针对进行补充，上一篇中，要在action中拼接JSON格式字符串，很容易手抖。直接用json处理一下转成json格式字符串即可。但之前也讲过，json对于hibernate级联关系的解析，不是很到位啊！

所以ajax那边就得层层循环剥离，找出想要的结果

action：

用的是

import com.alibaba.fastjson.JSON;

具体的jar包请自行百度！！

public String getStreets(){        StreetDao streetDao=new StreetDaoImpl();        try {            streetlist = streetDao.getStreetsByDistrictId(Integer.parseInt(district_id));            /*System.out.println("district_id=="+district_id);            System.out.println(streetlist.size());*/            String content = JSON.toJSONString(streetlist);            /*ObjectMapper mapper = new ObjectMapper();            String content = mapper.writeValueAsString(streetlist);*/            HttpServletResponse response = (HttpServletResponse) ActionContext.getContext().get(ServletActionContext.HTTP_RESPONSE);              response.setCharacterEncoding("utf-8");            System.out.println("array======="+content);            response.getWriter().print(content);         } catch (Exception e) {            e.printStackTrace();        }        return null;    }

action只是小小的改动，但语法简单了很多。

出来的json结果是：

array=======[{"district":{"id":1,"name":"天河区","streets":[{"district":{"$ref":"$[0].district"},"id":4,"name":"天河区街道4"},{"district":{"$ref":"$[0].district"},"id":2,"name":"天河区街道2"},{"$ref":"$[0]"},{"district":{"$ref":"$[0].district"},"id":3,"name":"天河区街道3"}]},"id":1,"name":"天河区街道1"},{"$ref":"$[0].district.streets[1]"},{"$ref":"$[0].district.streets[3]"},{"$ref":"$[0].district.streets[0]"}]

看上去真是头疼，即使json格式清晰要想取streets的id和name也不很规律啊，我用了firefox的hj插件JSON-Handle格式化了一下控制台的json字符串

[    {        "district": {            "id": 1,            "name": "天河区",            "streets": [                {                    "district": {                        "$ref": "$[0].district"                    },                    "id": 4,                    "name": "天河区街道4"                },                {                    "district": {                        "$ref": "$[0].district"                    },                    "id": 2,                    "name": "天河区街道2"                },                {                    "$ref": "$[0]"                },                {                    "district": {                        "$ref": "$[0].district"                    },                    "id": 3,                    "name": "天河区街道3"                }            ]        },        "id": 1,        "name": "天河区街道1"    },    {        "$ref": "$[0].district.streets[1]"    },    {        "$ref": "$[0].district.streets[3]"    },    {        "$ref": "$[0].district.streets[0]"    }]

那么ajax怎么获取街道呢？

好吧，我也是一点点试的！不行就每一步alert呗！