深刻剖析OkHttp系列（二） 來自官方的開發使用手冊（中英互譯）
同步Get請求php
Download a file, print its headers, and print its response body as a string.java
下載一個文件, 以字符串形式打印它的請求頭以及響應體The string() method on response body is convenient and efficient for small documents. But if the response body is large (greater than 1 MiB), avoid string() because it will load the entire document into memory. In that case, prefer to process the body as a stream.git
response body的string()方法對於小文檔是很是方便有效的。 不過若是response body很大（>1M）的話， 避免使用string()。由於它要加載整個文件到內存中。在這種狀況下， 推薦使用流處理。private final OkHttpClient client = new OkHttpClient();
public void run() throws Exception {
Request request = new Request.Builder()
.url("https://publicobject.com/helloworld.txt")
.build();
try (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());
}
}
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異步Get請求github
Download a file on a worker thread, and get called back when the response is readable. The callback is made after the response headers are ready. Reading the response body may still block. OkHttp doesn't currently offer asynchronous APIs to receive a response body in parts.web
在工做線程中下載一個文件， 並在響應返回時回調。 回調是在響應頭準備完成後進行的。 讀取響應體時可能依然會阻塞。 OkHttp目前並無提供異步的API來讀取響應體。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 {
try (ResponseBody responseBody = response.body()) {
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(responseBody.string());
}
}
});
}
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訪問Headerjson
Typically HTTP headers work like a Map<String, String>: each field has one value or none. But some headers permit multiple values, like Guava's Multimap. For example, it's legal and common for an HTTP response to supply multiple Vary headers. OkHttp's APIs attempt to make both cases comfortable.api
一般HTTP的headers的工做方式相似於Map (String, String): 每一個字段對應一個值或沒有值。 可是一些headers容許有多個值， 如Guava的MultiMap。 舉個例子， 提供多個Vary headers的HTTP響應是合法且常見的。 OkHttp努力是兩種狀況都很溫馨。When writing request headers, use header(name, value) to set the only occurrence of name to value. If there are existing values, they will be removed before the new value is added. Use addHeader(name, value) to add a header without removing the headers already present.緩存
在寫請求頭時， 使用header(name, value)的形式來設置value的惟一name。 若是已經有存在的值， 它們將會在新值添加以前被刪掉。使用addHeader(name, value)來添加header時， 不會移除現有的值。When reading response a header, use header(name) to return the last occurrence of the named value. Usually this is also the only occurrence! If no value is present, header(name) will return null. To read all of a field's values as a list, use headers(name).bash
在讀取響應的頭時， 使用header(name) 來返回最後一次出現的name value（解讀： 會存在一個name對應多個值的狀況， 這裏獲得的是最後添加的那一對name value）。一般這也是惟一的出現(OkHttp response中的內容取一次就關閉了)。 若是沒有值，則返回null。 若是要列出指定name下全部的values, 請使用headers(name)。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();
try (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"));
}
}
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發送字符串服務器
Use an HTTP POST to send a request body to a service. This example posts a markdown document to a web service that renders markdown as HTML. Because the entire request body is in memory simultaneously, avoid posting large (greater than 1 MiB) documents using this API.
使用HTTP POST來發送一個請求到服務。 本示例發送一個markdown文檔到Web服務器。 由於整個請求實體在內存中， 避免發送大文件（超過IM）。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();
try (Response response = client.newCall(request).execute()) {
if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);
System.out.println(response.body().string());
}
}
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發送流
Here we POST a request body as a stream. The content of this request body is being generated as it's being written. This example streams directly into the Okio buffered sink. Your programs may prefer an OutputStream, which you can get from BufferedSink.outputStream().
這裏咱們將以流的形式發送請求主體。 請求主體的內容在編寫時生成。 這個例子， 流直接寫入Okio的緩存。 你可能更喜歡OutputStream, 你能夠經過BufferedSink.outputStream()獲取它。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();
try (Response response = client.newCall(request).execute()) {
if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);
System.out.println(response.body().string());
}
}
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發送文件
It's easy to use a file as a request body.
使用文件做爲請求主體是很簡單的。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();
try (Response response = client.newCall(request).execute()) {
if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);
System.out.println(response.body().string());
}
}
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發送表單參數
Use FormBody.Builder to build a request body that works like an HTML
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