本文主要是介绍研究使用FastJson把Java对象转JsonObject的效率问题，以及改进方案。，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
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@Overridepublic 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@Overridepublic Object reSerialize() {return this;}@Overridepublic 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() {@Overridepublic 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() {@Overridepublic 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 02 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() {@Overridepublic 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() {@Overridepublic 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 04 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。
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