请参阅Vaadin 框架、Vaadin 数据模型、将数据绑定到表单：
转换
即使类型不匹配，您也可以将应用程序数据绑定到 UI 字段组件。
Binder#bindInstanceFields()说：
并不总是可以将字段绑定到属性，因为它们的类型不兼容。例如，需要自定义转换器来绑定HasValue<String>和Integer属性（这将是“年龄”属性的情况）。在这种情况下，除非在调用方法IllegalStateException之前手动配置了该字段，否则将抛出这种情况。bindInstanceFields(Object)
[...]：该bindInstanceFields(Object)方法不会覆盖现有绑定。
[我强调。]
所以，AFAIU，这应该有效：
private final TextField siblingsCount = new TextField( "№ of Siblings" );
...
binder.forField( siblingsCount )
.withNullRepresentation( "" )
.withConverter(
new StringToIntegerConverter( Integer.valueOf( 0 ), "integers only" ) )
.bind( Child::getSiblingsCount, Child::setSiblingsCount );
binder.bindInstanceFields( this );
但它仍然抛出：
java.lang.IllegalStateException: Property type 'java.lang.Integer' doesn't match the field type 'java.lang.String'. Binding should be configured manually using converter.
...
at com.vaadin.data.Binder.bindInstanceFields(Binder.java:2135)
...
你在开玩笑吧？我就是这么做的，不是吗？我相当怀疑“不会覆盖现有绑定”。或者，如果实际上没有被覆盖，它们似乎bindInstanceFields()至少在 中被忽略了。
相同的手动绑定配置在不使用Binder#bindInstanceFields()但为每个字段单独绑定的方法时有效。
另请参阅Vaadin 框架数据绑定论坛中的线程Binding from Integer not working和issue #8858 Binder.bindInstanceFields() overwrites existing bindings。
解决方法
比@cfrick 的回答更复杂：
/** Used for workaround for Vaadin issue #8858
* 'Binder.bindInstanceFields() overwrites existing bindings'
* https://github.com/vaadin/framework/issues/8858
*/
private final Map<String, Component> manualBoundComponents = new HashMap<>();
...
// Commented here and declared local below for workaround for Vaadin issue #8858
//private final TextField siblingsCount = new TextField( "№ of Siblings" );
...
public ChildView() {
...
// Workaround for Vaadin issue #8858
// Declared local here to prevent processing by Binder#bindInstanceFields()
final TextField siblingsCount = new TextField( "№ of Siblings" );
manualBoundComponents.put( "siblingsCount", siblingsCount );
binder.forField( siblingsCount )
.withNullRepresentation( "" )
.withConverter( new StringToIntegerConverter( Integer.valueOf( 0 ), "integers only" ) )
.bind( Child::getSiblingsCount, Child::setSiblingsCount );
binder.bindInstanceFields( this );
...
// Workaround for Vaadin issue #8858
addComponent( manualBoundComponents.get( "siblingsCount" ) );
//addComponent( siblingsCount );
...
}
更新
修复 #8998 使 bindInstanceFields 不绑定已使用函数绑定的字段。
该修复程序的源代码至少出现在Vaadin 8.1.0 alpha 4 预发行版（可能还有其他版本）中。
Basil Bourque 更新……</p>
您的想法，如上所示，Binder::bindInstanceFields在手动绑定不兼容（整数）属性后使用似乎确实对我有用。您抱怨在您的实验代码中，调用Binder::bindInstanceFields未能遵循记录的行为，即调用“不会覆盖现有绑定”。
但这似乎对我有用。这是 Vaadin 8.1.0 alpha 3 的示例应用程序。首先我手动绑定yearOfBirth属性。然后我binder.bindInstanceFields用来绑定带@PropertyId注释的name属性。这两个属性的字段显示为已填充并响应用户编辑。
我是否遗漏了什么，或者这是否按记录正常工作？如果我犯了错误，请删除此部分。
package com.example.vaadin.ex_formatinteger;
import com.vaadin.annotations.Theme;
import com.vaadin.annotations.VaadinServletConfiguration;
import com.vaadin.data.Binder;
import com.vaadin.data.converter.StringToIntegerConverter;
import com.vaadin.server.VaadinRequest;
import com.vaadin.server.VaadinServlet;
import com.vaadin.ui.*;
import javax.servlet.annotation.WebServlet;
/**
* This UI is the application entry point. A UI may either represent a browser window
* (or tab) or some part of a html page where a Vaadin application is embedded.
* <p>
* The UI is initialized using {@link #init(VaadinRequest)}. This method is intended to be
* overridden to add component to the user interface and initialize non-component functionality.
*/
@Theme ( "mytheme" )
public class MyUI extends UI {
Person person;
//@PropertyId ( "honorific" )
final TextField honorific = new TextField ( "Honorific:" ); // Bean property.
//@PropertyId ( "name" )
final TextField name = new TextField ( "Full name:" ); // Bean property.
// Manually bind property to field.
final TextField yearOfBirthField = new TextField ( "Year of Birth:" ); // Bean property.
final Label spillTheBeanLabel = new Label ( ); // Debug. Not a property.
@Override
protected void init ( VaadinRequest vaadinRequest ) {
this.person = new Person ( "Ms.", "Margaret Hamilton", Integer.valueOf ( 1936 ) );
Button button = new Button ( "Spill" );
button.addClickListener ( ( Button.ClickEvent e ) -> {
spillTheBeanLabel.setValue ( person.toString ( ) );
} );
// Binding
Binder < Person > binder = new Binder <> ( Person.class );
binder.forField ( this.yearOfBirthField )
.withNullRepresentation ( "" )
.withConverter ( new StringToIntegerConverter ( Integer.valueOf ( 0 ), "integers only" ) )
.bind ( Person:: getYearOfBirth, Person:: setYearOfBirth );
binder.bindInstanceFields ( this );
binder.setBean ( person );
setContent ( new VerticalLayout ( honorific, name, yearOfBirthField, button, spillTheBeanLabel ) );
}
@WebServlet ( urlPatterns = "/*", name = "MyUIServlet", asyncSupported = true )
@VaadinServletConfiguration ( ui = MyUI.class, productionMode = false )
public static class MyUIServlet extends VaadinServlet {
}
}
和简单的Person类。
package com.example.vaadin.ex_formatinteger;
import java.time.LocalDate;
import java.time.ZoneId;
/**
* Created by Basil Bourque on 2017-03-31.
*/
public class Person {
private String honorific ;
private String name;
private Integer yearOfBirth;
// Constructor
public Person ( String honorificArg , String nameArg , Integer yearOfBirthArg ) {
this.honorific = honorificArg;
this.name = nameArg;
this.yearOfBirth = yearOfBirthArg;
}
public String getHonorific ( ) {
return honorific;
}
public void setHonorific ( String honorific ) {
this.honorific = honorific;
}
// name property
public String getName ( ) {
return name;
}
public void setName ( String nameArg ) {
this.name = nameArg;
}
// yearOfBirth property
public Integer getYearOfBirth ( ) {
return yearOfBirth;
}
public void setYearOfBirth ( Integer yearOfBirth ) {
this.yearOfBirth = yearOfBirth;
}
// age property. Calculated, so getter only, no setter.
public Integer getAge ( ) {
int age = ( LocalDate.now ( ZoneId.systemDefault ( ) )
.getYear ( ) - this.yearOfBirth );
return age;
}
@Override
public String toString ( ) {
return "Person{ " +
"honorific='" + this.getHonorific () + '\'' +
", name='" + this.getName () +
", yearOfBirth=" + this.yearOfBirth +
", age=" + this.getAge () +
" }";
}
}