springMVC对简单对象、Set、List、Map的数据绑定和常见问题(一)

时间 2019-12-05

标签 springmvc 简单对象 set list map 数据绑定常见问题栏目 Spring 繁體版

原文原文链接

一、相关的类：
java

查看spring源码能够看出spring支持转换的数据类型：
org.springframework.beans.PropertyEditorRegistrySupport:spring

private void createDefaultEditors() { app
this.defaultEditors = new HashMap(64); jsp
// Simple editors, without parameterization capabilities. ide
// The JDK does not contain a default editor for any of these target types. post
this.defaultEditors.put(Charset.class, new CharsetEditor()); this
this.defaultEditors.put(Class.class, new ClassEditor()); spa
this.defaultEditors.put(Class[].class, new ClassArrayEditor()); code
this.defaultEditors.put(Currency.class, new CurrencyEditor()); orm
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);
}
}

二、基本数据类型绑定：

@RequestMapping("test.do")
public void test(int num) {
}
"test.do" method="post">
"num" value="10" type="text"/>
......

注意：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，若是不一致能够使用@RequestParam标注实现。值得一提的是，若是Controller方法参数中定义的是基本数据类型，可是从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""，因此，在开发过程当中，对可能为空的数据，最好将参数数据类型定义成包装类型。

三、包装类型

@RequestMapping("test.do")
public void test(Integer num) {
}

"test.do" method="post">
"num" value="10" type="text"/>
......

和基本数据类型基本同样，不一样之处在于，JSP表单传递过来的数据能够为null或""，以上面代码为例，若是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。

四、自定义对象类型

public class User {
private String firstName;
private String lastName;
...
}
@RequestMapping("test.do")
public void test(User user) {
}

"test.do" method="post">
"firstName" value="张" type="text"/>
"lastName" value="三" type="text"/>
......

只需将对象的属性名和input的name值一一对应便可。

五、自定义复合对象类型

public class ContactInfo {
private String tel;
private String address;
。。。
}
public class User {
private String firstName;
private String lastName;
private ContactInfo contactInfo;
。。。
}

@RequestMapping("test.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());
}

<form action="test.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>

User对象中有ContactInfo属性，Controller中的代码和第3点说的一致，可是，在jsp代码中，须要使用“属性名(对象类型的属性).属性名”来命名input的name。