fastJson将对象序列化成json字符串

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.60</version>
        </dependency>

JSON_OBJ_STR = "{"studentName":"lily","studentAge":12}";
JSON_ARRAY_STR = "[{"studentName":"lily","studentAge":12},{"studentName":"lucy","studentAge":15}]";

COMPLEX_JSON_STR="{"teacherName":"crystall","teacherAge":27,"course":{"courseName":"english","code":1270},"students":[{"studentName":"lily","studentAge":12},{"studentName":"lucy","studentAge":15}]}";

字符串转json对象：JSONObject jsonObject = JSON.parseObject(JSON_OBJ_STR);

字符串转json数组：JSONArray jsonArray = JSON.parseArray(JSON_ARRAY_STR);

字符串转复杂json对象（嵌套）：JSONObject jsonObject = JSON.parseObject(COMPLEX_JSON_STR);

获取嵌套里面的对象：JSONObject innerObject = jsonObject.getJSONObject("xxx");

json字符串转javaBean：Student student = JSON.parseObject(JSON_OBJ_STR, new TypeReference<Student>() {});

复杂对象同上一样转；

javaBean 转json字符串：String bookjson = JSONObject.toJSONString(book, SerializerFeature.WriteNullStringAsEmpty, SerializerFeature.WriteNullBooleanAsFalse)；

上面的SerializerFeature有好多枚举类型，上面的是null值写成“”，还有空值不写进字符串的

SerializerFeature.NotWriteDefaultValue,比如studentName为空的时候，序列化成json字符串就是{"studentAge":"21"},没有sthdentName