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研究使用FastJson把Java对象转JsonObject的效率问题，以及改进方案。

程序员文章站 2022-04-07 18:21:56
构造了一个稍微复杂的Java对象对比在不同情况下的转换效率，都是循环20次执行。https://gitee.com/icefire11/test-fast-json概述:Main方法示例:import com.alibaba.fastjson.JSONObject;public class Test { public static void main(String[] args) { School school = new School(); lon...

构造了一个稍微复杂的Java对象对比在不同情况下的转换效率，都是循环20次执行。

项目地址：https://gitee.com/icefire11/test-fast-json

概述:

Main方法示例:

import com.alibaba.fastjson.JSONObject;

public class Test {
    public static void main(String[] args) {
        School school = new School();
        long start = System.currentTimeMillis();

        for (int i = 0; i < 20; i++) {
            // 带过滤的方法
            JSONObject json = JsonUtils.toClientJSONObject(school);
            // 自定义转换规则
            //JSONObject json = (JSONObject)school.toJson();
            // 原生方法
            // Object json = JSONObject.toJSON(school);
        }
       // System.out.println(json);
        long end = System.currentTimeMillis();
        System.out.println("Time:" + (end - start) + "ms");
    }
}

构造的Java对象示例:

import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.annotation.JSONField;
import org.springframework.data.annotation.Transient;

/**
 * @desc: TODO
 * @author: zhangjiaqi
 * @time: 2020/11/25 11:55
 */
public class School implements ReSerializeModel{
    @Transient
    @JSONField(serialize = false, deserialize = false)
    RString p1 = new RString("打卡的框架阿里1");
    RString p2 = new RString("打卡的框架阿里2");
    RString p3 = new RString("打卡的框架阿里3");
    RString p4 = new RString("打卡的框架阿里4");
    @Transient
    @JSONField(serialize = false, deserialize = false)
    RString p5 = new RString("打卡的框架阿里5");

    RInteger p6 = new RInteger(1);
    RInteger p7 = new RInteger(2);
    @Transient
    @JSONField(serialize = false, deserialize = false)
    RInteger p8 = new RInteger(3);
    RInteger p9 = new RInteger(4);
    @Transient
    @JSONField(serialize = false, deserialize = false)
    RInteger p10 = new RInteger(5);


    RList<Article> list1 = new RList<>();
    RList<Book> list2 = new RList<>();
    RList<Student> list3 = new RList<>();
    RList<Teacher> list4 = new RList<>();

    RMap<Article> map1 = new RMap<>();
    RMap<Book> map2 = new RMap<>();
    RMap<Student> map3 = new RMap<>();
    RMap<Teacher> map4 = new RMap<>();

    public School(){
        list1.getList().add(new Article());
        list1.getList().add(new Article());
        list1.getList().add(new Article());
        list1.getList().add(new Article());
        list1.getList().add(new Article());
        list1.getList().add(new Article());
        list1.getList().add(new Article());

        list2.getList().add(new Book());
        list2.getList().add(new Book());
        list2.getList().add(new Book());
        list2.getList().add(new Book());
        list2.getList().add(new Book());
        list2.getList().add(new Book());

        list3.getList().add(new Student());
        list3.getList().add(new Student());
        list3.getList().add(new Student());
        list3.getList().add(new Student());
        list3.getList().add(new Student());
        list3.getList().add(new Student());
        list3.getList().add(new Student());

        list4.getList().add(new Teacher());
        list4.getList().add(new Teacher());
        list4.getList().add(new Teacher());
        list4.getList().add(new Teacher());
        list4.getList().add(new Teacher());
        list4.getList().add(new Teacher());
        list4.getList().add(new Teacher());

        map1.getMap().put("1", new Article());
        map1.getMap().put("2", new Article());
        map1.getMap().put("3", new Article());
        map1.getMap().put("4", new Article());
        map1.getMap().put("5", new Article());
        map1.getMap().put("6", new Article());
        map1.getMap().put("7", new Article());

        map2.getMap().put("1", new Book());
        map2.getMap().put("2", new Book());
        map2.getMap().put("3", new Book());
        map2.getMap().put("4", new Book());
        map2.getMap().put("5", new Book());
        map2.getMap().put("6", new Book());
        map2.getMap().put("7", new Book());

        map3.getMap().put("1", new Student());
        map3.getMap().put("2", new Student());
        map3.getMap().put("3", new Student());
        map3.getMap().put("4", new Student());
        map3.getMap().put("5", new Student());
        map3.getMap().put("6", new Student());
        map3.getMap().put("7", new Student());

        map4.getMap().put("1", new Teacher());
        map4.getMap().put("2", new Teacher());
        map4.getMap().put("3", new Teacher());
        map4.getMap().put("4", new Teacher());
        map4.getMap().put("5", new Teacher());
        map4.getMap().put("6", new Teacher());
        map4.getMap().put("7", new Teacher());
    }

    public RString getP1() {
        return p1;
    }

    ... 省去set get
    @Override
    public Object toJson() {
        JSONObject json = new JSONObject();
        json.put("p2", SerializaUtils.toJSON(p2));
        json.put("p3", SerializaUtils.toJSON(p3));
        json.put("p4", SerializaUtils.toJSON(p4));
        json.put("p6", SerializaUtils.toJSON(p6));
        json.put("p7", SerializaUtils.toJSON(p7));
        json.put("p8", SerializaUtils.toJSON(p8));

        json.put("list1", SerializaUtils.toJSON(list1));
        json.put("list2", SerializaUtils.toJSON(list2));
        json.put("list3", SerializaUtils.toJSON(list3));
        json.put("list4", SerializaUtils.toJSON(list4));
        json.put("map1", SerializaUtils.toJSON(map1));
        json.put("map2", SerializaUtils.toJSON(map2));
        json.put("map3", SerializaUtils.toJSON(map3));
        json.put("map4", SerializaUtils.toJSON(map4));
        return json;
        return json;
    }
}
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.annotation.JSONField;
import org.springframework.data.annotation.Transient;

/**
 * @desc: TODO
 * @author: zhangjiaqi
 * @time: 2020/11/25 14:22
 */
public class Student implements ReSerializeModel{

    @Transient
    @JSONField(serialize = false, deserialize = false)
    RString p1 = new RString("打卡的框架阿里1");
    RString p2 = new RString("打卡的框架阿里2");
    RString p3 = new RString("打卡的框架阿里3");
    @Transient
    @JSONField(serialize = false, deserialize = false)
    RString p4 = new RString("打卡的框架阿里4");
    RString p5 = new RString("打卡的框架阿里5");

    @Transient
    @JSONField(serialize = false, deserialize = false)
    RInteger p6 = new RInteger(1);
    RInteger p7 = new RInteger(2);
    RInteger p8 = new RInteger(3);
    @Transient
    @JSONField(serialize = false, deserialize = false)
    RInteger p9 = new RInteger(4);
    RInteger p10 = new RInteger(5);

    RList<Book> list1 = new RList<>();
    RList<Article> list2 = new RList<>();

    RMap<Book> map1 = new RMap<>();
    RMap<Article> map2 = new RMap<>();

    public Student(){
        list1.getList().add(new Book());
        list1.getList().add(new Book());
        list1.getList().add(new Book());
        list1.getList().add(new Book());
        list1.getList().add(new Book());
        list1.getList().add(new Book());
        list1.getList().add(new Book());
        list1.getList().add(new Book());

        list2.getList().add(new Article());
        list2.getList().add(new Article());
        list2.getList().add(new Article());
        list2.getList().add(new Article());
        list2.getList().add(new Article());
        list2.getList().add(new Article());
        list2.getList().add(new Article());
        list2.getList().add(new Article());

        map1.getMap().put("1", new Book());
        map1.getMap().put("2", new Book());
        map1.getMap().put("3", new Book());
        map1.getMap().put("4", new Book());
        map1.getMap().put("5", new Book());
        map1.getMap().put("6", new Book());
        map1.getMap().put("7", new Book());
        map1.getMap().put("8", new Book());

        map2.getMap().put("1", new Article());
        map2.getMap().put("2", new Article());
        map2.getMap().put("3", new Article());
        map2.getMap().put("4", new Article());
        map2.getMap().put("5", new Article());
        map2.getMap().put("6", new Article());
        map2.getMap().put("7", new Article());
        map2.getMap().put("8", new Article());
    }

    public RString getP1() {
        return p1;
    }

    ... 省去 set和get

    @Override
    public Object reSerialize() {
        return this;
    }

    @Override
    public Object toJson() {
       JSONObject json = new JSONObject();
        json.put("p2", SerializaUtils.toJSON(p2));
        json.put("p3", SerializaUtils.toJSON(p3));
        json.put("p5", SerializaUtils.toJSON(p5));
        json.put("p7", SerializaUtils.toJSON(p7));
        json.put("p8", SerializaUtils.toJSON(p8));
        json.put("p10", SerializaUtils.toJSON(p10));


        json.put("list1", SerializaUtils.toJSON(list1));
        json.put("list2", SerializaUtils.toJSON(list2));
        json.put("map1", SerializaUtils.toJSON(map1));
        json.put("map2", SerializaUtils.toJSON(map2));
        return json;
    }
}


1 使用注解过滤掉一些字段（不想发给客户端，不想存库等）调用 JsonUtils.toClientJSONObject(Object obj)

调用方法：

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.serializer.PropertyFilter;
import com.alibaba.fastjson.serializer.SerializeFilter;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.alibaba.fastjson.serializer.ValueFilter;

import java.lang.reflect.*;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;


public final class JsonUtils {

    public static final Map<Class<?>, Map<String, Boolean>> PR_IGNORE_FIELDS = new ConcurrentHashMap<>();
    public static final ValueFilter DPSVALUE_FILTER = new ValueFilter() {
        @Override
        public Object process(Object o, String propertyName, Object propertyValue) {
            if (propertyValue instanceof ReSerializeModel) {
                return ((ReSerializeModel) propertyValue).reSerialize();
            }
            return propertyValue;
        }
    };
    public static final PropertyFilter DPSPROPERTY_FILTER = new PropertyFilter() {
        @Override
        public boolean apply(Object object, String name, Object value) {
            Class<?> clz = object.getClass();
            PR_IGNORE_FIELDS.putIfAbsent(clz, new ConcurrentHashMap<>());
            Map<String, Boolean> clzIgnoreFields = PR_IGNORE_FIELDS.get(clz);
            if (!clzIgnoreFields.containsKey(name)) {
                Field field = ReflectUtils.getFieldWhatever(clz, name);
                if (field == null)
                    return true;
                clzIgnoreFields.put(name, field.isAnnotationPresent(ClientIgnore.class));
            }
            return !clzIgnoreFields.get(name);
        }
    };
    private JsonUtils(){

    }
    public static String toClientString(Object obj) {
        return JSON.toJSONString(obj, new SerializeFilter[] { DPSVALUE_FILTER, DPSPROPERTY_FILTER }, SerializerFeature.DisableCircularReferenceDetect);
    }


    public static JSONObject toClientJSONObject(Object obj) {
        String s = toClientString(obj);
        return JSON.parseObject(s);
    }
}

     执行结果:

Connected to the target VM, address: '127.0.0.1:54338', transport: 'socket'
Time:23180ms
Disconnected from the target VM, address: '127.0.0.1:54338', transport: 'socket'

Process finished with exit code 0

2 去掉带注解的过滤 调用 JsonUtils.toClientJSONObject(Object obj) 但 去掉了toClientString(Object obj) 里面的过滤规则

     执行结果:

Connected to the target VM, address: '127.0.0.1:54396', transport: 'socket'
Time:1323ms
Disconnected from the target VM, address: '127.0.0.1:54396', transport: 'socket'

Process finished with exit code 0

    调用方法： 注意下面的toClientString(Object obj)方法，里面去掉了注解过滤

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.serializer.PropertyFilter;
import com.alibaba.fastjson.serializer.SerializeFilter;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.alibaba.fastjson.serializer.ValueFilter;

import java.lang.reflect.*;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;


public final class JsonUtils {

    public static final Map<Class<?>, Map<String, Boolean>> PR_IGNORE_FIELDS = new ConcurrentHashMap<>();
    public static final ValueFilter DPSVALUE_FILTER = new ValueFilter() {
        @Override
        public Object process(Object o, String propertyName, Object propertyValue) {
            if (propertyValue instanceof ReSerializeModel) {
                return ((ReSerializeModel) propertyValue).reSerialize();
            }
            return propertyValue;
        }
    };
    public static final PropertyFilter DPSPROPERTY_FILTER = new PropertyFilter() {
        @Override
        public boolean apply(Object object, String name, Object value) {
            Class<?> clz = object.getClass();
            PR_IGNORE_FIELDS.putIfAbsent(clz, new ConcurrentHashMap<>());
            Map<String, Boolean> clzIgnoreFields = PR_IGNORE_FIELDS.get(clz);
            if (!clzIgnoreFields.containsKey(name)) {
                Field field = ReflectUtils.getFieldWhatever(clz, name);
                if (field == null)
                    return true;
                clzIgnoreFields.put(name, field.isAnnotationPresent(ClientIgnore.class));
            }
            return !clzIgnoreFields.get(name);
        }
    };
    private JsonUtils(){

    }
    public static String toClientString(Object obj) {
        return JSON.toJSONString(obj, new SerializeFilter[] { DPSVALUE_FILTER }, SerializerFeature.DisableCircularReferenceDetect);
    }


    public static JSONObject toClientJSONObject(Object obj) {
        String s = toClientString(obj);
        return JSON.parseObject(s);
    }
}

3 直接使用FastJson的  JSONObject.toJSON()方法，但是这样无法过滤掉一些字段
     执行结果:

Connected to the target VM, address: '127.0.0.1:54432', transport: 'socket'
Time:772ms
Disconnected from the target VM, address: '127.0.0.1:54432', transport: 'socket'

Process finished with exit code 0

4 使用自定义转换方法 调用对象中的toJson()方法

    自定义处理方法（由fastjson修改）：

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.parser.ParserConfig;
import com.alibaba.fastjson.util.TypeUtils;

import java.lang.reflect.Array;
import java.util.*;

/**
 * @desc: TODO
 * @author: zhangjiaqi
 * @time: 2020/11/27 17:08
 */
public class SerializaUtils {
    public static Object toJSON(Object javaObject) {
        if (javaObject == null) {
            return null;
        } else if (javaObject instanceof JSON) {
            return javaObject;
        } else {
            JSONObject json;
            int len;
            if (javaObject instanceof Map) {
                Map<Object, Object> map = (Map) javaObject;
                len = map.size();
                Object innerMap;
                if (map instanceof LinkedHashMap) {
                    innerMap = new LinkedHashMap(len);
                } else if (map instanceof TreeMap) {
                    innerMap = new TreeMap();
                } else {
                    innerMap = new HashMap(len);
                }
                json = new JSONObject((Map) innerMap);
                Iterator var24 = map.entrySet().iterator();
                while (var24.hasNext()) {
                    Map.Entry<Object, Object> entry = (Map.Entry) var24.next();
                    Object key = entry.getKey();
                    String jsonKey = TypeUtils.castToString(key);
                    Object jsonValue = toJSON(entry.getValue());
                    json.put(jsonKey, jsonValue);
                }
                return json;
            } else {
                if (javaObject instanceof Collection) {
                    Collection<Object> collection = (Collection) javaObject;
                    JSONArray array = new JSONArray(collection.size());
                    Iterator var19 = collection.iterator();
                    while (var19.hasNext()) {
                        Object item = var19.next();
                        item = toJSON(item);
                        array.add(item);
                    }
                    return array;
                } else if (javaObject instanceof ReSerializeModel) {
                    return ((ReSerializeModel) javaObject).toJson();
                } else {
                    Class<?> clazz = javaObject.getClass();
                    if (clazz.isEnum()) {
                        return ((Enum) javaObject).name();
                    } else if (clazz.isArray()) {
                        len = Array.getLength(javaObject);
                        JSONArray array = new JSONArray(len);
                        for (int i = 0; i < len; ++i) {
                            Object item = Array.get(javaObject, i);
                            Object jsonValue = toJSON(item);
                            array.add(jsonValue);
                        }
                        return array;
                    } else if (ParserConfig.isPrimitive2(clazz)) {
                        return javaObject;
                    } else {
                        // 未继承ReSerializeModel的未知对象 不进行转换
                        return null;
                    }
                }
            }
        }
    }
}


    执行结果:

Connected to the target VM, address: '127.0.0.1:57670', transport: 'socket'
Time:401ms
Disconnected from the target VM, address: '127.0.0.1:57670', transport: 'socket'

Process finished with exit code 0

 

结论:

       去掉注解过滤，转换效率是带注解过滤的近30倍，而直接使用fastjson的原生方法，不加任何其他规则，效率比不带注解过滤更快一些，这是显然对的，随着转换规则越来越少，转换效率越来越高，但是这其中的重点是加上注解过滤规则之后效率直接降低了近30倍，这在线上是很难接受的，这个Java对象还比较简单，真正游戏中用到的Java对象极其复杂，比如玩家对象，里面有玩家所有信息，这是一个很庞大的对象，使用带注解过滤的方式去处理这个对象，那效率简直是灾难。但是不加注解过滤，就无法过滤一些不想转json的字段，这也是不能接受的。

     我们想要效率高，又想要过滤一些字段，该怎么办，那就是使用自定义转换方法，把需要转换的字段写进方法里面，不需要转换的就不考虑，通过对比可以发现，这样做比直接使用原生Json不带任何规则还快了近1倍，时间只有其1/2，这样效率高，又能满足复杂规则的选择我们为什么不考虑呢，有人可能会说，这样会使写代码比较麻烦，我们可以把所有需要需要转换成Json的对象写在模板里面，通过FreeMarker生成代码的方式处理转换方法。这样做既简单又高效。

本文地址：https://blog.csdn.net/u012901117/article/details/110230305

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