package com.example.administrator.testapplication;

import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.view.Window;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.ImageView;

import java.io.File;
import java.io.IOException;
import java.math.BigDecimal;

public class MainActivity extends Activity {

    private ImageView img;
    private static final String TEMP_PATH = Environment.getExternalStorageDirectory().getAbsolutePath() + "/tmp/temp_" + System.currentTimeMillis() + ".jpg";
    private static final int REQ_CARMER = 0x002;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_main);

        isFolderExists(Environment.getExternalStorageDirectory().getAbsolutePath() + "/tmp/");//判斷目錄是否存在
        checkFile(TEMP_PATH);//檢查檔案是否存在
        img = (ImageView) findViewById(R.id.img);
        findViewById(R.id.btn).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                takePhoto();
            }
        });
    }
    //檢查檔案是否存在
    private void checkFile(String path)
    {
        File file = new File(path);
        if (!file.exists())
        {
            try
            {
                file.createNewFile();
            } catch (IOException e)
            {
                e.printStackTrace();
            }
        }
    }
    //判斷目錄是否存在
    boolean isFolderExists(String strFolder)
    {
        File file = new File(strFolder);
        if (!file.exists())
        {
            if (file.mkdirs())
            {
                return true;
            } else
            {
                return false;

            }
        }
        return true;

    }
    private void takePhoto()
    {
        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        //path為儲存圖片的路徑，執行完拍照以後能儲存到指定的路徑下
        File file = new File(TEMP_PATH);
        intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(file));
        intent.putExtra(MediaStore.Images.Media.ORIENTATION, 0);
        startActivityForResult(intent, REQ_CARMER);
    }
    //圖片壓縮
    public Bitmap setImage(String path, Intent intent)
    {
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(path, options);

//        double value = new BigDecimal(options.outWidth).divide(new BigDecimal(options.outHeight), 4, BigDecimal.ROUND_HALF_UP).doubleValue();

//        intent.putExtra(Constants.ISNULL, false);
//        intent.putExtra(Constants.IMGPATH, path);
//        intent.putExtra(Constants.ASPECT_RATIO, value == 0d ? "1.0000" : format.format(value));

        options.inJustDecodeBounds = false;

        int be = Math.max(options.outWidth, options.outHeight) / 20;
        if (be % 10 != 0)
            be += 10;
        be = be / 10;
        if (be <= 0)
            be = 1;
        options.inSampleSize = be;
        return BitmapFactory.decodeFile(path, options);
    }
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data)
    {
        if (resultCode == RESULT_OK)
        {
            switch (requestCode)
            {

                case REQ_CARMER:

                    img.setImageBitmap(setImage(TEMP_PATH, new Intent()));


                    break;

            }
        }
        super.onActivityResult(requestCode, resultCode, data);
    }

}
 

不要忘了新增許可權：

<uses-permission android:name="android.permission.CAMERA"></uses-permission>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"></uses-permission>