zoukankan      html  css  js  c++  java
  • WCF and Android: Part II

    Introduction

    The first part of this series WCF and Android Part I  describes how to setup a JSON REST WCF service. This post shows how to consume this service using Android.

    Simple Webservice invokation

    Android already comes with a ready to use HTTP-client located in the package org.apache.http.client.

    HttpParams httpParams = new BasicHttpParams();
    ThreadSafeClientConnManager connMgr = new ThreadSafeClientConnManager(httpParams, new SchemeRegistry()); 
    HttpClient client = new DefaultHttpClient(connMgr, httpParams);

    Therefore a simple webservice invocation looks as follows:

    HttpGet get = new HttpGet("http://requesturi/method");
    HttpResponse response = client.execute(get);
    HttpEntity entity = response.getEntity();

    JSON serialization

    Simple parameters can be passed in the URL but more complex objects are likely passed in the http body using the POST method. For modern and fast webservices  it is common to use JSON for data serialization. Android has some JSON features built in but Google GSON  provides a very flexible way to serialize and deserialize JSON objects, even for arbitrary object types. Download the library and include it in your build-path.  The first step is to create a GsonBuilder, where some de-/serialization options can be specified.

    GsonBuilder gson = new GsonBuilder()
      .registerTypeAdapter(Date.class, new DateSerializer())
      .serializeNulls()
      .setDateFormat(DateFormat.LONG)
      .setFieldNamingPolicy(FieldNamingPolicy.UPPER_CAMEL_CASE)
      .setPrettyPrinting()
      .create();

    Beside some others this example attaches a custom DateSerializer (thanks to Benjii Me)  to be able to read WCF serialized DateTime values. That's all you need to do. Serialization now looks as follows:

    String jsonString = gson.toJson(myObject);

    and deserialization very similar:

    MyObjectType myObj = gson.fromJson(jsonString, MyObjectType.class);

    Webservice invokation with JSON-POST arguments

    Every webservice requests only allows a single JSON object in the HTTP-body, therefore if multiple arguments are required they need to be wrapped  in a single JSON object and the WCF service contract needs to be aware of it (BodyStyle=WebMessageBodyStyle.WrappedRequest).

    Once the webservice is aware of the BodyStyle the client side is quite straight forward.  Create a Map from name to object, add all objects with the name of the webservice parameter and serialize the whole map:

    HashMap<String, Object> postParameters = new HashMap<String, Object>();
    postParameters.put("param1", objParam1);
    postParameters.put("param2", objParam2);
    postParameters.put("param3", objParam3);
    gson.toJson(postParameters);

    A complete webservice call looks as follows:

    HttpPost post = new HttpPost(requestUri);
    post.setHeader("Accept", "application/json");
    post.setHeader("Content-type", "application/json");
     
    String jsonParameters = gson.toJson(postParameters);
    post.setEntity(new StringEntity(jsonParameters));      
          
    HttpResponse response = client.execute(post);
    HttpEntity entity = response.getEntity();

    Reading the webservice response

    Assuming that the webservice was called successful a HttpEntity is returned.  This entity can be easily converted to the corresponding object as shown above. The only difficulty is to convert the HttpEntity to a JSON string:

    gson.fromJson(convertStreamToString(entity.getContent()), MyObjectType.class);
     
    public static String convertStreamToString(InputStream is) {
    BufferedReader reader = new BufferedReader(new InputStreamReader(is));
    StringBuilder sb = new StringBuilder();
     
    String line = null;
    try {
      while ((line = reader.readLine()) != null) {
      sb.append(line + "\n");
      }
    } catch (IOException e) {
      e.printStackTrace();
    } finally {
      try {
       is.close();
      } catch (IOException e) {
       e.printStackTrace();
      }
    }
    return sb.toString();
    }

    原文:http://www.codeproject.com/Articles/361107/WCF-and-Android-Part-II?msg=4358846#xx4358846xx
  • 相关阅读:
    MODIS系列之NDVI(MOD13Q1)三:.jdk文件配置+MRT安装
    MODIS系列之NDVI(MOD13Q1)二:modis数据相关信息
    MODIS系列之NDVI(MOD13Q1)一:数据下载(二)基于FTP
    MODIS系列之NDVI(MOD13Q1)一:数据下载(一)基于插件
    Python 1基础语法四(数字类型、输入输出汇总和命令行参数)
    Python 1基础语法三(变量和标识符的区别)
    mysql Can't connet MySQL server to '@localhost'
    使用get传参的时候,参数在后头获取不到或者出现别的错误。
    搭建nexus后,进入首页的时候出现warning: Could not connect to Nexus.错误
    在配置dubbo框架的时候出现dubbo:application标签无法识别问题。
  • 原文地址:https://www.cnblogs.com/ttssrs/p/2674045.html
Copyright © 2011-2022 走看看