发布于 2017-08-25 07:14:32 | 30 次阅读 | 评论: 0 | 来源: 网友投递

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Spring Framework 开源j2ee框架

Spring是什么呢?首先它是一个开源的项目,而且目前非常活跃;它是一个基于IOC和AOP的构架多层j2ee系统的框架,但它不强迫你必须在每一层 中必须使用Spring,因为它模块化的很好,允许你根据自己的需要选择使用它的某一个模块;它实现了很优雅的MVC,对不同的数据访问技术提供了统一的接口,采用IOC使得可以很容易的实现bean的装配,提供了简洁的AOP并据此实现Transcation Managment,等等


这篇文章主要介绍了 SpringMVC 数据绑定实例详解的相关资料,需要的朋友可以参考下

 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); 
  } 
} 

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) { 
   
} 

    JSP表单代码:


<form action="test.do" method="post"> 
  <input name="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:


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

   JSP表单代码:


<form action="test.do" method="post"> 
  <input name="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:


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代码:


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

    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> 

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; 
  } 
 
  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代码:


@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表单代码:


<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,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:


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代码:


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

    JSP表单代码:


<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:


<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> 

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:


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:


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代码:


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

    JSP表单代码:


<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:


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代码:


@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表单代码:


<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> 

打印结果:


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

感谢阅读,希望能帮助到大家,谢谢大家对本站的支持!



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