<uses-permission android:name="android.permission.CAMERA" />
    <uses-feature android:name="android.hardware.camera" />
    <uses-feature android:name="android.hardware.camera.autofocus" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);//調用Camera
startActivityForResult(intent, Activity.RESULT_OK);//如果正常，則返回    Activity.RESULT_OK    本質為 int類型的1

String sdStatus = Environment.getExternalStorageState();
if(!sdStatus.equals(Environment.MEDIA_MOUNTED)){
                System.out.println(" ------------- sd card is not avaiable ---------------");
                return;
}

String name = "photo.jpg";//定義圖片名稱

Bundle bundle = data.getExtras();//data為onActivityResult中的intent類型的參數
Bitmap bitmap = (Bitmap) bundle.get("data");//bitmap

//            File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath()+"/");
//            file.mkdirs(); //創建文件夾

//            String fileName = Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+name;
String fileName = "sdcard"+"/"+name;//初始化文件路徑

FileOutputStream fos =null;//初始化文件輸出流

try {
    // System.out.println(fileName);	// 測試用，查看文件路徑
    fos=new FileOutputStream(fileName);	// 輸出文件到外部存儲
    //今天第一次正視這個bitmap.compress()方法，它用來壓縮圖片大小。
    /*
    	這個方法有三個參數：
    	Bitmap.CompressFormat format 圖像的壓縮格式；
		int quality 圖像壓縮率，0-100。 0 壓縮100%，100意味著不壓縮；
		OutputStream stream 寫入壓縮數據的輸出流；
		public boolean compress(CompressFormat format, int quality, OutputStream stream) {}
		返回值boolean類型
		如果成功地把壓縮數據寫入輸出流，則返回true。
    */
    bitmap.compress(Bitmap.CompressFormat.JPEG,100,fos);	
    
} catch (FileNotFoundException e) {
    e.printStackTrace();
}finally {
    try {
        fos.flush();	//釋放輸出流
        fos.close();
    } catch (IOException e) {
        e.printStackTrace();
    }

}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_take_photo"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">


    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="take photo"
        android:id="@+id/takephoto"
        />
    <ImageView
        android:layout_below="@+id/takephoto"
        android:layout_width="400dp"
        android:layout_height="400dp"
        android:id="@+id/picture"
        />
</RelativeLayout>

package icu.whatsblog.CameraCrop;

import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.os.Environment;
import android.provider.MediaStore;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

import androidx.appcompat.app.AppCompatActivity;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

import lee.suk.cameracrop.R;

public class MainActivity extends AppCompatActivity {

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

        ((Button) findViewById(R.id.takephoto)).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

                startActivityForResult(intent, 1);
            }
        });
    }


    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (resultCode == Activity.RESULT_OK){
            String sdStatus = Environment.getExternalStorageState();

            if(!sdStatus.equals(Environment.MEDIA_MOUNTED)){
                System.out.println(" ------------- sd card is not avaiable ---------------");
                return;
            }


            String name = "photo.jpg";

            Bundle bundle = data.getExtras();
            Bitmap bitmap = (Bitmap) bundle.get("data");

//            File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath()+"/");
//            file.mkdirs(); //創建文件夾

//            String fileName = Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+name;
            String fileName = "sdcard"+"/"+name;

            FileOutputStream fos =null;

            try {
                System.out.println(fileName);
                fos=new FileOutputStream(fileName);
                bitmap.compress(Bitmap.CompressFormat.JPEG,100,fos);
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }finally {
                try {
                    fos.flush();
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }

            }
            ((ImageView) findViewById(R.id.picture)).setImageBitmap(bitmap);
        }
    }
}