1. fastjson的主要API
fastjson入口类是com.alibaba.fastjson.JSON,主要的API是JSON.toJSONString,和parseObject
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| package com.alibaba.fastjson;
public abstract class JSON {
public static final String toJSONString(Object object);
public static final <T> T parseObject(String text, Class<T> clazz, Feature... features);
}
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序列化:
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| String jsonString = JSON.toJSONString(obj);
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反序列化:
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| VO vo = JSON.parseObject("...", VO.class);
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泛型反序列化:
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| import com.alibaba.fastjson.TypeReference;
List<VO> list = JSON.parseObject("...", new TypeReference<List<VO>>() {});
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2. JSON、JSONObject、JSONArray三者之间的关系
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| public class JSONObject extends JSON implements Map<String, Object>;
public class JSONArray extends JSON implements List<Object>
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也就是说,JSONObject实际上就是一个Map,其处理方式和Map类似,而JSONArray实质上是一个List,其处理方式和List类似。
3. 实例讲解
涉及到的实体Bean:
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| public class User {
int id,
int name;
Date birthday;
List<Phone> phones;
public User() {
}
}
public class Phone {
int phoneNum;
public Phone() {
}
}
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测试:
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| public void testObject() {
User user = new User();
user.setId(1);
user.setName("abc");
user.setBirthday(new Date());
List<Phone> phones = new ArrayList<Phone>();
Phone p1 = new Phone();
p1.setPhoneNum(12123123);
Phone p2 = new Phone();
p2.setPhoneNum(23423423);
phones.add(p1);
phones.add(p2);
user.setPhones(phones);
JSON.DEFFAULT_DATE_FORMAT = "yyyy-MM-dd hh:mm:ss";
System.out.println("JSON:"+JSON.toJSONString(user,SerializerFeature.WriteDateUseDateFormat));
JSONObject jobj = new JSONObject();
jobj.put("user", user);
System.out.println("JSONObject:"+jobj.toJSONString());
JSONArray jArray = new JSONArray();
jArray.add(user);
System.out.println("JSONArray:"+jArray.toJSONString());
}
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输出:
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| JSON:
{
"birthday":"2015-09-30 03:06:36",
"id":1,
"name":"abc",
"phones":[
{
"phoneNum":12123123
},
{
"phoneNum":23423423
}
]
}
JSONObject:
{
"user": {
"birthday": 1443597247350,
"id": 1,
"name": "abc",
"phones": [
{
"phoneNum": 12123123
},
{
"phoneNum": 23423423
}
]
}
}
JSONArray:
[
{
"birthday": 1443597247350,
"id": 1,
"name": "abc",
"phones": [
{
"phoneNum": 12123123
},
{
"phoneNum": 23423423
}
]
}
]
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测试:
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| public void testList() {
List<User> list = new ArrayList<User>();
User u1 = new User();
u1.setId(2);
u1.setName("abc");
u1.setBirthday(new Date());
User u2 = new User();
u2.setId(3);
u2.setName("cde");
list.add(u1);list.add(u2);
String result = JSON.toJSONStringWithDateFormat(list, "yyyy-MM-dd hh:mm:ss");
System.out.println(result);
List<User> refList2 = JSON.parseObject(result, new TypeReference<List<User>>(){});
System.out.println(refList2.size());
List<User> users = JSON.parseArray(result, User.class);
System.out.println(users.size());
JSONObject obj = new JSONObject();
obj.put("abc", 123);
Boolean b = obj.getBoolean("ccc");
System.out.println(b);
}
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4. 控制哪些值序列化
可以通过扩展实现根据object或者属性名称或者属性值进行判断是否需要序列化。例如:
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| PropertyFilter filter = new PropertyFilter() {
public boolean apply(Object source, String name, Object value) {
if ("id".equals(name)) {
int id = ((Integer) value).intValue();
return id >= 100;
}
return false;
}
};
JSON.toJSONString(obj, filter);
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同样可以通过SimplePropertyPreFilter来决定哪些值可以序列化:
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| User vo = new User();
vo.setId(123);
vo.setName("flym");
SimplePropertyPreFilter filter = new SimplePropertyPreFilter(VO.class, "name");
Assert.assertEquals("{\"name\":\"flym\"}", JSON.toJSONString(vo, filter));
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同样可以通过注解的方式来判断哪些只需要序列化,详细请查看fastjson的官方文档
5. 参考文档
fastjson下载以及文档参考