一、介绍
OKHttp是一个高效的开源网络请求类库，具有以下特性：
- 支持HTTP/2，允许所有同一个主机地址的请求共享同一个socket连接
- 使用连接池，提高请求效率
- 透明的GZIp压缩减少响应数据的大小
- 缓存响应数据，避免一些完全重复的请求
- 当网络出现状态时，OKHTTP会进行尝试，如果服务有多个地址，OKHTTP会进行不同地址的请求尝试；注意，这里的重试指的是网络连接失败时的重试，而读取超时，连接超时不在范围内！
二、配置环境
网络权限
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
类库依赖
api 'com.squareup.okhttp3:okhttp:3.10.0'
api 'com.squareup.okio:okio:1.14.0'
三、基础使用
//创建一个OKHttpClient对象
OkHttpClient okHttpClient = new OkHttpClient();
//创建一个Request
Request request = new Request.Builder()
.url("https://api.github.com/users/jitmaos")
.addHeader("key","value")
.get()
.build();
//使用request，同步请求会返回一个Response，异步请求会回调成功、失败函数
Response response = okHttpClient.newCall(request).execute();
Log.d(TAG,response.body().string());
三、常用请求
//Get请求
OkHttpClient okHttpClient = new OkHttpClient();
//创建一个Request
Request request = new Request.Builder()
.url("https://api.github.com/users/JakeWharton")
.get()
.build();
okHttpClient.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
Log.d(TAG,e.getMessage());
}
@Override
public void onResponse(Call call, Response response) throws IOException {
Log.d(TAG,response.body().string());
}
});
//Post提交表单
OkHttpClient okHttpClient = new OkHttpClient();
//创建一个Request
RequestBody requestBody = new FormBody.Builder()
.add("key","value")
.build();
Request request = new Request.Builder()
.url("https://api.github.com/users/JakeWharton")
.post(requestBody)
.build();
okHttpClient.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
Log.d(TAG,e.getMessage());
}
@Override
public void onResponse(Call call, Response response) throws IOException {
Log.d(TAG,response.body().string());
}
});
//Post提交文件
MediaType mediaType = MediaType.parse("text/x-markdown; charset=utf-8");
OkHttpClient okHttpClient = new OkHttpClient();
File file = new File("test.md");
Request request = new Request.Builder()
.url("https://api.github.com/markdown/raw")
.post(RequestBody.create(mediaType, file))
.build();
okHttpClient.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
Log.d(TAG, "onFailure: " + e.getMessage());
}
@Override
public void onResponse(Call call, Response response) throws IOException {
Log.d(TAG, response.protocol() + " " +response.code() + " " + response.message());
Headers headers = response.headers();
for (int i = 0; i < headers.size(); i++) {
Log.d(TAG, headers.name(i) + ":" + headers.value(i));
}
Log.d(TAG, "onResponse: " + response.body().string());
}
});
四、拦截器
拦截器分为应用拦截器和网络拦截器
应用拦截器
- 不用关心中间过程的响应，如重定向和重试
- 总是只调用一次，即使HTTP响应式从缓存中获取的
- 观察应用程序的初衷，不关心OKHTTP注入的头信息，如If-None-Match
- 允许短路，而且不用调用Chain.proceed()
- 允许重试，使得Chain.proceed()可以调用多次
网路拦截器
- 能够操作中间过程的响应，如重定向和重试
- 当网络短路不会调用缓存响应
- 只观察网络上传输的数据
- 访问包含请求信息的连接
自定义拦截器
public class LoggingInterceptor implements Interceptor {
private static final String TAG = "LoggingInterceptor";
@Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
long startTime = System.nanoTime();
Log.d(TAG, String.format("Sending request %s on %s%n%s",
request.url(), chain.connection(), request.headers()));
Response response = chain.proceed(request);
long endTime = System.nanoTime();
Log.d(TAG, String.format("Received response for %s in %.1fms%n%s",
response.request().url(), (endTime - startTime) / 1e6d, response.headers()));
return response;
}
}
其他
缓存响应
本段参考：OkHttp3-使用进阶
要缓存响应数据，首先需要指定一个可以读写并确定大小的缓存目录，OKHttp会根据响应头的配置信息对数据进行缓存。服务器会在返回的响应数据中配置这个数据缓存多久的信息，如：Cache-Control:max-age=10000。我们也可以在请求头中添加自定义的缓存有效时间信息，如：Cache-control:max-stale=3600。可以通过Cache Control.FORCE_NETWORK指定不使用缓存直接从网络读取数据，也可以使用CacheControl.FORCE_CACHE指定不使用网络，直接从缓存读取数据。
private final OkHttpClient client;
public CacheResponse(File cacheDirectory) throws Exception {
int cacheSize = 10 * 1024 * 1024; // 10 MiB
Cache cache = new Cache(cacheDirectory, cacheSize);
client = new OkHttpClient.Builder()
.cache(cache)
.build();
}
public void run() throws Exception {
Request request = new Request.Builder()
.url("http://publicobject.com/helloworld.txt")
.build();
Response response1 = client.newCall(request).execute();
if (!response1.isSuccessful()) throw new IOException("Unexpected code " + response1);
String response1Body = response1.body().string();
System.out.println("Response 1 response: " + response1);
System.out.println("Response 1 cache response: " + response1.cacheResponse());
System.out.println("Response 1 network response: " + response1.networkResponse());
Response response2 = client.newCall(request).execute();
if (!response2.isSuccessful()) throw new IOException("Unexpected code " + response2);
String response2Body = response2.body().string();
System.out.println("Response 2 response: " + response2);
System.out.println("Response 2 cache response: " + response2.cacheResponse());
System.out.println("Response 2 network response: " + response2.networkResponse());
System.out.println("Response 2 equals Response 1? " + response1Body.equals(response2Body));
}
取消一个请求
在Android中适时的取消一个请求是有必要的，比如当一个请求还在返回中，关闭了按钮，此时就应该及时的取消这个页面所有未完成的请求动作。
服务器指定一个服务延时5秒执行
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
System.out.println(System.currentTimeMillis() + "-收到请求");
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
new BaseCURDOperator<Book>().search(this,req,resp,null,"id desc",null, Book.class,true);
System.out.println(System.currentTimeMillis() + "-完成处理");
}
Android端测试取消请求
val executor = Executors.newScheduledThreadPool(1)
val client = OkHttpClient()
object:Thread(){
override fun run() {
super.run()
val request = Request.Builder()
.url("http://192.168.1.6:8080/TP_S/BookList") // 服务器延时了5秒返回数据
.build()
val call = client.newCall(request)
// 1秒后取消请求
executor.schedule(Runnable { call.cancel() }, 1, TimeUnit.SECONDS)
try {
val response = call.execute()
} catch (e: IOException) {
//取消请求后，再尝试去拿response，报Socket closed，说明请求被取消了
e.printStackTrace()
}
}
}.start()
