Http

1.HttpClient综述

HttpClient有两个实现子类，一个是AndroidHttpClient,一个是Default
HttpClient;AndroidHttpClient继承自DefaultHttpClient,是针对Android
设备的对某些参数进行了默认设置。

DefaultHttpClient client = new DefaultHttpClient();

可以对client设置参数(HttpParams)，如连接超时

HttpParams params = new BasicHttpParams();
params.setIntParameter(AllClientPNames.CONNECTION_TIMEOUT,10*1000);
client.setParams(params);

1)对于get请求

HttpGet request = new HttpGet("http://www.renren.com?email="
       +"zhangsan"+"&password="+"123");
HttpResponse response = client.execute(request);
int statusCode = respose.getStatusLine().getStatusCode();
if(statusCode==HttpStatus.SC_OK){
    String str = EntityUtils.toString(response.getEntity());
    System.out.println(str);
}

2)对于post请求

HttpPost request = new HttpPost("http://www.renren.com");
List<NameValuePair> pairs = new ArrayList<NameValuePair>();
pairs.add(new BasicNameValuePair("email","zhangsan@126.com"));
pairs.add(new BasicNameValuePair("password","123"));
UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(pairs);
//或者指定编码，如下
//UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(pairs,"UTF-8");

request.setEntity(formEntity);
HttpResponse response = client.execute(request);
int statusCode = respose.getStatusLine().getStatusCode();
if(statusCode==HttpStatus.SC_OK){
    String str = EntityUtils.toString(response.getEntity());
    System.out.println(str);
}

EntityUtils是一个工具类，所以它的方法为静态方法，它用来解析实体。提供的方法有
EntityUtils.toString(HttpEntity entity)-->String 作用将response的entity
按照默认编码转为字符串
EntityUtils.toString(HttpEntity entity, String defaultCharset) -->String
按照指定编码转为字符串
EntityUtils.toByteArray(HttpEntity entity)-->byte[] 作用是将response
的entity转为byte数组，如：可以处理图片
如下边例子：

HttpEntity entity = response.getEntity();
byte[] bs = EntityUtils.toByteArray(entity);
Bitmap bitmap = BitmapFactory.decodeByteArray(bs, 0, bs.length);

得到Bitmap就可以设置到ImageView中了。

注意：需要联网权限
 

<uses-permission android:name="android.permission.INTERNET"/>

  

2.注意

127.0.0.1 和 localhost都表示android手机自己本身的地址。

3.HttpUrlConnection综述
HttpUrlConnection可以处理get请求也可以处理post请求。

get方式介绍：
使用方式：
step1.

URL url = new URL("http://119.97.113.180:8080/test/t?username=zhangsan&password=123");

step2.通过URL创建HttpUrlConnection对象

HttpUrlConnectioin connection = url.openCennection();

step3.得到输入流。读取服务器返回的数据。
step4.关闭流
step5.connection.disconnect();断开连接。

String httpUrl = "http://119.97.113.180:8080/test/t?username=zhangsan&password=123"
URL url = new URL(httpUrl);
if (url != null){
    HttpURLConnection urlConn = (HttpURLConnection) url
      .openConnection();
    InputStreamReader in = new InputStreamReader(urlConn
      .getInputStream());
    BufferedReader buffer = new BufferedReader(in);
    String inputLine = null;
    while ((inputLine = buffer.readLine()) != null) {
        resultData += inputLine + "\n";
    }
in.close();
urlConn.disconnect();

post方式：
step1.创建URL对象

URL url = new URL("http://192.168.1.108:8080/test/t");

step2.得到HttpURLConnection对象

HttpURLConnection urlConn = (HttpURLConnection) url
                .openConnection();
step3.对connection对象进行设置
urlConn.setDoInput(true);
urlConn.setDoOutput(true);
urlConn.setRequestMethod("POST");//注意：这里必须为大写
urlConn.setUseCaches(false);

step4.调用connection的connect()方法。
step5.得到输出流，输出传给服务器的参数，然后关闭流。
step6.得到输入流，读取服务器响应的数据，然后关闭流。
step7.connection.disconnect();

String httpUrl = "http://192.168.1.108:8080/test/t";
String resultData = "";
URL url = new URL(httpUrl);
if (url != null) {
        HttpURLConnection urlConn = (HttpURLConnection) url
                .openConnection();
        urlConn.setDoInput(true);
        urlConn.setDoOutput(true);
        urlConn.setRequestMethod("POST");
        urlConn.setUseCaches(false);
        urlConn.connect();
        DataOutputStream out = new DataOutputStream(
                urlConn.getOutputStream());
        // 用户名和密码
        String content = "username=" + URLEncoder.encode("******")
                + "&password=" + "*******";
        out.writeBytes(content);
        out.flush();
        out.close();

        BufferedReader reader = new BufferedReader(
                new InputStreamReader(urlConn.getInputStream()));
        String inputLine = null;
        while ((inputLine = reader.readLine()) != null) {
            resultData += inputLine + "\n";
        }
        reader.close();
        urlConn.disconnect();
}

4.WebView控件的使用

WebView用来加载网页
step0.manifest.xml增加联网权限
<uses-permission android:name="android.permission.INTERNET"/>
step1.在layout中定义
<WebView
    android:id="@+id/wv"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    />

step2.在Activity中
wv = (WebView) findViewById(R.id.wv);
wv.loadUrl("http://www.baiud.com");

step3.保证每次都使用WebView打开连接。
wv.setWebViewClient(new WebViewClient(){
   @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url) {
       view.loadUrl(url);
       return true;//一定要为true
    }
});