Android Volley 之自己定义Request

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mb5ff98246f093d 2015-05-16 20:09:00

文章标签 json ide java android 数据 文章分类 Html/CSS 前端开发

Volley的全部的请求的超类型是Resuest，类结构例如以下图，全部我们经常使用的请求都是这个类的子类，那么我们自己定义View肯定也是基于这个类的。

Android Volley 之自己定义Request_android

一些简单的使用方法实例：

RequestQueue newRequestQueue = Volley.newRequestQueue(MainActivity.this);
    StringRequest stringRequest = new StringRequest("http://www.baidu.com", new Response.Listener<String>()
    {

      @Override
      public void onResponse(String response)
      {
        Log.e("TAG", response);

      }
    }, new Response.ErrorListener()
    {
      @Override
      public void onErrorResponse(VolleyError error)
      {
        Log.e("TAG", error.getMessage(), error);
      }
    });

    JsonObjectRequest jsonObjectRequest = new JsonObjectRequest("http://m.weather.com.cn/data/101010100.html",
        null, new Response.Listener<JSONObject>()
        {

          @Override
          public void onResponse(JSONObject response)
          {
            Log.e("TAG", response.toString());
          }
        }, new Response.ErrorListener()
        {

          @Override
          public void onErrorResponse(VolleyError error)
          {
            Log.e("TAG", error.getMessage(), error);
          }
        });

    ImageRequest imageRequest = new ImageRequest("http://imgt6.bdstatic.com/it/u=2,887966933&fm=19&gp=0.jpg",
        new Response.Listener<Bitmap>()
        {

          @Override
          public void onResponse(Bitmap response)
          {
            mImageView.setImageBitmap(response);
          }
        }, 0, 0, Config.RGB_565, null);

    newRequestQueue.add(stringRequest);
    newRequestQueue.add(imageRequest);
    newRequestQueue.add(jsonObjectRequest);

基本都是new一个请求，增加请求队列即可了。

好了，以下进入正题，怎样自己定义自己的Request，事实上非常easy，咱们打开StringRequest的源代码：

public StringRequest(int method, String url, Listener<String> listener,
            ErrorListener errorListener) {
        super(method, url, errorListener);
        mListener = listener;
    }

构造方法中指明訪问的url，method，和回调的接口，毕竟我们要处理数据么。

@Override
    protected Response<String> parseNetworkResponse(NetworkResponse response) {
        String parsed;
        try {
            parsed = new String(response.data, HttpHeaderParser.parseCharset(response.headers));
        } catch (UnsupportedEncodingException e) {
            parsed = new String(response.data);
        }
        return Response.success(parsed, HttpHeaderParser.parseCacheHeaders(response));
    }

终于给我们返回的数据就是parsed，比方我们返回的是json字符串，我们就能够在这添几行代码，把字符串转换成对象返回。（非常重要的是，返回类型是咱们声明Request的时候定的，是个泛型）。

以下直接上样例：

样例是，通过client訪问server，server对client进行身份校验后，返回JSON字符串，client直接拿到对象。

1、对象：

package com.zhy.velloydemo;

public class User
{
  private String name;
  private int age;

  public String getName()
  {
    return name;
  }

  public void setName(String name)
  {
    this.name = name;
  }

  public int getAge()
  {
    return age;
  }

  public void setAge(int age)
  {
    this.age = age;
  }

  @Override
  public String toString()
  {
    return "User [name=" + name + ", age=" + age + "]";
  }


}

2、自己定义的Request

package com.zhy.velloydemo;

import java.io.UnsupportedEncodingException;
import java.util.HashMap;
import java.util.Map;

import com.android.volley.AuthFailureError;
import com.android.volley.NetworkResponse;
import com.android.volley.ParseError;
import com.android.volley.Request;
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.google.gson.Gson;
import com.google.gson.JsonSyntaxException;

public class JsonRequestWithAuth<T> extends Request<T>
{
  private final Gson gson = new Gson();
  private final Class<T> clazz;
  private final Listener<T> listener;

  private static Map<String, String> mHeader = new HashMap<String, String>();
  /**
   * 设置訪问自己server时必须传递的參数，密钥等
   */
  static
  {
    mHeader.put("APP-Key", "LBS-AAA");
    mHeader.put("APP-Secret", "ad12msa234das232in");
  }

  /**
   * @param url
   * @param clazz
   *            我们终于的转化类型
   * @param headers
   *            请求附带的头信息
   * @param listener
   * @param appendHeader
   *            附加头数据
   * @param errorListener
   */
  public JsonRequestWithAuth(String url, Class<T> clazz, Listener<T> listener, Map<String, String> appendHeader,
      ErrorListener errorListener)
  {
    super(Method.GET, url, errorListener);
    this.clazz = clazz;
    this.listener = listener;
    mHeader.putAll(appendHeader);
  }

  @Override
  public Map<String, String> getHeaders() throws AuthFailureError
  {
    // 默认返回 return Collections.emptyMap();
    return mHeader;
  }

  @Override
  protected void deliverResponse(T response)
  {
    listener.onResponse(response);
  }

  @Override
  protected Response<T> parseNetworkResponse(NetworkResponse response)
  {
    try
    {
      /**
       * 得到返回的数据
       */
      String jsonStr = new String(response.data, HttpHeaderParser.parseCharset(response.headers));
      /**
       * 转化成对象
       */
      return Response.success(gson.fromJson(jsonStr, clazz), HttpHeaderParser.parseCacheHeaders(response));
    } catch (UnsupportedEncodingException e)
    {
      return Response.error(new ParseError(e));
    } catch (JsonSyntaxException e)
    {
      return Response.error(new ParseError(e));
    }
  }
}

这里说一下，我在Header中放置了APP-key等数据，也就是说仅仅要我们这个请求发的都会有这几个值，大家开发app时肯定有非常多请求參数是须要每次都发往server校验的，能够在这里设置。

3、server代码：

package com.zhy.servelt;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class TestServlet extends HttpServlet
{
  public void doGet(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException
  {
    this.doPost(request, response);
  }

  public void doPost(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException
  {
    request.setCharacterEncoding("utf-8");

    String appKey = request.getHeader("APP-Key");
    String appSecret = request.getHeader("APP-Secret");

    String username = request.getHeader("username");
    String password = request.getHeader("password");

    if ("admin".equals(username) && "123".equals(password))
    {
      response.setContentType("text/plain;charset=utf-8");
      PrintWriter out = response.getWriter();
      out.print("{\"name\":\"鸿洋\",\"age\":32}");
      out.flush();

    }

  }

}

4、測试代码：

Map<String, String> appendHeader = new HashMap<String, String>();
    appendHeader.put("username", "admin");
    appendHeader.put("password", "123");

    String url = "http://172.27.35.1:8080/webTest/TestServlet";
    JsonRequestWithAuth<User> userRequest = new JsonRequestWithAuth<User>(url, User.class, new Listener<User>()
    {
      @Override
      public void onResponse(User response)
      {
        Log.e("TAG", response.toString());
      }
    }, appendHeader, null);

    newRequestQueue.add(userRequest);

Android Volley 之自己定义Request_数据_02