我试图解析这样的JSON字符串
[
{
"updated_at":"2012-03-02 21:06:01",
"fetched_at":"2012-03-02 21:28:37.728840",
"description":null,
"language":null,
"title":"JOHN",
"url":"http://rus.JOHN.JOHN/rss.php",
"icon_url":null,
"logo_url":null,
"id":"4f4791da203d0c2d76000035",
"modified":"2012-03-02 23:28:58.840076"
},
{
"updated_at":"2012-03-02 14:07:44",
"fetched_at":"2012-03-02 21:28:37.033108",
"description":null,
"language":null,
"title":"PETER",
"url":"http://PETER.PETER.lv/rss.php",
"icon_url":null,
"logo_url":null,
"id":"4f476f61203d0c2d89000253",
"modified":"2012-03-02 23:28:57.928001"
}
]
变成一个对象列表。
List<ChannelSearchEnum> lcs = (List<ChannelSearchEnum>) new Gson().fromJson( jstring , ChannelSearchEnum.class);
这是我使用的一个对象类。
import com.google.gson.annotations.SerializedName;
public class ChannelSearchEnum {
@SerializedName("updated_at")
private String updated_at;
@SerializedName("fetched_at")
private String fetched_at;
@SerializedName("description")
private String description;
@SerializedName("language")
private String language;
@SerializedName("title")
private String title;
@SerializedName("url")
private String url;
@SerializedName("icon_url")
private String icon_url;
@SerializedName("logo_url")
private String logo_url;
@SerializedName("id")
private String id;
@SerializedName("modified")
private String modified;
public final String get_Updated_at() {
return this.updated_at;
}
public final String get_Fetched_at() {
return this.fetched_at;
}
public final String get_Description() {
return this.description;
}
public final String get_Language() {
return this.language;
}
public final String get_Title() {
return this.title;
}
public final String get_Url() {
return this.url;
}
public final String get_Icon_url() {
return this.icon_url;
}
public final String get_Logo_url() {
return this.logo_url;
}
public final String get_Id() {
return this.id;
}
public final String get_Modified() {
return this.modified;
}
}
但这让我
com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 2
有什么好办法吗?
我不确定这是否是使用GSON的最佳方式,但对我来说是可行的。你可以在MainActivity上使用这样的代码:
public void readJson() {
dataArrayList = new ArrayList<>();
String json = "[\n" + IOHelper.getData(this) + "\n]\n";
Log.d(TAG, json);
try{
JSONArray channelSearchEnums = new JSONArray(json);
for(int i=0; i< channelSearchEnums.length(); i++)
{
JSONObject enum = channelSearchEnums.getJSONObject(i);
ChannelSearchEnum channel = new ChannelSearchEnum(
enum.getString("updated_at"), enum.getString("fetched_at"),
enum.getString("description"), enum.getString("language"),
enum.getString("title"), enum.getString("url"),
enum.getString("icon_url"), enum.getString("logo_url"),
enum.getString("id"), enum.getString("modified"))
dataArrayList.add(channel);
}
//The code and place you want to show your data
}catch (Exception e)
{
Log.d(TAG, e.getLocalizedMessage());
}
}
你只有字符串,但如果你有double或int,你也可以放getDouble或getInt。
IOHelper类的方法如下(这里,路径保存在内部存储中):
public static String getData(Context context) {
try {
File f = new File(context.getFilesDir().getPath() + "/" + fileName);
//check whether file exists
FileInputStream is = new FileInputStream(f);
int size = is.available();
byte[] buffer = new byte[size];
is.read(buffer);
is.close();
return new String(buffer);
} catch (IOException e) {
Log.e("TAG", "Error in Reading: " + e.getLocalizedMessage());
return null;
}
}
如果你想了解更多信息,你可以看这个视频,在那里我得到了readJson()的代码;和这个线程,我得到的getData()的代码。
在我的例子中是JSON字符串:
[{"category":"College Affordability",
"uid":"150151",
"body":"Ended more than $60 billion in wasteful subsidies for big banks and used the savings to put the cost of college within reach for more families.",
"url":"http:\/\/www.whitehouse.gov\/economy\/middle-class\/helping middle-class-families-pay-for-college",
"url_title":"ending subsidies for student loan lenders",
"type":"Progress",
"path":"node\/150385"}]
然后在recycleview中打印“category”和“url_title”
Datum.class
import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;
public class Datum {
@SerializedName("category")
@Expose
private String category;
@SerializedName("uid")
@Expose
private String uid;
@SerializedName("url_title")
@Expose
private String urlTitle;
/**
* @return The category
*/
public String getCategory() {
return category;
}
/**
* @param category The category
*/
public void setCategory(String category) {
this.category = category;
}
/**
* @return The uid
*/
public String getUid() {
return uid;
}
/**
* @param uid The uid
*/
public void setUid(String uid) {
this.uid = uid;
}
/**
* @return The urlTitle
*/
public String getUrlTitle() {
return urlTitle;
}
/**
* @param urlTitle The url_title
*/
public void setUrlTitle(String urlTitle) {
this.urlTitle = urlTitle;
}
}
RequestInterface
import java.util.List;
import retrofit2.Call;
import retrofit2.http.GET;
/**
* Created by Shweta.Chauhan on 13/07/16.
*/
public interface RequestInterface {
@GET("facts/json/progress/all")
Call<List<Datum>> getJSON();
}
DataAdapter
import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.List;
/**
* Created by Shweta.Chauhan on 13/07/16.
*/
public class DataAdapter extends RecyclerView.Adapter<DataAdapter.MyViewHolder>{
private Context context;
private List<Datum> dataList;
public DataAdapter(Context context, List<Datum> dataList) {
this.context = context;
this.dataList = dataList;
}
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view= LayoutInflater.from(parent.getContext()).inflate(R.layout.data,parent,false);
return new MyViewHolder(view);
}
@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
holder.categoryTV.setText(dataList.get(position).getCategory());
holder.urltitleTV.setText(dataList.get(position).getUrlTitle());
}
@Override
public int getItemCount() {
return dataList.size();
}
public class MyViewHolder extends RecyclerView.ViewHolder{
public TextView categoryTV, urltitleTV;
public MyViewHolder(View itemView) {
super(itemView);
categoryTV = (TextView) itemView.findViewById(R.id.txt_category);
urltitleTV = (TextView) itemView.findViewById(R.id.txt_urltitle);
}
}
}
最后是MainActivity.java
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;
public class MainActivity extends AppCompatActivity {
private RecyclerView recyclerView;
private DataAdapter dataAdapter;
private List<Datum> dataArrayList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initViews();
}
private void initViews(){
recyclerView=(RecyclerView) findViewById(R.id.recycler_view);
recyclerView.setLayoutManager(new LinearLayoutManager(getApplicationContext()));
loadJSON();
}
private void loadJSON(){
dataArrayList = new ArrayList<>();
Retrofit retrofit=new Retrofit.Builder().baseUrl("https://www.whitehouse.gov/").addConverterFactory(GsonConverterFactory.create()).build();
RequestInterface requestInterface=retrofit.create(RequestInterface.class);
Call<List<Datum>> call= requestInterface.getJSON();
call.enqueue(new Callback<List<Datum>>() {
@Override
public void onResponse(Call<List<Datum>> call, Response<List<Datum>> response) {
dataArrayList = response.body();
dataAdapter=new DataAdapter(getApplicationContext(),dataArrayList);
recyclerView.setAdapter(dataAdapter);
}
@Override
public void onFailure(Call<List<Datum>> call, Throwable t) {
Log.e("Error",t.getMessage());
}
});
}
}