使用BeanUtils设置属性转换String到Date类型

1 使用BeanUtils进行设置属性时，对于String,int可以自动转换。比如下面的例子

先定义一个Person类

package pkg6;

import java.util.Date;
import java.text.SimpleDateFormat;

public class Person {
    private String name;
    private String gender;
    private int age;
    private Date birthday;

    public Person() {

    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    @Override
    public String toString() {
        return "{name:"+name+" age:"+age+" birthday:"+birthday+"}";
    }

}

使用一个函数测试一下

package pkg6;

import java.lang.reflect.InvocationTargetException;

import org.apache.commons.beanutils.BeanUtils;

public class demo1 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Person p1 = new Person();
        String name = "eric";
        String gender = "M";
        int age = 12;
        String birthday = "1991-32-56";

        try {
            BeanUtils.setProperty(p1, "name", "eric");
            //BeanUtils.setProperty(p1, "birthday", birthday);

        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        System.out.println(p1);
    }

}

它的输出是

{name:eric age:0 birthday:null}

没有问题。在web开发过程中经常会遇到网页提交的用户数据是字符串，存到数据库中的数据是日期，那么直接进行设置会出现什么情况，如下所示

在设置属性的代码后面添加

BeanUtils.setProperty(p1, "birthday", birthday);

运行结果会报错

org.apache.commons.beanutils.ConversionException: String must be in JDBC format [yyyy-MM-dd] to create a java.sql.Date
at org.apache.commons.beanutils.converters.DateTimeConverter.toDate(DateTimeConverter.java:436)
at org.apache.commons.beanutils.converters.DateTimeConverter.convertToType(DateTimeConverter.java:343)
at org.apache.commons.beanutils.converters.AbstractConverter.convert(AbstractConverter.java:156){name:eric age:0 birthday:null}

这是因为beanutils不支持字符串转换成其他对象类型。要想转换需要注册一个转换器。

ConvertUtils.register(new Converter() {

            public Object convert(Class type, Object value) {

                SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
                try {
                    return simpleDateFormat.parse(value.toString());
                } catch (ParseException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                return null;
            }
        }, Date.class);

当遇到java.util.Date类型时，就使用这个转换器，将字符串转换成Date类型。

完整的代码如下：

package pkg6;

import java.lang.reflect.InvocationTargetException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

import org.apache.commons.beanutils.BeanUtils;
import org.apache.commons.beanutils.ConvertUtils;
import org.apache.commons.beanutils.Converter;

public class demo1 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Person p1 = new Person();
        String name = "eric";
        String gender = "M";
        int age = 12;
        String birthday = "1991-32-56";

        ConvertUtils.register(new Converter() {

            public Object convert(Class type, Object value) {

                SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
                try {
                    return simpleDateFormat.parse(value.toString());
                } catch (ParseException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                return null;
            }
        }, Date.class);

        try {
            BeanUtils.setProperty(p1, "name", "eric");
            BeanUtils.setProperty(p1, "birthday", birthday);

        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        System.out.println(p1);
    }

}

运行结果如下：

{name:eric age:0 birthday:Sat Sep 25 00:00:00 CST 1993}