SpringMVC数据绑定
SpringMVC数据绑定方式:
1. 基本数据类型(以int为例,其他类似):
Controller代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 @RequestMapping("saysth.do") 2 public void test(int count) { 3 }
表单代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 <form action="saysth.do" method="post"> 2 <input name="count" value="10" type="text"/> 3 ...... 4 </form>
表单中input的name值和Controller的参数变量名保持一致,就能完成数据绑定,如果不一致可以使用@RequestParam注解。通过@RequestParam中的required属性指定参数是否必须要传入,如果设置为true,没有传入参数就会报错。需要注意的是,如果Controller方法参数中定义的是基本数据类型,但是从页面提交过来的数据为null或者”"的话,会出现数据转换的异常。也就是必须保证表单传递过来的数据不能为null或”",所以,在开发过程中,对可能为空的数据,最好将参数数据类型定义成包装类型,具体参见下面的例子。
2. 包装类型(以Integer为例,其他类似):
Controller代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 @RequestMapping("saysth.do") 2 public void test(Integer count) { 3 }
表单代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 <form action="saysth.do" method="post"> 2 <input name="count" value="10" type="text"/> 3 ...... 4 </form>
和基本数据类型基本一样,不同之处在于,表单传递过来的数据可以为null或”",以上面代码为例,如果表单中num为”"或者表单中无num这个input,那么,Controller方法参数中的num值则为null。
3. 自定义对象类型:
Model代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 public class User { 2 private String firstName; 3 private String lastName; 4 5 public String getFirstName() { 6 return firstName; 7 } 8 9 public void setFirstName(String firstName) { 10 this.firstName = firstName; 11 } 12 13 public String getLastName() { 14 return lastName; 15 } 16 17 public void setLastName(String lastName) { 18 this.lastName = lastName; 19 } 20 21 }
Controller代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 @RequestMapping("saysth.do") 2 public void test(User user) { 3 }
表单代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 <form action="saysth.do" method="post"> 2 <input name="firstName" value="张" type="text"/> 3 <input name="lastName" value="三" type="text"/> 4 ...... 5 </form>
非常简单,只需将对象的属性名和input的name值一一匹配即可。
4. 自定义复合对象类型:
Model代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 public class ContactInfo { 2 private String tel; 3 private String address; 4 5 public String getTel() { 6 return tel; 7 } 8 9 public void setTel(String tel) { 10 this.tel = tel; 11 } 12 13 public String getAddress() { 14 return address; 15 } 16 17 public void setAddress(String address) { 18 this.address = address; 19 } 20 21 } 22 23 public class User { 24 private String firstName; 25 private String lastName; 26 private ContactInfo contactInfo; 27 28 public String getFirstName() { 29 return firstName; 30 } 31 32 public void setFirstName(String firstName) { 33 this.firstName = firstName; 34 } 35 36 public String getLastName() { 37 return lastName; 38 } 39 40 public void setLastName(String lastName) { 41 this.lastName = lastName; 42 } 43 44 public ContactInfo getContactInfo() { 45 return contactInfo; 46 } 47 48 public void setContactInfo(ContactInfo contactInfo) { 49 this.contactInfo = contactInfo; 50 } 51 52 }
Controller代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 @RequestMapping("saysth.do") 2 public void test(User user) { 3 System.out.println(user.getFirstName()); 4 System.out.println(user.getLastName()); 5 System.out.println(user.getContactInfo().getTel()); 6 System.out.println(user.getContactInfo().getAddress()); 7 }
表单代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 <form action="saysth.do" method="post"> 2 <input name="firstName" value="张" /><br> 3 <input name="lastName" value="三" /><br> 4 <input name="contactInfo.tel" value="13809908909" /><br> 5 <input name="contactInfo.address" value="北京海淀" /><br> 6 <input type="submit" value="Save" /> 7 </form>
User对象中有ContactInfo属性,Controller中的代码和第3点说的一致,但是,在表单代码中,需要使用“属性名(对象类型的属性).属性名”来命名input的name。
5. List绑定:
List需要绑定在对象上,而不能直接写在Controller方法的参数中。
Model代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 public class User { 2 private String firstName; 3 private String lastName; 4 5 public String getFirstName() { 6 return firstName; 7 } 8 9 public void setFirstName(String firstName) { 10 this.firstName = firstName; 11 } 12 13 public String getLastName() { 14 return lastName; 15 } 16 17 public void setLastName(String lastName) { 18 this.lastName = lastName; 19 } 20 21 } 22 23 public class UserListForm { 24 private List<User> users; 25 26 public List<User> getUsers() { 27 return users; 28 } 29 30 public void setUsers(List<User> users) { 31 this.users = users; 32 } 33 34 }
Controller代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 @RequestMapping("saysth.do") 2 public void test(UserListForm userForm) { 3 for (User user : userForm.getUsers()) { 4 System.out.println(user.getFirstName() + " - " + user.getLastName()); 5 } 6 }
表单代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 <form action="saysth.do" method="post"> 2 <table> 3 <thead> 4 <tr> 5 <th>First Name</th> 6 <th>Last Name</th> 7 </tr> 8 </thead> 9 <tfoot> 10 <tr> 11 <td colspan="2"><input type="submit" value="Save" /></td> 12 </tr> 13 </tfoot> 14 <tbody> 15 <tr> 16 <td><input name="users[0].firstName" value="aaa" /></td> 17 <td><input name="users[0].lastName" value="bbb" /></td> 18 </tr> 19 <tr> 20 <td><input name="users[1].firstName" value="ccc" /></td> 21 <td><input name="users[1].lastName" value="ddd" /></td> 22 </tr> 23 <tr> 24 <td><input name="users[2].firstName" value="eee" /></td> 25 <td><input name="users[2].lastName" value="fff" /></td> 26 </tr> 27 </tbody> 28 </table> 29 </form>
其实,这和第4点User对象中的contantInfo数据的绑定有点类似,但是这里的UserListForm对象里面的属性被定义成List,而不是普通自定义对象。所以,在表单中需要指定List的下标。值得一提的是,Spring会创建一个以最大下标值为size的List对象,所以,如果表单中有动态添加行、删除行的情况,就需要特别注意,譬如一个表格,用户在使用过程中经过多次删除行、增加行的操作之后,下标值就会与实际大小不一致,这时候,List中的对象,只有在表单中对应有下标的那些才会有值,否则会为null,看个例子:
表单代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 <form action="saysth.do" method="post"> 2 <table> 3 <thead> 4 <tr> 5 <th>First Name</th> 6 <th>Last Name</th> 7 </tr> 8 </thead> 9 <tfoot> 10 <tr> 11 <td colspan="2"><input type="submit" value="Save" /></td> 12 </tr> 13 </tfoot> 14 <tbody> 15 <tr> 16 <td><input name="users[0].firstName" value="aaa" /></td> 17 <td><input name="users[0].lastName" value="bbb" /></td> 18 </tr> 19 <tr> 20 <td><input name="users[1].firstName" value="ccc" /></td> 21 <td><input name="users[1].lastName" value="ddd" /></td> 22 </tr> 23 <tr> 24 <td><input name="users[20].firstName" value="eee" /></td> 25 <td><input name="users[20].lastName" value="fff" /></td> 26 </tr> 27 </tbody> 28 </table> 29 </form>
这个时候,Controller中的userForm.getUsers()获取到List的size为21,而且这21个User对象都不会为null,但是,第2到第19的User对象中的firstName和lastName都为null。打印结果:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 aaa - bbb 2 ccc - ddd 3 null - null 4 null - null 5 null - null 6 null - null 7 null - null 8 null - null 9 null - null 10 null - null 11 null - null 12 null - null 13 null - null 14 null - null 15 null - null 16 null - null 17 null - null 18 null - null 19 null - null 20 null - null 21 eee - fff
6. Set绑定:
Set和List类似,也需要绑定在对象上,而不能直接写在Controller方法的参数中。但是,绑定Set数据时,必须先在Set对象中add相应的数量的模型对象。
Model代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 public class User { 2 private String firstName; 3 private String lastName; 4 5 public String getFirstName() { 6 return firstName; 7 } 8 9 public void setFirstName(String firstName) { 10 this.firstName = firstName; 11 } 12 13 public String getLastName() { 14 return lastName; 15 } 16 17 public void setLastName(String lastName) { 18 this.lastName = lastName; 19 } 20 21 } 22 23 public class UserSetForm { 24 private Set<User> users = new HashSet<User>(); 25 26 public UserSetForm() { 27 users.add(new User()); 28 users.add(new User()); 29 users.add(new User()); 30 } 31 32 public Set<User> getUsers() { 33 return users; 34 } 35 36 public void setUsers(Set<User> users) { 37 this.users = users; 38 } 39 40 }
Controller代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 @RequestMapping("saysth.do") 2 public void test(UserSetForm userForm) { 3 for (User user : userForm.getUsers()) { 4 System.out.println(user.getFirstName() + " - " + user.getLastName()); 5 } 6 }
表单代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 <form action="saysth.do" method="post"> 2 <table> 3 <thead> 4 <tr> 5 <th>First Name</th> 6 <th>Last Name</th> 7 </tr> 8 </thead> 9 <tfoot> 10 <tr> 11 <td colspan="2"><input type="submit" value="Save" /></td> 12 </tr> 13 </tfoot> 14 <tbody> 15 <tr> 16 <td><input name="users[0].firstName" value="aaa" /></td> 17 <td><input name="users[0].lastName" value="bbb" /></td> 18 </tr> 19 <tr> 20 <td><input name="users[1].firstName" value="ccc" /></td> 21 <td><input name="users[1].lastName" value="ddd" /></td> 22 </tr> 23 <tr> 24 <td><input name="users[2].firstName" value="eee" /></td> 25 <td><input name="users[2].lastName" value="fff" /></td> 26 </tr> 27 </tbody> 28 </table> 29 </form>
基本和List绑定类似。
需要特别提醒的是,如果最大下标值大于Set的size,则会抛出org.springframework.beans.InvalidPropertyException异常。所以,在使用时有些不便。
7. Map绑定:
Map最为灵活,它也需要绑定在对象上,而不能直接写在Controller方法的参数中。
Model代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 public class User { 2 private String firstName; 3 private String lastName; 4 5 public String getFirstName() { 6 return firstName; 7 } 8 9 public void setFirstName(String firstName) { 10 this.firstName = firstName; 11 } 12 13 public String getLastName() { 14 return lastName; 15 } 16 17 public void setLastName(String lastName) { 18 this.lastName = lastName; 19 } 20 21 } 22 23 public class UserMapForm { 24 private Map<String, User> users; 25 26 public Map<String, User> getUsers() { 27 return users; 28 } 29 30 public void setUsers(Map<String, User> users) { 31 this.users = users; 32 } 33 34 }
Controller代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 @RequestMapping("saysth.do") 2 public void test(UserMapForm userForm) { 3 for (Map.Entry<String, User> entry : userForm.getUsers().entrySet()) { 4 System.out.println(entry.getKey() + ": " + entry.getValue().getFirstName() + " - " + 5 entry.getValue().getLastName()); 6 } 7 }
表单代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 <form action="saysth.do" method="post"> 2 <table> 3 <thead> 4 <tr> 5 <th>First Name</th> 6 <th>Last Name</th> 7 </tr> 8 </thead> 9 <tfoot> 10 <tr> 11 <td colspan="2"><input type="submit" value="Save" /></td> 12 </tr> 13 </tfoot> 14 <tbody> 15 <tr> 16 <td><input name="users['x'].firstName" value="aaa" /></td> 17 <td><input name="users['x'].lastName" value="bbb" /></td> 18 </tr> 19 <tr> 20 <td><input name="users['y'].firstName" value="ccc" /></td> 21 <td><input name="users['y'].lastName" value="ddd" /></td> 22 </tr> 23 <tr> 24 <td><input name="users['z'].firstName" value="eee" /></td> 25 <td><input name="users['z'].lastName" value="fff" /></td> 26 </tr> 27 </tbody> 28 </table> 29 </form>
打印结果:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 x: aaa - bbb 2 y: ccc - ddd 3 z: eee - fff
另一个解释例子: