Java对象到JSON对象转换中的性能问题

Question

我正在寻找更好的性能（转换时间应该非常少）。

本文显示的是来自这个答案的不同API之间的性能统计。

例如，我的发现是我提到的第一个链接（只有很少的记录）：

        ValueData object = new ValueData();
        List<ValueItems> information = new ArrayList<ValueItems>();

        ValueItems v1 = new ValueItems(String.valueOf(Calendar.getInstance().getTimeInMillis()), "feat1", 1, "data1");
        ValueItems v2 = new ValueItems(String.valueOf(Calendar.getInstance().getTimeInMillis()), "feat2", 2, "data2");
        ValueItems v3 = new ValueItems(String.valueOf(Calendar.getInstance().getTimeInMillis()), "feat3", 3, "data3");
        ValueItems v4 = new ValueItems(String.valueOf(Calendar.getInstance().getTimeInMillis()), "feat4", 4, "data4");
        ValueItems v5 = new ValueItems(String.valueOf(Calendar.getInstance().getTimeInMillis()), "feat5", 5, "data5");
        ValueItems v6 = new ValueItems(String.valueOf(Calendar.getInstance().getTimeInMillis()), "feat6", 6, "data6");
        ValueItems v7 = new ValueItems(String.valueOf(Calendar.getInstance().getTimeInMillis()), "feat7", 7, "data7");

        information.add(v1);
        information.add(v2);
        information.add(v3);
        information.add(v4);
        information.add(v5);
        information.add(v6);
        information.add(v7);

        object.setInformation(information);

    long smili = Calendar.getInstance().getTimeInMillis();

    ObjectWriter ow = new      ObjectMapper().writer().withDefaultPrettyPrinter();
    String json = ow.writeValueAsString(object);
    long emili = Calendar.getInstance().getTimeInMillis();
    System.out.println("taken time using jackson = " + (emili - smili) + " milli seconds");

    smili = Calendar.getInstance().getTimeInMillis();
    StringBuilder sb = new StringBuilder();
    sb.append("{\n\"information\" : [\n");

        for (ValueItems vi : object.getInformation()) {
            sb.append("{\n\"timestamp\" : \""+vi.getTimestamp()+"\",");
            sb.append("\"feature\" : \""+vi.getFeature()+"\",");
            sb.append("\"ean\" : "+vi.getEan()+",");
            sb.append("\"data\" : \""+vi.getData()+"\"\n},");               
        }

        sb.deleteCharAt(sb.length() - 1);
        sb.append("]\n}");
     emili = Calendar.getInstance().getTimeInMillis();
     System.out.println("taken time using StringBuilder = " + (emili - smili) + " milli seconds");

taken time using jackson = 534 milli seconds
taken time using StringBuilder = 1 milli seconds

null

请帮帮我。

Answer 1

谢谢Sam B。

我试过和雅克森-加力：

ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new AfterburnerModule());
ow = mapper.writer().withDefaultPrettyPrinter();
json = ow.writeValueAsString(object);

并且我测试了列表大小为7、7000、70000和700000：

taken time using jackson = 217 milli seconds
taken time using StringBuilder = 1 milli seconds
taken time using after-burner = 25 milli seconds

taken time using jackson = 310 milli seconds
taken time using StringBuilder = 31 milli seconds
taken time using after-burner = 65 milli seconds

taken time using jackson = 469 milli seconds
taken time using StringBuilder = 149 milli seconds
taken time using after-burner = 101 milli seconds

taken time using jackson = 1120 milli seconds
taken time using StringBuilder = 705 milli seconds
taken time using after-burner = 623 milli seconds