest;
 import org.springframework.web.servlet.mvc.method.annotation.ServletModelAttributeMethodProcessor;

 public class ExtServletModelAttributeMethodProcessor extends
         ServletModelAttributeMethodProcessor {

     public ExtServletModelAttributeMethodProcessor() {
         super(false);
     }

     public ExtServletModelAttributeMethodProcessor(boolean annotationNotRequired) {
         super(annotationNotRequired);
     }

     @Override
     public boolean supportsParameter(MethodParameter parameter) {
         if (parameter.hasParameterAnnotation(ExtModelAttribute.class)) {
             return true;
         } else {
             return false;
         }
     }

     @Override
     protected void bindRequestParameters(WebDataBinder binder, NativeWebRequest request) {
         ServletRequest servletRequest = request.getNativeRequest(ServletRequest.class);
         ServletRequestDataBinder servletBinder = (ServletRequestDataBinder) binder;
         servletBinder.setFieldDefaultPrefix(servletBinder.getObjectName() + ".");
         servletBinder.bind(servletRequest);
     }
 }

3,在springmvc配置文件中添加相应的加载驱动配置

 <mvc:annotation-driven>
         <!--添加在此处-->
       <mvc:argument-resolvers>
         <bean class="com.yemaozi.springmvc.ext.databind.ExtServletModelAttributeMethodProcessor"/>
     </mvc:argument-resolvers>
 </mvc:annotation-driven>

4,应用

在前台页面中:

<form action="${pageContext.request.contextPath}/test/test1" method="POST">
    学生姓名:<input type="text" name="stu.name"><br/>
    老师姓名:<input type="text" name="teacher.name"><br/>
    <input type="submit" value="提交">
</form>

在Controller中使用方式:

 @RequestMapping("/test2")
 public String test2(@ExtModelAttribute("stu") Student stu, @ExtModelAttribute("teacher")Teacher teacher){
     System.out.println(stu.getName() + teacher.getName());
     return "success";
 }

使用刚才自定义的注解来标注对应的属性.