ConfigurablePropertyResolver

此接口是大多数PropertyResolver实现类的父接口，它规范了使用property的方法，并且使用户可以定制化PropertyResolver在解析和转换property时候的逻辑

public interface ConfigurablePropertyResolver extends PropertyResolver {    /**     * 返回在解析属性时使用的ConfigurableConversionService。此方法的返回值可被用户定制化，     * 例如可以移除或者添加Converter     * ConfigurableConversionService cs = env.getConversionService();     * cs.addConverter(new FooConverter());     */    ConfigurableConversionService getConversionService();    /**     * 设置在涉及到属性转换操作时所使用到的ConfigurableConversionService。     * 全部替换ConfigurableConversionService的操作不常用，更常用的一种方法是使用getConversionService     *      * <p><strong>Note:</strong> as an alternative to fully replacing the     * {@code ConversionService}, consider adding or removing individual     * {@code Converter} instances by drilling into {@link #getConversionService()}     * and calling methods such as {@code #addConverter}.     * @see PropertyResolver#getProperty(String, Class)     * @see #getConversionService()     * @see org.springframework.core.convert.converter.ConverterRegistry#addConverter     */    void setConversionService(ConfigurableConversionService conversionService);    /**     * Set the prefix that placeholders replaced by this resolver must begin with.     */    void setPlaceholderPrefix(String placeholderPrefix);    /**     * Set the suffix that placeholders replaced by this resolver must end with.     */    void setPlaceholderSuffix(String placeholderSuffix);    /**     * Specify the separating character between the placeholders replaced by this     * resolver and their associated default value, or {@code null} if no such     * special character should be processed as a value separator.     */    void setValueSeparator(String valueSeparator);    /**     * Set whether to throw an exception when encountering an unresolvable placeholder     * nested within the value of a given property. A {@code false} value indicates strict     * resolution, i.e. that an exception will be thrown. A {@code true} value indicates     * that unresolvable nested placeholders should be passed through in their unresolved     * ${...} form.     * <p>Implementations of {@link #getProperty(String)} and its variants must inspect     * the value set here to determine correct behavior when property values contain     * unresolvable placeholders.     * @since 3.2     */    void setIgnoreUnresolvableNestedPlaceholders(boolean ignoreUnresolvableNestedPlaceholders);    /**     * Specify which properties must be present, to be verified by     * {@link #validateRequiredProperties()}.     */    void setRequiredProperties(String... requiredProperties);    /**     * Validate that each of the properties specified by     * {@link #setRequiredProperties} is present and resolves to a     * non-{@code null} value.     * @throws MissingRequiredPropertiesException if any of the required     * properties are not resolvable.     */    void validateRequiredProperties() throws MissingRequiredPropertiesException;}