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.
时间： 2024-10-29 05:21:05