FastJSON 简单使用

转载链接：http://blog.csdn.net/flysun3344/article/details/54707965
需要相关jar包，如果使用maven的话，在pom.xml文件加入一下依赖：
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.46</version>
</dependency>User.java
package com.accord.fastjson;

public class User {
private String userName;
private Integer age;

public User() {
super();
}

public User(String userName, Integer age) {
super();
this.userName = userName;
this.age = age;
}

public String getUserName() {
return userName;
}

public void setUserName(String userName) {
this.userName = userName;
}

public Integer getAge() {
return age;
}

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

}
FastJson.javapackage com.accord.fastjson;

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

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.TypeReference;
import com.alibaba.fastjson.parser.ParserConfig;
import com.alibaba.fastjson.serializer.SerializerFeature;

public class FastJson {
public static void main(String[] args) {
//基本的序列化
Map<String,Object> map = new HashMap<String, Object>();
map.put("key1", "one");
map.put("key2", "two");
String mapJson = JSON.toJSONString(map);
System.out.println(mapJson);

//将List<Map>转成JSON
List<Map<String,Object>> list = new ArrayList<Map<String,Object>>();
Map<String,Object> map1 = new HashMap<String, Object>();
map1.put("key1", "One");
map1.put("key2", "Two");

Map<String,Object> map2 = new HashMap<String, Object>();
map2.put("key1", "Three");
map2.put("key2", "Four");

list.add(map1);
list.add(map2);

String listJson = JSON.toJSONString(list);
System.out.println(listJson);

//自定义JavaBean User 转成Json
User user = new User();
user.setUserName("wjy");
user.setAge(25);
String userJson = JSON.toJSONString(user);
System.out.println(userJson);

//可以输出格式化后的JSON字符串
//传入一个对象和一个布尔类型（是否格式化），将对象转成格式化后的JSON字符串。
List<Map<String,Object>> list = new ArrayList<Map<String,Object>>();
Map<String,Object> map1 = new HashMap<String, Object>();
map1.put("key1", "One");
map1.put("key2", "Two");

Map<String,Object> map2 = new HashMap<String, Object>();
map2.put("key1", "Three");
map2.put("key2", "Four");

list.add(map1);
list.add(map2);

String listJson = JSON.toJSONString(list,true);
System.out.println(listJson);

//日期格式化：
//FastJSON可以直接对日期类型格式化，在缺省的情况下，FastJSON会将Date转成long
String dataJson = JSON.toJSONString(new Date());
System.out.println(dataJson); //结果：1401370199040

//使用SerializerFeature特性格式化日期。
String dateJson = JSON.toJSONString(new Date(),SerializerFeature.WriteDateUseDateFormat);
System.out.println(dateJson); //结果："2018-02-09 09:14:58"

//指定输出日期格式
String dateJson = JSON.toJSONStringWithDateFormat(new Date(),"yyyy-MM-dd");
System.out.println(dateJson); //结果："2018-02-09"

//使用单引号
List<Map<String,Object>> list = new ArrayList<Map<String,Object>>();
Map<String,Object> map1 = new HashMap<String, Object>();
map1.put("key1", "One");
map1.put("key2", "Two");

Map<String,Object> map2 = new HashMap<String, Object>();
map2.put("key1", "Three");
map2.put("key2", "Four");

list.add(map1);
list.add(map2);
//String listJson = JSON.toJSONString(list,SerializerFeature.UseSingleQuotes);
//System.out.println(listJson); //结果：[{'key2':'Two','key1':'One'},{'key2':'Four','key1':'Three'}]

String listJson = JSON.toJSONString(list,SerializerFeature.PrettyFormat);
System.out.println(listJson); //结果是带有格式的

//输出Null字段。
//缺省情况下FastJSON不输入为值Null的字段，可以使用SerializerFeature.WriteMapNullValue使其输出。
Map<String, Object> map = new HashMap<String, Object>();
String b = null;
Integer i = 1;
map.put("a", b);
map.put("b", i);
String listJson = JSON.toJSONString(map,SerializerFeature.WriteMapNullValue);
System.out.println(listJson); //结果：{"b":1,"a":null}

//序列化是写入类型信息
User user = new User();
user.setAge(26);
user.setUserName("wjy");
String listJson = JSON.toJSONString(user,SerializerFeature.WriteClassName);
System.out.println(listJson); //结果：{"@type":"com.accord.fastjson.User","age":26,"userName":"wjy"}

//将上面的反序列化
ParserConfig.getGlobalInstance().setAutoTypeSupport(true); //不加这句会报错：
/*Exception in thread "main" com.alibaba.fastjson.JSONException: autoType is not support. com.accord.fastjson.User
at com.alibaba.fastjson.parser.ParserConfig.checkAutoType(ParserConfig.java:1026)
at com.alibaba.fastjson.parser.DefaultJSONParser.parseObject(DefaultJSONParser.java:316)
at com.alibaba.fastjson.parser.DefaultJSONParser.parse(DefaultJSONParser.java:1356)
at com.alibaba.fastjson.parser.DefaultJSONParser.parse(DefaultJSONParser.java:1322)
at com.alibaba.fastjson.JSON.parse(JSON.java:152)
at com.alibaba.fastjson.JSON.parse(JSON.java:162)
at com.alibaba.fastjson.JSON.parse(JSON.java:131)
at com.accord.fastjson.FastJson.main(FastJson.java:111)*/
User user1 = (User)JSON.parse(listJson);
System.out.println(user1.getUserName()); //结果：wjy

//指定class信息反序列化
User user = new User();
user.setUserName("李四");
user.setAge(24);
String userJson = JSON.toJSONString(user);
User user1 = JSON.parseObject(userJson,User.class);
System.out.println(user1.getUserName());

//集合反序列化
List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
Map<String, Object> map1 = new HashMap<String, Object>();
map1.put("key1", "One");
map1.put("key2", "Two");
Map<String, Object> map2 = new HashMap<String, Object>();
map2.put("key1", "Three");
map2.put("key2", "Four");
list.add(map1);
list.add(map2);
String listJson = JSON.toJSONString(list);
List<Map> list1 = JSON.parseArray(listJson, Map.class);
for (Map<String,Object> map : list1) {
System.out.println(map.get("key1"));
System.out.println(map.get("key2"));
}

//泛型的反序列化（使用TypeReference传入类型信息）
Map<String, Object> map = new HashMap<String, Object>();
map.put("key1", "One");
map.put("key2", "Two");
String mapJson = JSON.toJSONString(map);
Map<String,Object> map1 = JSON.parseObject(mapJson,new TypeReference<Map<String,Object>>(){});
System.out.println(map1.get("key1"));
System.out.println(map1.get("key2"));

//将Map转成JSONObject，然后添加元素，输出
Map<String,Object> map = new HashMap<String, Object>();
map.put("key1", "One");
map.put("key2", "Two");

JSONObject j = new JSONObject(map);
j.put("key3", "Three");

System.out.println(j.get("key1"));
System.out.println(j.get("key2"));
System.out.println(j.get("key3"));

//将List对象转成JSONArray，然后输出
List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();

Map<String, Object> map = new HashMap<String, Object>();
map.put("key1", "One");
map.put("key2", "Two");

Map<String, Object> map2 = new HashMap<String, Object>();
map2.put("key1", "Three");
map2.put("key2", "Four");

list.add(map);
list.add(map2);

JSONArray j = JSONArray.parseArray(JSON.toJSONString(list));
for (int i = 0; i < j.size(); i++) {
System.out.println(j.get(i));
}
}
}

MyJsonUtil.javapackage com.accord.fastjson;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.serializer.SerializerFeature;

public class MyJsonUtil {
private static final SerializerFeature[] features = {
SerializerFeature.WriteMapNullValue, // 输出空置字段
SerializerFeature.WriteNullListAsEmpty,
// // list字段如果为null，输出为[]，而不是null
SerializerFeature.WriteNullNumberAsZero,
// // 数值字段如果为null，输出为0，而不是null
SerializerFeature.WriteNullBooleanAsFalse,
// // Boolean字段如果为null，输出为false，而不是null
SerializerFeature.WriteNullStringAsEmpty,
// // 字符类型字段如果为null，输出为""，而不是null
SerializerFeature.WriteDateUseDateFormat // 日期格式化yyyy-MM-dd HH:mm:ss
};

public static String toJson(Object object) {
return JSON.toJSONString(object, features);
}
}