Android的JSON解析与GSON

问题描述

我特林使用映射从GSON一个URL到我的java类JSON数据。这是code作为类：

 公共类会话{
公共布尔活跃;
公共字符串contributor_covu_id;
公共字符串created_at;
公共字符串键;
公共字符串状态;公共布尔getActive（）{
    返回活跃;
}
公共无效SETACTIVE（布尔有效）{
    this.active =有效;
}
公共字符串getContributor_covu_id（）{
    返回contributor_covu_id;
}
公共无效setContributor_covu_id（字符串contributor_covu_id）{
    this.contributor_covu_id = contributor_covu_id;
}
公共字符串getCreated_at（）{
    返回created_at;
}
公共无效setCreated_at（字符串created_at）{
    this.created_at = created_at;
}
公共字符串getKey（）{
    返回键;
}
公共无效的setkey（字符串键）{
    this.key =键;
}
公共字符串的getStatus（）{
    返回状态;
}
公共无效setStatus（字符串状态）{
    this.status =状态;
}
公共字符串的getType（）{
    返回类型;
}
公共无效的setType（字符串类型）{
    this.type =类型;
}
公共字符串类型;
 

}

这是调用服务和地图JSON之类的code

 公共静态列表＆LT;会议＆GT; getSessions（字符串urlString）
        抛出IOException    会话[]会议;
    清单＆LT;会议＆GT; tempList = NULL;
    网址URL =新的URL（urlString）;
    HttpURLConnection的康恩=（HttpURLConnection类）url.openConnection（）;
    GsonBuilder gsonb =新GsonBuilder（）;
    GSON GSON = gsonb.create（）;
    StringBuilder的SB =新的StringBuilder（）;
    串线;    //响应响应= NULL;
    JSONObject的J = NULL;    如果（conn.getResponse code（）！= 200）{
        抛出新IOException异常（conn.getResponseMessage（））;
    }    的BufferedReader的BufferedReader =新的BufferedReader（
            新的InputStreamReader（conn.getInputStream（）））;    而（（行= bufferedReader.readLine（））！= NULL）{
        sb.append（线）;
    }
    bufferedReader.close（）;
    conn.disconnect（）;    尝试{
        J =新的JSONObject（sb.toString（））;
        会议= gson.fromJson（j.toString（），会话[]类）;
        tempList = Arrays.asList（会话）;        //响应= gson.fromJson（j.toString（），Response.class）;
        // tempList.add（响应）;    }赶上（JSONException E）{
        e.printStackTrace（）;
    }
    返回tempList;
}
 

虽然code是正确的，我得到一个GSON异常无法调用类com.test.Sessions无参数的构造函数;.注册与GSON的InstanceCreator这种类型可能会解决这个问题。

我要如何解决这个问题，并返回GSON作为一个ArrayList

解决方案

解决的办法是：

 公共类会话{私人字符串状态;
私人列表＆LT;会议＆GT;会议;公共字符串的getStatus（）{
    返回状态;
}公共无效setStatus（字符串状态）{
    this.status =状态;
}公开名单＆LT;会议＆GT; getSessions（）{
    返回会议;
}公共无效setSessions（列表＆LT;会议＆GT;会话）{
    this.sessions =会议;
}公共静态类会话{
    公共布尔活跃;
    公共字符串contributor_covu_id;
    公共字符串created_at;
    公共字符串键;
    公共字符串状态;
    公共字符串名称;};
 

}

I am tring to map json data using Gson from a URL to my java class. This is the code for the class:

public class Sessions {
public Boolean active;
public String contributor_covu_id;
public String created_at;
public String key;
public String status;

public Boolean getActive() {
    return active;
}
public void setActive(Boolean active) {
    this.active = active;
}
public String getContributor_covu_id() {
    return contributor_covu_id;
}
public void setContributor_covu_id(String contributor_covu_id) {
    this.contributor_covu_id = contributor_covu_id;
}
public String getCreated_at() {
    return created_at;
}
public void setCreated_at(String created_at) {
    this.created_at = created_at;
}
public String getKey() {
    return key;
}
public void setKey(String key) {
    this.key = key;
}
public String getStatus() {
    return status;
}
public void setStatus(String status) {
    this.status = status;
}
public String getType() {
    return type;
}
public void setType(String type) {
    this.type = type;
}
public String type;

}

and this is the code of the class that calls the service and maps json

public static List<Sessions> getSessions(String urlString)
        throws IOException {

    Sessions[] sessions;
    List<Sessions> tempList = null;
    URL url = new URL(urlString);
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
    GsonBuilder gsonb = new GsonBuilder();
    Gson gson = gsonb.create();
    StringBuilder sb = new StringBuilder();
    String line;

    // Response response = null;
    JSONObject j = null;

    if (conn.getResponseCode() != 200) {
        throw new IOException(conn.getResponseMessage());
    }

    BufferedReader bufferedReader = new BufferedReader(
            new InputStreamReader(conn.getInputStream()));

    while ((line = bufferedReader.readLine()) != null) {
        sb.append(line);
    }
    bufferedReader.close();
    conn.disconnect();

    try {
        j = new JSONObject(sb.toString());
        sessions = gson.fromJson(j.toString(), Sessions[].class);
        tempList = Arrays.asList(sessions);

        // response = gson.fromJson(j.toString(), Response.class);
        // tempList.add(response);

    } catch (JSONException e) {
        e.printStackTrace();
    }
    return tempList;
}

Although the code is correct, I get a Gson exception "Unable to invoke no-args constructor for class com.test.Sessions;. Register an InstanceCreator with Gson for this type may fix this problem"

How do i solve this issue and return the Gson as an ArrayList?

解决方案

The solution is:

public class Sessions {

private String status;
private List<Session> sessions;

public String getStatus() {
    return status;
}

public void setStatus(String status) {
    this.status = status;
}

public List<Session> getSessions() {
    return sessions;
}

public void setSessions(List<Session> sessions) {
    this.sessions = sessions;
}

public static class Session {
    public Boolean active;
    public String contributor_covu_id;
    public String created_at;
    public String key;
    public String status;
    public String name;

};

}

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