Python Flask+Android+okhttp上传图片文件，支持Android6.0及以上的内部权限申请(附完整代码和项目工程)

重点难点

1. Android6.0以上不但需要在AndroidManifest.xml申请权限，还要在代码中动态申请。
2. 网络发送图片、文件必须使用线程发送，否则不会成功。

Android代码

1. MainActivity.java，申请权限和读取根目录图片

package com.example.androidclient;

import android.Manifest;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Environment;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ImageView;
import android.widget.Toast;
import java.io.File;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    // 申请权限的集合，同时要在AndroidManifest.xml中申请，Android 6以上需要动态申请权限
    String[] permissions = new String[]{
            Manifest.permission.WRITE_EXTERNAL_STORAGE,
            Manifest.permission.READ_EXTERNAL_STORAGE,
            Manifest.permission.INTERNET
    };
    // 声明一个集合，在后面的代码中用来存储用户拒绝授权的权
    List<String> mPermissionList = new ArrayList<>();
    //显示图片窗体
    private ImageView showImg;
    //图片路径
    private String path;
    //
    File f;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        showImg = findViewById(R.id.img);
        //6.0获取多个权限
        mPermissionList.clear();
        for (int i = 0; i < permissions.length; i++) {
            if (ContextCompat.checkSelfPermission(MainActivity.this, permissions[i]) != PackageManager.PERMISSION_GRANTED) {
                mPermissionList.add(permissions[i]);
            }
        }
        //未授予的权限为空，表示都授予了
        if (mPermissionList.isEmpty()) {
            //读取根目录下的一张图片
            path = Environment.getExternalStorageDirectory().getAbsolutePath() + "/1.png";
            boolean fileExist = fileIsExists(path);
            if(fileExist){
                Toast.makeText(MainActivity.this,"开始上传"+f.getAbsolutePath(),Toast.LENGTH_LONG).show();
                try {
                    //上传图片
                    ImageUpload.run(f);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            readImg(showImg);
        } else {//请求权限方法
            String[] permissions = mPermissionList.toArray(new String[mPermissionList.size()]);
            ActivityCompat.requestPermissions(MainActivity.this, permissions, 1);
        }
    }
    //界面显示图片
    public void readImg(View view) {
        Bitmap bitmap = BitmapFactory.decodeFile(path);
        showImg.setImageBitmap(bitmap);
    }
    //判断文件是否存在
    public boolean fileIsExists(String strFile) {
        try {
            f = new File(strFile);
            if (!f.exists()) {
                return false;
            }
        } catch (Exception e) {
            return false;
        }
        return true;
    }
    @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
        if (requestCode == 1) {
            for (int i = 0; i < grantResults.length; i++) {
                if (grantResults[i] != PackageManager.PERMISSION_GRANTED) {
                    //判断是否勾选禁止后不再询问
                    boolean showRequestPermission = ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this, permissions[i]);
                    if (showRequestPermission) {
                        Toast.makeText(MainActivity.this,"权限未申请",Toast.LENGTH_SHORT).show();
                    }
                }
            }
        }
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    }
}

2. ImageUpload.java，一定一定要用线程发送图片和文件，其他的代码很多都不对…

pjvackage com.example.androidclient;

import java.io.File;
import java.io.IOException;
import java.util.UUID;
import okhttp3.MediaType;
import okhttp3.MultipartBody;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

public class ImageUpload{
    /**
     * The imgur client ID for OkHttp recipes. If you're using imgur for anything other than running
     * these examples, please request your own client ID! https://api.imgur.com/oauth2
     */
    private static final String IMGUR_CLIENT_ID = "123";
    private static final MediaType MEDIA_TYPE_PNG = MediaType.parse("image/png");
    private static final OkHttpClient client = new OkHttpClient();
    public static void run(File f) throws Exception {
        final File file=f;
        new Thread() {
            @Override
            public void run() {
                //子线程需要做的工作
                RequestBody requestBody = new MultipartBody.Builder()
                        .setType(MultipartBody.FORM)
                        .addFormDataPart("title", "Square Logo")
                        .addFormDataPart("file", UUID.randomUUID().toString()+".png",
                                RequestBody.create(MEDIA_TYPE_PNG, file))
                        .build();
                //设置为自己的ip地址
                Request request = new Request.Builder()
                        .header("Authorization", "Client-ID " + IMGUR_CLIENT_ID)
                        .url("http://10.1.12.47:5000/upload")
                        .post(requestBody)
                        .build();
                try (Response response = client.newCall(request).execute()) {
                    if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

                    System.out.println(response.body().string());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }.start();
    }
}

3. activity_main.xml，布局代码，只添加了一个ImageView

<android.support.constraint.ConstraintLayout 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=".MainActivity">
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">
        <ImageView
            android:id="@+id/img"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            tools:srcCompat="@tools:sample/avatars" />
    LinearLayout>
android.support.constraint.ConstraintLayout>

4. AndroidManifest.xml，权限参数

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.androidclient">
    
    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            intent-filter>
        activity>
    application>

manifest>

测试

需要预先在手机根目录下放一个图片文件，1.png

1. APP界面
2. 服务器界面（UUID命名的图片上传成功）
   

完整工程

1. 已上传到github上，其中的AndroidClient就是其完整的代码。https://github.com/hrdhrdhrdhrd/okhttpFlaskDemo
2. FlaskServer则是通过python写的一个Flask服务器，用于接收Android传来的图片或者文本信息。