Java JSON转成List结构数据

ObjectMapper mapper = new ObjectMapper();
 JavaType javaType = mapper.getTypeFactory().constructParametricType(List.class, ApprWritUnionFormModel.class);
 /*List<FormModel> writUnionFormList = 
  JSON.parseArray(params, FormModel.class);*/
 List<FormModel> writUnionFormList=new ArrayList<FormModel>();
 try {
  writUnionFormList = (List<FormModel>)mapper.readValue(params, javaType);
 } catch (JsonParseException e) {
  e.printStackTrace();
 } catch (JsonMappingException e) {
  e.printStackTrace();
 } catch (IOException e) {
  e.printStackTrace();
 }

List<FormModel> writUnionFormList = 
  JSON.parseArray(params, FormModel.class);