SpringMVC 數(shù)據(jù)綁定實(shí)例詳解

更新時(shí)間：2017年04月25日 17:05:23 作者：Senton

這篇文章主要介紹了 SpringMVC 數(shù)據(jù)綁定實(shí)例詳解的相關(guān)資料,需要的朋友可以參考下

SpringMVC 數(shù)據(jù)綁定

查看spring源碼可以看出spring支持轉(zhuǎn)換的數(shù)據(jù)類型：

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); 
  } 
}

下面挑選一些常用的數(shù)據(jù)類型，舉例說明它們的綁定方式

1. 基本數(shù)據(jù)類型(以int為例，其他類似)：

Controller代碼：

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

JSP表單代碼：

<form action="test.do" method="post"> 
  <input name="num" value="10" type="text"/> 
  ...... 
</form>

表單中input的name值和Controller的參數(shù)變量名保持一致，就能完成基本數(shù)據(jù)類型的數(shù)據(jù)綁定，如果不一致可以使用@RequestParam標(biāo)注實(shí)現(xiàn)。值得一提的是，如果Controller方法參數(shù)中定義的是基本數(shù)據(jù)類型，但是從jsp提交過來的數(shù)據(jù)為null或者""的話，會(huì)出現(xiàn)數(shù)據(jù)轉(zhuǎn)換的異常。也就是說，必須保證表單傳遞過來的數(shù)據(jù)不能為null或""，所以，在開發(fā)過程中，對(duì)可能為空的數(shù)據(jù)，最好將參數(shù)數(shù)據(jù)類型定義成包裝類型，具體參見下面的第二條。

2. 包裝類型(以Integer為例，其他類似)：

Controller代碼：

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

JSP表單代碼：

<form action="test.do" method="post"> 
  <input name="num" value="10" type="text"/> 
  ...... 
</form>

和基本數(shù)據(jù)類型基本一樣，不同之處在于，JSP表單傳遞過來的數(shù)據(jù)可以為null或""，以上面代碼為例，如果jsp中num為""或者表單中無num這個(gè)input，那么，Controller方法參數(shù)中的num值則為null。

3. 自定義對(duì)象類型：

Model代碼：

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; 
  } 
 
}

Controller代碼：

@RequestMapping("test.do") 
public void test(User user) { 
   
}

JSP表單代碼：

<form action="test.do" method="post"> 
  <input name="firstName" value="張" type="text"/> 
  <input name="lastName" value="三" type="text"/> 
  ...... 
</form>

非常簡(jiǎn)單，只需將對(duì)象的屬性名和input的name值一一對(duì)應(yīng)即可。

4. 自定義復(fù)合對(duì)象類型：

Model代碼：

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; 
  } 
 
}

Controller代碼：

@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()); 
}

JSP表單代碼：

<form action="test.do" method="post"> 
  <input name="firstName" value="張" /><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對(duì)象中有ContactInfo屬性，Controller中的代碼和第3點(diǎn)說的一致，但是，在jsp代碼中，需要使用“屬性名(對(duì)象類型的屬性).屬性名”來命名input的name。

5. List綁定：

List需要綁定在對(duì)象上，而不能直接寫在Controller方法的參數(shù)中。

Model代碼：

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; 
  } 
 
}

Controller代碼：

@RequestMapping("test.do") 
public void test(UserListForm userForm) { 
  for (User user : userForm.getUsers()) { 
    System.out.println(user.getFirstName() + " - " + user.getLastName()); 
  } 
}

JSP表單代碼：

<form action="test.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>

其實(shí)，這和第4點(diǎn)User對(duì)象中的contantInfo數(shù)據(jù)的綁定有點(diǎn)類似，但是這里的UserListForm對(duì)象里面的屬性被定義成List，而不是普通自定義對(duì)象。所以，在JSP中需要指定List的下標(biāo)。值得一提的是，Spring會(huì)創(chuàng)建一個(gè)以最大下標(biāo)值為size的List對(duì)象，所以，如果JSP表單中有動(dòng)態(tài)添加行、刪除行的情況，就需要特別注意，譬如一個(gè)表格，用戶在使用過程中經(jīng)過多次刪除行、增加行的操作之后，下標(biāo)值就會(huì)與實(shí)際大小不一致，這時(shí)候，List中的對(duì)象，只有在jsp表單中對(duì)應(yīng)有下標(biāo)的那些才會(huì)有值，否則會(huì)為null，看個(gè)例子：

JSP表單代碼：

<form action="test.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>

這個(gè)時(shí)候，Controller中的userForm.getUsers()獲取到List的size為21，而且這21個(gè)User對(duì)象都不會(huì)為null，但是，第2到第19的User對(duì)象中的firstName和lastName都為null。打印結(jié)果：

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綁定：

Set和List類似，也需要綁定在對(duì)象上，而不能直接寫在Controller方法的參數(shù)中。但是，綁定Set數(shù)據(jù)時(shí)，必須先在Set對(duì)象中add相應(yīng)的數(shù)量的模型對(duì)象。

Model代碼：

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; 
  } 
 
}

Controller代碼：

@RequestMapping("test.do") 
public void test(UserSetForm userForm) { 
  for (User user : userForm.getUsers()) { 
    System.out.println(user.getFirstName() + " - " + user.getLastName()); 
  } 
}

JSP表單代碼：

<form action="test.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>

基本和List綁定類似。

需要特別提醒的是，如果最大下標(biāo)值大于Set的size，則會(huì)拋出org.springframework.beans.InvalidPropertyException異常。所以，在使用時(shí)有些不便。暫時(shí)沒找到解決方法，如果有網(wǎng)友知道，請(qǐng)回帖共享你的做法。

5. Map綁定：

Map最為靈活，它也需要綁定在對(duì)象上，而不能直接寫在Controller方法的參數(shù)中。

Model代碼：

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; 
  } 
 
}

Controller代碼：

@RequestMapping("test.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()); 
  } 
}

JSP表單代碼：

<form action="test.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>

打印結(jié)果：

x: aaa - bbb 
y: ccc - ddd 
z: eee - fff

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