Android网络编程之HttpUrlConnection、HttpClient

2019-11-09 15:04:36

字体：大中小

来源：转载

供稿：网友

这篇文章我们共同来学习HttpUrlConnection以及HttpClient.

首先，我们来了解一下通过Http协议，Android APP客户端与服务器交互的基本知识

客户端->服务器：客户端向服务器发送请求主要包含以下信息：请求的Url地址、请求头以及可选的请求体

服务器->客户端：服务器接收到客户端发来的请求后，会进行相应的处理，并向客户端输出信息，输出的信息包含响应头和响应体。

Http协议支持的操作有GET、POST、HEAD、PUT、TRACE、OPTIONS、DELETE，其中最常用的还是GET和POST。

GET vs POST

GET:

1、GET请求可以被缓存

2、当用GET请求发送键值对时，键值对会随着URL一起发送的

3、GET请求的安全性很低，不能用GET请求发送敏感的信息

4、GET请求发送数据是有长度限制的（URL不能超过2048个字符）

5、由于GET请求较低的安全性，我们不应该用GET请求去执行增加、删除、修改等操作，应该只用它来获取数据

POST:

1、POST请求从不会被缓存

2、POST请求的URL中追加键值对参数，这些键值对参数不是随着URL发送的，而是被放入到请求体中发送的

3、应该用POST请求发送敏感信息，而不是用GET

4、理论上POST请求不存在发送数据大小的限制

5、当执行增加、删除、修改等操作时，应该使用POST请求，而不应该使用GET请求

HttpURLConnection vs HttpClient

在Android 2.2版本以及之前的版本使用HttpClient是较好的选择，而在Android 2.3版本以及以后的版本，HttpURLConnection则是最佳的选择。

原因：Android 2.2之前（包括2.2），HttpURLConnection一直存在着一些令人厌烦的bug。而HttpClient是Apache用于发送http请求的客户端，其提供了强大的API支持，而且基本没有什么bug。

Android 2.2之后，HttpURLConnection的bug得到解决，并且其API简单，体积较小，也能够满足大部分的需求，因此非常适合Android项目。相反，HttpClient由于其太过复杂，Android团队在保持向后兼容的情况下，很难对其进行增强，另外从Android 6.0版本开始，HttpClient库被移除了。

HttpURLConnection使用

GET方式：

PRivate HttpURLConnection getHttpURLConnection(String url) {        HttpURLConnection httpURLConnection = null;        try {            URL mUrl = new URL(url);            httpURLConnection = (HttpURLConnection) mUrl.openConnection();            httpURLConnection.setConnectTimeout(15000);  //设置连接超时时间             httpURLConnection.setReadTimeout(15000);  //设置读取超时时间             httpURLConnection.setRequestMethod("GET");  //设置请求参数，也可以不设置，默认为GET             httpURLConnection.setRequestProperty("Connection", "Keep-Alive");  //添加Header            httpURLConnection.setDoInput(true);  //接收输入流。httpURLConnection默认也支持从服务端读取结果流，所以此设置也可以省略             httpURLConnection.setDoOutput(true);        } catch (IOException e) {            e.printStackTrace();        }        return httpURLConnection;    }public void useHttpUrlConnectionGet(String url){    InputStream inputStream = null;    HttpURLConnection httpURLConnection = getHttpURLConnection(url);    try {        httpURLConnection.connect();  //通过调用connect方法建立TCP连接，但是并未真正获取数据。该方法也不必显式调用，当调用getInputStream方法时内部也会自动调用connect方法的        inputStream = httpURLConnection.getInputStream();  //调用getInputStream方法后，服务端才会收到请求，并阻塞式地接收服务端返回的数据        int code = httpURLConnection.getResponseCode();        String response = converStreamToString(inputStream);        Log.i("Debug", "请求状态码:" + code + "/n请求结果/n" + response);        inputStream.close();    } catch (IOException e) {        e.printStackTrace();    }}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 response = sb.toString();    return response;}
POST方式：
private HttpURLConnection getHttpURLConnection(String url) {        HttpURLConnection httpURLConnection = null;        try {            URL mUrl = new URL(url);            httpURLConnection = (HttpURLConnection) mUrl.openConnection();            httpURLConnection.setConnectTimeout(15000);  //设置连接超时时间             httpURLConnection.setReadTimeout(15000);  //设置读取超时时间             httpURLConnection.setRequestMethod("POST");  //设置请求参数            httpURLConnection.setRequestProperty("Connection", "Keep-Alive");  //添加Header            httpURLConnection.setDoInput(true);  //接收输入流。httpURLConnection默认也支持从服务端读取结果流，所以此设置也可以省略             httpURLConnection.setDoOutput(true);        } catch (IOException e) {            e.printStackTrace();        }        return httpURLConnection;    }private void postParams(OutputStream outputStream, List<NameValuePair>paramsList) throws IOException {    StringBuilder stringBuilder = new StringBuilder();    for (NameValuePair pair:paramsList) {        if (!TextUtils.isEmpty(stringBuilder))        {            stringBuilder.append("&");        }        stringBuilder.append(URLEncoder.encode(pair.getName(), "UTF-8"));        stringBuilder.append("=");        stringBuilder.append(URLEncoder.encode(pair.getValue(), "UTF-8"));    }    BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));    writer.write(stringBuilder.toString());    writer.flush();    writer.close();}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 response = sb.toString();    return response;}public void useHttpUrlConnectionPost(String url){    InputStream inputStream = null;    HttpURLConnection httpURLConnection = getHttpURLConnection(url);    List<NameValuePair> postParams = new ArrayList<>();    //要传递的参数    postParams.add(new BasicNameValuePair("username", "moon"));    postParams.add(new BasicNameValuePair("passWord", "123"));    try {        postParams(httpURLConnection.getOutputStream(), postParams);        httpURLConnection.connect();  //通过调用connect方法建立TCP连接，但是并未真正获取数据。该方法也不必显式调用，当调用getInputStream方法时内部也会自动调用connect方法的        inputStream = httpURLConnection.getInputStream();  //调用getInputStream方法后，服务端才会收到请求，并阻塞式地接收服务端返回的数据        int code = httpURLConnection.getResponseCode();        String response = converStreamToString(inputStream);        Log.i("Debug", "请求状态码:" + code + "/n请求结果/n" + response);        inputStream.close();    } catch (IOException e) {        e.printStackTrace();    }}
HttpClient使用
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 response = sb.toString();    return response;}private HttpClient createHttpClient() {    HttpParams httpParams = new BasicHttpParams();    HttpConnectionParams.setConnectionTimeout(httpParams, 15000);  //设置连接超时时间    HttpConnectionParams.setSoTimeout(httpParams, 15000);  //设置请求超时时间    HttpConnectionParams.setTcpNoDelay(httpParams, true);    HttpProtocolParams.setVersion(httpParams, HttpVersion.HTTP_1_1);    HttpProtocolParams.setContentCharset(httpParams, HTTP.UTF_8);    HttpProtocolParams.setUseExpectContinue(httpParams, true);  //持续握手    HttpClient httpClient = new DefaultHttpClient(httpParams);    return httpClient;}
GET方式：
public void useHttpClientGet(String url){    HttpGet httpGet = new HttpGet(url);    httpGet.addHeader("Connection", "Keep-Alive");    HttpClient httpClient = createHttpClient();    try {        HttpResponse httpResponse = httpClient.execute(httpGet);        HttpEntity httpEntity = httpResponse.getEntity();        int code = httpResponse.getStatusLine().getStatusCode();        if (null != httpEntity)        {            InputStream inputStream = httpEntity.getContent();            String response = converStreamToString(inputStream);            Log.i("Debug", "请求状态码：" + code + "/n请求结果：/n" + response);            inputStream.close();        }    } catch (IOException e) {        e.printStackTrace();    }}POST方式：
private void useHttpClientPost(String url) {    HttpPost httpPost = new HttpPost(url);    httpPost.addHeader("Connection", "Keep-Alive");    HttpClient httpClient = createHttpClient();    List<NameValuePair> postParams = new ArrayList<>();    //要传递的参数    postParams.add(new BasicNameValuePair("username", "moon"));    postParams.add(new BasicNameValuePair("password", "123"));    try {        httpPost.setEntity(new UrlEncodedFormEntity(postParams));        HttpResponse httpResponse = httpClient.execute(httpPost);        HttpEntity httpEntity = httpResponse.getEntity();        int code = httpResponse.getStatusLine().getStatusCode();        if (null != httpEntity)        {            InputStream inputStream = httpEntity.getContent();            String response = converStreamToString(inputStream);            Log.i("Debug", "请求状态码：" + code + "/n请求结果：/n" + response);            inputStream.close();        }    } catch (UnsupportedEncodingException e) {        e.printStackTrace();    } catch (ClientProtocolException e) {        e.printStackTrace();    } catch (IOException e) {        e.printStackTrace();    }}