JsonEncapForMultilayer

一个用于将多层结构的数据封装成Json字符串的Demo.借助Gson实现。

使用场景：

需要多个层级展示，类似于树形结构。
比如菜单展示，第一层是一级菜单，一级菜单下面有二级菜单，二级下有三级菜单...
比如机构展示，第一层是省级机构，省级机构下有市级机构，市级下有区县...

类说明：

1.BaseModel

该类是所有Model的基类，需实现JsonEncapCondition接口。其中属性包括

private String id;    //当前Model的id
private String upId;  //上级id
private List<BaseModel> subModels;   //该Model下的子Model集合

重写了equals方法：

	@Override
public boolean equals(Object obj) {
	// TODO Auto-generated method stub
	return this.id.equals(((BaseModel) obj).getId());
}

2.JsonEncapCondition

该接口类只有一个方法：

public boolean condition();//用于设置判断顶级Model的条件

3.JsonEncap

该类封装了将List集合转换为Json字符串的方法。 其中关键代码是是toJson()方法

private List<? extends BaseModel> modelList;
public JsonEncap(List<? extends BaseModel> modelList) {
	super();
	this.modelList = modelList;
}
public String toJson() {
	List<BaseModel> removeModels = new ArrayList<BaseModel>();
	for (int i = 0; i < modelList.size(); i++) {
		BaseModel tempModel = modelList.get(i);

		// 如果是一级Model，则不处理
		if (tempModel.condition())
			continue;
		// 找到上级Model
		String upIndexId = tempModel.getUpId();
		BaseModel upTempBaseMode = new BaseModel(upIndexId);
		BaseModel upModel = modelList
				.get(modelList.indexOf(upTempBaseMode));

		// 获取上级Model下的下级Model集合
		List<BaseModel> subBaseModels = upModel.getSubModels();
		if (subBaseModels == null) {
			subBaseModels = new ArrayList<BaseModel>();
		}
		// 将当前Model添加到下级Model中
		subBaseModels.add(tempModel);
		upModel.setSubModels(subBaseModels);
		// 处理完的Model添加到需要移除的Model集合中
		removeModels.add(tempModel);
	}
	// 移除之前保存的Model
	for (BaseModel i : removeModels) {
		modelList.remove(i);
	}

	// 使用Gson 将List转换为json String
	Gson gson = new Gson();
	String jsonString = gson.toJson(modelList);
	return jsonString;
}

使用方法：

1. 创建的Model继承BaseModel.
2. 实现JsonEncapCondition接口，实现condition方法。
3. 创建JsonEncap，调用toJson()方法生成Json 字符串

测试用例：

  Organize orgInfo;
	// 生成测试数据
	List<Organize> lists = new ArrayList<Organize>();
	// 添加一级Model
	for (int i = 1; i < 4; i++) {
		orgInfo = new Organize("00" + i, "机构A00" + i, "00" + i);
		lists.add(orgInfo);
	}
	// 添加二级Model
	for (int i = 1; i < 4; i++) {
		orgInfo = new Organize("00100" + i, "机构A00100" + i, "001");
		lists.add(orgInfo);
		orgInfo = new Organize("00200" + i, "机构A00200" + i, "002");
		lists.add(orgInfo);
		orgInfo = new Organize("00300" + i, "机构A00300" + i, "003");
		lists.add(orgInfo);
	}
	// 添加三级Model
	for (int i = 1; i < 4; i++) {
		orgInfo = new Organize("00100200" + i, "机构A00100200" + i, "001002");
		lists.add(orgInfo);
		orgInfo = new Organize("00100300" + i, "机构A00100300" + i, "001003");
		lists.add(orgInfo);
		orgInfo = new Organize("00200100" + i, "机构A00200100" + i, "002001");
		lists.add(orgInfo);
	}

	JsonEncap jsonEncap = new JsonEncap(lists);

	String json = jsonEncap.toJson();
	System.out.println("json--->" + json);

json输出结果：

  [{"orgName":"机构A001","id":"001","upId":"001","subModels":[{"orgName":"机构A001001","id":"001001","upId":"001"},{"orgName":"机构A001002","id":"001002","upId":"001","subModels":[{"orgName":"机构A001002001","id":"001002001","upId":"001002"},{"orgName":"机构A001002002","id":"001002002","upId":"001002"},{"orgName":"机构A001002003","id":"001002003","upId":"001002"}]},{"orgName":"机构A001003","id":"001003","upId":"001","subModels":[{"orgName":"机构A001003001","id":"001003001","upId":"001003"},{"orgName":"机构A001003002","id":"001003002","upId":"001003"},{"orgName":"机构A001003003","id":"001003003","upId":"001003"}]}]},{"orgName":"机构A002","id":"002","upId":"002","subModels":[{"orgName":"机构A002001","id":"002001","upId":"002","subModels":[{"orgName":"机构A002001001","id":"002001001","upId":"002001"},{"orgName":"机构A002001002","id":"002001002","upId":"002001"},{"orgName":"机构A002001003","id":"002001003","upId":"002001"}]},{"orgName":"机构A002002","id":"002002","upId":"002"},{"orgName":"机构A002003","id":"002003","upId":"002"}]},{"orgName":"机构A003","id":"003","upId":"003","subModels":[{"orgName":"机构A003001","id":"003001","upId":"003"},{"orgName":"机构A003002","id":"003002","upId":"003"},{"orgName":"机构A003003","id":"003003","upId":"003"}]}]