HttpUtil.java

package com.example.networktest;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

import okhttp3.OkHttpClient;
import okhttp3.Request;

public class HttpUtil {
    public static void sendHttpRequest(final String address,final HttpCallbackListener listener) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                HttpURLConnection connection = null;
                try {
                    URL url = new URL(address);
                    connection = (HttpURLConnection) url.openConnection();
                    connection.setRequestMethod("GET");

                    //post的形式
                    //connection.setRequestMethod("POST");
                    // DataOutputStream out = new DataOutputStream(connection.getOutputStream());
                    //out.writeBytes("username=admin&password=123456");
                    connection.setConnectTimeout(8000);
                    connection.setReadTimeout(8000);
                    InputStream in = connection.getInputStream();

                    //下面对获取到的输入流进行读取
                    BufferedReader reader = new BufferedReader(new InputStreamReader(in));
                    StringBuilder response = new StringBuilder();
                    String line;
                    while ((line = reader.readLine()) != null) {
                        response.append(line);
                    }
                    if(listener!=null){
                        //回掉onFinish()方法
                        listener.onFinish(response.toString());
                    }
                    //return response.toString();

                } catch (Exception e) {
                    e.printStackTrace();
                    if(listener!=null){
                        //回调onError
                        listener.onError(e);
                    }
                    //return e.getMessage();
                } finally {
                    if (connection != null) {
                        connection.disconnect();
                    }

                }


            }
        }).start();

    }

    public static void sendOkHttpResponse(String address, okhttp3.Callback callback) {
        //okhttp自带回调接口类型自己写的HttpCallbackListener
        OkHttpClient client = new OkHttpClient();
        Request request = new Request.Builder()
                .url(address)
                .build();
        //enqueue内部帮我们开好子线程了，然后子线程去执行http请求
        client.newCall(request).enqueue(callback);
    }
}

接口HttpCallbackListener.java

package com.example.networktest;

import okhttp3.OkHttpClient;
import okhttp3.Request;

public interface HttpCallbackListener {
    void onFinish(String response);

    void one rror(Exception e);

}

MainActivity.java

package com.example.networktest;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import org.jetbrains.annotations.NotNull;

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

import okhttp3.Call;
import okhttp3.FormBody;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    TextView responseText;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button sendRequest = (Button) findViewById(R.id.send_request);
        responseText = (TextView) findViewById(R.id.response_text);
        sendRequest.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        if (v.getId() == R.id.send_request) {
            //sendRequestWithHttpURLConnection();
            //sendRequestWithOkHttp();
            String address = "http://www.baidu.com";
//            HttpUtil.sendHttpRequest(address, new HttpCallbackListener() {
//                @Override
//                public void onFinish(String response) {
//                    //根据返回的内容执行具体的逻辑
//                }
//
//                @Override
//                public void one rror(Exception e) {
//                    //根据返回的内容执行具体的逻辑
//                }
//            });
            HttpUtil.sendOkHttpResponse(address,new okhttp3.Callback(){

                @Override
                public void onResponse(@NotNull Call call, Response response) throws IOException {
                    //得到服务器返回的具体内容
                    String responseData = response.body().string();

                }

                @Override
                public void onFailure(@NotNull Call call, @NotNull IOException e) {

                }
            });

        }
    }

    private void sendRequestWithHttpURLConnection() {
        //  开启线程来发送网络请求
        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");

                    //post的形式
                    //connection.setRequestMethod("POST");
                    // DataOutputStream out = new DataOutputStream(connection.getOutputStream());
                    //out.writeBytes("username=admin&password=123456");
                    connection.setConnectTimeout(8000);
                    connection.setReadTimeout(8000);
                    InputStream in = connection.getInputStream();

                    //下面对获取到的输入流进行读取
                    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();
    }

    private void sendRequestWithOkHttp() {
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    //创建一个client实例
                    OkHttpClient client = new OkHttpClient();
                    //创建request对象
                    Request request = new Request.Builder().url("http://www.baidu.com").build();
                    Response response = client.newCall(request).execute();
                    String responseData = response.body().string();

//                    //post 需要先构建出一个Request Body对象存放待提交的参数
//                    RequestBody requestBody = new FormBody.Builder()
//                            .add("username","admin")
//                            .add("password","123456")
//                            .build();
                    //在调用post方法，传入RequestBody对象
//
//                    Request request1 = new Request.Builder().url("http://www.baidu.com").post(requestBody).build();
                    showResponse(responseData);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }

    private void showResponse(final String response) {
        //安卓不允许子线程中进行UI操作，我们切换到主线程
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                // 在这里进行ui操作，将结果显示到页面上
                responseText.setText(response);
            }
        });
    }
}