2013年8月25日星期日

Introduction 3 json and performance testing of the java classlibrary

JSON (JavaScript Object Notation) is a lightweight data interchange format. Easy to read and write. Also easy for machines to parse and generate. It is based on JavaScript Programming Language , Standard ECMA-262 3rd Edition - December 1999 is a subset. JSON is completely independent of the language used in text format, these properties make JSON an ideal data-interchange language.

Here are three of the java process json library: json-lib, gson, jackson

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. official website: http://json-lib.sourceforge.net/

maven dependency:

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

Example:

  
    /** 
     * 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); 
    }

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.

official website: https://code.google.com/p/google-gson/

maven dependency:

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

Example:

  
    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; 
    }

Jackson

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

maven dependency:

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

Example:

  
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); 
    }

performance test

1, Java objects serialized as Json string:

perform one million conversions, time-consuming each library as follows: (in seconds)

                                             
Gson 48.891s
Json-lib 311.446s
Jackson 19.439s

2, Json string deserialize Java objects

perform one million conversions, time-consuming each library as follows: (in seconds)

                                             
Gson 39.280s
Json-lib to use the library when converting method (test code see below), an exception is thrown. The reason is that the properties of the Person class: List friends, its List of the object is not an object of type Person, but net.sf.ezmorph.bean.MorphDynaBean type of object. Description, Json-lib for nested custom class support is poor, perhaps problems with the way I write.
Jackson 26.427s

3, Summary:

For Json serialization and deserialization performance Jackson> Gson> Json-lib. And Jackson and Gson can well support complex nested structure defined classes.

Jackson and Gson library has its own advantages, each with their own expertise, have a high availability.

4, test cases

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 library:

  
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); 
    } 
}

3) Java objects serialized as Json string test class:

  
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(JsonObjectUtil.bean2Json(p)); 
         
        for (int i = 0; i < 1000000; i++) { 
            JsonObjectUtil.bean2Json(p); 
        } 
    } 
     
     
    @Test 
    public void testJacksonBean2Json() throws Exception{ 
        System.out.println(JacksonUtil.bean2Json(p)); 
         
        for (int i = 0; i < 1000000; i++) { 
            JacksonUtil.bean2Json(p); 
        } 
    } 
     
}

4) Json string deserialize Java objects test class:

  
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 testJsonObjectjson2Bean() throws Exception{ 
        Person pp=JsonObjectUtil.json2Bean(jsonStr, Person.class); 
        System.out.println(pp); 
         
        for (int i = 0; i < 1000000; i++) { 
            JsonObjectUtil.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); 
        } 
    } 
}

Reference: http://www.json.org/json-zh.html

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