Spring MVC's data binding
Binding data is bound to one characteristic of the user input field model.
Http request data transmitted to a String, through data binding, data may be filled with different types of object properties.
The basic type binding
@RequestMapping("/int")
@ResponseBody
public String bindInt (int i) {
return "bindInt:" + i;
}Request:? / Int i = 10
in response to: bindInt: 3
Bad request: / int or / int 2?
Error Code: 500
When the basic types of data binding, it must pass keyand value.
Package Type Bind
@RequestMapping("/integer")
@ResponseBody
public String bindInteger (Integer i) {
return "bindInteger:" + i;
}Request:? / Integer i = 5
in response to: bindInteger: 5
请求：/integer or /integer?5 or /integer?i or /integer?i=
响应：bindInteger:null
The type of packaging data binding, keyand valuecan be empty.
If the required parameters must be passed, it can be added @RequestParam.
@RequestMapping("/integer")
@ResponseBody
public String bindInteger (@RequestParam Integer i) {
return "bindInteger:" + i;
}Bad request: / integer or / integer 5?
Error Code: 400
Request:?? / Integer i or / integer i =
response: bindInteger: null
Array bind
@RequestMapping("/array")
@ResponseBody
public String bindArray (String[] strs) {
StringBuilder sb = new StringBuilder();
sb.append("bindArray:");
for (String str : strs)
sb.append(str + " ");
return sb.toString();
}Request:? / Array strs = str1 & strs = str2
response: bindArray: str1 str2
Simple Object bind
@RequestMapping("/user")
@ResponseBody
public String bindUser (User user) {
return "bindUser:" + user.toString();
}public class User {
private String name;
private Integer age;
// getters and setters
// toString
}Request:? / User name = Tom & age = 15
Response: bindUser: User [name = Tom , age = 15]
Multi-level object bound
public class User {
private String name;
private Integer age;
private ContactInfo info;
// getters and setters
// toString
}
public class ContactInfo {
private String phone;
private String address;
// getters and setters
// toString
}Request:? / User name = Tom & info.phone = 123456
response: bindUser: User [name = Tom , age = null, info = ContactInfo [phone = 123456, address = null]]
With multi-object binding properties
@RequestMapping("/userandadmin")
@ResponseBody
public String bindUserAndAdmin (User user, Admin admin) {
return "bindUserAndAdmin:\n" + user.toString() + "\n" + admin.toString();
}public class Admin {
private String name;
private Integer age;
// getters and setters
// toString
}Request: / userandadmin name = Tom & age = 15?
Response:
bindUserAndAdmin:
the User [name = Tom, Age = 15]
the Admin [name = Tom, Age = 15]
While the data is bound to the two objects have the same properties.
Solution:
@InitBinder("user")
public void initUser(WebDataBinder binder) {
binder.setFieldDefaultPrefix("user.");
}
@InitBinder("admin")
public void initAdmin(WebDataBinder binder) {
binder.setFieldDefaultPrefix("admin.");
}Request:? / Userandadmin user.name = Tom & age = 15 & admin.name = Jack
response:
bindUserAndAdmin:
the User [name = Tom, Age = 15]
the Admin [name = Jack, Age = 15]
InitBinderIn the role of the controller, the controller first call into the InitBindercall back RequestMappingmethod.
Not configured InitBinderprefix invalid and can not successfully bind.
WebDataBinderParameter used to bind to a specific request JavaBean.
List Binding
@RequestMapping("/stringlist")
@ResponseBody
public String bindStringList (@RequestParam("name") List<String> strs) {
return "bindStringList:" + strs.toString();
}Request: / stringlist name = Tom & name = Jack?
Response: bindStringList: [Tom, Jack]
@RequestMapping("/userlist")
@ResponseBody
public String bindUserList(UserListForm userListForm){
return "bindUserList:\n" + usersModel.toString();
}public class UserListForm {
private List<User> list;
// getters and setters
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
for (User u : users)
sb.append(u.toString() + "\n");
return sb.toString();
}
}请求：/userlist?users[0].name=Tom&users[2].name=Jack
响应：
bindList:
User [name=Tom, age=null]
User [name=null, age=null]
User [name=Jack, age=null]
PS: High version of the tomcat [need to escape %5B, ]need to escape to%5D
Set Binding
Set the List Binding basically the same, but in use Set<User>, the need to initialize the Set capacity.
public class UserSetForm {
private Set<User> users;
private UserSetForm () {
// 设置 set 容量为 2 不能访问 size 外的对象
// 如果覆盖了 User 的 equals 和 hashcode 方法 则 set 容量为 1
users = new HashSet<User>();
users.add(new User());
users.add(new User());
System.out.println(users.size());
}
// getters and setters
// toString
}// User.java
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((age == null) ? 0 : age.hashCode());
result = prime * result + ((name == null) ? 0 : name.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
User other = (User) obj;
if (age == null) {
if (other.age != null)
return false;
} else if (!age.equals(other.age))
return false;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
return true;
}Request:? / Userset users [0] .name = Tom
response:
bindUserSet:
the User [name = Tom, Age = null]
Error Request:? / Userset users [0] .name = Tom & users [1] .name = Jack
Error Code: 500
Error Description: Can not get element with index 1 from Set of size 1, accessed using property path 'users [1]'
Map bindings
@RequestMapping("/usermap")
@ResponseBody
public String bindUserMap (UserMapForm userMapForm) {
return "bindUserMap:\n" + userMapForm.toString();
}public class UserMapForm {
private Map<String, User> users;
// getters and setters
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
for (String s : users.keySet())
sb.append("Users[" + s + "] = " + users.get(s) + "\n");
return sb.toString();
}
}请求：/usermap?users[x].name=Tom&users[y].name=Jack
响应：
bindUserMap:
Users[x] = User [name=Tom, age=null]
Users[y] = User [name=Jack, age=null]
JSON binding
@RequestMapping("/userjson")
@ResponseBody
public String bindUserJson (@RequestBody User user) {
return "bindUserJson:" + user.toString();
}请求：
Content-Type：application/json
Body:
{
"name":"Tom",
"age":15
} Response: bindUserJson: User [name = Tom , age = 15]
dependency: jackson-databind
XML Binding
@RequestMapping("/userxml")
@ResponseBody
public String bindUserXml (@RequestBody User user) {
return "bindUserXml:" + user.toString();
}@XmlRootElement(name="user")
public class User {
private String name;
private Integer age;
@XmlElement(name="name")
public String getName() {
return name;
}
@XmlElement(name="age")
public Integer getAge() {
return age;
}
// setters
// toString
}
Request:
the Content-the Type: file application / XML
Body:
<user>
<name>Tom</name>
<age>15</age>
</user> Response: bindUserXml: User [name = Tom , age = 15]
dependency: jaxb-api jaxb-impl spring -oxm
PropertyEditor
public interface PropertyEditor {
void setValue(Object value);
Object getValue();
String getAsText();
void setAsText(String text) throws java.lang.IllegalArgumentException;
// ...
}Use: general use of the built or inherited PropertyEditorSupport(implements PropertyEditor), with the WebDataBindertopical use.
@RequestMapping("/datepe")
@ResponseBody
public String bindDateByPropertyEditor (Date date1) {
return date1.toString();
}
@InitBinder("date1")
public void initDate (WebDataBinder binder) {
binder.registerCustomEditor(Date.class, new CustomDateEditor(new SimpleDateFormat("yyyy-MM-dd"), true));
}Request:? / Datepe date1 = 2019-11-11
Response: Mon Nov 11 00:00:00 CST 2019
Formatter
public interface Formatter<T> extends Printer<T>, Parser<T> {
}
public interface Printer<T> {
String print(T object, Locale locale);
}
public interface Parser<T> {
T parse(String text, Locale locale) throws ParseException;
}Use: Source type String, can be global or local use.
@RequestMapping("/dateformatter")
@ResponseBody
public String bindDateByFormatter (Date date2) {
return date2.toString();
}<mvc:annotation-driven conversion-service="formatter"/>
<!-- conversion-service 与 id 对应 -->
<bean id="formatter" class="org.springframework.format.support.FormattingConversionServiceFactoryBean">
<property name="formatters">
<set>
<bean class="org.springframework.format.datetime.DateFormatter">
<constructor-arg name="pattern" value="yyyy-MM-dd" />
</bean>
</set>
</property>
</bean>Request:? / Dateformatter date2 = 2019-12-12
Response: Thu Dec 12 00:00:00 CST 2019
Converter
public interface Converter<S, T> {
@Nullable
T convert(S source);
}Use: Built implemented as a final class, not extensible, customizable source type and destination type, global or local use.
@RequestMapping("/dateconverter")
@ResponseBody
public String bindDateByConverter (Date date3) {
return date3.toString();
}public class DateConverter implements Converter<String, Date> {
public Date convert(String source) {
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
try {
return format.parse(source);
} catch (ParseException e) {
e.printStackTrace();
}
return null;
}
}<mvc:annotation-driven conversion-service="converter"/>
<!-- 自定义 Converter 类 -->
<bean id="converter" class="org.springframework.format.support.FormattingConversionServiceFactoryBean">
<property name="converters">
<set>
<bean class="common.DateConverter" />
</set>
</property>
</bean>Request:? / Dateconverter date3 = 2019-10-24
Response: Thu Oct 24 00:00:00 CST 2019
Reference: SpringMVC data binding entry