Manual tutorial FastJson
/ Fastjson BeanToArray
Fastjson BeanToArray
在fastjson中，支持一种叫做BeanToArray的映射模式。普通模式下，JavaBean映射成json object，BeanToArray模式映射为json array。
Sample 1
class Mode {
public int id;
public int name;
}
Model model = new Model();
model.id = 1001;
model.name = "gaotie";
// {"id":1001,"name":"gaotie"}
String text_normal = JSON.toJSONString(model);
// [1001,"gaotie"]
String text_beanToArray = JSON.toJSONString(model, SerializerFeature.BeanToArray);
// support beanToArray & normal mode
JSON.parseObject(text_beanToArray, Feature.SupportArrayToBean);上面的例子中，BeanToArray模式下，少了Key的输出，节省了空间，json字符串较小，性能也会更好。
Sample 2
BeanToArray可以局部使用，比如：
class Company {
public int code;
public List<Department> departments = new ArrayList<Department>();
}
@JSONType(serialzeFeatures=SerializerFeature.BeanToArray, parseFeatures=Feature.SupportArrayToBean)
class Department {
public int id;
public Stirng name;
public Department() {}
public Department(int id, String name) {this.id = id; this.name = name;}
}
Company company = new Company();
company.code = 100;
company.departments.add(new Department(1001, "Sales"));
company.departments.add(new Department(1002, "Financial"));
// {"code":10,"departments":[[1001,"Sales"],[1002,"Financial"]]}
String text = JSON.toJSONString(commpany);在这个例子中，如果Company的属性departments元素很多，局部采用BeanToArray就可以获得很好的性能，而整体又能够获得较好的可读性。
Sample 3
上一个例子也可以这样写：
class Company {
public int code;
@JSONField(serialzeFeatures=SerializerFeature.BeanToArray, parseFeatures=Feature.SupportArrayToBean)
public List<Department> departments = new ArrayList<Department>();
}性能
使用BeanToArray模式，可以获得媲美protobuf的性能。
create ser deser total size +dfl protobuf 244 2297 1296 3593 239 149 json/fastjson_array/databind 123 1289 1567 2856 281 163 msgpack/databind 122 1525 2180 3705 233 146 json/fastjson/databind 120 2019 2610 4629 486 262 json/jackson+afterburner/databind 118 2142 3147 5289 485 261 json/jackson/databind 124 2914 4411 7326 485 261
这里的json/fastjson_array/databind就是fastjson启用BeanToArray模式，total性能比protobuf好，请看fastjson Benchmark