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分享Android 如何在JSON和list之间进行转化
本人Android 小白一枚， 最近在开发的时候遇到个问题：如何把对象的List类型数据保存成JSON然后从JSON中加载数据。PS:此对象还有其他类型的属性，也需要保存。
代码如下:
public class Project {
private static final String JSON_Name = "projectName";
private static final String JSON_ID = "projectID";
private static final String JSON_POINTS = "projectPoints";
private String projectName;
private UUID projectID;
private ArrayList<KnowPoint> knowPointArrayList;
public Project(String projectName){
projectID = UUID.randomUUID();
this.projectName = projectName;
this.knowPointArrayList = new ArrayList<>();
}
public Project(JSONObject jsonObject) throws JSONException{
projectID = UUID.fromString(jsonObject.getString(JSON_ID));
projectName = jsonObject.getString(JSON_Name);
//TODO
//从JSON数据中得到ArrayList
}
public JSONObject toJSON() throws JSONException{
JSONObject jsonObject = new JSONObject();
jsonObject.put(JSON_Name, projectName);
jsonObject.put(JSON_ID, projectID);
//TODO
//把ArrayList保存到JsonObject中
return jsonObject;
}
}
代码如下:
public class Project {
private static final String JSON_Name = "projectName";
private static final String JSON_ID = "projectID";
private static final String JSON_POINTS = "projectPoints";
private String projectName;
private UUID projectID;
private ArrayList<KnowPoint> knowPointArrayList;
public Project(String projectName){
projectID = UUID.randomUUID();
this.projectName = projectName;
this.knowPointArrayList = new ArrayList<>();
}
public Project(JSONObject jsonObject) throws JSONException{
projectID = UUID.fromString(jsonObject.getString(JSON_ID));
projectName = jsonObject.getString(JSON_Name);
//TODO
//从JSON数据中得到ArrayList
}
public JSONObject toJSON() throws JSONException{
JSONObject jsonObject = new JSONObject();
jsonObject.put(JSON_Name, projectName);
jsonObject.put(JSON_ID, projectID);
//TODO
//把ArrayList保存到JsonObject中
return jsonObject;
}
}
...全文
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梅明子 2016-12-17
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这是我的代码，直接拿过来给你参考一下，下面这个方法是把ArrayList数据转换成Json格式字符串的方法
/**
* 保存隐藏视频数据(先转换成json，再写入本地文件)
*
* @param list
*/
public static boolean setVideoHideJson(ArrayList<Video> list) {
if (list == null) {
return false;
}
L.i("JsonUtil", "保存的隐藏视频数据：" + list.toString());
try {
JSONArray array = new JSONArray();
for (Video ent : list) {
JSONObject object = new JSONObject();
object.put("_id", ent.getId());
object.put("name", ent.getName());
object.put("duration", ent.getDuration());
object.put("size", ent.getSize());
object.put("path", ent.getPath());
object.put("resolution", ent.getResolution());
object.put("datetaken", ent.getDatetaken());
object.put("bucketId", ent.getBucketId());
object.put("bucketName", ent.getBucketName());
object.put("width", ent.getWidth());
object.put("height", ent.getHeight());
array.put(object);
}
return HideFileUtil.saveVideoHideFile(array.toString());
} catch (JSONException e) {
e.printStackTrace();
return false;
}
}
/**
* 获取隐藏视频数据(先从本地文件获取json格式数据，再转换成ArrayList)
*
* @return
*/
public static ArrayList<Video> getVideoHideJson() {
String json = HideFileUtil.getVideoHideFile();
if (json == null) {
return null;
}
L.i("JsonUtil", "隐藏的JSON视频数据：" + json);
try {
ArrayList<Video> list = new ArrayList<Video>();
JSONArray array = new JSONArray(json);
for (int i = 0; i < array.length(); i++) {
JSONObject object = array.getJSONObject(i);
Video ent = new Video();
ent.setId(object.getInt("_id"));
if (object.has("name")) {
ent.setName(object.getString("name"));
}
ent.setDuration(object.getInt("duration"));
ent.setSize(object.getLong("size"));
if (object.has("path")) {
ent.setPath(object.getString("path"));
}
ent.setResolution(object.getLong("resolution"));
ent.setDatetaken(object.getLong("datetaken"));
ent.setBucketId(object.getInt("bucketId"));
if (object.has("bucketName")) {
ent.setBucketName(object.getString("bucketName"));
}
ent.setWidth(object.getInt("width"));
ent.setHeight(object.getInt("height"));
list.add(ent);
}
L.i("JsonUtil", "隐藏的LIST视频数据：" + list.toString());
return list;
} catch (JSONException e) {
e.printStackTrace();
return null;
}
}
R_ine 2016-12-16
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谢谢， 那请问 list 和arraylist之间怎么转化呢？[/quote]
2个不是一样吗。。。。
黄舒颖 咸丫蛋 2016-12-16
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百度搜索一下JSONObject和JSONArray的用法
ESC尛蜜蜂 2016-12-16
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Gson 可以看看
走菜 2016-12-15
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谢谢， 那请问 list 和arraylist之间怎么转化呢？
_周星星 2016-12-15
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public class JsonUtil {
static Gson gson = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().create();
public static String toJson(Object obj) {
return gson.toJson(obj);
}
public static Gson getGson() {
return gson;
}
/**
* 把json转换为列表
*
* @param json
* @param className
* @return
*/
public static ArrayList<BaseModel> getDomainList(String json, Class<? extends BaseModel> className) {
ArrayList<?> list = JsonUtil.getGson().fromJson(json,
new TypeToken<List<?>>() {
}.getType()
);
String jsonStr = null;
ArrayList<BaseModel> baseDomains = new ArrayList<BaseModel>();
BaseModel baseDomain = null;
for (int i = 0; i < list.size(); i++) {
jsonStr = JsonUtil.toJson(list.get(i));
baseDomain = JsonUtil.getGson().fromJson(jsonStr, className);
baseDomains.add(baseDomain);
}
return baseDomains;
}
public static BaseModel getDomain(String json, Class<? extends BaseModel> className) {
try {
BaseModel baseDomain = JsonUtil.getGson().fromJson(json, className);
return baseDomain;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}
_周星星 2016-12-15
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这个 不难吧 Gjson 把json转换为实体 实体转换为json
R_ine 2016-12-15
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=-=可以将josn转换为String类型，然后String类型和LIst直接转换。就是将list连接成String，然后String转换为list
/**
* 将list连接成字符串
*
* @param list
* @param joiner
* 连接字符
* @return
* @author c99999999 2015-6-27 下午3:08:00
* @param <T>
* @since v1.0
*/
public static <T> String join(List<T> list, String joiner) {
StringBuffer sb = new StringBuffer();
for (int i = 0; i < list.size(); i++) {
if (list.get(i) != null) {
sb.append(list.get(i).toString());
if (i < list.size() - 1) {
sb.append(joiner);
}
}
}
return sb.toString();
}
/**
* 将字符串转换为List
* @param 字符串
* @return List
*/
public static List getListString(String s)
{
String subS[] = s.split(",");
List list = Arrays.asList(subS);
return list;
}
