Android 网络框架OKHttp学习

OKHTTP

okHttp: OKHttp是Android版Http客户端。非常高效，支持SPDY、连接池、GZIP和 HTTP 缓存。默认情况下，OKHttp会自动处理常见的网络问题，像二次连接、SSL的握手问题。如果你的应用程序中集成了OKHttp，Retrofit默认会使用OKHttp处理其他网络层请求。
An HTTP & SPDY client for Android and Java applications 从Android4.4开始HttpURLConnection的底层实现采用的是okHttp.
使用要求:对于Android：2.3以上，对于Java:java7以上 两个模块： okhttp-urlconnection实现.HttpURLConnection API； okhttp-apache实现Apache HttpClient API. 依赖：okio(https://github.com/square/okio):
Okio, which OkHttp uses for fast I/O and resizable buffers.

安装：

maven:

com.squareup.okhttpokhttp2.3.0

Gradle:

compile 'com.squareup.okhttp:okhttp:2.3.0'

GET A URL

同步GET:

private final OkHttpClient client = new OkHttpClient();

public void run() throws Exception {
Request request = new Request.Builder()
.url(http://publicobject.com/helloworld.txt)
.build();

Response response = client.newCall(request).execute();
if (!response.isSuccessful()) throw new IOException(Unexpected code  + response);

Headers responseHeaders = response.headers();
for (int i = 0; i < responseHeaders.size(); i++) {
System.out.println(responseHeaders.name(i) + :  + responseHeaders.value(i));
}

System.out.println(response.body().string());
}

异步GET:

在一个工作线程中下载文件，当响应可读时回调Callback接口。读取响应时会阻塞当前线程。OkHttp现阶段不提供异步api来接收响应体。

private final OkHttpClient client = new OkHttpClient();

public void run() throws Exception {
Request request = new Request.Builder()
.url(http://publicobject.com/helloworld.txt)
.build();

client.newCall(request).enqueue(new Callback() {
@Override public void onFailure(Request request, Throwable throwable) {
throwable.printStackTrace();
}

@Override public void onResponse(Response response) throws IOException {
if (!response.isSuccessful()) throw new IOException(Unexpected code  + response);

Headers responseHeaders = response.headers();
for (int i = 0; i < responseHeaders.size(); i++) {
System.out.println(responseHeaders.name(i) + :  + responseHeaders.value(i));
}

System.out.println(response.body().string());
}
});
}

访问Header:

private final OkHttpClient client = new OkHttpClient();

public void run() throws Exception {
Request request = new Request.Builder()
.url(https://api.github.com/repos/square/okhttp/issues)
.header(User-Agent, OkHttp Headers.java)
.addHeader(Accept, application/json; q=0.5)
.addHeader(Accept, application/vnd.github.v3+json)
.build();

Response response = client.newCall(request).execute();
if (!response.isSuccessful()) throw new IOException(Unexpected code  + response);

System.out.println(Server:  + response.header(Server));
System.out.println(Date:  + response.header(Date));
System.out.println(Vary:  + response.headers(Vary));
}

POST TO A SERVER

Posting a String:

public static final MediaType jsonReq
= MediaType.parse(application/json; charset=utf-8);

OkHttpClient client = new OkHttpClient();

String post(String url, String json) throws IOException {
RequestBody body = RequestBody.create(jsonReq, json);
Request request = new Request.Builder()
.url(url)
.post(body)
.build();
Response response = client.newCall(request).execute();
return response.body().string();
}

Posting Streaming:

public static final MediaType MEDIA_TYPE_MARKDOWN
= MediaType.parse(text/x-markdown; charset=utf-8);

private final OkHttpClient client = new OkHttpClient();

public void run() throws Exception {
RequestBody requestBody = new RequestBody() {
@Override public MediaType contentType() {
return MEDIA_TYPE_MARKDOWN;
}

@Override public void writeTo(BufferedSink sink) throws IOException {
sink.writeUtf8(Numbers
);
sink.writeUtf8(-------
);
for (int i = 2; i <= 997; i++) {
sink.writeUtf8(String.format( * %s = %s
, i, factor(i)));
}
}

private String factor(int n) {
for (int i = 2; i < n; i++) {
int x = n / i;
if (x * i == n) return factor(x) +  ×  + i;
}
return Integer.toString(n);
}
};

Request request = new Request.Builder()
.url(https://api.github.com/markdown/raw)
.post(requestBody)
.build();

Response response = client.newCall(request).execute();
if (!response.isSuccessful()) throw new IOException(Unexpected code  + response);

System.out.println(response.body().string());
}

Posting a File:

public static final MediaType MEDIA_TYPE_MARKDOWN
= MediaType.parse(text/x-markdown; charset=utf-8);

private final OkHttpClient client = new OkHttpClient();

public void run() throws Exception {
File file = new File(README.md);

Request request = new Request.Builder()
.url(https://api.github.com/markdown/raw)
.post(RequestBody.create(MEDIA_TYPE_MARKDOWN, file))
.build();

Response response = client.newCall(request).execute();
if (!response.isSuccessful()) throw new IOException(Unexpected code  + response);

System.out.println(response.body().string());
}

Posting from parameters:

private final OkHttpClient client = new OkHttpClient();

public void run() throws Exception {
RequestBody formBody = new FormEncodingBuilder()
.add(search, Jurassic Park)
.build();
Request request = new Request.Builder()
.url(https://en.wikipedia.org/w/index.php)
.post(formBody)
.build();

Response response = client.newCall(request).execute();
if (!response.isSuccessful()) throw new IOException(Unexpected code  + response);

System.out.println(response.body().string());
}

Posting a multipart request:

private static final String IMGUR_CLIENT_ID = ...;
private static final MediaType MEDIA_TYPE_PNG = MediaType.parse(image/png);

private final OkHttpClient client = new OkHttpClient();

public void run() throws Exception {
// Use the imgur image upload API as documented at https://api.imgur.com/endpoints/image RequestBody requestBody = new MultipartBuilder()
.type(MultipartBuilder.FORM)
.addPart(
Headers.of(Content-Disposition, form-data; name=	itle),
RequestBody.create(null, Square Logo))
.addPart(
Headers.of(Content-Disposition, form-data; name=image),
RequestBody.create(MEDIA_TYPE_PNG, new File(website/static/logo-square.png)))
.build();

Request request = new Request.Builder()
.header(Authorization, Client-ID  + IMGUR_CLIENT_ID)
.url(https://api.imgur.com/3/image)
.post(requestBody)
.build();

Response response = client.newCall(request).execute();
if (!response.isSuccessful()) throw new IOException(Unexpected code  + response);

System.out.println(response.body().string());
}

Posing Json with Gson

private final OkHttpClient client = new OkHttpClient();
private final Gson gson = new Gson();

public void run() throws Exception {
Request request = new Request.Builder()
.url(https://api.github.com/gists/c2a7c39532239ff261be)
.build();
Response response = client.newCall(request).execute();
if (!response.isSuccessful()) throw new IOException(Unexpected code  + response);

Gist gist = gson.fromJson(response.body().charStream(), Gist.class);
for (Map.Entry entry : gist.files.entrySet()) {
System.out.println(entry.getKey());
System.out.println(entry.getValue().content);
}
}

static class Gist {
Map files;
}

static class GistFile {
String content;
}

Response Caching：

为了缓存响应，你需要一个你可以读写的缓存目录，和缓存大小的限制。这个缓存目录应该是私有的，不信任的程序应不能读取缓存内容。
一个缓存目录同时拥有多个缓存访问是错误的。大多数程序只需要调用一次 new OkHttp() ，在第一次调用时配置好缓存，然后其他地方只需要调用这个实例就可以了。否则两个缓存示例互相干扰，破坏响应缓存，而且有可能会导致程序崩溃。
响应缓存使用HTTP头作为配置。你可以在请求头中添加 Cache-Control: max-stale=3600 ,OkHttp缓存会支持。你的服务通过响应头确定响应缓存多长时间，例如使用 Cache-Control: max-age=9600 。

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();
client.setCache(cache);
}

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());
}

Canceling a Call

final Call call = client.newCall(request);
call.cancel();

Timeouts:

private final OkHttpClient client;

public ConfigureTimeouts() throws Exception {
client = new OkHttpClient();
client.setConnectTimeout(10, TimeUnit.SECONDS);
client.setWriteTimeout(10, TimeUnit.SECONDS);
client.setReadTimeout(30, TimeUnit.SECONDS);
}

Handling Authentication:

private final OkHttpClient client = new OkHttpClient();

public void run() throws Exception {
client.setAuthenticator(new Authenticator() {
@Override public Request authenticate(Proxy proxy, Response response) {
System.out.println(Authenticating for response:  + response);
System.out.println(Challenges:  + response.challenges());
String credential = Credentials.basic(jesse, password1);
return response.request().newBuilder()
.header(Authorization, credential)
.build();
}

@Override public Request authenticateProxy(Proxy proxy, Response response) {
return null; // Null indicates no attempt to authenticate.
}
});

Request request = new Request.Builder()
.url(http://publicobject.com/secrets/hellosecret.txt)
.build();

Response response = client.newCall(request).execute();
if (!response.isSuccessful()) throw new IOException(Unexpected code  + response);

System.out.println(response.body().string());
}

为避免当验证失败时多次重试，我们可以通过返回null来放弃验证：

if (responseCount(response) >= 3) {
return null; // If we've failed 3 times, give up.
}
//添加以下方法
private int responseCount(Response response) {
int result = 1;
while ((response = response.priorResponse()) != null) {
result++;
}
return result;
}

Interceptors

class LoggingInterceptor implements Interceptor {
@Override public Response intercept(Chain chain) throws IOException {
Request request = chain.request();

long t1 = System.nanoTime();
logger.info(String.format(Sending request %s on %s%n%s,
request.url(), chain.connection(), request.headers()));

Response response = chain.proceed(request);

long t2 = System.nanoTime();
logger.info(String.format(Received response for %s in %.1fms%n%s,
response.request().url(), (t2 - t1) / 1e6d, response.headers()));

return response;
}
}

Application Interceptors：

OkHttpClient client = new OkHttpClient();
client.interceptors().add(new LoggingInterceptor());

Network Interceptors

OkHttpClient client = new OkHttpClient();
client.networkInterceptors().add(new LoggingInterceptor());