I'm trying to create and use a cache for a server JSON response.
For example:
cache JSON objects to internal memory and use that when we don't have an internet connection.
In the following sample code, I can not find any document about how to cache it with Volley and reuse that when server header for update again don't expire.
Like this: set expiration to header and use cache and try to load again after expiration.
I'm trying to set cache mechanism for this method:
private void makeJsonArryReq() {
JsonArrayRequest req = new JsonArrayRequest(Const.URL_JSON_ARRAY,
new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
msgResponse.setText(response.toString());
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
AppController.getInstance().addToRequestQueue(req,tag_json_arry);
}
Cache method:
public static Cache.Entry parseIgnoreCacheHeaders(NetworkResponse response) {
long now = System.currentTimeMillis();
Map<String, String> headers = response.headers;
long serverDate = 0;
String serverEtag = null;
String headerValue;
headerValue = headers.get("Date");
if (headerValue != null) {
serverDate = HttpHeaderParser.parseDateAsEpoch(headerValue);
}
serverEtag = headers.get("ETag");
final long cacheHitButRefreshed = 3 * 60 * 1000; // in 3 minutes cache will be hit, but also refreshed on background
final long cacheExpired = 24 * 60 * 60 * 1000; // in 24 hours this cache entry expires completely
final long softExpire = now + cacheHitButRefreshed;
final long ttl = now + cacheExpired;
Cache.Entry entry = new Cache.Entry();
entry.data = response.data;
entry.etag = serverEtag;
entry.softTtl = softExpire;
entry.ttl = ttl;
entry.serverDate = serverDate;
entry.responseHeaders = headers;
return entry;
}
Please note that if the web service supports caching output, you don't have to use CacheRequest below, because Volley will automatically cache.
For your issue, I use some codes inside parseCacheHeaders (and refering to @oleksandr_yefremov's codes). The following code I have tested. Of course, can use for JsonArrayRequest also. Hope this help!
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(0, mUrl, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
try {
mTextView.setText(response.toString(5));
} catch (JSONException e) {
mTextView.setText(e.toString());
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
}) {
@Override
protected Response<JSONObject> parseNetworkResponse(NetworkResponse response) {
try {
Cache.Entry cacheEntry = HttpHeaderParser.parseCacheHeaders(response);
if (cacheEntry == null) {
cacheEntry = new Cache.Entry();
}
final long cacheHitButRefreshed = 3 * 60 * 1000; // in 3 minutes cache will be hit, but also refreshed on background
final long cacheExpired = 24 * 60 * 60 * 1000; // in 24 hours this cache entry expires completely
long now = System.currentTimeMillis();
final long softExpire = now + cacheHitButRefreshed;
final long ttl = now + cacheExpired;
cacheEntry.data = response.data;
cacheEntry.softTtl = softExpire;
cacheEntry.ttl = ttl;
String headerValue;
headerValue = response.headers.get("Date");
if (headerValue != null) {
cacheEntry.serverDate = HttpHeaderParser.parseDateAsEpoch(headerValue);
}
headerValue = response.headers.get("Last-Modified");
if (headerValue != null) {
cacheEntry.lastModified = HttpHeaderParser.parseDateAsEpoch(headerValue);
}
cacheEntry.responseHeaders = response.headers;
final String jsonString = new String(response.data,
HttpHeaderParser.parseCharset(response.headers));
return Response.success(new JSONObject(jsonString), cacheEntry);
} catch (UnsupportedEncodingException e) {
return Response.error(new ParseError(e));
} catch (JSONException e) {
return Response.error(new ParseError(e));
}
}
@Override
protected void deliverResponse(JSONObject response) {
super.deliverResponse(response);
}
@Override
public void deliverError(VolleyError error) {
super.deliverError(error);
}
@Override
protected VolleyError parseNetworkError(VolleyError volleyError) {
return super.parseNetworkError(volleyError);
}
};
MySingleton.getInstance(this).addToRequestQueue(jsonObjectRequest);
UPDATE:
If you want a base class, refer to the following codes:
public class CacheRequest extends Request<NetworkResponse> {
private final Response.Listener<NetworkResponse> mListener;
private final Response.ErrorListener mErrorListener;
public CacheRequest(int method, String url, Response.Listener<NetworkResponse> listener, Response.ErrorListener errorListener) {
super(method, url, errorListener);
this.mListener = listener;
this.mErrorListener = errorListener;
}
@Override
protected Response<NetworkResponse> parseNetworkResponse(NetworkResponse response) {
Cache.Entry cacheEntry = HttpHeaderParser.parseCacheHeaders(response);
if (cacheEntry == null) {
cacheEntry = new Cache.Entry();
}
final long cacheHitButRefreshed = 3 * 60 * 1000; // in 3 minutes cache will be hit, but also refreshed on background
final long cacheExpired = 24 * 60 * 60 * 1000; // in 24 hours this cache entry expires completely
long now = System.currentTimeMillis();
final long softExpire = now + cacheHitButRefreshed;
final long ttl = now + cacheExpired;
cacheEntry.data = response.data;
cacheEntry.softTtl = softExpire;
cacheEntry.ttl = ttl;
String headerValue;
headerValue = response.headers.get("Date");
if (headerValue != null) {
cacheEntry.serverDate = HttpHeaderParser.parseDateAsEpoch(headerValue);
}
headerValue = response.headers.get("Last-Modified");
if (headerValue != null) {
cacheEntry.lastModified = HttpHeaderParser.parseDateAsEpoch(headerValue);
}
cacheEntry.responseHeaders = response.headers;
return Response.success(response, cacheEntry);
}
@Override
protected void deliverResponse(NetworkResponse response) {
mListener.onResponse(response);
}
@Override
protected VolleyError parseNetworkError(VolleyError volleyError) {
return super.parseNetworkError(volleyError);
}
@Override
public void deliverError(VolleyError error) {
mErrorListener.onErrorResponse(error);
}
}
Then in MainActivity, you can call like this
CacheRequest cacheRequest = new CacheRequest(0, mUrl, new Response.Listener<NetworkResponse>() {
@Override
public void onResponse(NetworkResponse response) {
try {
final String jsonString = new String(response.data,
HttpHeaderParser.parseCharset(response.headers));
JSONObject jsonObject = new JSONObject(jsonString);
mTextView.setText(jsonObject.toString(5));
} catch (UnsupportedEncodingException | JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
mTextView.setText(error.toString());
}
});
MySingleton.getInstance(this).addToRequestQueue(cacheRequest);
UPDATE WITH FULL SOURCE CODE:
MainActivity.java:
package com.example.cachevolley;
import android.content.Context;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;
import android.widget.Toast;
import com.android.volley.Cache;
import com.android.volley.NetworkResponse;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.HttpHeaderParser;
import com.android.volley.toolbox.Volley;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.UnsupportedEncodingException;
public class MainActivity extends AppCompatActivity {
private final Context mContext = this;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final TextView textView = (TextView) findViewById(R.id.textView);
RequestQueue queue = Volley.newRequestQueue(this);
String url = "http://192.168.0.100/apitest";
CacheRequest cacheRequest = new CacheRequest(0, url, new Response.Listener<NetworkResponse>() {
@Override
public void onResponse(NetworkResponse response) {
try {
final String jsonString = new String(response.data,
HttpHeaderParser.parseCharset(response.headers));
JSONObject jsonObject = new JSONObject(jsonString);
textView.setText(jsonObject.toString(5));
Toast.makeText(mContext, "onResponse:\n\n" + jsonObject.toString(), Toast.LENGTH_SHORT).show();
} catch (UnsupportedEncodingException | JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(mContext, "onErrorResponse:\n\n" + error.toString(), Toast.LENGTH_SHORT).show();
}
});
// Add the request to the RequestQueue.
queue.add(cacheRequest);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
private class CacheRequest extends Request<NetworkResponse> {
private final Response.Listener<NetworkResponse> mListener;
private final Response.ErrorListener mErrorListener;
public CacheRequest(int method, String url, Response.Listener<NetworkResponse> listener, Response.ErrorListener errorListener) {
super(method, url, errorListener);
this.mListener = listener;
this.mErrorListener = errorListener;
}
@Override
protected Response<NetworkResponse> parseNetworkResponse(NetworkResponse response) {
Cache.Entry cacheEntry = HttpHeaderParser.parseCacheHeaders(response);
if (cacheEntry == null) {
cacheEntry = new Cache.Entry();
}
final long cacheHitButRefreshed = 3 * 60 * 1000; // in 3 minutes cache will be hit, but also refreshed on background
final long cacheExpired = 24 * 60 * 60 * 1000; // in 24 hours this cache entry expires completely
long now = System.currentTimeMillis();
final long softExpire = now + cacheHitButRefreshed;
final long ttl = now + cacheExpired;
cacheEntry.data = response.data;
cacheEntry.softTtl = softExpire;
cacheEntry.ttl = ttl;
String headerValue;
headerValue = response.headers.get("Date");
if (headerValue != null) {
cacheEntry.serverDate = HttpHeaderParser.parseDateAsEpoch(headerValue);
}
headerValue = response.headers.get("Last-Modified");
if (headerValue != null) {
cacheEntry.lastModified = HttpHeaderParser.parseDateAsEpoch(headerValue);
}
cacheEntry.responseHeaders = response.headers;
return Response.success(response, cacheEntry);
}
@Override
protected void deliverResponse(NetworkResponse response) {
mListener.onResponse(response);
}
@Override
protected VolleyError parseNetworkError(VolleyError volleyError) {
return super.parseNetworkError(volleyError);
}
@Override
public void deliverError(VolleyError error) {
mErrorListener.onErrorResponse(error);
}
}
}
Manifest file:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.cachevolley" >
<uses-permission android:name="android.permission.INTERNET" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
Layout file:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity">
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />
</RelativeLayout>
If the response is taking from server using String Request then just Replace the Line
return Response.success(new JSONObject(jsonString), cacheEntry);
with this
return Response.success(new String(jsonString), cacheEntry);
It works in my case. Try in your own code.
