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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
来源: http://www.phperz.com/article/17/0825/338960.html