Android 网络技术

WebView

webView应用内嵌浏览器

布局

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".Webview">

    <WebView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/web"/>

</LinearLayout>

活动

public class Webview extends AppCompatActivity {

    private WebView webView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_webview);

        webView=findViewById(R.id.web);
        webView.getSettings().setJavaScriptEnabled(true);  //支持JS脚本
        webView.setWebViewClient(new WebViewClient());  //网页跳转时在本控件内进行，而不是打开系统浏览器
        webView.loadUrl("https://bilibili.com"); //传入网址
    }
}

权限

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

使用Http协议访问网络

HttpURLConnection

Android团队推荐使用HttpURLConnection发送HTTP请求，其步骤如下：

• 1.获取HttpURLConnection实例：new一个URL对象，调用openConnection()即可
• 2.用实例设置请求所使用的方法，GET或POST，调用setRequestMethod()
• 3.自由定制，设置连接超时setConnectTimeout()、读取的毫秒数setReadTimeout()、消息头等等
• 4.获取输入流，getInputStream()
• 5.最后关闭连接，disconnect()

Demo 布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/send_request"
        android:text="发送请求"/>
    
    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/response_text"/>
    </ScrollView>

</LinearLayout>

Demo 活动

public class Http extends AppCompatActivity implements View.OnClickListener {
    private TextView textView;
    private Button sendRequest;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_http);

        sendRequest = findViewById(R.id.send_request);
        textView = findViewById(R.id.response_text);

        sendRequest.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.send_request:
                sendRequestWithHttpURLConnection();
                break;
        }
    }

    private void sendRequestWithHttpURLConnection() {
        //开启线程来发起网络请求
        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();
                    connection.setRequestMethod("GET");
                    connection.setConnectTimeout(8000);
                    connection.setReadTimeout(8000);
                    InputStream in = connection.getInputStream();
                    //对获取到的输入流读取
                    reader = new BufferedReader(new InputStreamReader(in));
                    StringBuilder response = new StringBuilder();
                    String line;
                    while ((line = reader.readLine()) != null) {
                        response.append(line);
                    }
                    Log.d("test", response.toString());
                    showResponse(response.toString());
                } 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 showResponse(final String response) {
        runOnUiThread(new Runnable() {  //切换到主线程
            @Override
            public void run() {
                textView.setText(response);
            }
        });
    }
}

权限

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

运行

使用Okhttp

地址

https://square.github.io/okhttp/

添加依赖

//okhttp
implementation "com.squareup.okhttp3:okhttp:4.3.1"

用法

• Request用法：

  • 创建OkHttpClient实例：new OkHttpClient()
  • 创建Request对象：new Request.Builder().url("").build()
  • 调用实例的newCall()创建Call对象，调用execute()发送请求获取数据：Response response = client.newCall(request).execute()
  • 获取返回的内容：response.body().String()

• Post用法：

  //先构造出一个RequestBody对象来存放待提交的参数
  RequestBody requestBody = new FormBody.Builder()
  	.add("username", "admin")
  	.add("password", "123456")
  	.build();
  
  //在Request.Build中调用post()方法，并将RequestBody对象传入
  Request request = new Request.Builder()
  	.url("")
  	.post(requestBody)
  	.build()
  
  //接下来的操作和GET用法一样

项目Code

在前面Http例子的基础上改一下这个方法:

private void sendRequestWithOkHttp() {
    new Thread(new Runnable() {
        @Override
        public void run() {
            try{
                OkHttpClient client = new OkHttpClient();
                Request request = new Request.Builder()
                        .url("https://baidu.com")
                        .build();
                Response response = client.newCall(request).execute();
                String responseData = response.body().string();
                showResponse(responseData);
            }catch (Exception e){
                e.printStackTrace();
            }
        }
    }).start();
}