浅谈SpringMVC数据绑定
2016-01-26 16:52
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转自:http://www.iteye.com/topic/973918
查看spring源码可以看出spring支持转换的数据类型:
org.springframework.beans.PropertyEditorRegistrySupport:
Java代码
/**
*Actuallyregisterthedefaulteditorsforthisregistryinstance.
*/
privatevoidcreateDefaultEditors(){
this.defaultEditors=newHashMap<Class,PropertyEditor>(64);
//Simpleeditors,withoutparameterizationcapabilities.
//TheJDKdoesnotcontainadefaulteditorforanyofthesetargettypes.
this.defaultEditors.put(Charset.class,newCharsetEditor());
this.defaultEditors.put(Class.class,newClassEditor());
this.defaultEditors.put(Class[].class,newClassArrayEditor());
this.defaultEditors.put(Currency.class,newCurrencyEditor());
this.defaultEditors.put(File.class,newFileEditor());
this.defaultEditors.put(InputStream.class,newInputStreamEditor());
this.defaultEditors.put(InputSource.class,newInputSourceEditor());
this.defaultEditors.put(Locale.class,newLocaleEditor());
this.defaultEditors.put(Pattern.class,newPatternEditor());
this.defaultEditors.put(Properties.class,newPropertiesEditor());
this.defaultEditors.put(Resource[].class,newResourceArrayPropertyEditor());
this.defaultEditors.put(TimeZone.class,newTimeZoneEditor());
this.defaultEditors.put(URI.class,newURIEditor());
this.defaultEditors.put(URL.class,newURLEditor());
this.defaultEditors.put(UUID.class,newUUIDEditor());
//Defaultinstancesofcollectioneditors.
//Canbeoverriddenbyregisteringcustominstancesofthoseascustomeditors.
this.defaultEditors.put(Collection.class,newCustomCollectionEditor(Collection.class));
this.defaultEditors.put(Set.class,newCustomCollectionEditor(Set.class));
this.defaultEditors.put(SortedSet.class,newCustomCollectionEditor(SortedSet.class));
this.defaultEditors.put(List.class,newCustomCollectionEditor(List.class));
this.defaultEditors.put(SortedMap.class,newCustomMapEditor(SortedMap.class));
//Defaulteditorsforprimitivearrays.
this.defaultEditors.put(byte[].class,newByteArrayPropertyEditor());
this.defaultEditors.put(char[].class,newCharArrayPropertyEditor());
//TheJDKdoesnotcontainadefaulteditorforchar!
this.defaultEditors.put(char.class,newCharacterEditor(false));
this.defaultEditors.put(Character.class,newCharacterEditor(true));
//Spring'sCustomBooleanEditoracceptsmoreflagvaluesthantheJDK'sdefaulteditor.
this.defaultEditors.put(boolean.class,newCustomBooleanEditor(false));
this.defaultEditors.put(Boolean.class,newCustomBooleanEditor(true));
//TheJDKdoesnotcontaindefaulteditorsfornumberwrappertypes!
//OverrideJDKprimitivenumbereditorswithourownCustomNumberEditor.
this.defaultEditors.put(byte.class,newCustomNumberEditor(Byte.class,false));
this.defaultEditors.put(Byte.class,newCustomNumberEditor(Byte.class,true));
this.defaultEditors.put(short.class,newCustomNumberEditor(Short.class,false));
this.defaultEditors.put(Short.class,newCustomNumberEditor(Short.class,true));
this.defaultEditors.put(int.class,newCustomNumberEditor(Integer.class,false));
this.defaultEditors.put(Integer.class,newCustomNumberEditor(Integer.class,true));
this.defaultEditors.put(long.class,newCustomNumberEditor(Long.class,false));
this.defaultEditors.put(Long.class,newCustomNumberEditor(Long.class,true));
this.defaultEditors.put(float.class,newCustomNumberEditor(Float.class,false));
this.defaultEditors.put(Float.class,newCustomNumberEditor(Float.class,true));
this.defaultEditors.put(double.class,newCustomNumberEditor(Double.class,false));
this.defaultEditors.put(Double.class,newCustomNumberEditor(Double.class,true));
this.defaultEditors.put(BigDecimal.class,newCustomNumberEditor(BigDecimal.class,true));
this.defaultEditors.put(BigInteger.class,newCustomNumberEditor(BigInteger.class,true));
//Onlyregisterconfigvalueeditorsifexplicitlyrequested.
if(this.configValueEditorsActive){
StringArrayPropertyEditorsae=newStringArrayPropertyEditor();
this.defaultEditors.put(String[].class,sae);
this.defaultEditors.put(short[].class,sae);
this.defaultEditors.put(int[].class,sae);
this.defaultEditors.put(long[].class,sae);
}
}
下面挑选一些常用的数据类型,举例说明它们的绑定方式
1. 基本数据类型(以int为例,其他类似):
Controller代码:
Java代码
@RequestMapping("test.do")
publicvoidtest(intnum){
}
JSP表单代码:
Java代码
<formaction="test.do"method="post">
<inputname="num"value="10"type="text"/>
......
</form>
表单中input的name值和Controller的参数变量名保持一致,就能完成基本数据类型的数据绑定,如果不一致可以使用@RequestParam标注实现。值得一提的是,如果Controller方法参数中定义的是基本数据类型,但是从jsp提交过来的数据为null或者""的话,会出现数据转换的异常。也就是说,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,具体参见下面的第二条。
2. 包装类型(以Integer为例,其他类似):
Controller代码:
Java代码
@RequestMapping("test.do")
publicvoidtest(Integernum){
}
JSP表单代码:
Java代码
<formaction="test.do"method="post">
<inputname="num"value="10"type="text"/>
......
</form>
和基本数据类型基本一样,不同之处在于,JSP表单传递过来的数据可以为null或"",以上面代码为例,如果jsp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:
Java代码
publicclassUser{
privateStringfirstName;
privateStringlastName;
publicStringgetFirstName(){
returnfirstName;
}
publicvoidsetFirstName(StringfirstName){
this.firstName=firstName;
}
publicStringgetLastName(){
returnlastName;
}
publicvoidsetLastName(StringlastName){
this.lastName=lastName;
}
}
Controller代码:
Java代码
@RequestMapping("test.do")
publicvoidtest(Useruser){
}
JSP表单代码:
Java代码
<formaction="test.do"method="post">
<inputname="firstName"value="张"type="text"/>
<inputname="lastName"value="三"type="text"/>
......
</form>
非常简单,只需将对象的属性名和input的name值一一对应即可。
4. 自定义复合对象类型:
Model代码:
Java代码
publicclassContactInfo{
privateStringtel;
privateStringaddress;
publicStringgetTel(){
returntel;
}
publicvoidsetTel(Stringtel){
this.tel=tel;
}
publicStringgetAddress(){
returnaddress;
}
publicvoidsetAddress(Stringaddress){
this.address=address;
}
}
publicclassUser{
privateStringfirstName;
privateStringlastName;
privateContactInfocontactInfo;
publicStringgetFirstName(){
returnfirstName;
}
publicvoidsetFirstName(StringfirstName){
this.firstName=firstName;
}
publicStringgetLastName(){
returnlastName;
}
publicvoidsetLastName(StringlastName){
this.lastName=lastName;
}
publicContactInfogetContactInfo(){
returncontactInfo;
}
publicvoidsetContactInfo(ContactInfocontactInfo){
this.contactInfo=contactInfo;
}
}
Controller代码:
Java代码
@RequestMapping("test.do")
publicvoidtest(Useruser){
System.out.println(user.getFirstName());
System.out.println(user.getLastName());
System.out.println(user.getContactInfo().getTel());
System.out.println(user.getContactInfo().getAddress());
}
JSP表单代码:
Java代码
<formaction="test.do"method="post">
<inputname="firstName"value="张"/><br>
<inputname="lastName"value="三"/><br>
<inputname="contactInfo.tel"value="13809908909"/><br>
<inputname="contactInfo.address"value="北京海淀"/><br>
<inputtype="submit"value="Save"/>
</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jsp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:
Java代码
publicclassUser{
privateStringfirstName;
privateStringlastName;
publicStringgetFirstName(){
returnfirstName;
}
publicvoidsetFirstName(StringfirstName){
this.firstName=firstName;
}
publicStringgetLastName(){
returnlastName;
}
publicvoidsetLastName(StringlastName){
this.lastName=lastName;
}
}
publicclassUserListForm{
privateList<User>users;
publicList<User>getUsers(){
returnusers;
}
publicvoidsetUsers(List<User>users){
this.users=users;
}
}
Controller代码:
Java代码
@RequestMapping("test.do")
publicvoidtest(UserListFormuserForm){
for(Useruser:userForm.getUsers()){
System.out.println(user.getFirstName()+"-"+user.getLastName());
}
}
JSP表单代码:
Java代码
<formaction="test.do"method="post">
<table>
<thead>
<tr>
<th>FirstName</th>
<th>LastName</th>
</tr>
</thead>
<tfoot>
<tr>
<tdcolspan="2"><inputtype="submit"value="Save"/></td>
</tr>
</tfoot>
<tbody>
<tr>
<td><inputname="users[0].firstName"value="aaa"/></td>
<td><inputname="users[0].lastName"value="bbb"/></td>
</tr>
<tr>
<td><inputname="users[1].firstName"value="ccc"/></td>
<td><inputname="users[1].lastName"value="ddd"/></td>
</tr>
<tr>
<td><inputname="users[2].firstName"value="eee"/></td>
<td><inputname="users[2].lastName"value="fff"/></td>
</tr>
</tbody>
</table>
</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JSP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JSP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jsp表单中对应有下标的那些才会有值,否则会为null,看个例子:
JSP表单代码:
Java代码
<formaction="test.do"method="post">
<table>
<thead>
<tr>
<th>FirstName</th>
<th>LastName</th>
</tr>
</thead>
<tfoot>
<tr>
<tdcolspan="2"><inputtype="submit"value="Save"/></td>
</tr>
</tfoot>
<tbody>
<tr>
<td><inputname="users[0].firstName"value="aaa"/></td>
<td><inputname="users[0].lastName"value="bbb"/></td>
</tr>
<tr>
<td><inputname="users[1].firstName"value="ccc"/></td>
<td><inputname="users[1].lastName"value="ddd"/></td>
</tr>
<tr>
<td><inputname="users[20].firstName"value="eee"/></td>
<td><inputname="users[20].lastName"value="fff"/></td>
</tr>
</tbody>
</table>
</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:
Java代码
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
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:
Java代码
publicclassUser{
privateStringfirstName;
privateStringlastName;
publicStringgetFirstName(){
returnfirstName;
}
publicvoidsetFirstName(StringfirstName){
this.firstName=firstName;
}
publicStringgetLastName(){
returnlastName;
}
publicvoidsetLastName(StringlastName){
this.lastName=lastName;
}
}
publicclassUserSetForm{
privateSet<User>users=newHashSet<User>();
publicUserSetForm(){
users.add(newUser());
users.add(newUser());
users.add(newUser());
}
publicSet<User>getUsers(){
returnusers;
}
publicvoidsetUsers(Set<User>users){
this.users=users;
}
}
Controller代码:
Java代码
@RequestMapping("test.do")
publicvoidtest(UserSetFormuserForm){
for(Useruser:userForm.getUsers()){
System.out.println(user.getFirstName()+"-"+user.getLastName());
}
}
JSP表单代码:
Java代码
<formaction="test.do"method="post">
<table>
<thead>
<tr>
<th>FirstName</th>
<th>LastName</th>
</tr>
</thead>
<tfoot>
<tr>
<tdcolspan="2"><inputtype="submit"value="Save"/></td>
</tr>
</tfoot>
<tbody>
<tr>
<td><inputname="users[0].firstName"value="aaa"/></td>
<td><inputname="users[0].lastName"value="bbb"/></td>
</tr>
<tr>
<td><inputname="users[1].firstName"value="ccc"/></td>
<td><inputname="users[1].lastName"value="ddd"/></td>
</tr>
<tr>
<td><inputname="users[2].firstName"value="eee"/></td>
<td><inputname="users[2].lastName"value="fff"/></td>
</tr>
</tbody>
</table>
</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。暂时没找到解决方法,如果有网友知道,请回帖共享你的做法。
5. 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:
Java代码
publicclassUser{
privateStringfirstName;
privateStringlastName;
publicStringgetFirstName(){
returnfirstName;
}
publicvoidsetFirstName(StringfirstName){
this.firstName=firstName;
}
publicStringgetLastName(){
returnlastName;
}
publicvoidsetLastName(StringlastName){
this.lastName=lastName;
}
}
publicclassUserMapForm{
privateMap<String,User>users;
publicMap<String,User>getUsers(){
returnusers;
}
publicvoidsetUsers(Map<String,User>users){
this.users=users;
}
}
Controller代码:
Java代码
@RequestMapping("test.do")
publicvoidtest(UserMapFormuserForm){
for(Map.Entry<String,User>entry:userForm.getUsers().entrySet()){
System.out.println(entry.getKey()+":"+entry.getValue().getFirstName()+"-"+
entry.getValue().getLastName());
}
}
JSP表单代码:
Java代码
<formaction="test.do"method="post">
<table>
<thead>
<tr>
<th>FirstName</th>
<th>LastName</th>
</tr>
</thead>
<tfoot>
<tr>
<tdcolspan="2"><inputtype="submit"value="Save"/></td>
</tr>
</tfoot>
<tbody>
<tr>
<td><inputname="users['x'].firstName"value="aaa"/></td>
<td><inputname="users['x'].lastName"value="bbb"/></td>
</tr>
<tr>
<td><inputname="users['y'].firstName"value="ccc"/></td>
<td><inputname="users['y'].lastName"value="ddd"/></td>
</tr>
<tr>
<td><inputname="users['z'].firstName"value="eee"/></td>
<td><inputname="users['z'].lastName"value="fff"/></td>
</tr>
</tbody>
</table>
</form>
打印结果:
Java代码
x:aaa-bbb
y:ccc-ddd
z:eee-fff
查看spring源码可以看出spring支持转换的数据类型:
org.springframework.beans.PropertyEditorRegistrySupport:
Java代码
/**
*Actuallyregisterthedefaulteditorsforthisregistryinstance.
*/
privatevoidcreateDefaultEditors(){
this.defaultEditors=newHashMap<Class,PropertyEditor>(64);
//Simpleeditors,withoutparameterizationcapabilities.
//TheJDKdoesnotcontainadefaulteditorforanyofthesetargettypes.
this.defaultEditors.put(Charset.class,newCharsetEditor());
this.defaultEditors.put(Class.class,newClassEditor());
this.defaultEditors.put(Class[].class,newClassArrayEditor());
this.defaultEditors.put(Currency.class,newCurrencyEditor());
this.defaultEditors.put(File.class,newFileEditor());
this.defaultEditors.put(InputStream.class,newInputStreamEditor());
this.defaultEditors.put(InputSource.class,newInputSourceEditor());
this.defaultEditors.put(Locale.class,newLocaleEditor());
this.defaultEditors.put(Pattern.class,newPatternEditor());
this.defaultEditors.put(Properties.class,newPropertiesEditor());
this.defaultEditors.put(Resource[].class,newResourceArrayPropertyEditor());
this.defaultEditors.put(TimeZone.class,newTimeZoneEditor());
this.defaultEditors.put(URI.class,newURIEditor());
this.defaultEditors.put(URL.class,newURLEditor());
this.defaultEditors.put(UUID.class,newUUIDEditor());
//Defaultinstancesofcollectioneditors.
//Canbeoverriddenbyregisteringcustominstancesofthoseascustomeditors.
this.defaultEditors.put(Collection.class,newCustomCollectionEditor(Collection.class));
this.defaultEditors.put(Set.class,newCustomCollectionEditor(Set.class));
this.defaultEditors.put(SortedSet.class,newCustomCollectionEditor(SortedSet.class));
this.defaultEditors.put(List.class,newCustomCollectionEditor(List.class));
this.defaultEditors.put(SortedMap.class,newCustomMapEditor(SortedMap.class));
//Defaulteditorsforprimitivearrays.
this.defaultEditors.put(byte[].class,newByteArrayPropertyEditor());
this.defaultEditors.put(char[].class,newCharArrayPropertyEditor());
//TheJDKdoesnotcontainadefaulteditorforchar!
this.defaultEditors.put(char.class,newCharacterEditor(false));
this.defaultEditors.put(Character.class,newCharacterEditor(true));
//Spring'sCustomBooleanEditoracceptsmoreflagvaluesthantheJDK'sdefaulteditor.
this.defaultEditors.put(boolean.class,newCustomBooleanEditor(false));
this.defaultEditors.put(Boolean.class,newCustomBooleanEditor(true));
//TheJDKdoesnotcontaindefaulteditorsfornumberwrappertypes!
//OverrideJDKprimitivenumbereditorswithourownCustomNumberEditor.
this.defaultEditors.put(byte.class,newCustomNumberEditor(Byte.class,false));
this.defaultEditors.put(Byte.class,newCustomNumberEditor(Byte.class,true));
this.defaultEditors.put(short.class,newCustomNumberEditor(Short.class,false));
this.defaultEditors.put(Short.class,newCustomNumberEditor(Short.class,true));
this.defaultEditors.put(int.class,newCustomNumberEditor(Integer.class,false));
this.defaultEditors.put(Integer.class,newCustomNumberEditor(Integer.class,true));
this.defaultEditors.put(long.class,newCustomNumberEditor(Long.class,false));
this.defaultEditors.put(Long.class,newCustomNumberEditor(Long.class,true));
this.defaultEditors.put(float.class,newCustomNumberEditor(Float.class,false));
this.defaultEditors.put(Float.class,newCustomNumberEditor(Float.class,true));
this.defaultEditors.put(double.class,newCustomNumberEditor(Double.class,false));
this.defaultEditors.put(Double.class,newCustomNumberEditor(Double.class,true));
this.defaultEditors.put(BigDecimal.class,newCustomNumberEditor(BigDecimal.class,true));
this.defaultEditors.put(BigInteger.class,newCustomNumberEditor(BigInteger.class,true));
//Onlyregisterconfigvalueeditorsifexplicitlyrequested.
if(this.configValueEditorsActive){
StringArrayPropertyEditorsae=newStringArrayPropertyEditor();
this.defaultEditors.put(String[].class,sae);
this.defaultEditors.put(short[].class,sae);
this.defaultEditors.put(int[].class,sae);
this.defaultEditors.put(long[].class,sae);
}
}
下面挑选一些常用的数据类型,举例说明它们的绑定方式
1. 基本数据类型(以int为例,其他类似):
Controller代码:
Java代码
@RequestMapping("test.do")
publicvoidtest(intnum){
}
JSP表单代码:
Java代码
<formaction="test.do"method="post">
<inputname="num"value="10"type="text"/>
......
</form>
表单中input的name值和Controller的参数变量名保持一致,就能完成基本数据类型的数据绑定,如果不一致可以使用@RequestParam标注实现。值得一提的是,如果Controller方法参数中定义的是基本数据类型,但是从jsp提交过来的数据为null或者""的话,会出现数据转换的异常。也就是说,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,具体参见下面的第二条。
2. 包装类型(以Integer为例,其他类似):
Controller代码:
Java代码
@RequestMapping("test.do")
publicvoidtest(Integernum){
}
JSP表单代码:
Java代码
<formaction="test.do"method="post">
<inputname="num"value="10"type="text"/>
......
</form>
和基本数据类型基本一样,不同之处在于,JSP表单传递过来的数据可以为null或"",以上面代码为例,如果jsp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:
Java代码
publicclassUser{
privateStringfirstName;
privateStringlastName;
publicStringgetFirstName(){
returnfirstName;
}
publicvoidsetFirstName(StringfirstName){
this.firstName=firstName;
}
publicStringgetLastName(){
returnlastName;
}
publicvoidsetLastName(StringlastName){
this.lastName=lastName;
}
}
Controller代码:
Java代码
@RequestMapping("test.do")
publicvoidtest(Useruser){
}
JSP表单代码:
Java代码
<formaction="test.do"method="post">
<inputname="firstName"value="张"type="text"/>
<inputname="lastName"value="三"type="text"/>
......
</form>
非常简单,只需将对象的属性名和input的name值一一对应即可。
4. 自定义复合对象类型:
Model代码:
Java代码
publicclassContactInfo{
privateStringtel;
privateStringaddress;
publicStringgetTel(){
returntel;
}
publicvoidsetTel(Stringtel){
this.tel=tel;
}
publicStringgetAddress(){
returnaddress;
}
publicvoidsetAddress(Stringaddress){
this.address=address;
}
}
publicclassUser{
privateStringfirstName;
privateStringlastName;
privateContactInfocontactInfo;
publicStringgetFirstName(){
returnfirstName;
}
publicvoidsetFirstName(StringfirstName){
this.firstName=firstName;
}
publicStringgetLastName(){
returnlastName;
}
publicvoidsetLastName(StringlastName){
this.lastName=lastName;
}
publicContactInfogetContactInfo(){
returncontactInfo;
}
publicvoidsetContactInfo(ContactInfocontactInfo){
this.contactInfo=contactInfo;
}
}
Controller代码:
Java代码
@RequestMapping("test.do")
publicvoidtest(Useruser){
System.out.println(user.getFirstName());
System.out.println(user.getLastName());
System.out.println(user.getContactInfo().getTel());
System.out.println(user.getContactInfo().getAddress());
}
JSP表单代码:
Java代码
<formaction="test.do"method="post">
<inputname="firstName"value="张"/><br>
<inputname="lastName"value="三"/><br>
<inputname="contactInfo.tel"value="13809908909"/><br>
<inputname="contactInfo.address"value="北京海淀"/><br>
<inputtype="submit"value="Save"/>
</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jsp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:
Java代码
publicclassUser{
privateStringfirstName;
privateStringlastName;
publicStringgetFirstName(){
returnfirstName;
}
publicvoidsetFirstName(StringfirstName){
this.firstName=firstName;
}
publicStringgetLastName(){
returnlastName;
}
publicvoidsetLastName(StringlastName){
this.lastName=lastName;
}
}
publicclassUserListForm{
privateList<User>users;
publicList<User>getUsers(){
returnusers;
}
publicvoidsetUsers(List<User>users){
this.users=users;
}
}
Controller代码:
Java代码
@RequestMapping("test.do")
publicvoidtest(UserListFormuserForm){
for(Useruser:userForm.getUsers()){
System.out.println(user.getFirstName()+"-"+user.getLastName());
}
}
JSP表单代码:
Java代码
<formaction="test.do"method="post">
<table>
<thead>
<tr>
<th>FirstName</th>
<th>LastName</th>
</tr>
</thead>
<tfoot>
<tr>
<tdcolspan="2"><inputtype="submit"value="Save"/></td>
</tr>
</tfoot>
<tbody>
<tr>
<td><inputname="users[0].firstName"value="aaa"/></td>
<td><inputname="users[0].lastName"value="bbb"/></td>
</tr>
<tr>
<td><inputname="users[1].firstName"value="ccc"/></td>
<td><inputname="users[1].lastName"value="ddd"/></td>
</tr>
<tr>
<td><inputname="users[2].firstName"value="eee"/></td>
<td><inputname="users[2].lastName"value="fff"/></td>
</tr>
</tbody>
</table>
</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JSP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JSP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jsp表单中对应有下标的那些才会有值,否则会为null,看个例子:
JSP表单代码:
Java代码
<formaction="test.do"method="post">
<table>
<thead>
<tr>
<th>FirstName</th>
<th>LastName</th>
</tr>
</thead>
<tfoot>
<tr>
<tdcolspan="2"><inputtype="submit"value="Save"/></td>
</tr>
</tfoot>
<tbody>
<tr>
<td><inputname="users[0].firstName"value="aaa"/></td>
<td><inputname="users[0].lastName"value="bbb"/></td>
</tr>
<tr>
<td><inputname="users[1].firstName"value="ccc"/></td>
<td><inputname="users[1].lastName"value="ddd"/></td>
</tr>
<tr>
<td><inputname="users[20].firstName"value="eee"/></td>
<td><inputname="users[20].lastName"value="fff"/></td>
</tr>
</tbody>
</table>
</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:
Java代码
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
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:
Java代码
publicclassUser{
privateStringfirstName;
privateStringlastName;
publicStringgetFirstName(){
returnfirstName;
}
publicvoidsetFirstName(StringfirstName){
this.firstName=firstName;
}
publicStringgetLastName(){
returnlastName;
}
publicvoidsetLastName(StringlastName){
this.lastName=lastName;
}
}
publicclassUserSetForm{
privateSet<User>users=newHashSet<User>();
publicUserSetForm(){
users.add(newUser());
users.add(newUser());
users.add(newUser());
}
publicSet<User>getUsers(){
returnusers;
}
publicvoidsetUsers(Set<User>users){
this.users=users;
}
}
Controller代码:
Java代码
@RequestMapping("test.do")
publicvoidtest(UserSetFormuserForm){
for(Useruser:userForm.getUsers()){
System.out.println(user.getFirstName()+"-"+user.getLastName());
}
}
JSP表单代码:
Java代码
<formaction="test.do"method="post">
<table>
<thead>
<tr>
<th>FirstName</th>
<th>LastName</th>
</tr>
</thead>
<tfoot>
<tr>
<tdcolspan="2"><inputtype="submit"value="Save"/></td>
</tr>
</tfoot>
<tbody>
<tr>
<td><inputname="users[0].firstName"value="aaa"/></td>
<td><inputname="users[0].lastName"value="bbb"/></td>
</tr>
<tr>
<td><inputname="users[1].firstName"value="ccc"/></td>
<td><inputname="users[1].lastName"value="ddd"/></td>
</tr>
<tr>
<td><inputname="users[2].firstName"value="eee"/></td>
<td><inputname="users[2].lastName"value="fff"/></td>
</tr>
</tbody>
</table>
</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。暂时没找到解决方法,如果有网友知道,请回帖共享你的做法。
5. 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:
Java代码
publicclassUser{
privateStringfirstName;
privateStringlastName;
publicStringgetFirstName(){
returnfirstName;
}
publicvoidsetFirstName(StringfirstName){
this.firstName=firstName;
}
publicStringgetLastName(){
returnlastName;
}
publicvoidsetLastName(StringlastName){
this.lastName=lastName;
}
}
publicclassUserMapForm{
privateMap<String,User>users;
publicMap<String,User>getUsers(){
returnusers;
}
publicvoidsetUsers(Map<String,User>users){
this.users=users;
}
}
Controller代码:
Java代码
@RequestMapping("test.do")
publicvoidtest(UserMapFormuserForm){
for(Map.Entry<String,User>entry:userForm.getUsers().entrySet()){
System.out.println(entry.getKey()+":"+entry.getValue().getFirstName()+"-"+
entry.getValue().getLastName());
}
}
JSP表单代码:
Java代码
<formaction="test.do"method="post">
<table>
<thead>
<tr>
<th>FirstName</th>
<th>LastName</th>
</tr>
</thead>
<tfoot>
<tr>
<tdcolspan="2"><inputtype="submit"value="Save"/></td>
</tr>
</tfoot>
<tbody>
<tr>
<td><inputname="users['x'].firstName"value="aaa"/></td>
<td><inputname="users['x'].lastName"value="bbb"/></td>
</tr>
<tr>
<td><inputname="users['y'].firstName"value="ccc"/></td>
<td><inputname="users['y'].lastName"value="ddd"/></td>
</tr>
<tr>
<td><inputname="users['z'].firstName"value="eee"/></td>
<td><inputname="users['z'].lastName"value="fff"/></td>
</tr>
</tbody>
</table>
</form>
打印结果:
Java代码
x:aaa-bbb
y:ccc-ddd
z:eee-fff
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