HttpClient与HttpURLConnection

一、HttpClient

Android SDK中包含了HttpClient，在Android6.0版本直接删除了HttpClient类库，如果仍想使用则解决方法是：

• 如果使用的是eclipse则在libs中加入org.apache.http.legacy.jar
  这个jar包在：**sdk\platforms\android-23\optional目录中（需要下载android
  6.0的SDK）
• 如果使用的是android studio则 在相应的module下的build.gradle中加入：

android{

	useLibrary 'org.apache.http.legacy'

}

HttpClient的GET请求

首先我们来用DefaultHttpClient类来实例化一个HttpClient，并配置好默认的请求参数：

//创建HttpClient

private HttpClient createHttpClient() {

HttpParams mDefaultHttpParams = new BasicHttpParams();

//设置连接超时

HttpConnectionParams.setConnectionTimeout(mDefaultHttpParams, 15000);

//设置请求超时

HttpConnectionParams.setSoTimeout(mDefaultHttpParams, 15000);

HttpConnectionParams.setTcpNoDelay(mDefaultHttpParams, true);

HttpProtocolParams.setVersion(mDefaultHttpParams, HttpVersion.HTTP_1_1);

HttpProtocolParams.setContentCharset(mDefaultHttpParams, HTTP.UTF_8);

//持续握手

HttpProtocolParams.setUseExpectContinue(mDefaultHttpParams, true);

HttpClient mHttpClient = new DefaultHttpClient(mDefaultHttpParams);

return mHttpClient;

}

接下来创建HttpGet和HttpClient，请求网络并得到HttpResponse，并对HttpResponse进行处理：

private void useHttpClientGet(String url) {

HttpGet mHttpGet = new HttpGet(url);

mHttpGet.addHeader("Connection", "Keep-Alive");

try {

HttpClient mHttpClient = createHttpClient();

HttpResponse mHttpResponse = mHttpClient.execute(mHttpGet);

HttpEntity mHttpEntity = mHttpResponse.getEntity();

int code = mHttpResponse.getStatusLine().getStatusCode();

if (null != mHttpEntity) {

InputStream mInputStream = mHttpEntity.getContent();

String respose = converStreamToString(mInputStream);

Log.i("wangshu", "请求状态码:" + code + "\n请求结果:\n" + respose);

mInputStream.close();

}

} catch (IOException e) {

e.printStackTrace();

}

}

converStreamToString方法将请求结果转换成String类型：

private String converStreamToString(InputStream is) throws IOException {
      BufferedReader reader = new BufferedReader(new InputStreamReader(is));
      StringBuffer sb = new StringBuffer();
      String line = null;
      while ((line = reader.readLine()) != null) {
         sb.append(line + "\n");
      }
      String respose = sb.toString();
      return respose;
}

最后我们开启线程访问百度：

new Thread(new Runnable() {
	@Override
	public void run() {
      		useHttpClientGet("http://www.baidu.com");
      	}
}).start();
请求的返回结果，请求状态码为200，结果就是个html页，这里只截取了部分html代码：

GET请求的参数暴露在URL中，这有些不大妥当，而且URL的长度也有限制：长度在2048字符之内，在HTTP 1.1后URL长度才没有限制。一般情况下POST可以替代GET，接下来我们来看看HttpClient的POST请求。

HttpClient的POST请求
post请求和get类似就是需要配置要传递的参数：
private void useHttpClientPost(String url) {
   HttpPost mHttpPost = new HttpPost(url);
   mHttpPost.addHeader("Connection", "Keep-Alive");
   try {
      HttpClient mHttpClient = createHttpClient();
      List<NameValuePair> postParams = new ArrayList<>();
      //要传递的参数
      postParams.add(new BasicNameValuePair("username", "moon"));
      postParams.add(new BasicNameValuePair("password", "123"));
      mHttpPost.setEntity(new UrlEncodedFormEntity(postParams));
      HttpResponse mHttpResponse = mHttpClient.execute(mHttpPost);
      HttpEntity mHttpEntity = mHttpResponse.getEntity();
      int code = mHttpResponse.getStatusLine().getStatusCode();
      if (null != mHttpEntity) {
         InputStream mInputStream = mHttpEntity.getContent();
         String respose = converStreamToString(mInputStream);
         Log.i("wangshu", "请求状态码:" + code + "\n请求结果:\n" + respose);
         mInputStream.close();
      }
   } catch (IOException e) {
      e.printStackTrace();
   }
}
因为我们要发送POST请求，所以在UrlConnManager类中再写一个postParams()方法用来组织一下请求参数并将请求参数写入到输出流中：

public static void postParams(OutputStream output,List<NameValuePair>paramsList) throws IOException{
   StringBuilder mStringBuilder=new StringBuilder();
   for (NameValuePair pair:paramsList){
      if(!TextUtils.isEmpty(mStringBuilder)){
         mStringBuilder.append("&");
      }
      mStringBuilder.append(URLEncoder.encode(pair.getName(),"UTF-8"));
      mStringBuilder.append("=");
      mStringBuilder.append(URLEncoder.encode(pair.getValue(),"UTF-8"));
   }
   BufferedWriter writer=new BufferedWriter(new OutputStreamWriter(output,"UTF-8"));
   writer.write(mStringBuilder.toString());
   writer.flush();
   writer.close();
}

接下来我们添加请求参数，调用postParams()方法将请求的参数组织好传给HttpURLConnection的输出流，请求连接并处理返回的结果：

private void useHttpUrlConnectionPost(String url) {
   InputStream mInputStream = null;
   HttpURLConnection mHttpURLConnection = UrlConnManager.getHttpURLConnection(url);
   try {
      List<NameValuePair> postParams = new ArrayList<>();
      //要传递的参数
      postParams.add(new BasicNameValuePair("username", "moon"));
      postParams.add(new BasicNameValuePair("password", "123"));
      UrlConnManager.postParams(mHttpURLConnection.getOutputStream(), postParams);
      mHttpURLConnection.connect();
      mInputStream = mHttpURLConnection.getInputStream();
      int code = mHttpURLConnection.getResponseCode();
      String respose = converStreamToString(mInputStream);
      Log.i("wangshu", "请求状态码:" + code + "\n请求结果:\n" + respose);
      mInputStream.close();
   } catch (IOException e) {
      e.printStackTrace();
   }
}

最后开启线程请求网络：

private void useHttpUrlConnectionGetThread() {
      new Thread(new Runnable() {
	@Override
	public void run() {
      		useHttpUrlConnectionPost("http://www.baidu.com");
      	}
      }).start();
}