android的volley框架使用日志1

时间:2021-12-08 15:28:22

看了一下volley框架的简单demo,发现使用后,如获取Json文件之类的,所写的代码非常的简单

public class JsonRequestAcitivity extends Activity implements OnClickListener,Listener<JSONObject>,ErrorListener{
	private Button requestBtn;
	private TextView dispText;
	RequestQueue rq;
	Request request;
	private static final String URL = "http://httpbin.org/get?param1=hello";
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_json_request);
		requestBtn = (Button) findViewById(R.id.requestBtn);
		dispText = (TextView) findViewById(R.id.dispText);
		requestBtn.setOnClickListener(this);
	}
	@Override
	public void onClick(View v) {
		dispText.setText("请求中...");
		doJsonRequest();
	}
	
	private void doJsonRequest() {
		//第三个参数
		//A JSONObject to post with the request. Null is allowed and indicates no parameters will be posted along with request.
		JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(
				Request.Method.GET,URL,null, JsonRequestAcitivity.this,JsonRequestAcitivity.this);
		jsonObjectRequest.setTag(JsonRequestAcitivity.class.getSimpleName());//设置tag callAll的时候使用
		VolleyTool.getInstance(this).getmRequestQueue().add(jsonObjectRequest);
	}
	@Override
	public void onResponse(JSONObject response) {
		//success 
		dispText.setText("Success::"+response.toString());
	}
	@Override
	public void onErrorResponse(VolleyError error) {
		dispText.setText("Fail::"+error.toString());
	}
	@Override
	protected void onDestroy() {
		super.onDestroy();
		VolleyTool.getInstance(this).getmRequestQueue().cancelAll(JsonRequestAcitivity.class.getSimpleName());
	}
	
	
}
显而易见,TextView中的setText方法并无直接的调用,而数据之间传递和交互只在那句简单的

         

VolleyTool.getInstance(this).getmRequestQueue().add(jsonObjectRequest);

首先是实例化一个VolleyTool,然后获取一个请求队列,然后将jsonObjectRequest放入队列之中执行;

而VolleyTool文件中,最关键的一句便是

mRequestQueue = Volley.newRequestQueue(context);
public class VolleyTool {
	private static VolleyTool mInstance = null;
    private RequestQueue mRequestQueue;
    private ImageLoader mImageLoader;
    
    private VolleyTool(Context context) {
    	mRequestQueue = Volley.newRequestQueue(context);
    	mImageLoader = new ImageLoader(mRequestQueue, new BitmapCache());
    }
    
    public static VolleyTool getInstance(Context context){
        if(mInstance == null){
    		mInstance = new VolleyTool(context);
        }
        return mInstance;
    }
    
	public RequestQueue getmRequestQueue() {
		return mRequestQueue;
	}

	public ImageLoader getmImageLoader() {
		return mImageLoader;
	}

	public void release() {
		this.mImageLoader = null;
		this.mRequestQueue = null;
		mInstance = null;
	}
}
因为这一句话,直接从Volley.jar包中调用了volley的这个类,从而获取里面的方法。

public class Volley {

    /** Default on-disk cache directory. */
    private static final String DEFAULT_CACHE_DIR = "volley";

    /**
     * Creates a default instance of the worker pool and calls {@link RequestQueue#start()} on it.
     *
     * @param context A {@link Context} to use for creating the cache dir.
     * @param stack An {@link HttpStack} to use for the network, or null for default.
     * @return A started {@link RequestQueue} instance.
     */
    public static RequestQueue newRequestQueue(Context context, HttpStack stack) {
        File cacheDir = new File(context.getCacheDir(), DEFAULT_CACHE_DIR);

        String userAgent = "volley/0";
        try {
            String packageName = context.getPackageName();

            PackageInfo info = context.getPackageManager().getPackageInfo(packageName, 0);
            userAgent = packageName + "/" + info.versionCode;
        } catch (NameNotFoundException e) {
        }

        if (stack == null) {
            if (Build.VERSION.SDK_INT >= 9) {
                stack = new HurlStack();
            } else {
                // Prior to Gingerbread, HttpUrlConnection was unreliable.
                // See: http://android-developers.blogspot.com/2011/09/androids-http-clients.html
                stack = new HttpClientStack(AndroidHttpClient.newInstance(userAgent));
            }
        }

        Network network = new BasicNetwork(stack);

        RequestQueue queue = new RequestQueue(new DiskBasedCache(cacheDir), network);
        queue.start();

        return queue;
    }

    /**
     * Creates a default instance of the worker pool and calls {@link RequestQueue#start()} on it.
     *
     * @param context A {@link Context} to use for creating the cache dir.
     * @return A started {@link RequestQueue} instance.
     */
    public static RequestQueue newRequestQueue(Context context) {
        return newRequestQueue(context, null);
    }
}
而后,从代码中显而易见的是queue.start()方法的执行,就可以从RequestQueue中的networkparseResponse()方法,获取真正的response并实例化。

若是自己也下载了这个volley.jar,便可以知道,实例化时所用的构造方法中,调用了success()方法,从而间接的实现了文本的获取。

-总结:

 - 要活用eclipse中的search功能,一步一步的解析问题,把问题简单话。

 -不懂解压包里面的文件就解压出来,一步步看,还可以改写。