利用帮助类和内部类简化JSON处理

在处理 JSON 的过程中， 往往要面对着解析和转换 ，异常处理的问题 。

普通的处理流程 ：

 

        HttpClient client = new HttpClient();
        String strUrl = CommonConstant.getBatchShowAssociationURL() + parm;
        PostMethod method = new PostMethod(strUrl);
        List<AssociationVO> associationList = new ArrayList<AssociationVO>();
        try {
            client.executeMethod(method);
        } catch (HttpException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
        String returnJson = "";
        try {
            returnJson = method.getResponseBodyAsString();// 返回json字符串值
            String strJson = returnJson.replace("?(", "").replace(")", "").replace(";", "");
            if (strJson.startsWith("{")) {
                JSONObject jsonObject = JSONObject.fromObject(strJson);
                String code = jsonObject.getString("code").toString();
                if ("200".equals(code)) {
                    JSONArray jsonArray = JSONArray.fromObject(jsonObject.get("result"));
                    for (int i = 0, len = jsonArray.size(); i < len; i++) {
                        AssociationVO vo = new AssociationVO();
                        JSONObject jsonClub = jsonArray.getJSONObject(i);
                        vo.setId(Long.valueOf(jsonClub.get("id").toString()));
                        associationList.add(vo);
                    }
                }
            }
        } catch (Exception e1) {
            e1.printStackTrace();
        } finally {
            // 使用完成后要释放链接
            method.releaseConnection();
        }

 

这样的处理每次都要定义 处理方法， 负责打开和关闭流 ，

 

如果处理的是规则的接口，返回的数据都是相对固定的字段，可以考虑

利用自己定义的帮助类和接口实现的内部类，能够极大简化， 可以直接得到类。

 

 首先是远程接口类， 调用得到JSON字串。。

 

public class RemoteRepositoryImpl implements RemoteRepository {


	public String executePost(String url, Entity...requestBody) throws RemoteException {
		PostMethod method = getPostMethod(url);
		if (requestBody!=null && requestBody.length>0) {
			method.setRequestBody(requestBody);
		}
		return execute(method);
	}


	protected PostMethod getPostMethod(String url) {
		PostMethod method = new PostMethod(url);
		method.getParams().setParameter(HttpMethodParams.SO_TIMEOUT, 5000); //设置 post 方法请求超时为 15 秒
		method.setRequestHeader("Content-Type", "application/x-www-form-urlencoded;charset=utf-8");
		return method;
	}



	public String execute(HttpMethodBase httpMethod) throws RemoteException {
		HttpClient client = new HttpClient();
		client.getHttpConnectionManager().getParams().setConnectionTimeout(5000);//设置 http 连接超时为 10 秒
		String url = "";
		long logT1 = System.currentTimeMillis();
		try {
			url = "" + httpMethod.getURI();
			int sc = client.executeMethod(httpMethod);
            if (sc != HttpStatus.SC_OK && sc!=HttpStatus.SC_CREATED && sc!=HttpStatus.SC_ACCEPTED) {
                throw new RemoteException("remote service ERROR! methodstatus=[" + sc + "]" + url, "HttpStatus");
            }
            return httpMethod.getResponseBodyAsString();
		} catch (URIException e) {
			throw new RemoteException("URIException remote service ERROR!" + url, "URIException", e);
		} catch (HttpException e) {
			throw new RemoteException("HttpException remote service ERROR!" + url, "HttpException", e);
		} catch (IOException e) {
			throw new RemoteException("IOException remote service ERROR!" + url, "IOException", e);
		} catch (RuntimeException e) {
			throw new RemoteException("RuntimeException","RuntimeException" , e);
		} finally {
			httpMethod.releaseConnection();
			long logT2 = System.currentTimeMillis();
			if (logger.isInfoEnabled()) {
				logger.info("Remote Time " + (logT2 - logT1) + " millisecounds:" + url);
			}
		}	
	}

}

 

在得到结果之后， 把返回字符串放到 JSON 包装类对象中去。 

 

public class JSONWrapper {

	protected JSONObject root;
	private String json;
	/**
	 * 构造
	 * @param json
	 */
	public JSONWrapper(String json) {
		json = json.replaceAll("\\n", "");
		this.json = json;
		String validJson = (json);
		if (validJson!=null) {
		    root = (JSONObject) JSONSerializer.toJSON((json));
		}else {
		    root = new JSONObject(true);
		}
	}

   private JSONWrapper(JSONObject json) {
       this.json = "";
        root = json;
    }
	/**
	 * 静态工厂
	 * @param json
	 * @return
	 */
	public static JSONWrapper valueOf(String json) {
		return new JSONWrapper(json);
	}


    private static <E> List<E> getJavaList(Object bean, String path,  ToJava<E> tojava){
		Object p = getProperty(bean, path);
		if (p==null) {
			return Collections.emptyList();
		}
		if (!(p instanceof JSON)) {// TODO trycache
			return Collections.emptyList();
//			throw new RuntimeException("path 路径错误，请检查:[" + p + "]不是一个JSON对象");
		}
		JSON jo = (JSON) p;
		List<E> res = new ArrayList<E>(jo.size());
		Collection arr = (jo instanceof JSONObject) ? ((JSONObject) jo).values() : (JSONArray) jo;
		JSONWrapper subWrapper = new JSONWrapper((JSONObject)null);
		for (Object obj : arr) {
			if (!(obj instanceof JSONObject)) {
			    logger.error("path 路径错误，请检查:[" + obj + "]不是一个JsonObject对象");
			    continue;
				//throw new RemoteException("path 路径错误，请检查:[" + obj + "]不是一个JsonObject对象", "json");
			}
			if (((JSONObject) obj).isNullObject()) {
				continue;
			}
			try {
			    subWrapper.root = (JSONObject) obj;
                E o = tojava.toJava(subWrapper);
                if (o!=null) {
                	res.add(o);
                }
            } catch (RuntimeException e) {
                logger.error("取tojava异常");
                //throw new RemoteException("取tojava异常", "json", e);
            }
		}
		return res;
	}


	//根据路径得到 JSON 对象
	private static Object getProperty(Object jo, String path) {
		if (StringUtils.hasText(path)) {
			for (String prop : path.split("\\.")) {
				if (jo==null) {
					return null;
				}
				if (jo instanceof JSONObject) {
					jo = getJSONObject((JSONObject) jo, prop);
				}
			}	
		}
		return jo;
	}


 	protected static Object getJSONObject(JSONObject jo, String propName) {
  	                return jo!=null && !jo.isNullObject()? jo.get(propName) : null;
 	}


}

 

 通用的接口类 ：

 

public interface ToJava<E>{
	E toJava(JSONWrapper wrapper);
}

 

这样，就可以使用内部类来得到JSON中的数据了

 

public class BusinessCircleServiceImpl implements BusinessCircleService {



    protected ToAssociationVO toAssociationVO = new ToAssociationVO();

    //内部实现类
    protected static class ToAssociationVO implements ToJava<AssociationVO> {
        public AssociationVO toJava(JSONWrapper wrapper) {
            AssociationVO vo = new AssociationVO();
            vo.setId(wrapper.getLong("id", null));
            vo.setTimeCreated(DateTimeUtils.formatPageDate(DateTimeUtils.parseFullDateTime(DateUtil
                    .getDateTimeByMillisecond(wrapper.getString("timeCreated", null)))));
            return vo;
        }
    }



    public List<AssociationVO> getRecommandList(int type, PaginationDto paginationDto) {

     ..................................
        //调用代码：

          try {
           String strJson = remoteRepository.executeGet(CommonConstant.getBatchShowAssociationURL() + ids);
           return JSONWrapper.valueOf(strJson).getJavaList("result", toAssociationVO);
          } catch (RemoteException e) {
           log.error("远程服务出错:" + CommonConstant.getBatchShowAssociationURL() + ids, e);
           return Collections.EMPTY_LIST;
          }






    }



  
}

 

 

 

评论

1 楼 Jason(aijun) 2011-05-09  

写的很好，怎么没有评论。吴总...................