用jackson包实现json、对象、Map之间的转换

主要用于测试学习用jackson包实现json、对象、Map之间的转换。

1、准备测试用的Java类

（1）Link类

package test;

/**
 * Description: 联系方式，被user使用
 */
public class Link
{
    private String phone; //移动电话
    private String address; //地址
    private String qq; //QQ

    public String getPhone()
    {
        return phone;
    }
    public void setPhone(String phone)
    {
        this.phone = phone;
    }
    public String getAddress()
    {
        return address;
    }
    public void setAddress(String address)
    {
        this.address = address;
    }
    public String getQq()
    {
        return qq;
    }
    public void setQq(String qq)
    {
        this.qq = qq;
    }
}

（2）User类

Java代码  

package test;

import java.util.Date;
import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * Description: 用户，测试模型类
 */
public class User
{
    private String id; //标识
    private String name;    //姓名
    private int age;    //年龄
    private double pay; //工资
    private boolean valid;  //是否有效
    private char one; //一个字符
    private Date birthday;  //生日

    private Link link; //联系方式，自定义

    private Map map; //测试用
    private List list; //测试用
    private Set set; //测试用
    public String getId()
    {
        return id;
    }
    public void setId(String id)
    {
        this.id = id;
    }
    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 double getPay()
    {
        return pay;
    }
    public void setPay(double pay)
    {
        this.pay = pay;
    }
    public boolean isValid()
    {
        return valid;
    }
    public void setValid(boolean valid)
    {
        this.valid = valid;
    }
    public char getOne()
    {
        return one;
    }
    public void setOne(char one)
    {
        this.one = one;
    }
    public Date getBirthday()
    {
        return birthday;
    }
    public void setBirthday(Date birthday)
    {
        this.birthday = birthday;
    }
    public Link getLink()
    {
        return link;
    }
    public void setLink(Link link)
    {
        this.link = link;
    }
    public Map getMap()
    {
        return map;
    }
    public void setMap(Map map)
    {
        this.map = map;
    }
    public List getList()
    {
        return list;
    }
    public void setList(List list)
    {
        this.list = list;
    }
    public Set getSet()
    {
        return set;
    }
    public void setSet(Set set)
    {
        this.set = set;
    }
}

2、测试类，没用Junit，用Main()方法输出。

package test;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;

/**
 * Description: 主要用于测试学习用jackson包实现json、对象、Map之间的转换
 *
 * Date: 2016年6月6日
 * Time: 下午3:23:23
 */
public class JsonTest
{

    public static void main(String[] args) throws JsonGenerationException, JsonMappingException, IOException
    {
        User user=new User();
        user.setId("01");
        user.setName("张三");
        user.setAge(33);
        user.setPay(6666.88);
        user.setValid(true);
        user.setOne('E');
        user.setBirthday(new Date(20l*366*24*3600*1000)); //1990年

        Link link = new Link();
        link.setAddress("河南省济源市");
        link.setPhone("13899995555");
        link.setQq("123456");
        user.setLink(link);

        Map map=new HashMap();
        map.put("aa", "this is aa");
        map.put("bb", "this is bb");
        map.put("cc", "this is cc");
        user.setMap(map);

        List list=new ArrayList(){};
        list.add("普洱");
        list.add("大红袍");
        user.setList(list);

        Set set=new HashSet();
        set.add("篮球");
        set.add("足球");
        set.add("乒乓球");
        user.setSet(set);

        ObjectMapper mapper = new ObjectMapper(); //转换器

        //测试01：对象--json
        String json=mapper.writeValueAsString(user); //将对象转换成json
        System.out.println(json);
        /* 结果如下：
        {"id":"01","name":"张三","age":33,"pay":6666.88,"valid":true,"one":"E","birthday":1465185448998,
        "link":{"phone":"13899995555","address":"河南省济源市","qq":"123456"},
        "map":{"aa":"this is aa","bb":"this is bb","cc":"this is cc"},
        "list":["普洱","大红袍"],
        "set":["乒乓球","足球","篮球"]}

        注意点：（1） 日期--长整型 （2）List、Set均转成数组
         */

        //测试02：json--map
        Map m = mapper.readValue(json, Map.class); //json转换成map

        System.out.println("pay："+m.get("pay").getClass().getName()); //java.lang.Double
        System.out.println("valid："+m.get("valid").getClass().getName()); //java.lang.Boolean
        System.out.println("birthday："+m.get("birthday").getClass().getName()); //java.lang.Long
        System.out.println("link："+m.get("link").getClass().getName()); //java.util.LinkedHashMap
        System.out.println("map："+m.get("map").getClass().getName()); //java.util.LinkedHashMap
        System.out.println("list："+m.get("list").getClass().getName()); //java.util.ArrayList
        System.out.println("set："+m.get("set").getClass().getName()); //java.util.ArrayList
        /*  结果如下：
            pay：java.lang.Double
            valid：java.lang.Boolean
            birthday：java.lang.Long
            link：java.util.LinkedHashMap
            map：java.util.LinkedHashMap
            list：java.util.ArrayList
            set：java.util.ArrayList

            注意点：（1） 日期--长整型  （2）map、子对象均转换成了LinkedHashMap （3）List、Set均转成ArrayList
         */

        //测试03：map--json
        json=mapper.writeValueAsString(m); //map转json
        System.out.println(json); //与之前格式完全相同，说明经过map转换后，信息没有丢失

        //测试04：json--对象
        User u=mapper.readValue(json, User.class); //json转java对象。经测，转成对象后，一切恢复正常
        System.out.println("pay："+u.getPay());
        System.out.println("valid："+u.isValid());
        System.out.println("birthday："+u.getBirthday());
        System.out.println("link："+u.getLink());
        System.out.println("map："+u.getMap());
        System.out.println("list："+u.getList());
        System.out.println("set："+u.getSet());

        //测试05：其他转换
        byte[] data=mapper.writeValueAsBytes(u); //对象转成二进制数组


    }

}

3、输出结果

{"id":"01","name":"张三","age":33,"pay":6666.88,"valid":true,"one":"E","birthday":632448000000,"link":{"phone":"13899995555","address":"河南省济源市","qq":"123456"},"map":{"aa":"this is aa","bb":"this is bb","cc":"this is cc"},"list":["普洱","大红袍"],"set":["乒乓球","足球","篮球"]}
pay：java.lang.Double
valid：java.lang.Boolean
birthday：java.lang.Long
link：java.util.LinkedHashMap
map：java.util.LinkedHashMap
list：java.util.ArrayList
set：java.util.ArrayList
{"id":"01","name":"张三","age":33,"pay":6666.88,"valid":true,"one":"E","birthday":632448000000,"link":{"phone":"13899995555","address":"河南省济源市","qq":"123456"},"map":{"aa":"this is aa","bb":"this is bb","cc":"this is cc"},"list":["普洱","大红袍"],"set":["乒乓球","足球","篮球"]}
pay：6666.88
valid：true
birthday：Tue Jan 16 08:00:00 CST 1990
link：test.Link@350385f1
map：{aa=this is aa, bb=this is bb, cc=this is cc}
list：[普洱, 大红袍]
set：[足球, 乒乓球, 篮球]