FastJSON 原理剖析 以及 和 Jackson的对比 who is the most fast!
FastJSON定义: FastJSON是一个阿里巴巴内部人员开发的,用于JSON对象和普通类对象互相转换的库。号称性能超越Jackson,今天我们就来看看,阿里巴巴大牛 vs Tatu Saloranta,到底 who is the most awesome!
FastJSON原理:
-对象 to JSON :利用反射找到对象类的所有Get方法,然后把”get”去掉,小写化,作为JSON的每个key值,如 getA 对应的key值为 a,而与真实的类成员名无关。
-JSON to pojo :先同样通过反射找到对象类所有的Set方法,然后使用无参数构造函数(所以一定要有无参数的构造函数)新建一个类对象,从JSON字符串中取出一个key 如 a,先大写化为A,那么从所有Set方法中找到 SetA(),然后进行赋值。 如果找不到 setA (seta也不行),那么该值被忽略,也不报错。
Jackson 的原理和FastJson一致,但是在 JSON to Java pojo的步骤中,做了更加科学的check,因而能识别seta这样的小写。但是如果getA 和geta都找不到,则会抛出异常(除非把a设置为忽略)。
其他的步骤原理和FastJSON类似。
测试验证代码:
[java] view plaincopy在CODE上查看代码片派生到我的代码片
- package jar;
- import com.alibaba.fastjson.JSON;
- public class Test{
- private int aaa=0;
- private String bbb = "000";
- public Test() {
- // TODO Auto-generated constructor stub
- aaa = 1;
- bbb = "111";
- System.out.println(" default construct function is called!!!");
- }
- public Test(int a,String b) {
- // TODO Auto-generated constructor stub
- aaa = a;
- bbb = b;
- System.out.println("construct 2 function is called!!!");
- }
- public int getA() {
- return aaa;
- }
- public void seta(int a)
- {
- this.aaa =a;
- }
- public String getB() {
- return bbb;
- }
- //test
- public static void main(String[] args) throws Exception
- {
- Test test =new Test(2,"222");
- String code = JSON.toJSONString(test);
- System.out.println(code);
- Test reverse = JSON.parSEObject(code,Test.class);
- System.out.println(reverse.getA());
- System.out.println(reverse.getB());
- }
- }
下面是对 FastJson 和 Jackson (pojo to json-编码) 以及 (json to pojo-解码)以及综合(编码+解码) 在不同成员数量 下 ,不同循环次数的耗时(ns纳秒)对比。
[java] view plaincopy在CODE上查看代码片派生到我的代码片
- // code + decode -----------------------------------------------------
- // 10000 - 23 members
- // Jackson :235750737 ns
- // FastJSON:347795550 ns
- // 10000 - 2 members
- // Jackson :164173126 ns
- // FastJSON:159078284 ns
- // 100000 - 23 members
- // Jackson :1004902734 ns
- // FastJSON:1689072614 ns
- // 100000 - 2 members
- // Jackson :392344461 ns
- // FastJSON:299521240 ns
- // 1000000 - 23 members
- // Jackson :8547741285 ns
- // FastJSON:15377369425 ns
- // 1000000 - 2 members
- // Jackson :2581267623 ns
- // FastJSON:1591827729 ns
- // code only -------------------------------------------------------
- // 10000 - 23 members
- // Jackson :115036100 ns
- // FastJSON:158681243 ns
- // 10000 - 2 members
- // Jackson :87886170 ns
- // FastJSON:103086025 ns
- // 100000 - 23 members
- // Jackson :417539325 ns
- // FastJSON:349358062 ns
- // 100000 - 2 members
- // Jackson :185865488 ns
- // FastJSON:144893485 ns
- // 1000000 - 23 members
- // Jackson :3384171740 ns
- // FastJSON:2200190119 ns
- // 1000000 - 2 members
- // Jackson :1193815955 ns
- // FastJSON:568776506 ns
- // decode only -------------------------------------------------------
- // 10000 - 23 members
- // Jackson :122597862 ns
- // FastJSON:183567261 ns
- // 10000 - 2 members
- // Jackson :75418145 ns
- // FastJSON:47832689 ns
- // 100000 - 23 members
- // Jackson :497670344 ns
- // FastJSON:1254994458 ns
- // 100000 - 2 members
- // Jackson :165368101 ns
- // FastJSON:117555618 ns
- // 1000000 - 23 members
- // Jackson :4189147981 ns
- // FastJSON:12004873228 ns
- // 1000000 - 2 members
- // Jackson :999578584 ns
- // FastJSON:863444723 ns
结论:
编码(pojo to json): 当循环数量较小时,FastJSON的性能 低于 JackSON;
解码( json to pojo):当成员数量越大时,FastJSON的相对性能越差,JackSON的相对性能则越好;
综合(编码+解码): 当成员变量数量越大时,Jackson 获胜。无关于循环数量。
当成员变量数量越小时,FastJSON获胜。
一般情况下,系统中的循环数量一般不会大的惊人,应该是偏小的。而成员变量变多,是一个企业级系统常见的情况。
SO, who is the most fast or best? 我就不点出了。
。。。
Whatever, 两个JSON框架都是很棒的。而且本人很喜欢FastJSON的易用性,干净。
有时间,有兴趣的可以继续研究研究FastJSON在多成员变量解码时的劣势是什么原因导致的。
付上测试代码:
[java] view plaincopy在CODE上查看代码片派生到我的代码片
- package jar;
- import java.io.StringWriter;
- import org.codehaus.jackson.JsonEncoding;
- import org.codehaus.jackson.JsonGenerator;
- import org.codehaus.jackson.map.ObjectMapper;
- import com.alibaba.fastjson.JSON;
- public class Test{
- private int aaa=0;
- private String bbb = "000";
- private String c1 = "000";
- private String c2 = "000";
- private String c3 = "000";
- private String c4 = "000";
- private String c5 = "000";
- private String c6 = "000";
- private String c7 = "000";
- private String c8 = "000";
- private String c9 = "000";
- private String c10 = "000";
- private String c11 = "000";
- private String c12 = "000";
- private String c13 = "000";
- private String c14 = "000";
- private String c15 = "000";
- private String c16 = "000";
- private String c17 = "000";
- private String c18 = "000";
- private String c19 = "000";
- private String c20 = "000";
- private String c21 = "000";
- public Test()
- {
- }
- public Test(int a,String b) {
- // TODO Auto-generated constructor stub
- aaa = a;
- bbb = b;
- //System.out.println("construct 2 function is called!!!");
- }
- public int getA() {
- return aaa;
- }
- public void setA(int a)
- {
- this.aaa = a;
- }
- public String getB() {
- return bbb;
- }
- public void setB(String b) {
- this.bbb = b;
- }
- public String getC1() {
- return c1;
- }
- public void setC1(String c1) {
- this.c1 = c1;
- }
- public String getC2() {
- return c2;
- }
- public void setC2(String c2) {
- this.c2 = c2;
- }
- public String getC3() {
- return c3;
- }
- public void setC3(String c3) {
- this.c3 = c3;
- }
- public String getC4() {
- return c4;
- }
- public void setC4(String c4) {
- this.c4 = c4;
- }
- public String getC5() {
- return c5;
- }
- public void setC5(String c5) {
- this.c5 = c5;
- }
- public String getC6() {
- return c6;
- }
- public void setC6(String c6) {
- this.c6 = c6;
- }
- public String getC7() {
- return c7;
- }
- public void setC7(String c7) {
- this.c7 = c7;
- }
- public String getC8() {
- return c8;
- }
- public void setC8(String c8) {
- this.c8 = c8;
- }
- public String getC9() {
- return c9;
- }
- public void setC9(String c9) {
- this.c9 = c9;
- }
- public String getC10() {
- return c10;
- }
- public void setC10(String c10) {
- this.c10 = c10;
- }
- public String getC11() {
- return c11;
- }
- public void setC11(String c11) {
- this.c11 = c11;
- }
- public String getC12() {
- return c12;
- }
- public void setC12(String c12) {
- this.c12 = c12;
- }
- public String getC13() {
- return c13;
- }
- public void setC13(String c13) {
- this.c13 = c13;
- }
- public String getC14() {
- return c14;
- }
- public void setC14(String c14) {
- this.c14 = c14;
- }
- public String getC15() {
- return c15;
- }
- public void setC15(String c15) {
- this.c15 = c15;
- }
- public String getC16() {
- return c16;
- }
- public void setC16(String c16) {
- this.c16 = c16;
- }
- public String getC17() {
- return c17;
- }
- public void setC17(String c17) {
- this.c17 = c17;
- }
- public String getC18() {
- return c18;
- }
- public void setC18(String c18) {
- this.c18 = c18;
- }
- public String getC19() {
- return c19;
- }
- public void setC19(String c19) {
- this.c19 = c19;
- }
- public String getC20() {
- return c20;
- }
- public void setC20(String c20) {
- this.c20 = c20;
- }
- public String getC21() {
- return c21;
- }
- public void setC21(String c21) {
- this.c21 = c21;
- }
- //test
- /**
- * @param args
- * @throws Exception
- */
- public static void main(String[] args) throws Exception
- {
- Test test =new Test(2,"222");
- //JackJSON 初始化
- ObjectMapper objectMapper = new ObjectMapper();
- long startTime=0; //获取开始时间
- long endTime=0; //获取结束时间
- int loopCount =100000;
- // code + decode -----------------------------------------------------
- // 10000 - 23 members
- // Jackson :235750737 ns
- // FastJSON:347795550 ns
- // 10000 - 2 members
- // Jackson :164173126 ns
- // FastJSON:159078284 ns
- // 100000 - 23 members
- // Jackson :1004902734 ns
- // FastJSON:1689072614 ns
- // 100000 - 2 members
- // Jackson :392344461 ns
- // FastJSON:299521240 ns
- // 1000000 - 23 members
- // Jackson :8547741285 ns
- // FastJSON:15377369425 ns
- // 1000000 - 2 members
- // Jackson :2581267623 ns
- // FastJSON:1591827729 ns
- // code only -------------------------------------------------------
- // 10000 - 23 members
- // Jackson :115036100 ns
- // FastJSON:158681243 ns
- // 10000 - 2 members
- // Jackson :87886170 ns
- // FastJSON:103086025 ns
- // 100000 - 23 members
- // Jackson :417539325 ns
- // FastJSON:349358062 ns
- // 100000 - 2 members
- // Jackson :185865488 ns
- // FastJSON:144893485 ns
- // 1000000 - 23 members
- // Jackson :3384171740 ns
- // FastJSON:2200190119 ns
- // 1000000 - 2 members
- // Jackson :1193815955 ns
- // FastJSON:568776506 ns
- // decode only -------------------------------------------------------
- // 10000 - 23 members
- // Jackson :122597862 ns
- // FastJSON:183567261 ns
- // 10000 - 2 members
- // Jackson :75418145 ns
- // FastJSON:47832689 ns
- // 100000 - 23 members
- // Jackson :497670344 ns
- // FastJSON:1254994458 ns
- // 100000 - 2 members
- // Jackson :165368101 ns
- // FastJSON:117555618 ns
- // 1000000 - 23 members
- // Jackson :4189147981 ns
- // FastJSON:12004873228 ns
- // 1000000 - 2 members
- // Jackson :999578584 ns
- // FastJSON:863444723 ns
- //Jackson
- startTime = System.nanoTime();
- for(int i=0;i<loopCount;i++)
- {
- StringWriter sw = new StringWriter();
- JsonGenerator jsonGenerator = objectMapper.getJsonFactory().createJsonGenerator(sw);
- jsonGenerator.writeObject(test);
- String result = sw.toString();
- // Test acc = objectMapper.readValue(result,Test.class);
- }
- endTime = System.nanoTime();
- System.out.println("Jackson :"+(endTime-startTime)+" ns");
- startTime = System.nanoTime();
- //FastJSON
- for(int i=0;i<loopCount;i++)
- {
- String code = JSON.toJSONString(test);
- // Test reverse = JSON.parSEObject(code,Test.class);
- }
- endTime = System.nanoTime();
- System.out.println("FastJSON:"+(endTime-startTime)+" ns");
- }
- }