JAVA在Web开发项目中，经常会接收各种参数，并将这些参数保存到对象里面去，比如，http://127.0.0.1/Servlet/?username=liqiu&password=123456&age=29。需要将这些内容保存在User对象里面去，User.java代码如下：

public class User {    private String username;    private String password;    private int age;public String getUsername() {        return username;    }.............................}

那么，如果不使用BeanUtils，需要一个参数一个参数的判断，转换和赋值，反之：

Map map = request.getParameterMap();        User user = new User();        try {            BeanUtils.populate(user, map);        } catch (IllegalAccessException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (InvocationTargetException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }

当然也有略复杂的情况，比如传输时间类型的数据

package com.taobao.beanutils;.............................................public class Demo01 {// 自定义转换器    @Test    public void test2() throws Exception {        Person p = new Person();        ConvertUtils.register(new Converter() {            @Override            public Object convert(Class type, Object value) {                if (value == null) {                    return null;                }                if (!(value instanceof String)) {                    throw new ConversionException("conversion error");                }                String str = (String) value;                if (str.trim().equals("")) {                    return null;                }                SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");                try {                    return sdf.parse(str);                } catch (ParseException e) {                    throw new RuntimeException(e);                }            }        }, Date.class);        BeanUtils.setProperty(p, "birth", "2011-10-10");        System.out.println(p.getBirth().toLocaleString());    }    // 使用内置的转换器    @Test    public void test3() throws Exception {        Person p = new Person();        ConvertUtils.register(new DateLocaleConverter(), Date.class);        BeanUtils.setProperty(p, "birth", "2011-10-10");        System.out.println(p.getBirth().toLocaleString());    }}