對象的克隆，Dozer的使用

　　現在有個復雜對象bean需要在賦值后在另一個地方用，想通過復制的方式拿到這個對象。首選是深度克隆，雖然發現該對象的父類已經實現了Cloneable接口，但父類是通過jar包引入的，而且在clone方法中對該bean一個map<String, Object>屬性的處理有問題：獲取到map的value時，直接強制轉型為某一具體bean，而子類這個map在put時並非該具體bean的類型，因此克隆時報轉型失敗錯誤。考慮方案二，通過java序列化方式克隆，父類也已經實現了Serializable接口，但寫對象和度對象方法都是空實現，本地重新實現后也報錯了。使用json序列化倒是可以，就是性能不高。最后決定采用Dozer框架，Dozer底層也是apache的beanUtils方式復制bean，但更易用，可以直接用xml文件或者注解映射兩個類，類可以是不同類型，字段也可以是不同類型、不同名稱。

　　使用前需要導入5個jar包：

commons-beanutils-1.9.3.jar

commons-lang3-3.5.jar

commons-logging-1.2.jar

dozer-5.4.0.jar

slf4j-api-1.7.25.jar

　　這里通過注解來實現一個例子，具體使用參見下面代碼：

package com.wulinfeng.dozer;

import java.util.Date;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;

public class CopyComponent {

    private String name;

    private int age;

    private Date date;

    private Map<String, String> internalMap;

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

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

    public Date getDate() {
        return date;
    }

    public void setDate(Date date) {
        this.date = date;
    }

    public Map<String, String> getInternalMap() {
        return internalMap;
    }

    public void setInternalMap(Map<String, String> internalMap) {
        this.internalMap = internalMap;
    }

    @Override
    public String toString() {
        StringBuilder names = new StringBuilder();
        if (null != internalMap && internalMap.entrySet() != null) {
            Iterator<Entry<String, String>> iter = internalMap.entrySet().iterator();
            while (iter.hasNext()) {
                Entry<String, String> c = iter.next();
                names.append("key: ");
                names.append(c.getKey());
                names.append("value: ");
                names.append(c.getValue());
            }
        }
        return "name: " + name + ", age: " + age + ", date: " + date + ", list : " + names.toString();
    }

}

package com.wulinfeng.dozer;

import java.util.Date;
import java.util.HashMap;
import java.util.Map;

import org.dozer.DozerBeanMapper;
import org.dozer.Mapping;

public class Component {

    @Mapping("age")
    private String desc;

    @Mapping("name")
    private Integer price;

    private Date date;

    @Mapping("internalMap")
    private Map<String, String> externalAttrMap;

    public String getDesc() {
        return desc;
    }

    public void setDesc(String desc) {
        this.desc = desc;
    }

    public Integer getPrice() {
        return price;
    }

    public void setPrice(Integer price) {
        this.price = price;
    }

    public Date getDate() {
        return date;
    }

    public void setDate(Date date) {
        this.date = date;
    }

    public Map<String, String> getExternalAttrMap() {
        return externalAttrMap;
    }

    public void setExternalAttrMap(Map<String, String> externalAttrMap) {
        this.externalAttrMap = externalAttrMap;
    }

    public static void main(String[] args) {
        Component component = new Component();

        // String -> int
        component.setDesc("9999");

        // int -> String
        component.setPrice(30);

        // date -> date
        component.setDate(new Date());

        // Map -> List
        Component componentpage = new Component();
        componentpage.setDesc("hello");
        Map<String, String> ext = new HashMap<String, String>();
        ext.put("name", "fengjiangtao");
        component.setExternalAttrMap(ext);

        DozerBeanMapper dozerBeanMapper = new DozerBeanMapper();
        CopyComponent copy = dozerBeanMapper.map(component, CopyComponent.class);
        System.out.println(copy);
    }

}

　　運行結果：

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
name: 30, age: 9999, date: Sun Apr 23 23:06:02 CST 2017, list : key: namevalue: fengjiangtao