Java Json 序列化与反序列化

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JSON(JavaScript Object Notation) 是一种轻量级的数据交换格式。易于人阅读和编写。同时也易于机器解析和生成。它基于JavaScript Programming Language, Standard ECMA-262 3rd Edition - December 1999的一个子集。 JSON采用完全独立于语言的文本格式，这些特性使JSON成为理想的数据交换语言。

下面介绍两款自己在开发中常用的处理Json的Java开源类库：Gson和Fastjson

1、Gson

Gson is a Java library that can be used to convert Java Objects into their JSON representation. It can also be used to convert a JSON string to an equivalent Java object. Gson can work with arbitrary Java objects including pre-existing objects that you do not have source-code of.

Gson官网：http://code.google.com/p/google-gson/

Gson User Guide：https://sites.google.com/site/gson/gson-user-guide

2、Fastjson

Fastjson是一个json处理工具包，由阿里巴巴公司开发，包括“序列化”和“反序列化”两部分，它具备如下特征：

速度最快，测试表明，fastjson具有极快的性能，超越任其他的java json parser。包括自称最快的jackson。
功能强大，完全支持java bean、集合、Map、日期、Enum，支持范型，支持自省。
无依赖，能够直接运行在Java SE 5.0以上版本
支持Android。
开源 (Apache 2.0)

Fastjson 官网：http://code.alibabatech.com/wiki/display/FastJSON/Overview

下面通过一个简单Demo，对比两者序列化与反序列化的用法

JavaBean 实体Person

package com.example.testjson.entity;import java.util.Date;import java.util.List;import java.util.Map;public class Person {    private String name;    private FullName fullName;    private int age;    private Date birthday;    private List<String> hobbies;    private Map<String, String> clothes;    private List<Person> friends;        public String getName() {return name;}public void setName(String name) {this.name = name;}public FullName getFullName() {return fullName;}public void setFullName(FullName fullName) {this.fullName = fullName;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public Date getBirthday() {return birthday;}public void setBirthday(Date birthday) {this.birthday = birthday;}public List<String> getHobbies() {return hobbies;}public void setHobbies(List<String> hobbies) {this.hobbies = hobbies;}public Map<String, String> getClothes() {return clothes;}public void setClothes(Map<String, String> clothes) {this.clothes = clothes;}public List<Person> getFriends() {return friends;}public void setFriends(List<Person> friends) {this.friends = friends;}@Override    public String toString() {        String str= "Person [name=" + name + ", fullName=" + fullName + ", age="                + age + ", birthday=" + birthday + ", hobbies=" + hobbies                + ", clothes=" + clothes +  "]\n";        if(friends!=null){            str+="Friends:\n";            for (Person f : friends) {                str+="\t"+f;            }        }        return str;    }    }class FullName {    private String firstName;    private String middleName;    private String lastName;        public FullName(){    }        public FullName(String firstName, String middleName, String lastName) {super();this.firstName = firstName;this.middleName = middleName;this.lastName = lastName;}public String getFirstName() {return firstName;}public void setFirstName(String firstName) {this.firstName = firstName;}public String getMiddleName() {return middleName;}public void setMiddleName(String middleName) {this.middleName = middleName;}public String getLastName() {return lastName;}public void setLastName(String lastName) {this.lastName = lastName;}@Override    public String toString() {        return "[firstName=" + firstName + ", middleName="                + middleName + ", lastName=" + lastName + "]";    }    }

负责创建Person的Bean Factory

package com.example.testjson.entity;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;public class PersonFactory {private static Person createABSPerson(String name,List<Person> friends) {        Person newPerson = new Person();        newPerson.setName(name);        newPerson.setFullName(new FullName(name+"_first", name+"_middle", name+"_last"));        newPerson.setAge(24);        List<String> hobbies=new ArrayList<String>();        hobbies.add("篮球");        hobbies.add("游泳");        hobbies.add("coding");        newPerson.setHobbies(hobbies);        Map<String,String> clothes=new HashMap<String, String>();        clothes.put("coat", "Nike");        clothes.put("trousers", "adidas");        clothes.put("shoes", "安踏");        newPerson.setClothes(clothes);        newPerson.setFriends(friends);        return newPerson;    }        public static Person create(String name){        List<Person> friends=new ArrayList<Person>();        friends.add(createABSPerson("小明",null));        friends.add(createABSPerson("Tony",null));        friends.add(createABSPerson("陈小二",null));        return createABSPerson(name,friends);    }}

Gson 工具类GsonUtil

package com.example.testjson.gson;import com.google.gson.Gson;import com.google.gson.GsonBuilder;import com.google.gson.JsonElement;import com.google.gson.JsonParser;public class GsonUtil {private static Gson gson = new GsonBuilder().create();        public static String bean2Json(Object obj){        return gson.toJson(obj);    }        public static <T> T json2Bean(String jsonStr,Class<T> objClass){        return gson.fromJson(jsonStr, objClass);    }        public static String jsonFormatter(String uglyJsonStr){        Gson gson = new GsonBuilder().setPrettyPrinting().create();        JsonParser jp = new JsonParser();        JsonElement je = jp.parse(uglyJsonStr);        String prettyJsonString = gson.toJson(je);        return prettyJsonString;    }}

Fastjson 工具类FastJsonUtil

package com.example.testjson.fastjson;import com.alibaba.fastjson.JSON;public class FastJsonUtil {public static String bean2Json(Object obj){        return JSON.toJSONString(obj);    }        public static <T> T json2Bean(String jsonStr,Class<T> objClass){        return JSON.parseObject(jsonStr, objClass);    }}

最后两个测试类

GsonTest

package com.example.testjson;import com.example.testjson.entity.Person;import com.example.testjson.entity.PersonFactory;import com.example.testjson.gson.GsonUtil;public class GsonTest {/** * @param args */public static void main(String[] args) {// TODO Auto-generated method stubPerson p = PersonFactory.create("Kobe");String json = GsonUtil.bean2Json(p);String prettyJsonString = GsonUtil.jsonFormatter(json);System.out.println("FastJson Serializing="+json);System.out.println("FastJson Serializing PrettyPrinting="+prettyJsonString);Person newPerson = GsonUtil.json2Bean(json, Person.class);System.out.println("FastJson Deserializing="+newPerson);}}

FastJsonTest

package com.example.testjson;import com.example.testjson.entity.Person;import com.example.testjson.entity.PersonFactory;import com.example.testjson.fastjson.FastJsonUtil;public class FastJsonTest {/** * @param args */public static void main(String[] args) {// TODO Auto-generated method stubPerson p = PersonFactory.create("Kobe");String json = FastJsonUtil.bean2Json(p);System.out.println("FastJson Serializing="+json);Person newPerson = FastJsonUtil.json2Bean(json, Person.class);System.out.println("FastJson Deserializing="+newPerson);}}

示例Demo下载：http://download.csdn.net/detail/fx_sky/6771327

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