一、OkHttp请求方法
OkHttp是一个高效的HTTP库:
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支持 SPDY ,共享同一个 Socket 来处理同一个服务器的所有请求
如果 SPDY 不可用,则通过连接池来减少请求延时
无缝的支持GZIP来减少数据流量
缓存响应数据来减少重复的网络请求
OkHttp 处理了很多网络疑难杂症:会从很多常用的连接问题中自动恢复。如果您的服务器配置了多个IP地址,当第一个IP连接失败的时候,OkHttp会自动尝试下一个IP。OkHttp还处理了代理服务器问题和SSL握手失败问题。
OkHttp是一个相对成熟的解决方案,据说Android4.4的源码中可以看到HttpURLConnection已经替换成OkHttp实现了。所以我们更有理由相信OkHttp的强大。
1、HTTP请求方法
同步GET请求
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()); }
Response类的string()方法会把文档的所有内容加载到内存,适用于小文档,对应大于1M的文档,应 使用流()的方式获取。
response.body().byteStream()
异步GET请求
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, IOException e) { e.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()); } }); }
读取响应会阻塞当前线程,所以发起请求是在主线程,回调的内容在非主线程中。
POST方式提交字符串
private 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()); }
因为整个请求体都在内存中,应避免提交1M以上的文件。
POST方式提交流
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()); }
使用Okio框架以流的形式将内容写入,这种方式不会出现内存溢出问题。
POST方式提交文件
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方式提交表单
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()); }
表单的每个Names-Values都进行了URL编码。如果服务器端接口未进行URL编码,可定制个 FormBuilder。
文件上传(兼容html文件上传)
private static final String IMGUR_CLIENT_ID = "..."; private static final MediaType MEDIA_TYPE_PNG = MediaType.parse("p_w_picpath/png"); private final OkHttpClient client = new OkHttpClient(); public void run() throws Exception { // Use the imgur p_w_picpath upload API as documented at /upload/otherpic57/200136.jpg"))) .build(); Request request = new Request.Builder() .header("Authorization", "Client-ID " + IMGUR_CLIENT_ID) .url("https://api.imgur.com/3/p_w_picpath") .post(requestBody) .build(); Response response = client.newCall(request).execute(); if (!response.isSuccessful()) throw new IOException("Unexpected code " + response); System.out.println(response.body().string()); }
文章名称:一、OkHttp请求方法
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