Android 使用OkHttp

其他 2020-09-21 10:35:58 阅读次数: 0

为什么需要一个HTTP库

Android系统提供了两种HTTP通信类，HttpURLConnection和HttpClient。

关于HttpURLConnection和HttpClient的选择>>官方博客

尽管Google在大部分安卓版本中推荐使用HttpURLConnection，但是这个类相比HttpClient实在是太难用，太弱爆了。

OkHttp是一个相对成熟的解决方案，据说Android4.4的源码中可以看到HttpURLConnection已经替换成OkHttp实现了。所以我们更有理由相信OkHttp的强大。

入门

官方资料

使用范围

OkHttp支持Android 2.3及其以上版本。 对于Java, JDK1.7以上。

jar包准备

官方介绍页面有链接位置。这里把下载链接也写在下面。

OkHttp

Okio

基本使用

HTTP GET

<code style="padding: 0.3em; font-family: Monaco, Menlo, Consolas, 'Courier New', monospace; border: 0px; display: block; overflow-y: auto;">OkHttpClient client = <span class="keyword" style="font-weight: bold;">new</span> OkHttpClient();

String run(String url) throws IOException {
<span class="indent">  </span>Request request = <span class="keyword" style="font-weight: bold;">new</span> Request.Builder().url(url).build();
<span class="indent">  </span>Response response = client.newCall(request).execute();
<span class="indent">  </span><span class="keyword" style="font-weight: bold;">if</span> (response.isSuccessful()) {
<span class="indent">  </span><span class="indent">  </span><span class="keyword" style="font-weight: bold;">return</span> response.body().<span class="keyword" style="font-weight: bold;">string</span>();
<span class="indent">  </span>} <span class="keyword" style="font-weight: bold;">else</span> {
<span class="indent">  </span><span class="indent">  </span><span class="keyword" style="font-weight: bold;">throw</span> <span class="keyword" style="font-weight: bold;">new</span> IOException(<span class="string" style="color: rgb(221, 17, 68);">"Unexpected code "</span> + response);
<span class="indent">  </span>}
}</code>

Request是OkHttp中访问的请求，Builder是辅助类。Response即OkHttp中的响应。

Response类：

<code style="padding: 0.3em; font-family: Monaco, Menlo, Consolas, 'Courier New', monospace; border: 0px; display: block; overflow-y: auto;"><span class="keyword" style="font-weight: bold;">public</span> boolean isSuccessful()
Returns <span class="keyword" style="font-weight: bold;">true</span> <span class="keyword" style="font-weight: bold;">if</span> the code <span class="keyword" style="font-weight: bold;">is</span> <span class="keyword" style="font-weight: bold;">in</span> [<span class="number" style="color: rgb(0, 153, 153);">200.</span><span class="number" style="color: rgb(0, 153, 153);">.300</span>), which means the request was successfully received, understood, and accepted.</code>

response.body()返回ResponseBody类

可以方便的获取string

<code style="padding: 0.3em; font-family: Monaco, Menlo, Consolas, 'Courier New', monospace; border: 0px; display: block; overflow-y: auto;"><span class="keyword" style="font-weight: bold;">public</span> final String <span class="keyword" style="font-weight: bold;">string</span>() throws IOException
Returns the response <span class="keyword" style="font-weight: bold;">as</span> a <span class="keyword" style="font-weight: bold;">string</span> decoded with the charset of the Content-Type header. If that header <span class="keyword" style="font-weight: bold;">is</span> either absent or lacks a charset, <span class="keyword" style="font-weight: bold;">this</span> will attempt to decode the response body <span class="keyword" style="font-weight: bold;">as</span> UTF-<span class="number" style="color: rgb(0, 153, 153);">8.</span>
Throws:
IOException</code>

当然也能获取到流的形式：

<code style="padding: 0.3em; font-family: Monaco, Menlo, Consolas, 'Courier New', monospace; border: 0px; display: block; overflow-y: auto;"><span class="keyword" style="font-weight: bold;">public</span> <span class="keyword" style="font-weight: bold;">final</span> InputStream byteStream()</code>

HTTP POST

POST提交Json数据

<code style="padding: 0.3em; font-family: Monaco, Menlo, Consolas, 'Courier New', monospace; border: 0px; display: block; overflow-y: auto;"><span class="keyword" style="font-weight: bold;">public</span> <span class="keyword" style="font-weight: bold;">static</span> <span class="keyword" style="font-weight: bold;">final</span> MediaType JSON = MediaType.parse(<span class="string" style="color: rgb(221, 17, 68);">"application/json; charset=utf-8"</span>);
OkHttpClient client = <span class="keyword" style="font-weight: bold;">new</span> OkHttpClient();
String post(String url, String json) <span class="keyword" style="font-weight: bold;">throws</span> IOException {
 	RequestBody body = RequestBody.create(JSON, json);
  	Request request = <span class="keyword" style="font-weight: bold;">new</span> Request.Builder()
<span class="indent">  </span>  .url(url)
<span class="indent">  </span>  .post(body)
<span class="indent">  </span>  .build();
  	Response response = client.newCall(request).execute();
<span class="indent">  </span>f (response.isSuccessful()) {
<span class="indent">  </span><span class="indent">  </span><span class="keyword" style="font-weight: bold;">return</span> response.body().string();
<span class="indent">  </span>} <span class="keyword" style="font-weight: bold;">else</span> {
<span class="indent">  </span><span class="indent">  </span><span class="keyword" style="font-weight: bold;">throw</span> <span class="keyword" style="font-weight: bold;">new</span> IOException(<span class="string" style="color: rgb(221, 17, 68);">"Unexpected code "</span> + response);
<span class="indent">  </span>}
}</code>

使用Request的post方法来提交请求体RequestBody

POST提交键值对

很多时候我们会需要通过POST方式把键值对数据传送到服务器。 OkHttp提供了很方便的方式来做这件事情。

<code style="padding: 0.3em; font-family: Monaco, Menlo, Consolas, 'Courier New', monospace; border: 0px; display: block; overflow-y: auto;">OkHttpClient client = <span class="keyword" style="font-weight: bold;">new</span> OkHttpClient();
String post(String url, String json) throws IOException {

 	RequestBody formBody = <span class="keyword" style="font-weight: bold;">new</span> FormEncodingBuilder()
<span class="indent">  </span>.add(<span class="string" style="color: rgb(221, 17, 68);">"platform"</span>, <span class="string" style="color: rgb(221, 17, 68);">"android"</span>)
<span class="indent">  </span>.add(<span class="string" style="color: rgb(221, 17, 68);">"name"</span>, <span class="string" style="color: rgb(221, 17, 68);">"bug"</span>)
<span class="indent">  </span>.add(<span class="string" style="color: rgb(221, 17, 68);">"subject"</span>, <span class="string" style="color: rgb(221, 17, 68);">"XXXXXXXXXXXXXXX"</span>)
<span class="indent">  </span>.build();

  	Request request = <span class="keyword" style="font-weight: bold;">new</span> Request.Builder()
      .url(url)
      .post(body)
      .build();

  	Response response = client.newCall(request).execute();
<span class="indent">  </span><span class="keyword" style="font-weight: bold;">if</span> (response.isSuccessful()) {
<span class="indent">  </span>    <span class="keyword" style="font-weight: bold;">return</span> response.body().<span class="keyword" style="font-weight: bold;">string</span>();
<span class="indent">  </span>} <span class="keyword" style="font-weight: bold;">else</span> {
<span class="indent">  </span>    <span class="keyword" style="font-weight: bold;">throw</span> <span class="keyword" style="font-weight: bold;">new</span> IOException(<span class="string" style="color: rgb(221, 17, 68);">"Unexpected code "</span> + response);
<span class="indent">  </span>}
}</code>

总结

通过上面的例子我们可以发现，OkHttp在很多时候使用都是很方便的，而且很多代码也有重复，因此特地整理了下面的工具类。 注意：

  • OkHttp官方文档并不建议我们创建多个OkHttpClient，因此全局使用一个。 如果有需要，可以使用clone方法，再进行自定义。这点在后面的高级教程里会提到。
  • enqueue为OkHttp提供的异步方法，入门教程中并没有提到，后面的高级教程里会有解释。
<code style="padding: 0.3em; font-family: Monaco, Menlo, Consolas, 'Courier New', monospace; border: 0px; display: block; overflow-y: auto;"><span class="keyword" style="font-weight: bold;">import</span> java.io.IOException;
<span class="keyword" style="font-weight: bold;">import</span> java.util.List;
<span class="keyword" style="font-weight: bold;">import</span> java.util.concurrent.TimeUnit;
<span class="keyword" style="font-weight: bold;">import</span> org.apache.http.client.utils.URLEncodedUtils;
<span class="keyword" style="font-weight: bold;">import</span> org.apache.http.message.BasicNameValuePair;
<span class="keyword" style="font-weight: bold;">import</span> cn.wiz.sdk.constant.WizConstant;
<span class="keyword" style="font-weight: bold;">import</span> com.squareup.okhttp.Callback;
<span class="keyword" style="font-weight: bold;">import</span> com.squareup.okhttp.OkHttpClient;
<span class="keyword" style="font-weight: bold;">import</span> com.squareup.okhttp.Request;
<span class="keyword" style="font-weight: bold;">import</span> com.squareup.okhttp.Response; 
 
<span class="keyword" style="font-weight: bold;">public</span> <span class="class" style="color: rgb(68, 85, 136); font-weight: bold;"><span class="keyword" style="color: rgb(51, 51, 51);">class</span> <span class="title">OkHttpUtil</span> {</span>
<span class="indent">  </span><span class="keyword" style="font-weight: bold;">private</span> <span class="keyword" style="font-weight: bold;">static</span> <span class="keyword" style="font-weight: bold;">final</span> OkHttpClient mOkHttpClient = <span class="keyword" style="font-weight: bold;">new</span> OkHttpClient();
<span class="indent">  </span><span class="keyword" style="font-weight: bold;">static</span>{
<span class="indent">  </span><span class="indent">  </span>mOkHttpClient.setConnectTimeout(<span class="number" style="color: rgb(0, 153, 153);">30</span>, TimeUnit.SECONDS);
<span class="indent">  </span>}
<span class="indent">  </span><span class="javadoc" style="color: rgb(153, 153, 136); font-style: italic;">/**
<span class="indent">  </span> * 该不会开启异步线程。
<span class="indent">  </span> * <span class="javadoctag">@param</span> request
<span class="indent">  </span> * <span class="javadoctag">@return</span>
<span class="indent">  </span> * <span class="javadoctag">@throws</span> IOException
<span class="indent">  </span> */</span>
<span class="indent">  </span><span class="keyword" style="font-weight: bold;">public</span> <span class="keyword" style="font-weight: bold;">static</span> Response execute(Request request) <span class="keyword" style="font-weight: bold;">throws</span> IOException{
<span class="indent">  </span><span class="indent">  </span><span class="keyword" style="font-weight: bold;">return</span> mOkHttpClient.newCall(request).execute();
<span class="indent">  </span>}
<span class="indent">  </span><span class="javadoc" style="color: rgb(153, 153, 136); font-style: italic;">/**
<span class="indent">  </span> * 开启异步线程访问网络
<span class="indent">  </span> * <span class="javadoctag">@param</span> request
<span class="indent">  </span> * <span class="javadoctag">@param</span> responseCallback
<span class="indent">  </span> */</span>
<span class="indent">  </span><span class="keyword" style="font-weight: bold;">public</span> <span class="keyword" style="font-weight: bold;">static</span> <span class="keyword" style="font-weight: bold;">void</span> enqueue(Request request, Callback responseCallback){
<span class="indent">  </span><span class="indent">  </span>mOkHttpClient.newCall(request).enqueue(responseCallback);
<span class="indent">  </span>}
<span class="indent">  </span><span class="javadoc" style="color: rgb(153, 153, 136); font-style: italic;">/**
<span class="indent">  </span> * 开启异步线程访问网络, 且不在意返回结果（实现空callback）
<span class="indent">  </span> * <span class="javadoctag">@param</span> request
<span class="indent">  </span> */</span>
<span class="indent">  </span><span class="keyword" style="font-weight: bold;">public</span> <span class="keyword" style="font-weight: bold;">static</span> <span class="keyword" style="font-weight: bold;">void</span> enqueue(Request request){
<span class="indent">  </span><span class="indent">  </span>mOkHttpClient.newCall(request).enqueue(<span class="keyword" style="font-weight: bold;">new</span> Callback() {
<span class="indent">  </span><span class="indent">  </span><span class="indent">  </span>
<span class="indent">  </span><span class="indent">  </span><span class="indent">  </span><span class="annotation">@Override</span>
<span class="indent">  </span><span class="indent">  </span><span class="indent">  </span><span class="keyword" style="font-weight: bold;">public</span> <span class="keyword" style="font-weight: bold;">void</span> onResponse(Response arg0) <span class="keyword" style="font-weight: bold;">throws</span> IOException {
<span class="indent">  </span><span class="indent">  </span><span class="indent">  </span><span class="indent">  </span>
<span class="indent">  </span><span class="indent">  </span><span class="indent">  </span>}
<span class="indent">  </span><span class="indent">  </span><span class="indent">  </span>
<span class="indent">  </span><span class="indent">  </span><span class="indent">  </span><span class="annotation">@Override</span>
<span class="indent">  </span><span class="indent">  </span><span class="indent">  </span><span class="keyword" style="font-weight: bold;">public</span> <span class="keyword" style="font-weight: bold;">void</span> onFailure(Request arg0, IOException arg1) {
<span class="indent">  </span><span class="indent">  </span><span class="indent">  </span><span class="indent">  </span>
<span class="indent">  </span><span class="indent">  </span><span class="indent">  </span>}
<span class="indent">  </span><span class="indent">  </span>});
<span class="indent">  </span>}
<span class="indent">  </span><span class="keyword" style="font-weight: bold;">public</span> <span class="keyword" style="font-weight: bold;">static</span> String getStringFromServer(String url) <span class="keyword" style="font-weight: bold;">throws</span> IOException{
<span class="indent">  </span><span class="indent">  </span>Request request = <span class="keyword" style="font-weight: bold;">new</span> Request.Builder().url(url).build();
<span class="indent">  </span><span class="indent">  </span>Response response = execute(request);
<span class="indent">  </span><span class="indent">  </span><span class="keyword" style="font-weight: bold;">if</span> (response.isSuccessful()) {
<span class="indent">  </span><span class="indent">  </span><span class="indent">  </span>String responseUrl = response.body().string();
<span class="indent">  </span><span class="indent">  </span><span class="indent">  </span><span class="keyword" style="font-weight: bold;">return</span> responseUrl;
<span class="indent">  </span><span class="indent">  </span>} <span class="keyword" style="font-weight: bold;">else</span> {
<span class="indent">  </span><span class="indent">  </span><span class="indent">  </span><span class="keyword" style="font-weight: bold;">throw</span> <span class="keyword" style="font-weight: bold;">new</span> IOException(<span class="string" style="color: rgb(221, 17, 68);">"Unexpected code "</span> + response);
<span class="indent">  </span><span class="indent">  </span>}
<span class="indent">  </span>}
<span class="indent">  </span><span class="keyword" style="font-weight: bold;">private</span> <span class="keyword" style="font-weight: bold;">static</span> <span class="keyword" style="font-weight: bold;">final</span> String CHARSET_NAME = <span class="string" style="color: rgb(221, 17, 68);">"UTF-8"</span>;
<span class="indent">  </span><span class="javadoc" style="color: rgb(153, 153, 136); font-style: italic;">/**
<span class="indent">  </span> * 这里使用了HttpClinet的API。只是为了方便
<span class="indent">  </span> * <span class="javadoctag">@param</span> params
<span class="indent">  </span> * <span class="javadoctag">@return</span>
<span class="indent">  </span> */</span>
<span class="indent">  </span><span class="keyword" style="font-weight: bold;">public</span> <span class="keyword" style="font-weight: bold;">static</span> String formatParams(List<BasicNameValuePair> params){
<span class="indent">  </span><span class="indent">  </span><span class="keyword" style="font-weight: bold;">return</span> URLEncodedUtils.format(params, CHARSET_NAME);
<span class="indent">  </span>}
<span class="indent">  </span><span class="javadoc" style="color: rgb(153, 153, 136); font-style: italic;">/**
<span class="indent">  </span> * 为HttpGet 的 url 方便的添加多个name value 参数。
<span class="indent">  </span> * <span class="javadoctag">@param</span> url
<span class="indent">  </span> * <span class="javadoctag">@param</span> params
<span class="indent">  </span> * <span class="javadoctag">@return</span>
<span class="indent">  </span> */</span>
<span class="indent">  </span><span class="keyword" style="font-weight: bold;">public</span> <span class="keyword" style="font-weight: bold;">static</span> String attachHttpGetParams(String url, List<BasicNameValuePair> params){
<span class="indent">  </span><span class="indent">  </span><span class="keyword" style="font-weight: bold;">return</span> url + <span class="string" style="color: rgb(221, 17, 68);">"?"</span> + formatParams(params);
<span class="indent">  </span>}
<span class="indent">  </span><span class="javadoc" style="color: rgb(153, 153, 136); font-style: italic;">/**
<span class="indent">  </span> * 为HttpGet 的 url 方便的添加1个name value 参数。
<span class="indent">  </span> * <span class="javadoctag">@param</span> url
<span class="indent">  </span> * <span class="javadoctag">@param</span> name
<span class="indent">  </span> * <span class="javadoctag">@param</span> value
<span class="indent">  </span> * <span class="javadoctag">@return</span>
<span class="indent">  </span> */</span>
<span class="indent">  </span><span class="keyword" style="font-weight: bold;">public</span> <span class="keyword" style="font-weight: bold;">static</span> String attachHttpGetParam(String url, String name, String value){
<span class="indent">  </span><span class="indent">  </span><span class="keyword" style="font-weight: bold;">return</span> url + <span class="string" style="color: rgb(221, 17, 68);">"?"</span> + name + <span class="string" style="color: rgb(221, 17, 68);">"="</span> + value;
<span class="indent">  </span>}
}</code>

高级

高级属性其实用的不多，这里主要是对OkHttp github官方教程进行了翻译。

请看我的另一篇博客： OkHttp使用进阶 译自OkHttp Github官方教程

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