调用摄像头拍照并显示

package com.example.choosepictest;

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.View;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.ImageView;

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

public class MainActivity extends AppCompatActivity {

public static  final  int TAKE_PHOTO = 1;

public  static final int CROP_PHOTO = 2 ;

private Button takephoto;

private ImageView picture ;

private Uri imageUri ;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
takephoto = (Button) findViewById(R.id.take_phone);
picture = (ImageView) findViewById( R.id.picture) ;
takephoto.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//创建File对象，用于存储拍照后的照片
File outputImage = new File(Environment.getExternalStorageDirectory(),"output_image.jpg");
System.out.println(Environment.getExternalStorageDirectory());
try {
if(outputImage.exists()){
outputImage.delete();
}
outputImage.createNewFile();
}catch (IOException e){
e.printStackTrace();
}
imageUri = Uri.fromFile(outputImage);
Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
intent.putExtra(MediaStore.EXTRA_OUTPUT,imageUri);
startActivityForResult(intent , TAKE_PHOTO);//需要返回结果判断拍照成功的故用这个方法
}
});

}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (requestCode){
case TAKE_PHOTO:
if(resultCode == RESULT_OK){
Intent intent = new Intent("com.android.camera.action.CROP");//为系统剪裁的Action

intent.setDataAndType(imageUri ,"image/*"); //设置剪裁的属性类型
intent.putExtra("scale",true);//scale为缩放的意思

intent.putExtra(MediaStore.EXTRA_OUTPUT , imageUri);
startActivityForResult(intent , CROP_PHOTO); //需要返回结果来判断是否截图成功的故用这个方法

}
break;
case CROP_PHOTO:
if(resultCode==RESULT_OK){
try{

Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));//而contentresolver则是用于管理所有程序的contentprovider实例
picture.setImageBitmap(bitmap);
}catch (FileNotFoundException e){
e.printStackTrace();
}
}
break;
default:break;
}
}
}

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

<?xml version="1.0" encoding="utf-8"?>
<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"
>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Take photo"
android:id="@+id/take_phone"/>
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/picture"
android:layout_gravity="center_vertical"/>
</LinearLayout>