Android OKHttp介绍与使用（二）

在Android OKHttp介绍与使用（一）中只是简单的介绍了一下OKHttp并贴了一个小Demo来尝试一下OkHttp。在本篇博客中将对OKHttp的使用进行系统的介绍。

OKHttp简单体验

使用前提： Android Studio添加依赖库

compile 'com.squareup.okio:okio:1.9.0' compile 'com.squareup.okhttp3:okhttp:3.4.1'

Ecplise： https://github.com/square/okhttp 下载最新jar

一般Get请求三步：

（1）创建OKHttpClient OkHttpClient client = new OkHttpClient();

（2）创建Request Request request = new Request.Builder().url(url).build(); （3）回调并执行或加入请求行列 client.newCall(request).execute() 或者client.newCall(request).enqueue(new Callback() { @Override public void onFailure(Call call, IOException e) { 　　　 } @Override public void onResponse(Call call, Response response) throws IOException { if(response.isSuccessful()){ 　　 } 　　 } }) 例： http://blog.csdn.net/danfengw/article/details/52189581

OkHttpClient client = new OkHttpClient(); String run(String url) throws IOException { Request request = new Request.Builder() .url(url) .build(); Response response = client.newCall(request).execute(); return response.body().string(); }

一般Post请求

与get请求相比多了一个RequestBody 用来传递参数

public static final MediaType JSON = MediaType.parse("application/json; charset=utf-8"); OkHttpClient client = new OkHttpClient(); String post(String url, String json) throws IOException { RequestBody body = RequestBody.create(JSON, json); Request request = new Request.Builder() .url(url) .post(body) .build(); Response response = client.newCall(request).execute(); return response.body().string(); }

OKHttp具体使用

添加请求头

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();

请求超时

client = new OkHttpClient.Builder() .connectTimeout(10, TimeUnit.SECONDS) .writeTimeout(10, TimeUnit.SECONDS) .readTimeout(30, TimeUnit.SECONDS) .build();

Get

同步Get请求

下面的response.body().string()方法对于下载小文件而言是一种比较方便且高效的方式。但是对于大文件（大于1M），最好采用inputstream输入流的形式。这是因为String方式会将下载的文件放在内存中占用空间。

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(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()); } }); }

同步请求与异步请求

两者区别在于一个直接调用execute方法一个调用enqueue方法。

Post

Posting a String

适用于小于1M的文本传输

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 = "aaa"; 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()); }

Post 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();

OKHttp的用法不止这些，可以在Github上面找到OkHttp再研究研究。我想说的是从上面的代码中可以看出来要在项目中使用OKHttp还需要我们自己进行封装才行。