volley二次封装

     产品中使用Volley框架已有多时，本身已有良好封装的Volley确实给程序开发带来了很多便利与快捷。但随着产品功能的不断增加，服务器接口的不断复杂化，直接使用Volley原生的JSONObjectRequest已经导致Activity或Fragment层中耦合了大量的数据解析代码，同时当多处调用同一接口时，类似的数据解析代码还不可复用，导致大量重复代码的出现，已经让我越发地无法忍受。基于此，最近思考着对Volley原生的JSONObjectRequest（因为产品中目前和服务器交互所有的接口，数据都是json格式的）进行二次封装，把Activity和Fragment中大量的数据解析代码剥离出来，同时实现数据解析代码的复用。

为了把问题表现出来，先上一段坑爹的代码。

package com.backup;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.json.JSONException;
import org.json.JSONObject;

import com.amuro.volleytest01_image.R;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;

public class TestActivity02 extends Activity
{
    private RequestQueue mQueue;
    private ListView listView;
    private List<Map<String, String>> list = new ArrayList<Map<String,String>>();
    
    String url = "http://10.24.4.196:8081/weather.html";
    
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test02_layout);
        listView = (ListView)findViewById(R.id.lv_test02);
        mQueue = Volley.newRequestQueue(this);
        getWeatherInfo();
        
        SimpleAdapter simpleAdapter = new SimpleAdapter(this, list,   
                        android.R.layout.simple_list_item_2, new String[] {"title","content"},   
                       new int[] {android.R.id.text1, android.R.id.text2});              
                  
        listView.setAdapter(simpleAdapter);  

        listView.setOnItemClickListener(new OnItemClickListener()
        {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id)
            {
                TextView tv = (TextView)view.findViewById(android.R.id.text1);
                tv.setText("111111111111111111");
            }
        });
    }
    
    public void getWeatherInfo()
    {
        JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(url, null,

        new Response.Listener<JSONObject>()
        {

            @SuppressWarnings("unchecked")
            @Override
            public void onResponse(JSONObject jsonObject)
            {
                list.clear();
                Iterator<String> it = jsonObject.keys();
                while (it.hasNext())
                {
                    String key = it.next();
                    JSONObject obj = null;
                    try
                    {
                        obj = jsonObject.getJSONObject(key);
                    }
                    catch (JSONException e)
                    {
                        e.printStackTrace();
                    }
                    if (obj != null)
                    {
                        Iterator<String> objIt = obj.keys();
                        while (objIt.hasNext())
                        {
                            String objKey = objIt.next();
                            String objValue;
                            try
                            {
                                objValue = obj.getString(objKey);
                                HashMap<String, String> map = new HashMap<String, String>();
                                map.put("title", objKey);
                                map.put("content", objValue);
                                list.add(map);
                            }
                            catch (JSONException e)
                            {
                                e.printStackTrace();
                            }
                        }
                    }
                }
            }
        },

        new Response.ErrorListener()
        {
            @Override
            public void onErrorResponse(VolleyError arg0)
            {
            }
        });

        mQueue.add(jsonObjectRequest);
    }
}

上面的代码大家可以看到，复杂的json解析代码全部写在Activity里，现在如果又来一个Activity需要调用这个接口，这些解析json的代码是完全无法复用的，这不科学

下面开始分析：

1. 面向对象，对于Activity这层来说，它要的只是拿到数据进行展示，至于数据怎么变出来的，它不应该关注，所以第一件事，对数据进行封装，每个接口返回的最终数据，不应该是一个未经解析的jsonObject，而应该是一个bean，千千万万的bean最终可通过泛型来统一，so，我们先需要一个监听器，让我们封装后的Volley层直接把bean回调给Activity。

2. 对错误的处理，从目前的产品需求来看，上层Activity就是要对不同的错误展示不同的界面或跳转不同的界面，所以我们把错误统一为errorCode和errorMessage，在底层封装好后，直接抛给Activity。所以这样一个返回bean或者error的接口就出来了。

package com.amuro.volley_framwork.network_helper;

public interface UIDataListener<T>
{
    public void onDataChanged(T data);
    public void onErrorHappened(String errorCode, String errorMessage);
}

3. 好，监听器剥离了Activity与我们的Volley层，下面我们就要自己对Volley的JsonObjectRequest进行封装了，先贴这个类：

package com.amuro.volley_framwork.network_request;

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.List;
import java.util.Map;

import org.apache.http.NameValuePair;
import org.apache.http.client.utils.URLEncodedUtils;
import org.json.JSONObject;

import com.android.volley.DefaultRetryPolicy;
import com.android.volley.NetworkResponse;
import com.android.volley.ParseError;
import com.android.volley.Response;
import com.android.volley.Response.ErrorListener;
import com.android.volley.Response.Listener;
import com.android.volley.toolbox.HttpHeaderParser;
import com.android.volley.toolbox.JsonRequest;

public class NetworkRequest extends JsonRequest<JSONObject>
{
    private Priority mPriority = Priority.HIGH;
    
    public NetworkRequest(int method, String url,
            Map<String, String> postParams, Listener<JSONObject> listener,
            ErrorListener errorListener) 
    {
        super(method, url, paramstoString(postParams), listener, errorListener);
        setRetryPolicy(new DefaultRetryPolicy(30000, 0, DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
    }

    public NetworkRequest(String url, List<NameValuePair> params,
            Listener<JSONObject> listener, ErrorListener errorListener) 
    {
        this(Method.GET, urlBuilder(url, params), null, listener, errorListener);
    }
    
    public NetworkRequest(String url, Listener<JSONObject> listener, ErrorListener errorListener) 
    {
        this(Method.GET, url, null, listener, errorListener);
    }
    
    private static String paramstoString(Map<String, String> params)
    {
        if (params != null && params.size() > 0)
        {
            String paramsEncoding = "UTF-8";
            StringBuilder encodedParams = new StringBuilder();
            try
            {
                for (Map.Entry<String, String> entry : params.entrySet())
                {
                    encodedParams.append(URLEncoder.encode(entry.getKey(),
                            paramsEncoding));
                    encodedParams.append('=');
                    encodedParams.append(URLEncoder.encode(entry.getValue(),
                            paramsEncoding));
                    encodedParams.append('&');
                    
                }
                return encodedParams.toString();
            }
            catch (UnsupportedEncodingException uee)
            {
                throw new RuntimeException("Encoding not supported: "
                        + paramsEncoding, uee);
            }
        }
        return null;
    }

    @Override
    protected Response<JSONObject> parseNetworkResponse(NetworkResponse response)
    {
        
        try
        {

            JSONObject jsonObject = new JSONObject(new String(response.data, "UTF-8"));

            return Response.success(jsonObject,
                    HttpHeaderParser.parseCacheHeaders(response));

        }
        catch (Exception e)
        {

            return Response.error(new ParseError(e));

        }
    }

    @Override
    public Priority getPriority()
    {
        return mPriority;
    }

    public void setPriority(Priority priority)
    {
        mPriority = priority;
    }

    private static String urlBuilder(String url, List<NameValuePair> params) 
    {
        return url + "?" + URLEncodedUtils.format(params, "UTF-8");
    }
}

4. 接下来就是我们的重头戏，写一个Controller来操作这个request，同时对数据进行bean或error的封装，这是一个抽象类，让不同的子类根据不同的接口，趋实现不同的数据解析方式：

package com.amuro.volley_framwork.network_helper;

import java.util.List;
import java.util.Map;

import org.apache.http.NameValuePair;
import org.json.JSONObject;

import android.content.Context;
import android.util.Log;

import com.amuro.volley_framwork.network_request.NetworkRequest;
import com.amuro.volley_framwork.volley_queue_controller.VolleyQueueController;
import com.android.volley.Request.Method;
import com.android.volley.Response;
import com.android.volley.Response.ErrorListener;
import com.android.volley.VolleyError;

public abstract class NetworkHelper<T> implements Response.Listener<JSONObject>, ErrorListener
{
    private Context context;
    
    public NetworkHelper(Context context)
    {
        this.context = context;
    }
    
    protected Context getContext()
    {
        return context;
    }
    
    protected NetworkRequest getRequestForGet(String url, List<NameValuePair> params)
    {
        if(params == null)
        {
            return new NetworkRequest(url, this, this);
        }
        else
        {
            return new NetworkRequest(url, params, this, this);
        }
        
    }
    
    protected NetworkRequest getRequestForPost(String url, Map<String, String> params)
    {
        return new NetworkRequest(Method.POST, url, params, this, this);
    }
    
    public void sendGETRequest(String url, List<NameValuePair> params)
    {
        VolleyQueueController.getInstance().
            getRequestQueue(getContext()).add(getRequestForGet(url, params));
    }
    
    public void sendPostRequest(String url, Map<String, String> params)
    {
        VolleyQueueController.getInstance().
            getRequestQueue(context).add(getRequestForPost(url, params));
    }

    @Override
    public void onErrorResponse(VolleyError error)
    {
        Log.d("Amuro", error.getMessage());
        disposeVolleyError(error);
    }

    protected abstract void disposeVolleyError(VolleyError error);

    @Override
    public void onResponse(JSONObject response)
    {
        Log.d("Amuro", response.toString());
        disposeResponse(response);
    }

    protected abstract void disposeResponse(JSONObject response);

    private UIDataListener<T> uiDataListener;
    
    public void setUiDataListener(UIDataListener<T> uiDataListener)
    {
        this.uiDataListener = uiDataListener;
    }
    
    protected void notifyDataChanged(T data)
    {
        if(uiDataListener != null)
        {
            uiDataListener.onDataChanged(data);
        }
    }
    
    protected void notifyErrorHappened(String errorCode, String errorMessage)
    {
        if(uiDataListener != null)
        {
            uiDataListener.onErrorHappened(errorCode, errorMessage);
        }
    }
    
}

这里对外直接提供了sendGetRequest方法和sendPostRequest方法，做为api就是要清晰明了，不要让调用者去了解还有Method.GET这样的东西，同时getRequestForGet方法和getRequestForPost方法把最常用的request直接封装好，不需要子类再去写new request的代码。当然为了拓展，这两个方法是protected的，default的request不能符合要求的时候，子类就可直接覆盖这两个方法返回自己的request，而disposeResponse和disponseError两个方法都为抽象方法，让子类针对不同的接口，实现不同的功能。

5. 下面来个子类实例，一看就懂。

package com.amuro.controller.networkhelper;

import org.json.JSONObject;

import android.content.Context;

import com.amuro.bean.RRBean;
import com.amuro.utils.SystemParams;
import com.amuro.volley_framwork.network_helper.NetworkHelper;
import com.android.volley.VolleyError;

//{"errorCode":"0000","errorMessage":"成功","respMsg":"success","success":"true"}
public class ReverseRegisterNetworkHelper extends NetworkHelper<RRBean>
{
    

    public ReverseRegisterNetworkHelper(Context context)
    {
        super(context);
    }

    @Override
    protected void disposeVolleyError(VolleyError error)
    {
        notifyErrorHappened(
                SystemParams.VOLLEY_ERROR_CODE, 
                error == null ? "NULL" : error.getMessage());
    }

    @Override
    protected void disposeResponse(JSONObject response)
    {
        RRBean rrBean = null;
        
        if(response != null)
        {
            try
            {
                String errorCode = response.getString("errorCode");
                String errorMessage = response.getString("errorMessage");
                String respMsg = response.getString("respMsg");
                String success = response.getString("success");
                
                if("0000".equals(errorCode))
                {
                    rrBean = new RRBean();
                    rrBean.setErrorCode(errorCode);
                    rrBean.setErrorMessage(errorMessage);
                    rrBean.setRespMsg(respMsg);
                    rrBean.setSuccess(success);
                    
                    notifyDataChanged(rrBean);
                }
                else
                {
                    notifyErrorHappened(errorCode, errorMessage);
                }
            }
            catch(Exception e)
            {
                notifyErrorHappened(SystemParams.RESPONSE_FORMAT_ERROR, "Response format error");
            }
        }
        else
        {
            notifyErrorHappened(SystemParams.RESPONSE_IS_NULL, "Response is null!");
        }
        
    }
    
    

}

5. 大功告成，这个NetworkHelper封装了数据解析的代码，完全可复用，最后看Activity

package com.amuro.ui;

import com.amuro.bean.RRBean;
import com.amuro.controller.networkhelper.ReverseRegisterNetworkHelper;
import com.amuro.utils.SystemParams;
import com.amuro.volley_framwork.network_helper.NetworkHelper;
import com.amuro.volley_framwork.network_helper.UIDataListener;
import com.amuro.volleytest01_image.R;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class MyVolleyTestActivity extends Activity implements UIDataListener<RRBean>
{
    private Button button;
    
    private NetworkHelper<RRBean> networkHelper;
    
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my_volley_test_layout);
        
        networkHelper = new ReverseRegisterNetworkHelper(this);
        networkHelper.setUiDataListener(this);
        
        button = (Button)findViewById(R.id.bt);
        button.setOnClickListener(new OnClickListener()
        {
            
            @Override
            public void onClick(View v)
            {
                sendRequest();
            }
        });
    }
    
    private void sendRequest()
    {
        networkHelper.sendGETRequest(SystemParams.TEST_URL, null);
    }

    @Override
    public void onDataChanged(RRBean data)
    {
        Toast.makeText(
                this, 
                data.getErrorCode() + ":" + 
                data.getErrorMessage() + ":" + 
                data.getRespMsg() + ":" + 
                data.getSuccess(), 
                Toast.LENGTH_SHORT).show();
        
    }

    @Override
    public void onErrorHappened(String errorCode, String errorMessage)
    {
        Toast.makeText(
                this, 
                errorCode + ":" + errorMessage, 
                Toast.LENGTH_SHORT).show();
        
    }
}

看，Activity直接拿到的就是数据或者errorCode，把一大堆复杂的数据解析代码剥离了。

转自：http://www.aichengxu.com/view/46975