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SpringMVC 数据绑定
查看spring源码可以看出spring支持转换的数据类型：
org.springframework.beans.PropertyEditorRegistrySupport:
/**
* Actually register the default editors for this registry instance.
*/
private void createDefaultEditors() {
this.defaultEditors = new HashMap<Class, PropertyEditor>(64);
// Simple editors, without parameterization capabilities.
// The JDK does not contain a default editor for any of these target types.
this.defaultEditors.put(Charset.class, new CharsetEditor());
this.defaultEditors.put(Class.class, new ClassEditor());
this.defaultEditors.put(Class[].class, new ClassArrayEditor());
this.defaultEditors.put(Currency.class, new CurrencyEditor());
this.defaultEditors.put(File.class, new FileEditor());
this.defaultEditors.put(InputStream.class, new InputStreamEditor());
this.defaultEditors.put(InputSource.class, new InputSourceEditor());
this.defaultEditors.put(Locale.class, new LocaleEditor());
this.defaultEditors.put(Pattern.class, new PatternEditor());
this.defaultEditors.put(Properties.class, new PropertiesEditor());
this.defaultEditors.put(Resource[].class, new ResourceArrayPropertyEditor());
this.defaultEditors.put(TimeZone.class, new TimeZoneEditor());
this.defaultEditors.put(URI.class, new URIEditor());
this.defaultEditors.put(URL.class, new URLEditor());
this.defaultEditors.put(UUID.class, new UUIDEditor());
// Default instances of collection editors.
// Can be overridden by registering custom instances of those as custom editors.
this.defaultEditors.put(Collection.class, new CustomCollectionEditor(Collection.class));
this.defaultEditors.put(Set.class, new CustomCollectionEditor(Set.class));
this.defaultEditors.put(SortedSet.class, new CustomCollectionEditor(SortedSet.class));
this.defaultEditors.put(List.class, new CustomCollectionEditor(List.class));
this.defaultEditors.put(SortedMap.class, new CustomMapEditor(SortedMap.class));
// Default editors for primitive arrays.
this.defaultEditors.put(byte[].class, new ByteArrayPropertyEditor());
this.defaultEditors.put(char[].class, new CharArrayPropertyEditor());
// The JDK does not contain a default editor for char!
this.defaultEditors.put(char.class, new CharacterEditor(false));
this.defaultEditors.put(Character.class, new CharacterEditor(true));
// Spring's CustomBooleanEditor accepts more flag values than the JDK's default editor.
this.defaultEditors.put(boolean.class, new CustomBooleanEditor(false));
this.defaultEditors.put(Boolean.class, new CustomBooleanEditor(true));
// The JDK does not contain default editors for number wrapper types!
// Override JDK primitive number editors with our own CustomNumberEditor.
this.defaultEditors.put(byte.class, new CustomNumberEditor(Byte.class, false));
this.defaultEditors.put(Byte.class, new CustomNumberEditor(Byte.class, true));
this.defaultEditors.put(short.class, new CustomNumberEditor(Short.class, false));
this.defaultEditors.put(Short.class, new CustomNumberEditor(Short.class, true));
this.defaultEditors.put(int.class, new CustomNumberEditor(Integer.class, false));
this.defaultEditors.put(Integer.class, new CustomNumberEditor(Integer.class, true));
this.defaultEditors.put(long.class, new CustomNumberEditor(Long.class, false));
this.defaultEditors.put(Long.class, new CustomNumberEditor(Long.class, true));
this.defaultEditors.put(float.class, new CustomNumberEditor(Float.class, false));
this.defaultEditors.put(Float.class, new CustomNumberEditor(Float.class, true));
this.defaultEditors.put(double.class, new CustomNumberEditor(Double.class, false));
this.defaultEditors.put(Double.class, new CustomNumberEditor(Double.class, true));
this.defaultEditors.put(BigDecimal.class, new CustomNumberEditor(BigDecimal.class, true));
this.defaultEditors.put(BigInteger.class, new CustomNumberEditor(BigInteger.class, true));
// Only register config value editors if explicitly requested.
if (this.configValueEditorsActive) {
StringArrayPropertyEditor sae = new StringArrayPropertyEditor();
this.defaultEditors.put(String[].class, sae);
this.defaultEditors.put(short[].class, sae);
this.defaultEditors.put(int[].class, sae);
this.defaultEditors.put(long[].class, sae);
}
}
</div>
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：
@RequestMapping("test.do")
public void test(int num) {
}
</div>
JSP表单代码：
<form action="test.do" method="post"> <input name="num" value="10" type="text"/> ...... </form></div>
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：
@RequestMapping("test.do")
public void test(Integer num) {
}
</div>
JSP表单代码：
<form action="test.do" method="post"> <input name="num" value="10" type="text"/> ...... </form></div>
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：
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;
}
}
</div>
Controller代码：
@RequestMapping("test.do")
public void test(User user) {
}
</div>
JSP表单代码：
<form action="test.do" method="post"> <input name="firstName" value="张" type="text"/> <input name="lastName" value="三" type="text"/> ...... </form></div>
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：
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;
}
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