SpringMVC的各种参数绑定方式
1. 基本数据类型(以int为例,其他类似):
Controller代码:
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@RequestMapping ( "saysth.do" )
public void test( int count) {
}
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表单代码:
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< form action = "saysth.do" method = "post" >
< input name = "count" value = "10" type = "text" />
......
</ form >
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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。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:
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@RequestMapping ( "saysth.do" )
public void test(Integer count) {
}
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表单代码:
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< form action = "saysth.do" method = "post" >
< input name = "count" value = "10" type = "text" />
......
</ form >
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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:
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public class User {
private String firstName;
private String lastName;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this .firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this .lastName = lastName;
}
}
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Controller代码:
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@RequestMapping ( "saysth.do" )
public void test(User user) {
}
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表单代码:
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< form action = "saysth.do" method = "post" >
< input name = "firstName" value = "张" type = "text" />
< input name = "lastName" value = "三" type = "text" />
......
</ form >
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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:
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public class ContactInfo {
private String tel;
private String address;
public String getTel() {
return tel;
}
public void setTel(String tel) {
this .tel = tel;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this .address = address;
}
}
public class User {
private String firstName;
private String lastName;
private ContactInfo contactInfo;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this .firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this .lastName = lastName;
}
public ContactInfo getContactInfo() {
return contactInfo;
}
public void setContactInfo(ContactInfo contactInfo) {
this .contactInfo = contactInfo;
}
}
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Controller代码:
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@RequestMapping ( "saysth.do" )
public void test(User user) {
System.out.println(user.getFirstName());
System.out.println(user.getLastName());
System.out.println(user.getContactInfo().getTel());
System.out.println(user.getContactInfo().getAddress());
}
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表单代码:
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< form action = "saysth.do" method = "post" >
< input name = "firstName" value = "张" />< br >
< input name = "lastName" value = "三" />< br >
< input name = "contactInfo.tel" value = "13809908909" />< br >
< input name = "contactInfo.address" value = "北京海淀" />< br >
< input type = "submit" value = "Save" />
</ form >
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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:
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public class User {
private String firstName;
private String lastName;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this .firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this .lastName = lastName;
}
}
public class UserListForm {
private List<User> users;
public List<User> getUsers() {
return users;
}
public void setUsers(List<User> users) {
this .users = users;
}
}
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Controller代码:
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@RequestMapping ( "saysth.do" )
public void test(UserListForm userForm) {
for (User user : userForm.getUsers()) {
System.out.println(user.getFirstName() + " - " + user.getLastName());
}
}
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表单代码:
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< form action = "saysth.do" method = "post" >
< table >
< thead >
< tr >
< th >First Name</ th >
< th >Last Name</ th >
</ tr >
</ thead >
< tfoot >
< tr >
< td colspan = "2" >< input type = "submit" value = "Save" /></ td >
</ tr >
</ tfoot >
< tbody >
< tr >
< td >< input name = "users[0].firstName" value = "aaa" /></ td >
< td >< input name = "users[0].lastName" value = "bbb" /></ td >
</ tr >
< tr >
< td >< input name = "users[1].firstName" value = "ccc" /></ td >
< td >< input name = "users[1].lastName" value = "ddd" /></ td >
</ tr >
< tr >
< td >< input name = "users[2].firstName" value = "eee" /></ td >
< td >< input name = "users[2].lastName" value = "fff" /></ td >
</ tr >
</ tbody >
</ table >
</ form >
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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:
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< form action = "saysth.do" method = "post" >
< table >
< thead >
< tr >
< th >First Name</ th >
< th >Last Name</ th >
</ tr >
</ thead >
< tfoot >
< tr >
< td colspan = "2" >< input type = "submit" value = "Save" /></ td >
</ tr >
</ tfoot >
< tbody >
< tr >
< td >< input name = "users[0].firstName" value = "aaa" /></ td >
< td >< input name = "users[0].lastName" value = "bbb" /></ td >
</ tr >
< tr >
< td >< input name = "users[1].firstName" value = "ccc" /></ td >
< td >< input name = "users[1].lastName" value = "ddd" /></ td >
</ tr >
< tr >
< td >< input name = "users[20].firstName" value = "eee" /></ td >
< td >< input name = "users[20].lastName" value = "fff" /></ td >
</ tr >
</ tbody >
</ table >
</ form >
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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:
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aaa - bbb
ccc - ddd
null - null
null - null
null - null
null - null
null - null
null - null
null - null
null - null
null - null
null - null
null - null
null - null
null - null
null - null
null - null
null - null
null - null
null - null
eee - fff
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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:
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public class User {
private String firstName;
private String lastName;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this .firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this .lastName = lastName;
}
}
public class UserSetForm {
private Set<User> users = new HashSet<User>();
public UserSetForm() {
users.add( new User());
users.add( new User());
users.add( new User());
}
public Set<User> getUsers() {
return users;
}
public void setUsers(Set<User> users) {
this .users = users;
}
}
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Controller代码:
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@RequestMapping ( "saysth.do" )
public void test(UserSetForm userForm) {
for (User user : userForm.getUsers()) {
System.out.println(user.getFirstName() + " - " + user.getLastName());
}
}
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表单代码:
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< form action = "saysth.do" method = "post" >
< table >
< thead >
< tr >
< th >First Name</ th >
< th >Last Name</ th >
</ tr >
</ thead >
< tfoot >
< tr >
< td colspan = "2" >< input type = "submit" value = "Save" /></ td >
</ tr >
</ tfoot >
< tbody >
< tr >
< td >< input name = "users[0].firstName" value = "aaa" /></ td >
< td >< input name = "users[0].lastName" value = "bbb" /></ td >
</ tr >
< tr >
< td >< input name = "users[1].firstName" value = "ccc" /></ td >
< td >< input name = "users[1].lastName" value = "ddd" /></ td >
</ tr >
< tr >
< td >< input name = "users[2].firstName" value = "eee" /></ td >
< td >< input name = "users[2].lastName" value = "fff" /></ td >
</ tr >
</ tbody >
</ table >
</ form >
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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:
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public class User {
private String firstName;
private String lastName;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this .firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this .lastName = lastName;
}
}
public class UserMapForm {
private Map<String, User> users;
public Map<String, User> getUsers() {
return users;
}
public void setUsers(Map<String, User> users) {
this .users = users;
}
}
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Controller代码:
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@RequestMapping ( "saysth.do" )
public void test(UserMapForm userForm) {
for (Map.Entry<String, User> entry : userForm.getUsers().entrySet()) {
System.out.println(entry.getKey() + ": " + entry.getValue().getFirstName() + " - " +
entry.getValue().getLastName());
}
}
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表单代码:
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< form action = "saysth.do" method = "post" >
< table >
< thead >
< tr >
< th >First Name</ th >
< th >Last Name</ th >
</ tr >
</ thead >
< tfoot >
< tr >
< td colspan = "2" >< input type = "submit" value = "Save" /></ td >
</ tr >
</ tfoot >
< tbody >
< tr >
< td >< input name = "users['x'].firstName" value = "aaa" /></ td >
< td >< input name = "users['x'].lastName" value = "bbb" /></ td >
</ tr >
< tr >
< td >< input name = "users['y'].firstName" value = "ccc" /></ td >
< td >< input name = "users['y'].lastName" value = "ddd" /></ td >
</ tr >
< tr >
< td >< input name = "users['z'].firstName" value = "eee" /></ td >
< td >< input name = "users['z'].lastName" value = "fff" /></ td >
</ tr >
</ tbody >
</ table >
</ form >
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打印结果:
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x: aaa - bbb
y: ccc - ddd
z: eee - fff
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以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。
原文链接:http://www.cnblogs.com/HD/p/4107674.html