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]