學(xué)習(xí)目的：1.使用HTTP訪問(wèn)網(wǎng)絡(luò) 2.使用HttpURIConnection</h3>

1.使用HTTP訪問(wèn)網(wǎng)絡(luò)

工作原理：客戶(hù)端向服務(wù)器發(fā)出HTTP請(qǐng)求 服務(wù)器接收到請(qǐng)求返回?cái)?shù)據(jù) 客戶(hù)端解析處理

2.使用HttpURIConnection（本例獲取的是html代碼）

布局

<Button
        android:id="@+id/send_request"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Send Request" />

    <ScrollView//滾動(dòng)查看界面顯示不了的內(nèi)容
        android:layout_width="match_parent"
        android:layout_height="match_parent" >

        <TextView
            android:id="@+id/response_text"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
    </ScrollView>

MainActivity類(lèi)

@Override
   public void onClick(View v) {
       if (v.getId() == R.id.send_request) {
         sendRequestWithHttpURLConnection();

       }
   }
private void sendRequestWithHttpURLConnection() {
       // 開(kāi)啟線程來(lái)發(fā)起網(wǎng)絡(luò)請(qǐng)求
       new Thread(new Runnable() {
           @Override
           public void run() {
               HttpURLConnection connection = null;
               BufferedReader reader = null;
               try {
                   URL url = new URL("http://www.baidu.com");
                   connection = (HttpURLConnection) url.openConnection();
                   connection.setRequestMethod("GET");
                   connection.setConnectTimeout(8000);
                   connection.setReadTimeout(8000);
                   InputStream in = connection.getInputStream();
                   // 下面對(duì)獲取到的輸入流進(jìn)行讀取
                   reader = new BufferedReader(new InputStreamReader(in));
                   StringBuilder response = new StringBuilder();
                   String line;
                   while ((line = reader.readLine()) != null) {
                       response.append(line);
                   }
                   showResponse(response.toString());
               } catch (Exception e) {
                   e.printStackTrace();
               } finally {
                   if (reader != null) {
                       try {
                           reader.close();
                       } catch (IOException e) {
                           e.printStackTrace();
                       }
                   }
                   if (connection != null) {
                       connection.disconnect();
                   }
               }
           }
       }).start();
   }

添加權(quán)限

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

3.提交數(shù)據(jù)給服務(wù)器（如：提交用戶(hù)名和密碼）數(shù)據(jù)用&隔開(kāi)

connection.setRequestMethod("POST");
DataOutPutStream out=new DataOutPutStream(connection.getOutPutStream());
out.writeBytes("username=admin&password=123456789");

4.使用Okhttp

添加依賴(lài)

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:24.2.1'
    compile 'com.squareup.okhttp3:okhttp:3.4.1'//自動(dòng)下載兩個(gè)庫(kù)Okhttp庫(kù) Okio庫(kù)

}

用Okhttp重寫(xiě)http的例子

public void onClick(View v) {
       if (v.getId() == R.id.send_request) {
//            sendRequestWithHttpURLConnection();
           sendRequestWithOkHttp();
       }
   }

   private void sendRequestWithOkHttp() {
       new Thread(new Runnable() {
           @Override
           public void run() {
               try {
                   OkHttpClient client = new OkHttpClient();
                   Request request = new Request.Builder()

                           .url("http://www.baidu.com")
                           .build();
                   Response response = client.newCall(request).execute();
                   String responseData = response.body().string();

                  showResponse(responseData);
               } catch (Exception e) {
                   e.printStackTrace();
               }
           }
       }).start();
   }

   private void showResponse(final String response) {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                // 在這里進(jìn)行UI操作，將結(jié)果顯示到界面上
                responseText.setText(response);
            }
        });
    }