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:

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

实体类:

 1 package com.yemaozi.rms.domain;
 2
 3 public class Student {
 4     private Integer id;
 5     private String name;
 6     public Integer getId() {
 7         return id;
 8     }
 9     public void setId(Integer id) {
10         this.id = id;
11     }
12     public String getName() {
13         return name;
14     }
15     public void setName(String name) {
16         this.name = name;
17     }
18 }

对应的Controller:

 1 @Controller
 2 @Scope(value="prototype")
 3 @RequestMapping("/test")
 4 public class TestController {
 5     @RequestMapping("/test")
 6     public String test(Student stu){
 7         System.out.println(stu.getName());
 8         return "success";
 9     }
10 }

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:

 1 public class Teacher {
 2     private Integer id;
 3     private String name;
 4     public Integer getId() {
 5         return id;
 6     }
 7     public void setId(Integer id) {
 8         this.id = id;
 9     }
10     public String getName() {
11         return name;
12     }
13     public void setName(String name) {
14         this.name = name;
15     }
16 }

Controller:

1 @RequestMapping("/test")
2 public String test(Student stu, Teacher teacher){
3     System.out.println(stu.getName() + teacher.getName());
4     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:

 1 public class StuTeacher {
 2     private Student stu;
 3     private Teacher teacher;
 4     public Student getStu() {
 5         return stu;
 6     }
 7     public void setStu(Student stu) {
 8         this.stu = stu;
 9     }
10     public Teacher getTeacher() {
11         return teacher;
12     }
13     public void setTeacher(Teacher teacher) {
14         this.teacher = teacher;
15     }
16 }

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.

1 <form action="${pageContext.request.contextPath}/test/test1" method="POST">
2     学生姓名:<input type="text" name="stu.name"><br/>
3     老师姓名:<input type="text" name="teacher.name"><br/>
4     <input type="submit" value="提交">
5 </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:

1 @RequestMapping("/test1")
2 public String test1(StuTeacher stuTeacher){
3     System.out.println(stuTeacher);
4     return "success";
5 }

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:

 1 import java.lang.annotation.Documented;
 2 import java.lang.annotation.ElementType;
 3 import java.lang.annotation.Retention;
 4 import java.lang.annotation.RetentionPolicy;
 5 import java.lang.annotation.Target;
 6
 7
 8 @Target({ElementType.PARAMETER, ElementType.METHOD})
 9 @Retention(RetentionPolicy.RUNTIME)
10 @Documented
11 public @interface ExtModelAttribute {
12     String value() default "";
13 }

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

 1 import javax.servlet.ServletRequest;
 2
 3 import org.springframework.core.MethodParameter;
 4 import org.springframework.web.bind.ServletRequestDataBinder;
 5 import org.springframework.web.bind.WebDataBinder;
 6 import org.springframework.web.context.request.NativeWebRequest;
 7 import org.springframework.web.servlet.mvc.method.annotation.ServletModelAttributeMethodProcessor;
 8
 9 public class ExtServletModelAttributeMethodProcessor extends
10         ServletModelAttributeMethodProcessor {
11
12     public ExtServletModelAttributeMethodProcessor() {
13         super(false);
14     }
15
16     public ExtServletModelAttributeMethodProcessor(boolean annotationNotRequired) {
17         super(annotationNotRequired);
18     }
19
20     @Override
21     public boolean supportsParameter(MethodParameter parameter) {
22         if (parameter.hasParameterAnnotation(ExtModelAttribute.class)) {
23             return true;
24         } else {
25             return false;
26         }
27     }
28
29     @Override
30     protected void bindRequestParameters(WebDataBinder binder, NativeWebRequest request) {
31         ServletRequest servletRequest = request.getNativeRequest(ServletRequest.class);
32         ServletRequestDataBinder servletBinder = (ServletRequestDataBinder) binder;
33         servletBinder.setFieldDefaultPrefix(servletBinder.getObjectName() + ".");
34         servletBinder.bind(servletRequest);
35     }
36 }

3,在springmvc配置文件中添加相应的加载驱动配置

1 <mvc:annotation-driven>
2         <!--添加在此处-->
3       <mvc:argument-resolvers>
4         <bean class="com.yemaozi.springmvc.ext.databind.ExtServletModelAttributeMethodProcessor"/>
5     </mvc:argument-resolvers>
6 </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:

1 @RequestMapping("/test2")
2 public String test2(@ExtModelAttribute("stu") Student stu, @ExtModelAttribute("teacher")Teacher teacher){
3     System.out.println(stu.getName() + teacher.getName());
4     return "success";
5 }

使用刚才自定义的注解来标注对应的属性.