Android Volley框架使用(三)

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Android Volley框架使用(一)
Android Volley框架使用(二)

这次主要是自定义请求队列

主要代码：

package com.example.hfs.volleycustomrequestqueuedemo;import android.content.Context;import android.os.Environment;import com.android.volley.Cache;import com.android.volley.Network;import com.android.volley.RequestQueue;import com.android.volley.toolbox.BasicNetwork;import com.android.volley.toolbox.DiskBasedCache;import com.android.volley.toolbox.HttpStack;import com.android.volley.toolbox.HurlStack;import java.io.File;/** * Created by HFS on 2016/4/26. *///这个类对外提供RequestQueue请求队列public class MyVolley {    //    声明一个全局的RequestQueue    public static RequestQueue mRequestQueue;//    采用单例模式//    1.私有构造方法 只能自己调用自己    private MyVolley(Context context) {//        在私有的构造方法中进行赋值        if (mRequestQueue == null) {            String sdPath = null;            if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {                sdPath = Environment.getExternalStorageDirectory().getAbsolutePath() + File.separator + "myVolleyCache";            } else {                sdPath = context.getCacheDir().getAbsolutePath() + File.separator + "myVolleyCache";            }            File rootDirectory = new File(sdPath);            if (!rootDirectory.exists()) {//                文件夹不存在,创建                rootDirectory.mkdirs();            }            Cache cache = new DiskBasedCache(rootDirectory, 1024 * 1024 * 200);//            如果使用HurlStack,RequestQueue联网请求方式采用HttpUrlConnection//            HttpClientStack 联网请求方式采用HttpClient            HttpStack httpStack = new HurlStack();            Network network = new BasicNetwork(httpStack);            mRequestQueue = new RequestQueue(cache, network, 6);        }    }    //    2.提供公共的访问方法    public static RequestQueue newInstance(Context context) {//调用私有的构造方法        new MyVolley(context);        return mRequestQueue;    }}

package com.example.hfs.volleycustomrequestqueuedemo;import android.graphics.Bitmap;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.widget.ImageView;import android.widget.Toast;import com.android.volley.RequestQueue;import com.android.volley.Response;import com.android.volley.VolleyError;import com.android.volley.toolbox.ImageRequest;public class MainActivity extends AppCompatActivity {    private ImageView mImageView;    private RequestQueue mRequestQueue;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);//        1.创建RequestQueue//      这是自定义的RequestQueue缓存在SD卡        mRequestQueue = MyVolley.newInstance(this);//        如果是自定义的RequestQueue 必须调用start方法        mRequestQueue.start();        initView();    }    private void initView() {        mImageView = (ImageView) findViewById(R.id.showImg);    }    public void btnCustomRequest(View view) {//        2创建一个请求        String url = "http://img.my.csdn.net/uploads/201407/26/1406382879_2553.jpg";        ImageRequest request = new ImageRequest(url,                new Response.Listener<Bitmap>() {                    @Override                    public void onResponse(Bitmap response) {                        if (response != null) {                            mImageView.setImageBitmap(response);                        } else {                            mImageView.setImageResource(R.mipmap.ic_launcher);                        }                    }                },                150,                300,                ImageView.ScaleType.FIT_XY,                Bitmap.Config.ARGB_8888,                new Response.ErrorListener() {                    @Override                    public void onErrorResponse(VolleyError error) {                        Toast.makeText(MainActivity.this, "请求图片失败", Toast.LENGTH_SHORT).show();                    }                });//        3.添加到请求队列中        mRequestQueue.add(request);    }}

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