介绍4款json的java类库及其性能测试

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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。

下面介绍四款处理json的java类库：Json-lib、Gson、Jackson、Fastjson

一、Json-lib

JSON-lib is a java library for transforming beans, maps, collections, java arrays and XML to JSON and back again to beans and DynaBeans. 官网：http://json-lib.sourceforge.net/

maven依赖配置：

         <dependency>            <groupId>net.sf.json-lib</groupId>            <artifactId>json-lib</artifactId>            <version>2.4</version>            <classifier>jdk15</classifier>        </dependency>

示例：

    /**     * 将对象序列化成json字符串     * @param obj     * @return     */    public static String bean2Json(Object obj){        JSONObject jsonObject=JSONObject.fromObject(obj);        return jsonObject.toString();    }        /**     * 将json字符串反序列化为对象     * @param jsonStr     * @param objClass 反序列化为该类的对象     * @return     */    @SuppressWarnings("unchecked")    public static <T> T json2Bean(String jsonStr,Class<T> objClass){        return (T)JSONObject.toBean(JSONObject.fromObject(jsonStr), objClass);    }

二、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.

官网：https://code.google.com/p/google-gson/

maven依赖：

        <dependency>            <groupId>com.google.code.gson</groupId>            <artifactId>gson</artifactId>            <version>2.2.4</version>        </dependency>

示例：

    public static String bean2Json(Object obj){        Gson gson = new GsonBuilder().create();        return gson.toJson(obj);    }        public static <T> T json2Bean(String jsonStr,Class<T> objClass){        Gson gson = new GsonBuilder().create();        return gson.fromJson(jsonStr, objClass);    }        /**     * 把混乱的json字符串整理成缩进的json字符串     * @param uglyJsonStr     * @return     */    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;    }

三、Jackson

Jackson is a high-performance JSON processor (parser, generator)。官网：http://jackson.codehaus.org/Home

maven依赖：

<dependency>            <groupId>org.codehaus.jackson</groupId>            <artifactId>jackson-mapper-asl</artifactId>            <version>1.9.13</version>        </dependency>

示例：

public static String bean2Json(Object obj) throws IOException {        ObjectMapper mapper = new ObjectMapper();        StringWriter sw = new StringWriter();        JsonGenerator gen = new JsonFactory().createJsonGenerator(sw);        mapper.writeValue(gen, obj);        gen.close();        return sw.toString();    }    public static <T> T json2Bean(String jsonStr, Class<T> objClass)            throws JsonParseException, JsonMappingException, IOException {        ObjectMapper mapper = new ObjectMapper();        return mapper.readValue(jsonStr, objClass);    }

四、FastJson

Fastjson是一个Java语言编写的JSON处理器,由阿里巴巴公司开发。网址：https://github.com/alibaba/fastjson

maven依赖配置：

        <dependency>            <groupId>com.alibaba</groupId>            <artifactId>fastjson</artifactId>            <version>1.1.35</version>        </dependency>

示例：

    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);    }

五、性能测试

1、Java对象序列化为Json字符串：

执行100 0000次转换，各个类库的耗时如下：（以秒为单位）

Gson 48.891sJson-lib311.446sJackson19.439sFastJson21.706

2、Json字符串反序列化为Java对象

执行100 0000次转换，各个类库的耗时如下：（以秒为单位）

Gson 39.280sJson-lib使用该类库的方法进行转换时（测试代码见下面），抛出异常。其原因是Person类的属性：List<Person> friends，其List中的对象不是Person类型的对象，而是net.sf.ezmorph.bean.MorphDynaBean类型的对象。说明，Json-lib对嵌套的自定义类支持的很差，或许是我写的方法有问题。Jackson26.427sFastJson40.556

3、总结：

Java Bean序列化为Json，性能：Jackson > FastJson > Gson > Json-lib。这4中类库的序列化结构都正确。

Json字符串反序列化为Java Bean时，性能：Jackson > Gson > FastJson >Json-lib。并且Jackson、Gson、FastJson可以很好的支持复杂的嵌套结构定义的类，而Json-lib对于复制的反序列化会出错。

Jackson、FastJson、Gson类库各有优点，各有自己的专长，都具有很高的可用性。

4、测试用例

1）Java Bean

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;        //getter setter 方法。略    @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;    
　　//构造方法、getter setter 方法，略 　　    @Override    public String toString() {        return "[firstName=" + firstName + ", middleName="                + middleName + ", lastName=" + lastName + "]";    }    }

2）Json-lib、Gson、Jackson、FastJson类库：

import net.sf.json.JSONObject;public class JsonObjectUtil {    public static String bean2Json(Object obj){        JSONObject jsonObject=JSONObject.fromObject(obj);        return jsonObject.toString();    }        @SuppressWarnings("unchecked")    public static <T> T json2Bean(String jsonStr,Class<T> objClass){        return (T)JSONObject.toBean(JSONObject.fromObject(jsonStr), objClass);    }    }

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;    }}

import java.io.IOException;import java.io.StringWriter;import org.codehaus.jackson.JsonFactory;import org.codehaus.jackson.JsonGenerator;import org.codehaus.jackson.JsonParseException;import org.codehaus.jackson.map.JsonMappingException;import org.codehaus.jackson.map.ObjectMapper;public class JacksonUtil {    private static ObjectMapper mapper = new ObjectMapper();        public static String bean2Json(Object obj) throws IOException {        StringWriter sw = new StringWriter();        JsonGenerator gen = new JsonFactory().createJsonGenerator(sw);        mapper.writeValue(gen, obj);        gen.close();        return sw.toString();    }    public static <T> T json2Bean(String jsonStr, Class<T> objClass)            throws JsonParseException, JsonMappingException, IOException {        return mapper.readValue(jsonStr, objClass);    }}

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);    }}

3）Java对象序列化为Json字符串测试类：

public class TestBean2Json {    private Person p;        private Person createAPerson(String name,List<Person> friends) {        Person newPerson=new Person();        newPerson.setName(name);        newPerson.setFullName(new FullName("xxx_first", "xxx_middle", "xxx_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;    }        @Before    public void init(){        List<Person> friends=new ArrayList<Person>();        friends.add(createAPerson("小明",null));        friends.add(createAPerson("Tony",null));        friends.add(createAPerson("陈小二",null));         p=createAPerson("邵同学",friends);    }    //    @Test    public void testGsonBean2Json(){        System.out.println(GsonUtil.bean2Json(p));                for (int i = 0; i < 1000000; i++) {            GsonUtil.bean2Json(p);        }    }            //@Test    public void testJsonObjectBean2Json(){        System.out.println(JsonlibUtil.bean2Json(p));                for (int i = 0; i < 1000000; i++) {            JsonlibUtil.bean2Json(p);        }    }        //    @Test    public void testJacksonBean2Json() throws Exception{        System.out.println(JacksonUtil.bean2Json(p));                for (int i = 0; i < 1000000; i++) {            JacksonUtil.bean2Json(p);        }    }        @Test    public void testFastJsonBean2Json() throws Exception{        System.out.println(FastJsonUtil.bean2Json(p));                for (int i = 0; i < 1000000; i++) {            FastJsonUtil.bean2Json(p);        }    }    }

4）Json字符串反序列化为Java对象测试类：

public class TestJson2Bean {    private String jsonStr;        @Before    public void init(){         jsonStr="{\"name\":\"邵同学\",\"fullName\":{\"firstName\":\"xxx_first\",\"middleName\":\"xxx_middle\",\"lastName\":\"xxx_last\"},\"age\":24,\"birthday\":null,\"hobbies\":[\"篮球\",\"游泳\",\"coding\"],\"clothes\":{\"shoes\":\"安踏\",\"trousers\":\"adidas\",\"coat\":\"Nike\"},\"friends\":[{\"name\":\"小明\",\"fullName\":{\"firstName\":\"xxx_first\",\"middleName\":\"xxx_middle\",\"lastName\":\"xxx_last\"},\"age\":24,\"birthday\":null,\"hobbies\":[\"篮球\",\"游泳\",\"coding\"],\"clothes\":{\"shoes\":\"安踏\",\"trousers\":\"adidas\",\"coat\":\"Nike\"},\"friends\":null},{\"name\":\"Tony\",\"fullName\":{\"firstName\":\"xxx_first\",\"middleName\":\"xxx_middle\",\"lastName\":\"xxx_last\"},\"age\":24,\"birthday\":null,\"hobbies\":[\"篮球\",\"游泳\",\"coding\"],\"clothes\":{\"shoes\":\"安踏\",\"trousers\":\"adidas\",\"coat\":\"Nike\"},\"friends\":null},{\"name\":\"陈小二\",\"fullName\":{\"firstName\":\"xxx_first\",\"middleName\":\"xxx_middle\",\"lastName\":\"xxx_last\"},\"age\":24,\"birthday\":null,\"hobbies\":[\"篮球\",\"游泳\",\"coding\"],\"clothes\":{\"shoes\":\"安踏\",\"trousers\":\"adidas\",\"coat\":\"Nike\"},\"friends\":null}]}";    }        //    @Test    public void testGsonjson2Bean() throws Exception{        Person pp=GsonUtil.json2Bean(jsonStr, Person.class);        System.out.println(pp);                for (int i = 0; i < 1000000; i++) {            GsonUtil.json2Bean(jsonStr, Person.class);        }    }        //    @Test    public void testJsonlibJson2Bean() throws Exception{        Person pp=JsonlibUtil.json2Bean(jsonStr, Person.class);        System.out.println(pp);                for (int i = 0; i < 1000000; i++) {            JsonlibUtil.json2Bean(jsonStr, Person.class);        }    }        //    @Test    public void testJacksonJson2Bean() throws Exception{        Person pp=JacksonUtil.json2Bean(jsonStr, Person.class);        System.out.println(pp);                for (int i = 0; i < 1000000; i++) {            JacksonUtil.json2Bean(jsonStr, Person.class);        }    }        @Test    public void testFastJsonJson2Bean() throws Exception{        Person pp=FastJsonUtil.json2Bean(jsonStr, Person.class);        System.out.println(pp);                for (int i = 0; i < 1000000; i++) {            FastJsonUtil.json2Bean(jsonStr, Person.class);        }    }}

参考：http://www.json.org/json-zh.html

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