Fastjson 是一个Java库,可以将Java对象转换为 JSON 格式,当然它也可以将 JSON 字符串转换为 Java 对象。那fastjson怎么解析数组?接下来，我们就来给大家以实例讲解一下。
常见的json解析实例,以map为例：
Mapmap = new HashMap();
map.put("code", "0");
map.put("message", "ok");
String json = JSON.toJSONString(map);
System.out.println(json);
String code = JSONObject.fromObject(json)
.getString("code");
String message = JSONObject.fromObject(json)
.getString("message");
System.out.println("code=" + code + ",message" + message);1. Json解析出字符串
String rootnode = JSONObject.fromObject(jsonData)
.from("attribute");
String childnode = JSONObject.fromObject(rootnode)
.from("attribute");以此类推
2. Json解析出单个对象
JSON.parseObject(jsonString,user.class);
3.Json解析出多个对象
List list=new ArrayList (JSONArray.parseArray(jsonString,user.class));
FastJSON,GSON,JSON的三种解析方式：
一、JSON解析之传统的JSON解析
1、生成json字符串
public static String createJsonString(String key, Object value)
{
JSONObject jsonObject = new JSONObject();
jsonObject.put(key, value);
return jsonObject.toString();
}2、解析JSON字符串
分为以下三种情况，一个JavaBean，一个List数组，一个嵌套Map的List数组：
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.json.JSONArray;
import org.json.JSONObject;
import com.android.myjson.domain.Person;
public class JsonTools
{
public static Person getPerson(String key, String jsonString)
{
Person person = new Person();
try
{
JSONObject jsonObject = new JSONObject(jsonString);
JSONObject personObject = jsonObject.getJSONObject("person");
person.setId(personObject.getInt("id"));
person.setName(personObject.getString("name"));
person.setAddress(personObject.getString("address"));
}
catch (Exception e)
{
// TODO: handle exception }
return person;
}
public static List getPersons(String key, String jsonString)
{
List list = new ArrayList();
try
{
JSONObject jsonObject = new JSONObject(jsonString);
// 返回json的数组
JSONArray jsonArray = jsonObject.getJSONArray(key);
for (int i = 0; i < jsonArray.length(); i++)
{
JSONObject jsonObject2 = jsonArray.getJSONObject(i);
Person person = new Person();
person.setId(jsonObject2.getInt("id"));
person.setName(jsonObject2.getString("name"));
person.setAddress(jsonObject2.getString("address"));
list.add(person);
}
}
catch (Exception e)
{
// TODO: handle exception }
return list;
}
public static List getList(String key, String jsonString)
{
List list = new ArrayList();
try
{
JSONObject jsonObject = new JSONObject(jsonString);
JSONArray jsonArray = jsonObject.getJSONArray(key);
for (int i = 0; i < jsonArray.length(); i++)
{
String msg = jsonArray.getString(i);
list.add(msg);
}
}
catch (Exception e)
{
// TODO: handle exception }
return list;
}
public static List > listKeyMaps(String key
, String jsonString)
{
List > list = new ArrayList > ();
try
{
JSONObject jsonObject = new JSONObject(jsonString);
JSONArray jsonArray = jsonObject.getJSONArray(key);
for (int i = 0; i < jsonArray.length(); i++)
{
JSONObject jsonObject2 = jsonArray.getJSONObject(i);
Map map = new HashMap();
Iterator iterator = jsonObject2.keys();
while (iterator.hasNext())
{
String json_key = iterator.next();
Object json_value = jsonObject2.get(json_key);
if (json_value == null)
{
json_value = "";
}
map.put(json_key, json_value);
}
list.add(map);
}
}
catch (Exception e)
{
// TODO: handle exception }
return list;
}
}二、JSON解析之GSON
1、生成JSON字符串
import com.google.gson.Gson;
public class JsonUtils
{
public static String createJsonObject(Object obj)
{
Gson gson = new Gson();
String str = gson.toJson(obj);
return str;
}
}2、解析JSON
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;;
public class GsonTools
{
public GsonTools()
{
// TODO Auto-generated constructor stub }
public static T getPerson(String jsonString, Class cls)
{
T t = null;
try
{
Gson gson = new Gson();
t = gson.fromJson(jsonString, cls);
}
catch (Exception e)
{
// TODO: handle exception }
return t;
}
public static List getPersons(String jsonString, Class cls)
{
List list = new ArrayList();
try
{
Gson gson = new Gson();
list = gson.fromJson(jsonString, new TypeToken > ()
{}.getType());
}
catch (Exception e)
{}
return list;
}
public static List getList(String jsonString)
{
List list = new ArrayList();
try
{
Gson gson = new Gson();
list = gson.fromJson(jsonString, new TypeToken > ()
{}.getType());
}
catch (Exception e)
{
// TODO: handle exception }
return list;
}
public static List > listKeyMaps(String jsonString)
{
List > list = new ArrayList > ();
try
{
Gson gson = new Gson();
list = gson.fromJson(jsonString
, new TypeToken >> ()
{}.getType());
}
catch (Exception e)
{
// TODO: handle exception }
return list;
}
}三、JSON解析之FastJSON
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.TypeReference;
public class JsonTool
{
public static T getPerson(String jsonstring, Class cls)
{
T t = null;
try
{
t = JSON.parseObject(jsonstring, cls);
}
catch (Exception e)
{
// TODO: handle exception }
return t;
}
public static List getPersonList(String jsonstring, Class cls)
{
List list = new ArrayList();
try
{
list = JSON.parseArray(jsonstring, cls);
}
catch (Exception e)
{
// TODO: handle exception }
return list;
}
public static List > getPersonListMap1(
String jsonstring)
{
List > list = new ArrayList > ();
try
{
list = JSON.parseObject(jsonstring
, new TypeReference >> ()
{}.getType());
}
catch (Exception e)
{
// TODO: handle exception }
return list;
}
}在这三种解析方式中FastJson是效率最高的，推荐大家去使用。另外，fastjson解析数组的案例希望大家可以多多研究，提高自己的技能!最后大家如果想要了解更多json相关知识，敬请关注奇Q工具网。
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