Spring Security 3-如何自定义用户名/密码参数？

使用时如何自定义 UsernamePasswordAuthenticationFilter usernameParameter (j_username) 和 passwordParameter (j_password) 属性<http ... />Spring Security 3 命名空间？这是我的理解<http ... />创建过滤器，但我不知道如何自定义它。

这是我根据 axtavt 的建议创建的解决方案：

弹簧配置：

<beans:bean id="userPassAuthFilterBeanPostProcessor"
    class="com.my.package.UserPassAuthFilterBeanPostProcessor">
    <beans:property name="usernameParameter" value="username" />
    <beans:property name="passwordParameter" value="password" />
</beans:bean>

Java类：

package com.my.package;

import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.security.web.authentication.
    UsernamePasswordAuthenticationFilter;

public class UserPassAuthFilterBeanPostProcessor implements BeanPostProcessor {

    private String usernameParameter;
    private String passwordParameter;

    @Override
    public final Object postProcessAfterInitialization(final Object bean,
        final String beanName) {
        return bean;
    }

    @Override
    public final Object postProcessBeforeInitialization(final Object bean,
        final String beanName) {
        if (bean instanceof UsernamePasswordAuthenticationFilter) {
            final UsernamePasswordAuthenticationFilter filter =
                (UsernamePasswordAuthenticationFilter) bean;
            filter.setUsernameParameter(getUsernameParameter());
            filter.setPasswordParameter(getPasswordParameter());
        }

        return bean;
    }

    public final void setUsernameParameter(final String usernameParameter) {
        this.usernameParameter = usernameParameter;
    }

    public final String getUsernameParameter() {
        return usernameParameter;
    }

    public final void setPasswordParameter(final String passwordParameter) {
        this.passwordParameter = passwordParameter;
    }

    public final String getPasswordParameter() {
        return passwordParameter;
    }

}