今天遇到一个问题,前端ajax获取到一个javaBean对象,好多方法发ajax请求需要把这个对象再传到后端,后端再根据这个对象进行操作(之前计划传递id,但发现传递id的话,后端多个方法都需要根据id查询数据库获取这个javaBean,因此就修改为直接传递javaBean),这就涉及到了json字符串与java对象转化,特此记录一下。大概有两种方式比较方便:
一、Gson的方式
二、json-lib的方式
1.前端jquery把对象转为json字符串
"dclLine":JSON.stringify(selectedDclLine);
2.后端Gson转java对象
/** * * @return */ @RequestMapping("/getDayCharge") @ResponseBody public List<Object> getDayCharge(HttpServletRequest request){ Map<String, Object> params = new HashMap<String, Object>(16); //前端左侧树回路信息 String dclLineStr = request.getParameter("dclLine"); Gson gson = new Gson(); //Gson转换json字符串到java对象 DclLine dclLine = gson.fromJson(dclLineStr, DclLine.class); params.put("dclLine", dclLine); List<Object> result = runningReportsService.getDayCharge(params); return result; }
转换过程报错:
threw exception [Request processing failed; nested exception is
com.google.gson.JsonSyntaxException: java.lang.NumberFormatException: empty String] with root cause
比较了下json数据与javaBean的类型发现javaBean定义的类型是Double,json数据是"",类型转换报错了
把javaBean中的Double类型改为String类型后,转换成功
但是改javaBean类型涉及改动太大,
在不改变javaBean类型的情况下,试着用json-lib转换了下,发现json-lib转换不报错
3.后端使用json-lib把json字符串转为java对象
/** * 日用电负荷 * @return */ @RequestMapping("/getDayCharge") @ResponseBody public List<Object> getDayCharge(HttpServletRequest request){ Map<String, Object> params = new HashMap<String, Object>(16); //前端左侧树回路信息 String dclLineStr = request.getParameter("dclLine"); JSONObject json = JSONObject.fromObject(dclLineStr); DclLine dclLine = (DclLine) JSONObject.toBean(json, DclLine.class); params.put("dclLine", dclLine); List<Object> result = runningReportsService.getDayCharge(params); return result; }
4.pom配置:
<dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-lang3</artifactId> <version>3.7</version> </dependency> <dependency> <groupId>com.google.code.gson</groupId> <artifactId>gson</artifactId> </dependency> <dependency> <groupId>net.sf.json-lib</groupId> <artifactId>json-lib</artifactId> <version>2.2.3</version> <classifier>jdk15</classifier> </dependency>
5.总结:
Gson:
String dclLineStr = request.getParameter("dclLine");//获取到json字符串 Gson gson = new Gson();//com.google.gson.Gson //Gson转换json字符串到java对象 DclLine dclLine = gson.fromJson(dclLineStr, DclLine.class);
json-lib:
String dclLineStr = request.getParameter("dclLine");//获取到json字符串 JSONObject json = JSONObject.fromObject(dclLineStr);//net.sf.json.JSONObject DclLine dclLine = (DclLine) JSONObject.toBean(json, DclLine.class);
6.参考博客:
https://blog.csdn.net/chenbin520/article/details/8776915
https://www.cnblogs.com/echo-ling/p/8097698.html