Bean复制

有的时候我们需要将一个bean的属性赋值到另一个bean的属性中，比如用户提交过来的表单bean需要将该bean中的属性值赋值到对应的数据库bean，我们通常会以这样的方式做：

User user = new User("1", "Jon_China", "123456", "1992-11-17", "127.0.0.1");
2 TargetUser target = new TargetUser();
target.setId(user.getId());
target.setUserName(user.getUserName());
target.setPassword(user.getPassword());

当bean的属性过多时是不是感觉“嘿打脑壳”。不要紧，Apache提供bean的copy工具BeanUtil. 

当然是用也是比较简单的，楼主一步一步说明：

1、先搞两个bean

package com.jon.china.beancopy;
//假设是用户提交过来的bean
public class User {
    private String Id;
    private String userName;
    private String password;
    private String birthday;
    private String loginIp;
    public String getId() {
        return Id;
    }
    public void setId(String id) {
        Id = id;
    }
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String getBirthday() {
        return birthday;
    }
    public void setBirthday(String birthday) {
        this.birthday = birthday;
    }
    public String getLoginIp() {
        return loginIp;
    }
    public void setLoginIp(String loginIp) {
        this.loginIp = loginIp;
    }
    public User(String id, String userName, String password, String birthday,
            String loginIp) {        
        Id = id;
        this.userName = userName;
        this.password = password;
        this.birthday = birthday;
        this.loginIp = loginIp;
    }
    
}

定义目标bean，目的将User属性值复制到TargetUser中,需要注意的是属性birthday类型的变化。

package com.jon.china.beancopy;

import java.util.Date;

public class TargetUser {
    private String Id;
    private String userName;
    private String password;
    private Date birthday;
    private String loginIp;
    public String getId() {
        return Id;
    }
    public void setId(String id) {
        Id = id;
    }
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    public String getLoginIp() {
        return loginIp;
    }
    public void setLoginIp(String loginIp) {
        this.loginIp = loginIp;
    }
    
}

2、由于birthday需要将String转换为Date类型，这里定义个转换器，实现Converter接口：

package com.jon.china.beancopy;

import java.text.ParseException;
import java.text.SimpleDateFormat;

import org.apache.commons.beanutils.Converter;

public class BeanConvert implements Converter {
    /**
     * 日期类型转换器
     */
    @Override
    public Object convert(Class type, Object value) {
        if(value==null){
            return null;
        }
        String v = (String) value;
        if("".equals(v.trim())){
            return null;
        }
        SimpleDateFormat sf = new SimpleDateFormat("yyyy-mm-dd");
        try {
            return sf.parse(v);
        } catch (ParseException e) {
            throw new RuntimeException(e);
        }        
    }

}

3、初始化User，注册转换器，开始转换：

package com.jon.china.beancopy;


import java.util.Date;

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

public class Test {

    
    public static void main(String[] args) {
        User user = new User("1", "Jon_China", "123456", "1992-11-17", "127.0.0.1");
        TargetUser target = new TargetUser();        
        //注册日期转换器
        ConvertUtils.register(new BeanConvert(), Date.class);
        try {
            BeanUtils.copyProperties(target, user);//开始复制bean
        } catch (Exception e) {
            throw new RuntimeException(e);
        } 
        System.out.println(target.getLoginIp());
    }

}

4、成功，结束。

源码地址：https://github.com/LJunChina/BeanCopy