23、Android -- OKHttp3 基础学习

说明

OKHttp3 主要是一个网络请求

• 网络请求方式一般为PUT，DELETE，POST，GET等。常用的是get、post
• 文件的上传下载
• 加载图片(内部会图片大小自动压缩)
• 支持请求回调，直接返回对象、对象集合
• 支持session的保持

示例

1、添加依赖库、和网络权限

• 依赖库
  build.gradle

    // okhttp3 的依赖库
    implementation 'com.squareup.okhttp3:okhttp:4.9.0'
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网络权限
AndroidManifest.xml

	<uses-permission android:name="android.permission.INTERNET"/>
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2、布局文件

主要用于示例中按钮处方请求
res/layout/activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<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"
    android:orientation="vertical"
    tools:context=".MainActivity">
    <Button
        android:id="@+id/btn_mian_one"
        android:text="Get同步请求"
        android:onClick="GetSyn"
        android:layout_width="200dp"
        android:layout_height="50dp"
        />
    <Button
        android:id="@+id/btn_mian_two"
        android:text="Get异步请求"
        android:onClick="GetAsync"
        android:layout_width="200dp"
        android:layout_height="50dp"
        />
    <Button
        android:id="@+id/btn_mian_three"
        android:text="Post同步请求"
        android:onClick="PostSyn"
        android:layout_width="200dp"
        android:layout_height="50dp"
        />
    <Button
        android:id="@+id/btn_mian_four"
        android:text="post异步请求"
        android:onClick="PostAsync"
        android:layout_width="200dp"
        android:layout_height="50dp"
        />
</LinearLayout>
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网络请求

1、公共

主要各种请求提取相同代码
定义 okHttpClient

private OkHttpClient okHttpClient;
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实例化

okHttpClient = new OkHttpClient();
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2、Get同步请求

 // get 同步步请求
    public void GetSyn(View view) {
        Request request = new Request.Builder().url("https://www.baidu.com/s?wd=12").build();
        Call call = okHttpClient.newCall(request);
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    Response response = call.execute();
                    Log.e(TAG, "GetSyn: " +response.body().string());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }
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**3、Get异步请求 **

// get 异步请求
    public void GetAsync(View view) {
        Request request = new Request.Builder().url("https://www.baidu.com/s?wd=12").build();
        Call call = okHttpClient.newCall(request);
        call.enqueue(new Callback() {
            @Override
            public void onFailure(@NonNull Call call, @NonNull IOException e) {
                Log.e(TAG, "GetAsync: " +e);
            }

            @Override
            public void onResponse(@NonNull Call call, @NonNull Response response) throws IOException {
                Log.e(TAG, "GetAsync: " +response.body().string());
            }
        });
    }
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备注1
Get的同步、异步大部分很相似。
1、第一步都是-创建OkHttpClient对象(公共中创建的)
2、第二步都是-通过Request.Builder来创建Request对象
3、第三步都是-创将抽象Call 执行请求的对象

 		Request request = new Request.Builder().url("https://www.baidu.com/s?wd=12").build();
        Call call = okHttpClient.newCall(request);
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区别在于
4、第四步的区别：
同步：用call.execute();执行，并用Response接收响应
异步：call.enqueue()
5、注意问题：同步代码一般单开线程，避免时间过程

备注2

• Reques：该t对象是http请求的抽象对象（包括请求地址，请求方法，请求头，请求体等内容）。通常用Request.Builder来创建该对象。通过request对象的url，method，headers，body等方法能够获取到请求的对应信息。
• Response对象是http响应的抽象对象（包括响应头，响应体等内容）。
• Call对象抽象的是一个正在准备执行的请求

Post 同步请求

 // post 同步请求
    public void PostSyn(View view) {
        FormBody formBody = new FormBody.Builder().add("wd","12")
                .build();
        Request request = new Request.Builder().url("https://www.baidu.com/s").post(formBody).build();
        Call call = okHttpClient.newCall(request);
        new Thread(){
            @Override
            public void run() {

                try {
                    Response response = call.execute();
                    Log.e(TAG, "PostAsync: " +response.body().string());
                } catch (IOException e) {
                    e.printStackTrace();
                }

            }
        }.start();
    }
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Post 异步请求

// post 异步请求
    public void PostAsync(View view) {
        FormBody formBody = new FormBody.Builder().add("wd","12")
                .build();
        Request request = new Request.Builder().url("https://www.baidu.com/s").post(formBody).build();
        Call call = okHttpClient.newCall(request);
        call.enqueue(new Callback() {
            @Override
            public void onFailure(@NonNull Call call, @NonNull IOException e) {

            }

            @Override
            public void onResponse(@NonNull Call call, @NonNull Response response) throws IOException {
                Log.e(TAG, "PostAsync: "+response.body().string());
            }
        });
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备注3
Post 的同步和异步相差不多，同“备注1”

备注4
get 和post的同步代码也很相似
区别主要在于post 需要通过FormBody.Builder()创建表单参数。然后才可以传给Request。
其他的步骤基本相似
同理，get 和post的异步代码一样

最终代码java/com/pha/four/MainActivity.java

package com.pha.four;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;
import android.view.View;

import java.io.IOException;

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


public class MainActivity extends AppCompatActivity {

    private static final String TAG = "MainActivity";
    private OkHttpClient okHttpClient;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        okHttpClient = new OkHttpClient();
    }
    // get 同步步请求
    public void GetSyn(View view) {
        Request request = new Request.Builder().url("https://www.baidu.com/s?wd=12")
                .build();
        Call call = okHttpClient.newCall(request);
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    Response response = call.execute();
                    Log.e(TAG, "GetSyn: " +response.body().string());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }
    // get 异步请求
    public void GetAsync(View view) {
        Request request = new Request.Builder().url("https://www.baidu.com/s?wd=12").build();
        Call call = okHttpClient.newCall(request);
        call.enqueue(new Callback() {
            @Override
            public void onFailure(@NonNull Call call, @NonNull IOException e) {
                Log.e(TAG, "GetAsync: " +e);
            }

            @Override
            public void onResponse(@NonNull Call call, @NonNull Response response) throws IOException {
                Log.e(TAG, "GetAsync: " +response.body().string());
            }
        });
    }
    // post 同步请求
    public void PostSyn(View view) {
        FormBody formBody = new FormBody.Builder().add("wd","12")
                .build();
        Request request = new Request.Builder().url("https://www.baidu.com/s").post(formBody).build();
        Call call = okHttpClient.newCall(request);
        new Thread(){
            @Override
            public void run() {

                try {
                    Response response = call.execute();
                    Log.e(TAG, "PostAsync: " +response.body().string());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }.start();
    }
    // post 异步请求
    public void PostAsync(View view) {
        FormBody formBody = new FormBody.Builder().add("wd","12")
                .build();
        Request request = new Request.Builder().url("https://www.baidu.com/s").post(formBody).build();
        Call call = okHttpClient.newCall(request);
        call.enqueue(new Callback() {
            @Override
            public void onFailure(@NonNull Call call, @NonNull IOException e) {

            }

            @Override
            public void onResponse(@NonNull Call call, @NonNull Response response) throws IOException {
                Log.e(TAG, "PostAsync: "+response.body().string());
            }
        });
    }
}
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