转自:http://blog.csdn.net/lmj623565791/article/details/24589837
今天群里一哥们需要自定义Volley的Request的例子,于是产生了这篇博客。关于Volley的介绍就不多说了,网上例子特别多。
Volley的所有的请求的超类型是Resuest,类结构如下图,所有我们常用的请求都是这个类的子类,那么我们自定义View肯定也是基于这个类的。
![](https://img-blog.csdn.net/20140427153839734?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvbG1qNjIzNTY1Nzkx/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center)
一些简单的用法实例:
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RequestQueue newRequestQueue = Volley.newRequestQueue(MainActivity.this);
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StringRequest stringRequest = new StringRequest("http://www.baidu.com", new Response.Listener<String>()
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{
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@Override
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public void onResponse(String response)
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{
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Log.e("TAG", response);
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}
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}, new Response.ErrorListener()
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{
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@Override
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public void onErrorResponse(VolleyError error)
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{
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Log.e("TAG", error.getMessage(), error);
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}
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});
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JsonObjectRequest jsonObjectRequest = new JsonObjectRequest("http://m.weather.com.cn/data/101010100.html",
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null, new Response.Listener<JSONObject>()
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{
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@Override
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public void onResponse(JSONObject response)
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{
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Log.e("TAG", response.toString());
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}
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}, new Response.ErrorListener()
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{
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@Override
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public void onErrorResponse(VolleyError error)
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{
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Log.e("TAG", error.getMessage(), error);
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}
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});
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ImageRequest imageRequest = new ImageRequest("http://imgt6.bdstatic.com/it/u=2,887966933&fm=19&gp=0.jpg",
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new Response.Listener<Bitmap>()
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{
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@Override
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public void onResponse(Bitmap response)
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{
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mImageView.setImageBitmap(response);
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}
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}, 0, 0, Config.RGB_565, null);
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newRequestQueue.add(stringRequest);
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newRequestQueue.add(imageRequest);
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newRequestQueue.add(jsonObjectRequest);
基本都是new一个请求,加入请求队列就行了。
好了,下面进入正题,如何自定义自己的Request,其实很简单,咱们打开StringRequest的源码:
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public StringRequest(int method, String url, Listener<String> listener,
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ErrorListener errorListener) {
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super(method, url, errorListener);
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mListener = listener;
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}
构造方法中指明访问的url,method,和回调的接口,毕竟我们要处理数据么。
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@Override
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protected Response<String> parseNetworkResponse(NetworkResponse response) {
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String parsed;
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try {
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parsed = new String(response.data, HttpHeaderParser.parseCharset(response.headers));
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} catch (UnsupportedEncodingException e) {
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parsed = new String(response.data);
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}
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return Response.success(parsed, HttpHeaderParser.parseCacheHeaders(response));
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}
最终给我们返回的数据就是parsed,比如我们返回的是json字符串,我们就可以在这添几行代码,把字符串转换成对象返回。(很重要的是,返回类型是咱们声明Request的时候定的,是个泛型)。
下面直接上例子:
例子是,通过客户端访问服务器,服务器对客户端进行身份校验后,返回JSON字符串,客户端直接拿到对象。
1、对象:
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package com.zhy.velloydemo;
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public class User
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{
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private String name;
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private int age;
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public String getName()
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{
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return name;
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}
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public void setName(String name)
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{
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this.name = name;
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}
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public int getAge()
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{
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return age;
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}
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public void setAge(int age)
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{
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this.age = age;
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}
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@Override
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public String toString()
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{
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return "User [name=" + name + ", age=" + age + "]";
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}
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}
2、自定义的Request
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package com.zhy.velloydemo;
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import java.io.UnsupportedEncodingException;
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import java.util.HashMap;
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import java.util.Map;
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import com.android.volley.AuthFailureError;
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import com.android.volley.NetworkResponse;
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import com.android.volley.ParseError;
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import com.android.volley.Request;
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import com.android.volley.Response;
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import com.android.volley.Response.ErrorListener;
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import com.android.volley.Response.Listener;
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import com.android.volley.toolbox.HttpHeaderParser;
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import com.google.gson.Gson;
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import com.google.gson.JsonSyntaxException;
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public class JsonRequestWithAuth<T> extends Request<T>
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{
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private final Gson gson = new Gson();
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private final Class<T> clazz;
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private final Listener<T> listener;
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private static Map<String, String> mHeader = new HashMap<String, String>();
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static
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{
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mHeader.put("APP-Key", "LBS-AAA");
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mHeader.put("APP-Secret", "ad12msa234das232in");
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}
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public JsonRequestWithAuth(String url, Class<T> clazz, Listener<T> listener, Map<String, String> appendHeader,
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ErrorListener errorListener)
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{
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super(Method.GET, url, errorListener);
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this.clazz = clazz;
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this.listener = listener;
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mHeader.putAll(appendHeader);
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}
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@Override
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public Map<String, String> getHeaders() throws AuthFailureError
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{
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return mHeader;
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}
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@Override
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protected void deliverResponse(T response)
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{
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listener.onResponse(response);
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}
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@Override
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protected Response<T> parseNetworkResponse(NetworkResponse response)
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{
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try
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{
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String jsonStr = new String(response.data, HttpHeaderParser.parseCharset(response.headers));
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return Response.success(gson.fromJson(jsonStr, clazz), HttpHeaderParser.parseCacheHeaders(response));
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} catch (UnsupportedEncodingException e)
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{
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return Response.error(new ParseError(e));
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} catch (JsonSyntaxException e)
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{
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return Response.error(new ParseError(e));
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}
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}
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}
这里说一下,我在Header中放置了APP-key等数据,也就是说只要我们这个请求发的都会有这几个值,大家开发app时肯定有很多请求参数是需要每次都发往服务器校验的,可以在这里设置。
3、服务器代码:
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package com.zhy.servelt;
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import java.io.IOException;
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import java.io.PrintWriter;
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import javax.servlet.ServletException;
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import javax.servlet.ServletOutputStream;
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import javax.servlet.http.HttpServlet;
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import javax.servlet.http.HttpServletRequest;
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import javax.servlet.http.HttpServletResponse;
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public class TestServlet extends HttpServlet
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{
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public void doGet(HttpServletRequest request, HttpServletResponse response)
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throws ServletException, IOException
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{
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this.doPost(request, response);
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}
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public void doPost(HttpServletRequest request, HttpServletResponse response)
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throws ServletException, IOException
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{
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request.setCharacterEncoding("utf-8");
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String appKey = request.getHeader("APP-Key");
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String appSecret = request.getHeader("APP-Secret");
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String username = request.getHeader("username");
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String password = request.getHeader("password");
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if ("admin".equals(username) && "123".equals(password))
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{
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response.setContentType("text/plain;charset=utf-8");
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PrintWriter out = response.getWriter();
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out.print("{\"name\":\"鸿洋\",\"age\":32}");
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out.flush();
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}
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}
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}
4、测试代码:
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Map<String, String> appendHeader = new HashMap<String, String>();
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appendHeader.put("username", "admin");
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appendHeader.put("password", "123");
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String url = "http://172.27.35.1:8080/webTest/TestServlet";
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JsonRequestWithAuth<User> userRequest = new JsonRequestWithAuth<User>(url, User.class, new Listener<User>()
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{
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@Override
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public void onResponse(User response)
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{
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Log.e("TAG", response.toString());
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}
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}, appendHeader, null);
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newRequestQueue.add(userRequest);
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可以看到我们使用自定义请求实现了我们上述的需求,这里还要说一下,这个例子有两个目的:
1、自定义Request其实很简单,如果不需要Header直接不用复写getHeader那个方法。
2、我们可以利用Header传递一些固定的参数,这比对安全比较高的系统,每次拼一堆xml去服务器,代码能简洁很多,当然了,注意信息安全。
最后补充一下:
哥们问这句什么意思:HttpHeaderParser.parseCharset(response.headers)其实就是获取我们的返回流的编码,也就是我上面服务器设置的utf-8
对于请求的Header和响应Header理解,随便打开个网站,使用浏览器的工具查看一下,每个请求都会包含这两个Header数据。
好了,就到这里~各位留个言、赞一个算对我们的支持~