package com.example.myapplication;
import android.util.Log;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.math.BigDecimal;
public class MakeUtils {
    private static final String XML_HEADER = "<?xml version=\"1.0\" encoding=\"utf-8\"?>\r\n";
    private static final String XML_RESOURCE_START = "<resources>\r\n";
    private static final String XML_RESOURCE_END = "</resources>\r\n";
    private static final String XML_DIMEN_TEMPLETE = "<dimen name=\"qb_%1$spx_%2$d\">%3$.2fdp</dimen>\r\n";
    private static final String XML_BASE_DPI = "<dimen name=\"base_dpi\">%ddp</dimen>\r\n";
    private  static final int MAX_SIZE = 720;
    private static final String XML_NAME = "dimens.xml";
    public static float px2dip(float pxValue, int sw,int designWidth) {
        float dpValue =   (pxValue/(float)designWidth) * sw;
        BigDecimal bigDecimal = new BigDecimal(dpValue);
        float dp = bigDecimal.setScale(2, BigDecimal.ROUND_HALF_UP).floatValue();
        return dp;
    }
    /**
     * 生成所有的尺寸数据
     */
    private static String createDimens(DimenTypes type, int designWidth) {
        float dpValue;
        String temp;
        StringBuilder sb = new StringBuilder();
        try {
            sb.append(XML_HEADER);
            sb.append(XML_RESOURCE_START);
            //备份生成的相关信息
            temp = String.format(XML_BASE_DPI, type.getSwWidthDp());
            sb.append(temp);
            for (int i = 0; i <= MAX_SIZE; i++) {
                dpValue = px2dip((float) i,type.getSwWidthDp(),designWidth);
                temp = String.format(XML_DIMEN_TEMPLETE,"", i, dpValue);
                sb.append(temp);
            }
            sb.append(XML_RESOURCE_END);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return sb.toString();
    }
    /**
     * 生成的目标文件夹
     */
    public static void create(int designWidth, DimenTypes type, String buildDir) {
        try {
            //生成规则
            final String folderName;
            if (type.getSwWidthDp() > 0) {
                //适配Android 3.2+
                folderName = "values-sw" + type.getSwWidthDp() + "dp";
            }else {
                return;
            }
            //生成目标目录
            File file = new File(buildDir + File.separator + folderName);
            if (!file.exists()) {
                file.mkdirs();
            }
            Log.e("===",file.getAbsolutePath());
            //生成values文件
            FileOutputStream fos = new FileOutputStream(file.getAbsolutePath() + File.separator + XML_NAME);
            fos.write(createDimens(type,designWidth).getBytes());
            fos.flush();
            fos.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

package com.example.myapplication;
/**
 * created by YooJin.
 * date: 2021/2/3 13:50
 * ldpi: 120 density:1dp=0.75px 代表尺寸 240*320
 * mdpi: 160 density:1dp=1px 代表尺寸 320*480
 * hdpi: 240 density:1dp=1.5px 代表尺寸 480*800
 * xhdpi: 320 density:1dp=2px 代表尺寸720*1280
 * xxhdpi: 480 density:1dp=3px 代表尺寸1080*1920
 */
enum DimenTypes {
    DP_sw__160(160),
    DP_sw__240(240),
    DP_sw__280(280),
    DP_sw__320(320),  
    DP_sw__360(360),
    DP_sw__400(400),
    DP_sw__420(420),
    DP_sw__440(440),
    DP_sw__480(480),
    DP_sw__560(560),
    DP_sw__640(640),
    DP_sw__720(720),
    DP_sw__800(800);
    /**
     * 屏幕最小宽度
     */
    private int swWidthDp;
    DimenTypes(int swWidthDp) {
        this.swWidthDp = swWidthDp;
    }
    public int getSwWidthDp() {
        return swWidthDp;
    }
    public void setSwWidthDp(int swWidthDp) {
        this.swWidthDp = swWidthDp;
    }
}

package com.example.myapplication;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import android.Manifest;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.os.Environment;
import android.widget.TextView;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
    /**
     * 设计稿尺寸，从零开始，生成的最大尺寸
     */
    private static final int DESIGN_WIDTH = 375;
    String[] permissions = new String[]{Manifest.permission.CAMERA, Manifest.permission.WRITE_EXTERNAL_STORAGE};
    List<String> mPermissionList = new ArrayList<>();
    private static final int PERMISSION_REQUEST = 1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        checkPermission();
        String path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getAbsolutePath() + File.separator + "res";
        TextView tvTag = findViewById(R.id.tv_tag);
        tvTag.setText(path);
        DimenTypes[] values = DimenTypes.values();
        for (DimenTypes value : values) {
            MakeUtils.create(DESIGN_WIDTH, value, path);
        }
    }
    private void checkPermission() {
        mPermissionList.clear();
        //判断哪些权限未授予
        for (int i = 0; i < permissions.length; i++) {
            if (ContextCompat.checkSelfPermission(this, permissions[i]) != PackageManager.PERMISSION_GRANTED) {
                mPermissionList.add(permissions[i]);
            }
        }
        /**
         * 判断是否为空
         */
        if (mPermissionList.isEmpty()) {//未授予的权限为空，表示都授予了
        } else {//请求权限方法
            String[] permissions = mPermissionList.toArray(new String[mPermissionList.size()]);//将List转为数组
            ActivityCompat.requestPermissions(MainActivity.this, permissions, PERMISSION_REQUEST);
        }
    }
    /**
     * 响应授权
     * 这里不管用户是否拒绝，都进入首页，不再重复申请权限
     */
    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        switch (requestCode) {
            case PERMISSION_REQUEST:
                break;
            default:
                super.onRequestPermissionsResult(requestCode, permissions, grantResults);
                break;
        }
    }
}