【Android】HttpURLConnection在子線程請求、在主線程處理數據

HttpURLConnection可以發起網絡請求，比如說我們需要從服務器獲取數據

一、layout佈局

方便起見，就放一個button就行了

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    tools:context=".MainActivity">
    <Button
        android:id="@+id/btn_send"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="請求"/>
</LinearLayout>

二、Java代碼

MainActivity.java

public class MainActivity extends AppCompatActivity {
    private Button btn_send;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn_send = findViewById(R.id.btn_send);
        btn_send.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                startHttpURLConnection();
            }
        });
    }

    private void startHttpURLConnection(){
        //耗時操作必須要放在子線程
        new Thread(new Runnable() {
            @Override
            public void run() {
                HttpURLConnection connection = null;
                BufferedReader reader = null;
                try{
                    URL url = new URL("https://www.baidu.com");
                    connection = (HttpURLConnection) url.openConnection();//打開openConnection鏈接
                    connection.setRequestMethod("GET");//以GET方式發起請求（默認）

                    /*//若是以POST方式提交數據
                    connection.setRequestMethod("POST");
                    DataOutputStream outputStream = new DataOutputStream(connection.getOutputStream());
                    outputStream.writeBytes("usename=name&password=111111");//提交的數據用&分割     */

                    connection.setConnectTimeout(5000);//設置請求超時時間爲5秒
                    connection.setReadTimeout(5000);//設置讀取超時時間爲5秒
                    InputStream inputStream = connection.getInputStream();//獲得數據流
                    reader = new BufferedReader(new InputStreamReader(inputStream));
                    StringBuilder response = new StringBuilder();
                    String line;
                    while ((line = reader.readLine()) != null){
                        response.append(line);
                    }
                    dealWithResult(response.toString());//新建一個方法處理請求得到的數據
                }catch (Exception e){e.printStackTrace();}
                finally {
                    if (reader != null){
                        try{reader.close();}catch (Exception e){e.printStackTrace();}
                    }
                    if(connection != null){
                        connection.disconnect();
                    }
                }
            }
        }).start();
    }

    private void dealWithResult(final String res){
      
    }
}

三、更新UI線程

方法一：

private void dealWithResult(final String res){
        //在UI主線程操作，比如說用TextView顯示
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                Log.e("res", "dealWithResult: "+res);
            }
        });

    }

方法二：

private void dealWithResult(final String res){
        //在UI主線程操作，比如說用TextView顯示
        new Handler(getApplicationContext().getMainLooper()).post(new Runnable() {
            @Override
            public void run() {
                Log.e("res", "run: "+res );
            }
        });

    }

四、添加網絡權限

在Androidmanifest中使用權限

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

若是Android 9或以上，還需要在application標籤中加入

android:usesCleartextTraffic="true"