3. 验证、数据绑定和类型转换

3.1 使用Spring的验证器接口进行验证

public class Person {

    private String name;
    private int age;

    // the usual getters and setters...
}

public class PersonValidator implements Validator {

    /**
     * This Validator validates only Person instances
     */
    public boolean supports(Class clazz) {
        return Person.class.equals(clazz);
    }

    public void validate(Object obj, Errors e) {
        ValidationUtils.rejectIfEmpty(e, "name", "name.empty");
        Person p = (Person) obj;
        if (p.getAge() < 0) {
            e.rejectValue("age", "negativevalue");
        } else if (p.getAge() > 110) {
            e.rejectValue("age", "too.darn.old");
        }
    }
}

public class CustomerValidator implements Validator {

    private final Validator addressValidator;

    public CustomerValidator(Validator addressValidator) {
        if (addressValidator == null) {
            throw new IllegalArgumentException("The supplied [Validator] is " +
                "required and must not be null.");
        }
        if (!addressValidator.supports(Address.class)) {
            throw new IllegalArgumentException("The supplied [Validator] must " +
                "support the validation of [Address] instances.");
        }
        this.addressValidator = addressValidator;
    }

    /**
     * This Validator validates Customer instances, and any subclasses of Customer too
     */
    public boolean supports(Class clazz) {
        return Customer.class.isAssignableFrom(clazz);
    }

    public void validate(Object target, Errors errors) {
        ValidationUtils.rejectIfEmptyOrWhitespace(errors, "firstName", "field.required");
        ValidationUtils.rejectIfEmptyOrWhitespace(errors, "surname", "field.required");
        Customer customer = (Customer) target;
        try {
            errors.pushNestedPath("address");
            ValidationUtils.invokeValidator(this.addressValidator, customer.getAddress(), errors);
        } finally {
            errors.popNestedPath();
        }
    }
}

3.2 将代码解析为错误信息

3.3 Bean Manipulation and the BeanWrapper

3.3.1 设置和获取基本属性和嵌套属性。

expression	explanation
name	表示与getName()或isName()和setName()方法相对应的属性name
account.name	表示与getAccount().setName()或getAccount().getName()方法（例如）相对应的属性account的嵌套属性 name
account[2]	表示索引account的第三个元素。索引属性的类型可以是array、list或其他自然有序的集合
account[COMPANYNAME]	表示由account Map属性的COMPANYNAME键索引的地图条目的值

ublic class Company {

    private String name;
    private Employee managingDirector;

    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Employee getManagingDirector() {
        return this.managingDirector;
    }

    public void setManagingDirector(Employee managingDirector) {
        this.managingDirector = managingDirector;
    }
}

public class Employee {

    private String name;

    private float salary;

    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public float getSalary() {
        return salary;
    }

    public void setSalary(float salary) {
        this.salary = salary;
    }
}

BeanWrapper company = new BeanWrapperImpl(new Company());
// setting the company name..
company.setPropertyValue("name", "Some Company Inc.");
// ... can also be done like this:
PropertyValue value = new PropertyValue("name", "Some Company Inc.");
company.setPropertyValue(value);

// ok, let's create the director and tie it to the company:
BeanWrapper jim = new BeanWrapperImpl(new Employee());
jim.setPropertyValue("name", "Jim Stravinsky");
company.setPropertyValue("managingDirector", jim.getWrappedInstance());

// retrieving the salary of the managingDirector through the company
Float salary = (Float) company.getPropertyValue("managingDirector.salary");

3.3.2 内置PropertyEditor实现

class	explanation
ByteArrayPropertyEditor	字节数组编辑器。将字符串转换为响应的字节表示。默认由BeanWrapperImpl注册
ClassEditor	将表示类的字符串解析为实际的类，反之亦然。找不到类时，会抛出IllegalArgumentException。默认情况下，用BeanWrapperImpl注册
CustomBooleanEditor	用于Boolean熟悉开的可定制属性编辑器。默认情况下，该编辑器有BeanWrapperImpl注册，但可以通过注册一个自定义编辑器实例来重载
CustomCollectionEditor	用于集合的属性编辑器，可将任何源Collection转换为给定目标Collection类型
CustomDateEditor	用于java.util.Date的可定制属性编辑器，支持自定义DateFormat。默认未注册。用户必须根据需要使用适当的格式注册
CustomNumberEditor	用于任何Number子类的可定制属性编辑器，例如Integer、Long、Float或Double .默认情况下，该编辑器由BeanWrapperImpl注册，但可以通过将其自定义实例注册为自定义编辑器来重写
FileEditor	将字符串解析为java.io.File对象。默认情况下，由BeanWrapperImpl
InputStreamEditor	单向属性编辑器，可以接受字符串并生成（通过中间ResourceEditor和Resource）InputeStream，这样InputStream属性可以直接设置为字符串。请注意，默认用法不会为你关闭InputStream。默认情况下，由BeanWrapperImpl注册
LocaleEditor	可以将字符串解析为Locale对象，反之亦然（字符串格式为[language] [country] [variant],与Locale的toSting()方法相同。还接受空格作为分隔符，以替代下划线。默认情况下，由BeanWrapperImpl注册。
PatternEditor	可将字符串解析为java.util.regex.Pattern对象，反之依然。
PropertiesEditor	可以将字符串（格式为java.util.Properties类的javadoc中定义的格式）转换为Properties对象。默认情况下，由BeanWrapperImpl注册
StringTrimmerEditor	用于修剪字符串的属性编辑器。可选择字符串转换为null值。默认情况下未注册，必须由用户注册
URLEditor	可将URL的字符串表示解析为实际的URL对象。默认情况下，由BeanWrapperImpl注册。

com
  chank
    pop
      Something
      SomethingEditor // the PropertyEditor for the Something class

com
  chank
    pop
      Something
      SomethingBeanInfo // the BeanInfo for the Something class

public class SomethingBeanInfo extends SimpleBeanInfo {

    public PropertyDescriptor[] getPropertyDescriptors() {
        try {
            final PropertyEditor numberPE = new CustomNumberEditor(Integer.class, true);
            PropertyDescriptor ageDescriptor = new PropertyDescriptor("age", Something.class) {
                @Override
                public PropertyEditor createPropertyEditor(Object bean) {
                    return numberPE;
                }
            };
            return new PropertyDescriptor[] { ageDescriptor };
        }
        catch (IntrospectionException ex) {
            throw new Error(ex.toString());
        }
    }
}

注册其他自定义PropertyEditor实现

ackage example;

public class ExoticType {

    private String name;

    public ExoticType(String name) {
        this.name = name;
    }
}

public class DependsOnExoticType {

    private ExoticType type;

    public void setType(ExoticType type) {
        this.type = type;
    }
}

<bean id="sample" class="example.DependsOnExoticType">
    <property name="type" value="aNameForExoticType"/>
</bean>

// converts string representation to ExoticType object
package example;

public class ExoticTypeEditor extends PropertyEditorSupport {

    public void setAsText(String text) {
        setValue(new ExoticType(text.toUpperCase()));
    }
}

<bean class="org.springframework.beans.factory.config.CustomEditorConfigurer">
    <property name="customEditors">
        <map>
            <entry key="example.ExoticType" value="example.ExoticTypeEditor"/>
        </map>
    </property>
</bean>

使用PropertyEditorRegistrar

package com.foo.editors.spring;

public final class CustomPropertyEditorRegistrar implements PropertyEditorRegistrar {

    public void registerCustomEditors(PropertyEditorRegistry registry) {

        // it is expected that new PropertyEditor instances are created
        registry.registerCustomEditor(ExoticType.class, new ExoticTypeEditor());

        // you could register as many custom property editors as are required here...
    }
}

<bean class="org.springframework.beans.factory.config.CustomEditorConfigurer">
    <property name="propertyEditorRegistrars">
        <list>
            <ref bean="customPropertyEditorRegistrar"/>
        </list>
    </property>
</bean>

<bean id="customPropertyEditorRegistrar"
      class="com.foo.editors.spring.CustomPropertyEditorRegistrar"/>

@Controller
public class RegisterUserController {

    private final PropertyEditorRegistrar customPropertyEditorRegistrar;

    RegisterUserController(PropertyEditorRegistrar propertyEditorRegistrar) {
        this.customPropertyEditorRegistrar = propertyEditorRegistrar;
    }

    @InitBinder
    void initBinder(WebDataBinder binder) {
        this.customPropertyEditorRegistrar.registerCustomEditors(binder);
    }

    // other methods related to registering a User
}

3.4 Spring Type Conversion

3.4.1 Converter SPI

package org.springframework.core.convert.converter;

public interface Converter<S, T> {

    T convert(S source);
}

package org.springframework.core.convert.support;

final class StringToInteger implements Converter<String, Integer> {

    public Integer convert(String source) {
        return Integer.valueOf(source);
    }
}

3.4.2 使用ConverterFactory

package org.springframework.core.convert.converter;

public interface ConverterFactory<S, R> {

    <T extends R> Converter<S, T> getConverter(Class<T> targetType);
}

package org.springframework.core.convert.support;

final class StringToEnumConverterFactory implements ConverterFactory<String, Enum> {

    public <T extends Enum> Converter<String, T> getConverter(Class<T> targetType) {
        return new StringToEnumConverter(targetType);
    }

    private final class StringToEnumConverter<T extends Enum> implements Converter<String, T> {

        private Class<T> enumType;

        public StringToEnumConverter(Class<T> enumType) {
            this.enumType = enumType;
        }

        public T convert(String source) {
            return (T) Enum.valueOf(this.enumType, source.trim());
        }
    }
}

3.4.3 使用GenericConverter

package org.springframework.core.convert.converter;

public interface GenericConverter {

    public Set<ConvertiblePair> getConvertibleTypes();

    Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType);
}

使用ConditionalGenericConverter

public interface ConditionalConverter {

    boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType);
}

public interface ConditionalGenericConverter extends GenericConverter, ConditionalConverter {
}

3.4.4 ConversionService应用程序接口

package org.springframework.core.convert;

public interface ConversionService {

    boolean canConvert(Class<?> sourceType, Class<?> targetType);

    <T> T convert(Object source, Class<T> targetType);

    boolean canConvert(TypeDescriptor sourceType, TypeDescriptor targetType);

    Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType);
}

3.4.5 配置ConversionService

<bean id="conversionService"
      class="org.springframework.context.support.ConversionServiceFactoryBean"/>

<bean id="conversionService"
      class="org.springframework.context.support.ConversionServiceFactoryBean">
    <property name="converters">
        <set>
            <bean class="example.MyCustomConverter"/>
        </set>
    </property>
</bean>

3.4.6 以编程方式使用ConversionService

@Service
public class MyService {

    public MyService(ConversionService conversionService) {
        this.conversionService = conversionService;
    }

    public void doIt() {
        this.conversionService.convert(...)
    }
}

DefaultConversionService cs = new DefaultConversionService();

List<Integer> input = ...
cs.convert(input,
    TypeDescriptor.forObject(input), // List<Integer> type descriptor
    TypeDescriptor.collection(List.class, TypeDescriptor.valueOf(String.class)));

3.5 Spring Field Formatting

3.5.1 Formatter SPI

package org.springframework.format;

public interface Formatter<T> extends Printer<T>, Parser<T> {
}

public interface Printer<T> {

    String print(T fieldValue, Locale locale);
}

import java.text.ParseException;

public interface Parser<T> {

    T parse(String clientValue, Locale locale) throws ParseException;
}

package org.springframework.format.datetime;

public final class DateFormatter implements Formatter<Date> {

    private String pattern;

    public DateFormatter(String pattern) {
        this.pattern = pattern;
    }

    public String print(Date date, Locale locale) {
        if (date == null) {
            return "";
        }
        return getDateFormat(locale).format(date);
    }

    public Date parse(String formatted, Locale locale) throws ParseException {
        if (formatted.length() == 0) {
            return null;
        }
        return getDateFormat(locale).parse(formatted);
    }

    protected DateFormat getDateFormat(Locale locale) {
        DateFormat dateFormat = new SimpleDateFormat(this.pattern, locale);
        dateFormat.setLenient(false);
        return dateFormat;
    }
}

3.5.2 注解驱动的格式化

package org.springframework.format;

public interface AnnotationFormatterFactory<A extends Annotation> {

    Set<Class<?>> getFieldTypes();

    Printer<?> getPrinter(A annotation, Class<?> fieldType);

    Parser<?> getParser(A annotation, Class<?> fieldType);
}

public final class NumberFormatAnnotationFormatterFactory
        implements AnnotationFormatterFactory<NumberFormat> {

    public Set<Class<?>> getFieldTypes() {
        return new HashSet<Class<?>>(asList(new Class<?>[] {
            Short.class, Integer.class, Long.class, Float.class,
            Double.class, BigDecimal.class, BigInteger.class }));
    }

    public Printer<Number> getPrinter(NumberFormat annotation, Class<?> fieldType) {
        return configureFormatterFrom(annotation, fieldType);
    }

    public Parser<Number> getParser(NumberFormat annotation, Class<?> fieldType) {
        return configureFormatterFrom(annotation, fieldType);
    }

    private Formatter<Number> configureFormatterFrom(NumberFormat annotation, Class<?> fieldType) {
        if (!annotation.pattern().isEmpty()) {
            return new NumberStyleFormatter(annotation.pattern());
        } else {
            Style style = annotation.style();
            if (style == Style.PERCENT) {
                return new PercentStyleFormatter();
            } else if (style == Style.CURRENCY) {
                return new CurrencyStyleFormatter();
            } else {
                return new NumberStyleFormatter();
            }
        }
    }
}

public class MyModel {

    @NumberFormat(style=Style.CURRENCY)
    private BigDecimal decimal;
}

public class MyModel {

    @DateTimeFormat(iso=ISO.DATE)
    private Date date;
}

3.5.3 FormatterRegistry SPi

package org.springframework.format;

public interface FormatterRegistry extends ConverterRegistry {

    void addPrinter(Printer<?> printer);

    void addParser(Parser<?> parser);

    void addFormatter(Formatter<?> formatter);

    void addFormatterForFieldType(Class<?> fieldType, Formatter<?> formatter);

    void addFormatterForFieldType(Class<?> fieldType, Printer<?> printer, Parser<?> parser);

    void addFormatterForFieldAnnotation(AnnotationFormatterFactory<? extends Annotation> annotationFormatterFactory);
}

3.5.4 FormatterRegistrarSPI

package org.springframework.format;

public interface FormatterRegistrar {

    void registerFormatters(FormatterRegistry registry);
}

3.6 配置全局日期和时间的格式

@Configuration
public class AppConfig {

    @Bean
    public FormattingConversionService conversionService() {

        // Use the DefaultFormattingConversionService but do not register defaults
        DefaultFormattingConversionService conversionService =
            new DefaultFormattingConversionService(false);

        // Ensure @NumberFormat is still supported
        conversionService.addFormatterForFieldAnnotation(
            new NumberFormatAnnotationFormatterFactory());

        // Register JSR-310 date conversion with a specific global format
        DateTimeFormatterRegistrar dateTimeRegistrar = new DateTimeFormatterRegistrar();
        dateTimeRegistrar.setDateFormatter(DateTimeFormatter.ofPattern("yyyyMMdd"));
        dateTimeRegistrar.registerFormatters(conversionService);

        // Register date conversion with a specific global format
        DateFormatterRegistrar dateRegistrar = new DateFormatterRegistrar();
        dateRegistrar.setFormatter(new DateFormatter("yyyyMMdd"));
        dateRegistrar.registerFormatters(conversionService);

        return conversionService;
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd>

    <bean id=" conversionService" class="org.springframework.format.support.FormattingConversionServiceFactoryBean">
        <property name="registerDefaultFormatters" value="false" />
        <property name="formatters">
            <set>
                <bean class="org.springframework.format.number.NumberFormatAnnotationFormatterFactory" />
            </set>
        </property>
        <property name="formatterRegistrars">
            <set>
                <bean class="org.springframework.format.datetime.standard.DateTimeFormatterRegistrar">
                    <property name="dateFormatter">
                        <bean class="org.springframework.format.datetime.standard.DateTimeFormatterFactoryBean">
                            <property name="pattern" value="yyyyMMdd"/>
                        </bean>
                    </property>
                </bean>
            </set>
        </property>
    </bean>
</beans>

3.7 Java Bean验证

3.7.1 Bean 校验

public class PersonForm {
    private String name;
    private int age;
}

ublic class PersonForm {

    @NotNull
    @Size(max=64)
    private String name;

    @Min(0)
    private int age;
}

3.7.2 配置Bean验证提供程序

import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;

@Configuration
public class AppConfig {

    @Bean
    public LocalValidatorFactoryBean validator() {
        return new LocalValidatorFactoryBean();
    }
}

Injecting a Validator

import javax.validation.Validator;

@Service
public class MyService {

    @Autowired
    private Validator validator;
}

import org.springframework.validation.Validator;

@Service
public class MyService {

    @Autowired
    private Validator validator;
}

配置自定义限制

@Target({ElementType.METHOD, ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy=MyConstraintValidator.class)
public @interface MyConstraint {
}

import javax.validation.ConstraintValidator;

public class MyConstraintValidator implements ConstraintValidator {

    @Autowired
    private Foo aDependency;

    // ...
}

Spring-driven Method Validation

import org.springframework.validation.beanvalidation.MethodValidationPostProcessor;

@Configuration
public class AppConfig {

    @Bean
    public MethodValidationPostProcessor validationPostProcessor() {
        return new MethodValidationPostProcessor();
    }
}

3.7.3 配置 DataBinder

Foo target = new Foo();
DataBinder binder = new DataBinder(target);
binder.setValidator(new FooValidator());

// bind to the target object
binder.bind(propertyValues);

// validate the target object
binder.validate();

// get BindingResult that includes any validation errors
BindingResult results = binder.getBindingResult();

3. 验证、数据绑定和类型转换﻿

3.1 使用Spring的验证器接口进行验证﻿

3.2 将代码解析为错误信息﻿

3.3 Bean Manipulation and the BeanWrapper﻿

3.3.1 设置和获取基本属性和嵌套属性。﻿

3.3.2 内置PropertyEditor实现﻿

注册其他自定义PropertyEditor实现﻿

使用PropertyEditorRegistrar﻿

3.4 Spring Type Conversion﻿

3.4.1 Converter SPI﻿

3.4.2 使用ConverterFactory﻿

3.4.3 使用GenericConverter﻿

tip

使用ConditionalGenericConverter﻿

3.4.4 ConversionService应用程序接口﻿

3.4.5 配置ConversionService﻿

tip

3.4.6 以编程方式使用ConversionService﻿

3.5 Spring Field Formatting﻿

3.5.1 Formatter SPI﻿

3.5.2 注解驱动的格式化﻿

3.5.3 FormatterRegistry SPi﻿

3.5.4 FormatterRegistrarSPI﻿

3.5.5 在SpringMVC中配置格式化﻿

3.6 配置全局日期和时间的格式﻿

3.7 Java Bean验证﻿

3.7.1 Bean 校验﻿

3.7.2 配置Bean验证提供程序﻿

Injecting a Validator﻿

配置自定义限制﻿

Spring-driven Method Validation﻿

tip

其他配置选项﻿

3.7.3 配置 DataBinder﻿

3.7.4 Spring MVC Validation﻿

3. 验证、数据绑定和类型转换

3.1 使用Spring的验证器接口进行验证

3.2 将代码解析为错误信息

3.3 Bean Manipulation and the BeanWrapper

3.3.1 设置和获取基本属性和嵌套属性。

3.3.2 内置PropertyEditor实现

注册其他自定义PropertyEditor实现

使用PropertyEditorRegistrar

3.4 Spring Type Conversion

3.4.1 Converter SPI

3.4.2 使用ConverterFactory

3.4.3 使用GenericConverter

使用ConditionalGenericConverter

3.4.4 ConversionService应用程序接口

3.4.5 配置ConversionService

3.4.6 以编程方式使用ConversionService

3.5 Spring Field Formatting

3.5.1 Formatter SPI

3.5.2 注解驱动的格式化

3.5.3 FormatterRegistry SPi

3.5.4 FormatterRegistrarSPI

3.5.5 在SpringMVC中配置格式化

3.6 配置全局日期和时间的格式

3.7 Java Bean验证

3.7.1 Bean 校验

3.7.2 配置Bean验证提供程序

Injecting a Validator

配置自定义限制

Spring-driven Method Validation

其他配置选项

3.7.3 配置 DataBinder

3.7.4 Spring MVC Validation