调用系统相机

import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.text.format.DateFormat;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Calendar;
import java.util.Locale;

public class MainActivity extends AppCompatActivity {

    private Button button;
    private ImageView view;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button = (Button) findViewById(R.id.button);
        view= (ImageView)findViewById(R.id.image);
        button.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) {
        // TODO Auto-generated method stub
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode == Activity.RESULT_OK) {
            String sdStatus = Environment.getExternalStorageState();
            if (!sdStatus.equals(Environment.MEDIA_MOUNTED)) { // 检测sd是否可用
                Log.i("TestFile",
                        "SD card is not avaiable/writeable right now.");
                return;
            }
            new DateFormat();
            String name = DateFormat.format("yyyyMMdd_hhmmss", Calendar.getInstance(Locale.CHINA)) + ".jpg";
            Toast.makeText(this, name, Toast.LENGTH_LONG).show();
            Bundle bundle = data.getExtras();
            Bitmap bitmap = (Bitmap) bundle.get("data");// 获取相机返回的数据，并转换为Bitmap图片格式

            FileOutputStream b = null;
            File file = new File("/sdcard/Image/");
            file.mkdirs();// 创建文件夹
            String fileName = "/sdcard/Image/"+name;

            try {
                b = new FileOutputStream(fileName);
                bitmap.compress(Bitmap.CompressFormat.JPEG, 100, b);// 把数据写入文件
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } finally {
                try {
                    b.flush();
                    b.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            try
            {
                view.setImageBitmap(bitmap);// 将图片显示在ImageView里
            }catch(Exception e)
            {
                Log.e("error", e.getMessage());
            }

        }
    }
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="de.hdodenhof.picture.MainActivity">

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="点击选择图片" />

    <ImageView
        android:id="@+id/image"
        android:layout_width="250dp"
        android:layout_height="250dp" />
</LinearLayout>

 <!-- 在SDCard中创建与删除文件权限 -->
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />
    <!-- 往SDCard写入数据权限 -->
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

    <uses-feature android:name="android.hardware.camera" />
    <uses-feature android:name="android.hardware.camera.autofocus" />