OkHttp：基本使用详解_移动开发_尘埃zza的博客-CSDN博客
简介
OkHttp是一个高效的HTTP客户端，它有以下默认特性：
- 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
- 连接池减少请求延时
- 透明的GZIP压缩减少响应数据的大小
- 缓存响应内容，避免一些完全重复的请求
当网络出现问题的时候OkHttp依然坚守自己的职责，它会自动恢复一般的连接问题，如果你的服务有多个IP地址，当第一个IP请求失败时，OkHttp会交替尝试你配置的其他IP，这对于使用IPv4+IPv6托管在冗余数据中心中的服务是必需的，OkHttp使用现代TLS技术(TLS 1.3、ALPN、证书固定)初始化新的连接，当握手失败时会回退到TLS 1.0。
OkHttp官网地址：http://square.github.io/okhttp/
OkHttp GitHub地址：https://github.com/square/okhttp
本文代码下载地址：GitHub
使用
implementation 'com.squareup.okhttp3:okhttp:3.14.2'
我使用的是3.14.2版本，4.XX.XX版本使用的是Kotlin
需要在清单文件声明访问Internet的权限，如果使用缓存，那还得声明写外存的权限
同步Get请求
/**
* 异步GET请求:
* new OkHttpClient;
* 构造Request对象；
* 通过前两步中的对象构建Call对象；
* 通过Call#enqueue(Callback)方法来提交异步请求；
*/
private void asynchronousGetRequests() {
String url = "https://wwww.baidu.com";
OkHttpClient okHttpClient = new OkHttpClient();
final Request request = new Request.Builder()
.url(url)
.get()//默认就是GET请求
.build();
Call call = okHttpClient.newCall(request);
call.enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
runOnUiThread(() -> tvContent.setText("asynchronousGetRequests onFailure: " + e.getMessage()));
}
@Override
public void onResponse(Call call, Response response) throws IOException {
String result = response.body().string();
runOnUiThread(() -> tvContent.setText("asynchronousGetRequests onResponse: " + result));
}
});
}
异步发起的请求会被加入到 Dispatcher 中的 runningAsyncCalls双端队列中通过线程池来执行。
响应体的 string() 方法对于小文档来说十分方便、高效。但是如果响应体太大（超过1MB），应避免适应 string()方法，因为他会将把整个文档加载到内存中。对于超过1MB的响应body，应使用流的方式来处理body。
同步Get请求
在Android中应放在子线程中执行，否则有可能引起ANR异常，Android3.0 以后已经不允许在主线程访问网络。
/**
* 同步GET请求
* new OkHttpClient;
* 构造Request对象；
* 通过前两步中的对象构建Call对象；
* 在子线程中通过Call#execute()方法来提交同步请求；
*/
private void synchronizedGetRequests() {
String url = "https://wwww.baidu.com";
OkHttpClient okHttpClient = new OkHttpClient();
final Request request = new Request.Builder()
.url(url)
.get()//默认就是GET请求
.build();
final Call call = okHttpClient.newCall(request);
new Thread(() -> {
try {
//直接execute call
Response response = call.execute();
String result = response.body().string();
runOnUiThread(() -> tvContent.setText("synchronizedGetRequests run: " + result));
} catch (IOException e) {
e.printStackTrace();
}
}).start();
}
POST方式提交String
RequstBody的几种构造方式：
/**
* POST方式提交String
* 在构造 Request对象时，需要多构造一个RequestBody对象，携带要提交的数据。
* 在构造 RequestBody 需要指定MediaType，用于描述请求/响应 body 的内容类型
*/
private void postString() {
MediaType mediaType = MediaType.parse("text/x-markdown; charset=utf-8");
String requestBody = "I am zza.";
Request request = new Request.Builder()
.url("https://api.github.com/markdown/raw")
.post(RequestBody.create(mediaType, requestBody))
.build();
OkHttpClient okHttpClient = new OkHttpClient();
okHttpClient.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
runOnUiThread(() -> tvContent.setText("postString onFailure: " + e.getMessage()));
}
@Override
public void onResponse(Call call, Response response) throws IOException {
StringBuffer buffer = new StringBuffer();
buffer.append("postString: " + "\r\n");
buffer.append(response.protocol() + " " + response.code() + " " + response.message() + "\r\n");
Headers headers = response.headers();
for (int i = 0; i < headers.size(); i++) {
buffer.append(headers.name(i) + ":" + headers.value(i) + "\r\n");
}
buffer.append("onResponse: " + response.body().string());
runOnUiThread(() -> tvContent.setText(buffer.toString()));
}
});
}
POST方式提交流
/**
* POST方式提交流
*/
private void postStream() {
RequestBody requestBody = new RequestBody() {
@Nullable
@Override
public MediaType contentType() {
return MediaType.parse("text/x-markdown; charset=utf-8");
}
@Override
public void writeTo(BufferedSink sink) throws IOException {
sink.writeUtf8("I am zza.");
}
};
Request request = new Request.Builder()
.url("https://api.github.com/markdown/raw")
.post(requestBody)
.build();
OkHttpClient okHttpClient = new OkHttpClient();
okHttpClient.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
runOnUiThread(() -> tvContent.setText("postStream onFailure: " + e.getMessage()));
}
@Override
public void onResponse(Call call, Response response) throws IOException {
StringBuffer buffer = new StringBuffer();
buffer.append("postStream: " + "\r\n");
buffer.append(response.protocol() + " " + response.code() + " " + response.message() + "\r\n");
Headers headers = response.headers();
for (int i = 0; i < headers.size(); i++) {
buffer.append(headers.name(i) + ":" + headers.value(i) + "\r\n");
}
buffer.append("onResponse: " + response.body().string());
runOnUiThread(() -> tvContent.setText(buffer.toString()));
}
});
}
POST提交文件
/**
* POST提交文件
* 文件没有的话会失败
* 需要在路径下添加文件
* 还需要权限
*/
private void postFile() {
MediaType mediaType = MediaType.parse("text/x-markdown; charset=utf-8");
OkHttpClient okHttpClient = new OkHttpClient();
String path = Environment.getExternalStorageDirectory().getPath() + "/zza.md";
File file = new File(path);
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) {
runOnUiThread(() -> tvContent.setText("postFile onFailure: " + e.getMessage()));
}
@Override
public void onResponse(Call call, Response response) throws IOException {
StringBuffer buffer = new StringBuffer();
buffer.append("postFile: " + "\r\n");
buffer.append(response.protocol() + " " + response.code() + " " + response.message() + "\r\n");
Headers headers = response.headers();
for (int i = 0; i < headers.size(); i++) {
buffer.append(headers.name(i) + ":" + headers.value(i) + "\r\n");
}
buffer.append("postFile: " + response.body().string());
runOnUiThread(() -> tvContent.setText(buffer.toString()));
}
});
}
POST方式提交表单
提交表单时，使用 RequestBody 的实现类FormBody来描述请求体，它可以携带一些经过编码的 key-value 请求体，键值对存储在下面两个集合中：
private final List<String> encodedNames;
private final List<String> encodedValues;
/**
* POST方式提交表单
* 通过FormBody#Builder构造RequestBody
*/
private void postForm() {
//https://www.wanandroid.com/article/query/0/json
//方法：POST
//参数：
// 页码：拼接在链接上，从0开始。
// k ： 搜索关键词
RequestBody requestBody = new FormBody.Builder()
.add("k", "okhttp")
.build();
Request request = new Request.Builder()
.url("https://www.wanandroid.com/article/query/0/json")
.post(requestBody)
.build();
OkHttpClient okHttpClient = new OkHttpClient();
okHttpClient.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
runOnUiThread(() -> tvContent.setText("postForm onFailure: " + e.getMessage()));
}
@Override
public void onResponse(Call call, Response response) throws IOException {
StringBuffer buffer = new StringBuffer();
buffer.append("postForm: " + "\r\n");
buffer.append(response.protocol() + " " + response.code() + " " + response.message() + "\r\n");
Headers headers = response.headers();
for (int i = 0; i < headers.size(); i++) {
buffer.append(headers.name(i) + ":" + headers.value(i) + "\r\n");
}
buffer.append("postForm: " + response.body().string());
runOnUiThread(() -> tvContent.setText(buffer.toString()));
}
});
}
POST方式提交分块请求
MultipartBody 可以构建复杂的请求体，与HTML文件上传形式兼容。多块请求体中每块请求都是一个请求体，可以定义自己的请求头。这些请求头可以用来描述这块请求，例如它的 Content-Disposition。如果 Content-Length和 Content-Type可用的话，他们会被自动添加到请求头中。
/**
* POST方式提交分块请求
* <p>
* 使用公司项目的一个接口调试通过，为避免一些问题，接口和参数删掉
*/
private void postMultipartBody() {
OkHttpClient client = new OkHttpClient();
File file = new File(Environment.getExternalStorageDirectory().getPath() + "/logo_star_dust.png");
MediaType MEDIA_TYPE_PNG = MediaType.parse("image/png");
RequestBody filebody = MultipartBody.create(MEDIA_TYPE_PNG, file);
MultipartBody body = new MultipartBody.Builder()
.setType(MultipartBody.FORM)
.addFormDataPart("data", file.getName(), filebody)
.addPart(
Headers.of("Content-Disposition", "form-data; name=\"vin\""),
RequestBody.create(null, ""))
.addPart(
Headers.of("Content-Disposition", "form-data; name=\"iccid\""),
RequestBody.create(null, ""))
.addPart(
Headers.of("Content-Disposition", "form-data; name=\"type\""),
RequestBody.create(null, ""))
.addPart(
Headers.of("Content-Disposition", "form-data; name=\"jobId\""),
RequestBody.create(null, ""))
.build();
Request request = new Request.Builder()
.url("https://www.baidu.com")
.post(body)
.build();
Call call = client.newCall(request);
call.enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
runOnUiThread(() -> tvContent.setText("postMultipartBody onFailure: " + e.getMessage()));
}
@Override
public void onResponse(Call call, Response response) throws IOException {
String result = response.body().string();
runOnUiThread(() -> tvContent.setText("postMultipartBody onResponse: " + result));
}
});
}
拦截器
OkHttp的拦截器链可谓是其整个框架的精髓，用户可传入的 interceptor分为两类：
应用拦截器(Interceptors)
addInterceptor()- 不必要担心响应和重定向之间的中间响应。
- 通常只调用一次，即使HTTP响应是通过缓存提供的。
- 遵从应用层的最初目的。与OkHttp的注入头部无关，如If-None-Match。
- 允许短路而且不调用Chain.proceed()。
- 允许重试和多次调用Chain.proceed()。
网络拦截器(networkInterceptors)
addNetworkInterceptor()- 允许像重定向和重试一样操作中间响应。
- 网络发生短路时不调用缓存响应。
- 在数据被传递到网络时观察数据。
- 有权获得装载请求的连接。
/**
* 拦截器
* <p>
* 请查看打印输出
*/
private void testInterceptor() {
OkHttpClient okHttpClient = new OkHttpClient.Builder()
.addInterceptor(new LoggingInterceptor())
.build();
Request request = new Request.Builder()
.url("https://www.publicobject.com/helloworld.txt")
.header("User-Agent", "OkHttp Example")
.build();
okHttpClient.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
runOnUiThread(() -> tvContent.setText("testInterceptor onFailure: " + e.getMessage()));
}
@Override
public void onResponse(Call call, Response response) throws IOException {
ResponseBody body = response.body();
String result = response.body().string();
if (body != null) {
LogUtil.d("testInterceptor: " + result);
body.close();
}
runOnUiThread(() -> tvContent.setText("testInterceptor onResponse: " + result));
}
});
}
支持缓存
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。
/**
* 支持缓存
*/
private void responseCaching() {
String url = "https://publicobject.com/helloworld.txt";
File cacheDirectory = new File(Environment.getExternalStorageDirectory() + "/cache");
int cacheSize = 10 * 1024 * 1024; // 10 MiB
Cache cache = new Cache(cacheDirectory, cacheSize);
OkHttpClient okHttpClient = new OkHttpClient.Builder()
.cache(cache)
.build();
final Request request = new Request.Builder()
.url(url)
.get()//默认就是GET请求
.build();
final Call call1 = okHttpClient.newCall(request);
final Call call2 = okHttpClient.newCall(request);
new Thread(() -> {
try {
StringBuffer buffer = new StringBuffer();
//直接execute call
Response response1 = call1.execute();
if (!response1.isSuccessful()) {
runOnUiThread(() -> tvContent.setText("responseCaching onFailure"));
} else {
String result = response1.body().string();
buffer.append("responseCaching1 onResponse: " + result + "\r\n");
buffer.append("responseCaching1 cache response: " + response1.cacheResponse() + "\r\n");
buffer.append("responseCaching1 network response: " + response1.networkResponse() + "\r\n");
runOnUiThread(() -> tvContent.setText(buffer));
}
Response response2 = call2.execute();
if (!response2.isSuccessful()) {
runOnUiThread(() -> tvContent.setText("responseCaching onFailure"));
} else {
String result = response2.body().string();
buffer.append("responseCaching2 onResponse: " + result + "\r\n");
buffer.append("responseCaching2 cache response: " + response2.cacheResponse() + "\r\n");
buffer.append("responseCaching2 network response: " + response2.networkResponse() + "\r\n");
runOnUiThread(() -> tvContent.setText(buffer));
}
} catch (IOException e) {
e.printStackTrace();
}
}).start();
}
为了防止使用缓存的响应，可以用CacheControl.FORCE_NETWORK。为了防止它使用网络，使用CacheControl.FORCE_CACHE。需要注意的是：如果您使用FORCE_CACHE和网络的响应需求，OkHttp则会返回一个504提示，告诉你不可满足请求响应。
取消请求
使用Call.cancel()可以立即停止掉一个正在执行的call。如果一个线程正在写请求或者读响应，将会引发IOException。当call没有必要的时候，使用这个api可以节约网络资源。例如当用户离开一个应用时。
不管同步还是异步的call都可以取消。
你可以通过tags来同时取消多个请求。当你构建一请求时，使用RequestBuilder.tag(tag)来分配一个标签。之后你就可以用OkHttpClient.cancel(tag)来取消所有带有这个tag的call。.
/**
* 取消请求
*/
private void cancelCall() {
final ScheduledExecutorService executor = Executors.newScheduledThreadPool(2);
final OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
.url("https://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);
StringBuffer buffer = new StringBuffer();
// Schedule a job to cancel the call in 1 second.
executor.schedule(new Runnable() {
@Override
public void run() {
buffer.append(String.format("%.2f Canceling call.%n",
(System.nanoTime() - startNanos) / 1e9f));
call.cancel();
buffer.append(String.format("%.2f Canceled call.%n",
(System.nanoTime() - startNanos) / 1e9f) );
runOnUiThread(() -> tvContent.setText(buffer));
}
}, 1, TimeUnit.SECONDS);
executor.schedule(new Runnable() {
@Override
public void run() {
buffer.append(String.format("%.2f Executing call.%n", (System.nanoTime() - startNanos) / 1e9f) );
try (Response response = call.execute()) {
buffer.append(String.format("%.2f Call was expected to fail, but completed: %s%n",
(System.nanoTime() - startNanos) / 1e9f, response));
} catch (IOException e) {
buffer.append(String.format("%.2f Call failed as expected: %s%n",
(System.nanoTime() - startNanos) / 1e9f, e) );
}
}
}, 0, TimeUnit.SECONDS);
}
超时
OkHttp支持连接，读取和写入超时。
/**
* 超时
*/
private void timeout() {
OkHttpClient client = new OkHttpClient.Builder()
.connectTimeout(10, TimeUnit.SECONDS)
.writeTimeout(10, TimeUnit.SECONDS)
.readTimeout(10, TimeUnit.SECONDS)
.build();
Request request = new Request.Builder()
.url("https://httpbin.org/delay/12")
.get()
.build();
final Call call = client.newCall(request);
call.enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
runOnUiThread(() -> tvContent.setText("timeout onFailure: " + e.getMessage()));
}
@Override
public void onResponse(Call call, Response response) throws IOException {
String result = response.body().string();
StringBuffer buffer = new StringBuffer();
buffer.append("timeout onResponse: " + result + "\r\n");
runOnUiThread(() -> tvContent.setText(buffer));
}
});
}
每个call配置
使用OkHttpClient，所有的HTTP Client配置包括代理设置、超时设置、缓存设置。当你需要为单个call改变配置的时候，clone 一个 OkHttpClient。这个api将会返回一个浅拷贝（shallow copy），你可以用来单独自定义。
/**
* 每个call配置
*/
private void perCallConfiguration() {
OkHttpClient client = new OkHttpClient.Builder()
.build();
Request request = new Request.Builder()
.url("https://httpbin.org/delay/1")
.get()
.build();
OkHttpClient clientCopy = client.newBuilder()
.readTimeout(500, TimeUnit.MILLISECONDS)
.build();
final Call call = clientCopy.newCall(request);
StringBuffer buffer = new StringBuffer();
call.enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
runOnUiThread(() -> tvContent.setText("perCallConfiguration onFailure: " + e.getMessage()));
}
@Override
public void onResponse(Call call, Response response) throws IOException {
String result = response.body().string();
buffer.append("perCallConfiguration onResponse: " + result + "\r\n");
runOnUiThread(() -> tvContent.setText(buffer));
}
});
}
处理身份验证
OkHttp会自动重试未验证的请求。当响应是401 Not Authorized时，Authenticator会被要求提供证书。Authenticator的实现中需要建立一个新的包含证书的请求。如果没有证书可用，返回null来跳过尝试。
/**
* 处理身份验证
*/
private void handlingAuthentication() {
StringBuffer buffer = new StringBuffer();
OkHttpClient client = new OkHttpClient.Builder()
.authenticator(new Authenticator() {
@Override
public Request authenticate(Route route, Response response) throws IOException {
if (response.request().header("Authorization") != null) {
return null; // Give up, we've already attempted to authenticate.
}
buffer.append("Authenticating for response: " + response + "\r\n");
buffer.append("Challenges: " + response.challenges() + "\r\n");
String credential = Credentials.basic("jesse", "password1");
return response.request().newBuilder()
.header("Authorization", credential)
.build();
}
})
.build();
Request request = new Request.Builder()
.url("http://publicobject.com/secrets/hellosecret.txt")
.get()
.build();
final Call call = client.newCall(request);
call.enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
runOnUiThread(() -> tvContent.setText("handlingAuthentication onFailure: " + e.getMessage()));
}
@Override
public void onResponse(Call call, Response response) throws IOException {
String result = response.body().string();
buffer.append("handlingAuthentication onResponse: " + result + "\r\n");
runOnUiThread(() -> tvContent.setText(buffer));
}
});
}
其他
- 推荐让
OkHttpClient保持单例，用同一个OkHttpClient实例来执行你的所有请求，因为每一个OkHttpClient实例都拥有自己的连接池和线程池，重用这些资源可以减少延时和节省资源，如果为每个请求创建一个OkHttpClient实例，显然就是一种资源的浪费。 - 每一个Call（其实现是RealCall）只能执行一次，否则会报异常，具体参见
RealCall#execute()
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Original url: Access
Created at: 2020-03-03 18:57:12
Category: default
Tags: none
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