導入
compile 'com.squareup.okhttp3:okhttp:3.8.1'
混淆:
-dontwarn okio.**
-dontwarn javax.annotation.Nullable
-dontwarn javax.annotation.ParametersAreNonnullByDefault
使用示例:
同步Get
response.body().string()
對於小文件來說很方便,但是如果文件大小大於1MB的話,儘量避免使用response.body().string()
,因爲這會把這個文件都加載到內存當中,應該使用流來讀取比較好。
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());
}
異步Get
在一個子線程進行下載,有response的時候才觸發回調。回調在response的headers可用的時候觸發,但是讀取response的body還是可能會阻塞住。OkHttp當前不提供異步API來分部分接收response的body。
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(Call call, IOException e) {
e.printStackTrace();
}
@Override public void onResponse(Call call, Response response) throws IOException {
if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);
Headers responseHeaders = response.headers();
for (int i = 0, size = responseHeaders.size(); i < size; i++) {
System.out.println(responseHeaders.name(i) + ": " + responseHeaders.value(i));
}
System.out.println(response.body().string());
}
});
}
headers的獲取
Http的headers一般是類似Map<String, String>
的結構,即每個header字段對應着一個或者零個值。不過也存在一個header對應多個值的情況。
編寫請求headers的時候,如果是一對一形式,則調用header(name, value)
來設置,也就是舊值會覆蓋新值;如果是一對多形式,則調用addHeader(name, value)
。
讀取響應的headers的時候,調用header(name)
來獲取該鍵名對應的最後一個值,如果沒有就返回null。如果要返回該鍵名對應的所有值,則調用headers(name)
。
如果要獲取所有的headers,可以使用Headers
這個類來按序號獲取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發送字符串
以下示例把一個markdown文件發送到服務器,該服務器會把markdown渲染爲HTML。注意此時請求的body是在內存中的,所以儘量避免發送大於1MB的文件。
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 {
String postBody = ""
+ "Releases\n"
+ "--------\n"
+ "\n"
+ " * _1.0_ May 6, 2013\n"
+ " * _1.1_ June 15, 2013\n"
+ " * _1.2_ August 11, 2013\n";
Request request = new Request.Builder()
.url("https://api.github.com/markdown/raw")
.post(RequestBody.create(MEDIA_TYPE_MARKDOWN, postBody))
.build();
Response response = client.newCall(request).execute();
if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);
System.out.println(response.body().string());
}
流式發送Post請求
以下的示例以寫入Okio緩存池的形式發送Post請求,如果想要使用OutputStream可以調用BufferedSink.outputStream()
來獲取。
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\n");
sink.writeUtf8("-------\n");
for (int i = 2; i <= 997; i++) {
sink.writeUtf8(String.format(" * %s = %s\n", 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());
}
Post發送文件
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());
}
Post發送表單
使用FormBody.Builder()
來構建一個表單形式的請求體。表單的鍵值對會使用適配HTML表單的URL編碼處理。
private final OkHttpClient client = new OkHttpClient();
public void run() throws Exception {
RequestBody formBody = new FormBody.Builder()
.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());
}
Post一個multipart請求
MultipartBody.Builder
可以構建一個與HTML文件上傳表單匹配的複雜的請求體。multipart請求體的本身也是一個請求體,還可以定義自己的headers。如果有相應headers的話,應該是用來描述這個小請求體的,比如說Content-Disposition
。如果文件長度或者文件類型可知的話,就會自動加上Content-Length
和Content-Type
頭部。
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 MultipartBody.Builder()
.setType(MultipartBody.FORM)
.addFormDataPart("title", "Square Logo")
.addFormDataPart("image", "logo-square.png",
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());
}
使用Gson解析JSON格式的response
response.body().charStream()
是使用Content-Type
這個響應頭指定的字符集來解碼響應體。如果沒有指定的話默認使用UTF-8。
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<String, GistFile> entry : gist.files.entrySet()) {
System.out.println(entry.getKey());
System.out.println(entry.getValue().content);
}
}
static class Gist {
Map<String, GistFile> files;
}
static class GistFile {
String content;
}
Response的緩存
如果要緩存response的話,要有一個限制大小的可讀寫的緩存目錄。注意這個目錄必須是private,其他應用不能訪問到。
大部分應用都應該只調用一次new OkHttpClient()
,配置好相應緩存實例,保證只有一個緩存實例讀寫緩存目錄避免出錯。
Response caching uses HTTP headers for all configuration. You can add request headers like Cache-Control: max-stale=3600 and OkHttp’s cache will honor them. Your webserver configures how long responses are cached with its own response headers, like Cache-Control: max-age=9600. There are cache headers to force a cached response, force a network response, or force the network response to be validated with a conditional GET.
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));
}
使用CacheControl.FORCE_NETWORK
和CacheControl.FORCE_CACHE
來強制使用網絡或者強制使用緩存來獲取response。注意當使用強制緩存的時候,如果需要網絡請求才能獲取到response,就會返回一個504 Unsatisfiable Request
的response。
取消請求
調用Call.cancel()
來立即取消一個同步或者異步請求,如果正在編寫請求或者讀取響應的過程中,就會拋出一個IOException。
private final ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);
private final OkHttpClient client = new OkHttpClient();
public void run() throws Exception {
Request request = new Request.Builder()
.url("http://httpbin.org/delay/2") // This URL is served with a 2 second delay.
.build();
final long startNanos = System.nanoTime();
final Call call = client.newCall(request);
// Schedule a job to cancel the call in 1 second.
executor.schedule(new Runnable() {
@Override public void run() {
System.out.printf("%.2f Canceling call.%n", (System.nanoTime() - startNanos) / 1e9f);
call.cancel();
System.out.printf("%.2f Canceled call.%n", (System.nanoTime() - startNanos) / 1e9f);
}
}, 1, TimeUnit.SECONDS);
try {
System.out.printf("%.2f Executing call.%n", (System.nanoTime() - startNanos) / 1e9f);
Response response = call.execute();
System.out.printf("%.2f Call was expected to fail, but completed: %s%n",
(System.nanoTime() - startNanos) / 1e9f, response);
} catch (IOException e) {
System.out.printf("%.2f Call failed as expected: %s%n",
(System.nanoTime() - startNanos) / 1e9f, e);
}
}
設置超時
OkHttp支持連接、讀取、寫入三種超時。
private final OkHttpClient client;
public ConfigureTimeouts() throws Exception {
client = new OkHttpClient.Builder()
.connectTimeout(10, TimeUnit.SECONDS)
.writeTimeout(10, TimeUnit.SECONDS)
.readTimeout(30, TimeUnit.SECONDS)
.build();
}
public void run() throws Exception {
Request request = new Request.Builder()
.url("http://httpbin.org/delay/2") // This URL is served with a 2 second delay.
.build();
Response response = client.newCall(request).execute();
System.out.println("Response completed: " + response);
}
單次請求設置
所有的Http設置都存在於OkHttpClient當中。如果需要改變設置的時候,可以調用OkHttpClient.newBuilder()
來返回一個與原client相同連接池、分配者和配置的builder,然後可以進行修改,比如下面對於兩個請求配置了兩個不同的讀取超時時間:
private final OkHttpClient client;
public ConfigureTimeouts() throws Exception {
client = new OkHttpClient.Builder()
.connectTimeout(10, TimeUnit.SECONDS)
.writeTimeout(10, TimeUnit.SECONDS)
.readTimeout(30, TimeUnit.SECONDS)
.build();
}
public void run() throws Exception {
Request request = new Request.Builder()
.url("http://httpbin.org/delay/2") // This URL is served with a 2 second delay.
.build();
Response response = client.newCall(request).execute();
System.out.println("Response completed: " + response);
}
private final OkHttpClient client = new OkHttpClient();
public void run() throws Exception {
Request request = new Request.Builder()
.url("http://httpbin.org/delay/1") // This URL is served with a 1 second delay.
.build();
try {
// Copy to customize OkHttp for this request.
OkHttpClient copy = client.newBuilder()
.readTimeout(500, TimeUnit.MILLISECONDS)
.build();
Response response = copy.newCall(request).execute();
System.out.println("Response 1 succeeded: " + response);
} catch (IOException e) {
System.out.println("Response 1 failed: " + e);
}
try {
// Copy to customize OkHttp for this request.
OkHttpClient copy = client.newBuilder()
.readTimeout(3000, TimeUnit.MILLISECONDS)
.build();
Response response = copy.newCall(request).execute();
System.out.println("Response 2 succeeded: " + response);
} catch (IOException e) {
System.out.println("Response 2 failed: " + e);
}
}
處理認證:
對於未認證的請求,OkHttp會自動重試。如果請求返回401 Not Authorized
,就需要提供一個Authenticator進行認證,如果不提供就不會重試了。提供Authenticator的話就是創建一個包含Authenticator的新request。
調用Response.challenges()
來獲取認證要求的schemes和範圍。調用Credentials.basic(username, password)
來設置用戶名密碼。
private final OkHttpClient client;
public Authenticate() {
client = new OkHttpClient.Builder()
.authenticator(new Authenticator() {
@Override public Request authenticate(Route route, Response response) throws IOException {
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();
}
})
.build();
}
public void run() throws Exception {
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());
}
假如已經重試過了可以返回null取消重試:
if (credential.equals(response.request().header("Authorization"))) {
return null;
}
或者根據重試次數決定是否重試:
... {
if (responseCount(response) >= 3) {
return null; // If we've failed 3 times, give up.
}
}
...
private int responseCount(Response response) {
int result = 1;
while ((response = response.priorResponse()) != null) {
result++;
}
return result;
}