学步园

在Android的网络开发中，会常用到Http请求，为了避免代码的重复编写，我们要学会封装一个Http请求类。

方法1：

public class Network {
public String  makeHttpRequest(String url, 
List<NameValuePair> params) {
try{
 .............

}catch (JSONException e) {
         e.printStackTrace();   
 }
    }
}

首先在makeHttpResquest 的方法中建立HTTP Post联机

DefaultHttpClient httpClient = new DefaultHttpClient();

new 一个新的httppost对象

HttpPost httpPost = new HttpPost(url);

设置请求时候的编码格式

httpPost.setEntity(new UrlEncodedFormEntity(params,HTTP.UTF_8));

执行请求

HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();        

利用BufferedReader获取输入流

BufferedReader reader = new BufferedReader(new InputStreamReader(is, "UTF-8"));
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
        sb.append(line + "\n");
        }
is.close();

return line;

当然这中间要捕获各种异常。最后当我们需要用的时候 实例化出一个就行了。

Network net=new Network();
net.makeHttpRequest(url_up,params);

方法2：

只对url进行请求,这个实例在我用Dom解析XML文件时候用到了:

public String getXmlFromUrl(String url) {
        String xml = null;
        try {
            // defaultHttpClient
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);
            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            xml = EntityUtils.toString(httpEntity,"utf-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        // return XML
        return xml;
    }
    

跟方法一不同的是，这里用到了 EntityUtils 这个类，直接获得httpEntity。