SpringFramework中的BeanWrapper丶PropertyEditor

BeanWrapper是org.springframework.beans包下的一个借口，对应的实现类为BeanWrapperImpl,提供对应的get/set方法，并且设置属性的可读性和可写性。

public 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");
从以上这些代码看一看出来，BeanWrapper可以看成是POJOs转化为bean之后的父类型。

　　Spring中引出PropertyEditor的概念，主要是为了实现String类型与其他类型的转化。最常见的就是String类型和日期类型的转换，CustomDateEditor是面向java.util.Data
专门的属性编辑器，支持常用的DataFormat。在实际操作中经常会碰到表单中的日期 字符串和Javabean中的日期类型的属性自动转换， 而springMVC默认不支持这个格式的转换，所以必
须要手动配置， 自定义数据类型的绑定才能实现这个功能。比较简单的可以直接应用springMVC的注解@initbinder和spring自带的WebDataBinder类和操作。
@InitBinder
public void initBinder(WebDataBinder binder) {
　　SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
　　dateFormat.setLenient(false);
　　binder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, true));
}