上一篇我们了解了HTTP协议原理,这一篇我们来讲讲Apache的HttpClient和Java的HttpURLConnection,这两种都是我们平常请求网络会用到的。无论我们是自己封装的网络请求类还是第三方的网络请求框架都离不开这两个类库。
Android SDK中包含了HttpClient,在Android6.0版本直接删除了HttpClient类库,如果仍想使用则解决方法是:
android {
useLibrary 'org.apache.http.legacy'
}
首先我们来用DefaultHttpClient类来实例化一个HttpClient,并配置好默认的请求参数:
//创建HttpClient
private HttpClient createHttpClient() {
HttpParams mDefaultHttpParams = new BasicHttpParams(); //设置连接超时
HttpConnectionParams.setConnectionTimeout(mDefaultHttpParams, 15000); //设置请求超时
HttpConnectionParams.setSoTimeout(mDefaultHttpParams, 15000);
HttpConnectionParams.setTcpNoDelay(mDefaultHttpParams, true);
HttpProtocolParams.setVersion(mDefaultHttpParams, HttpVersion.HTTP_1_1);
HttpProtocolParams.setContentCharset(mDefaultHttpParams, HTTP.UTF_8); //持续握手
HttpProtocolParams.setUseExpectContinue(mDefaultHttpParams, true);
HttpClient mHttpClient = new DefaultHttpClient(mDefaultHttpParams); return mHttpClient;
}
接下来创建HttpGet和HttpClient,请求网络并得到HttpResponse,并对HttpResponse进行处理:
private void useHttpClientGet(String url) {
HttpGet mHttpGet = new HttpGet(url);
mHttpGet.addHeader("Connection", "Keep-Alive"); try {
HttpClient mHttpClient = createHttpClient();
HttpResponse mHttpResponse = mHttpClient.execute(mHttpGet);
HttpEntity mHttpEntity = mHttpResponse.getEntity();
int code = mHttpResponse.getStatusLine().getStatusCode();
if (null != mHttpEntity) {
InputStream mInputStream = mHttpEntity.getContent();
String respose = converStreamToString(mInputStream);
Log.i("wangshu", "请求状态码:" + code + "\n请求结果:\n" + respose);
mInputStream.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
converStreamToString方法将请求结果转换成String类型:
private String converStreamToString(InputStream is) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuffer sb = new StringBuffer();
String line = null; while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
String respose = sb.toString(); return respose;
}
最后我们开启线程访问百度:
new Thread(new Runnable() { @Override
public void run() {
useHttpClientGet("http://www.baidu.com");
}
}).start();
请求的返回结果,请求状态码为200,结果就是个html页,这里只截取了部分html代码:
GET请求的参数暴露在URL中,这有些不大妥当,而且URL的长度也有限制:长度在2048字符之内,在HTTP 1.1后URL长度才没有限制。一般情况下POST可以替代GET,接下来我们来看看HttpClient的POST请求。