BeanUtils(apache)使用

• 官网地址：http://commons.apache.org/proper/commons-beanutils/

• org.apache.commons.beanutils.BeanUtils

• 将HttpServletRequest中的参数封装成Bean类 ``` @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

    User loginUser = new User();
    try {
        Map<String, String[]> parameterMap = req.getParameterMap();
        BeanUtils.populate(loginUser,parameterMap);
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    } catch (InvocationTargetException e) {
        e.printStackTrace();
    }
}

- 原理
> BeanUtils.setProperty(user,"username","张三");
> 
> BeanUtils.getProperty(user, "username");

    User user = new User();
    try {
        // 会去找setUsername方法设置值
        BeanUtils.setProperty(user,"username","张三");
        // 会去找getUsername方法取值
        String username = BeanUtils.getProperty(user, "username");
        System.out.println(username);
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    } catch (InvocationTargetException e) {
        e.printStackTrace();
    } catch (NoSuchMethodException e) {
        e.printStackTrace();
    }
    // User{id=0, username='张三', password='null'}
    System.out.println(user.toString());

```