Android实现调用摄像头和相册的方法

<?xml version="1.0" encoding="utf-8"?  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
  android:layout_width="match_parent" 
  android:layout_height="match_parent" 
  android:orientation="vertical"   
 
  <Button 
    android:id="@+id/take_photo" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:text="启动相机" /  
 
  <Button 
    android:id="@+id/choose_from_album" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:text="从相册中选择图片" /  
 
  <ImageView 
    android:id="@+id/picture" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_gravity="center_horizontal" /  
 
</LinearLayout  

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

package com.example.luoxn28.activity; 
import android.annotation.TargetApi; 
import android.content.ContentUris; 
import android.content.Intent; 
import android.database.Cursor; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.net.Uri; 
import android.os.Bundle; 
import android.os.Environment; 
import android.provider.DocumentsContract; 
import android.provider.MediaStore; 
import android.support.v7.app.ActionBarActivity; 
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.IOException; 
public class MainActivity extends ActionBarActivity { 
private static final String TAG = "hdu"; 
public static final int TAKE_PHOTO = 1; 
public static final int CROP_PHOTO = 2; 
public static final int CHOOSE_PHOTO = 3; 
private Button takePhoto; 
private ImageView picture; 
private Uri imageUri; 
private Button chooseFromAlbum; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
//requestWindowFeature(Window.FEATURE_NO_TITLE); 
setContentView(R.layout.activity_main); 
takePhoto = (Button) findViewById(R.id.take_photo); 
picture = (ImageView) findViewById(R.id.picture); 
chooseFromAlbum = (Button) findViewById(R.id.choose_from_album); 
takePhoto.setOnClickListener(new View.OnClickListener() { 
@Override 
public void onClick(View v) { 
// 创建File对象，用于存储拍摄后照片 
File saveImage = new File(Environment.getExternalStorageDirectory(), "saveImage.jpg"); 
try { 
if (saveImage.exists()) { 
saveImage.delete(); 
} 
saveImage.createNewFile(); 
} 
catch (IOException ex) { 
ex.printStackTrace(); 
} 
imageUri = Uri.fromFile(saveImage); 
Intent intent = new Intent("android.media.action.IMAGE_CAPTURE"); 
intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri); 
// 启动相机 
startActivityForResult(intent, TAKE_PHOTO); 
} 
}); 
chooseFromAlbum.setOnClickListener(new View.OnClickListener() { 
@Override 
public void onClick(View v) { 
Intent intent = new Intent("android.intent.action.GET_CONTENT"); 
intent.setType("image/*"); 
// 打开相册 
startActivityForResult(intent, CHOOSE_PHOTO); 
} 
}); 
} 
@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"); 
intent.setDataAndType(imageUri, "image/*"); 
intent.putExtra("scale", true); 
intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri); 
// 启动裁剪程序 
startActivityForResult(intent, CROP_PHOTO); 
} 
break; 
case CROP_PHOTO: 
if (resultCode == RESULT_OK) { 
try { 
Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri)); 
// 显示裁剪后的图片 
picture.setImageBitmap(bitmap); 
} 
catch (FileNotFoundException ex) { 
ex.printStackTrace(); 
} 
} 
break; 
case CHOOSE_PHOTO: 
if (resultCode == RESULT_OK) { 
handleImage(data); 
} 
break; 
default: 
break; 
} 
} 
// 只在Android4.4及以上版本使用 
@TargetApi(19) 
private void handleImage(Intent data) { 
String imagePath = null; 
Uri uri = data.getData(); 
if (DocumentsContract.isDocumentUri(this, uri)) { 
// 通过document id来处理 
String docId = DocumentsContract.getDocumentId(uri); 
if ("com.android.providers.media.documents".equals(uri.getAuthority())) { 
// 解析出数字id 
String id = docId.split(":")[1]; 
String selection = MediaStore.Images.Media._ID + "=" + id; 
imagePath = getImagePath(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, selection); 
} 
else if ("com.android.providers.downloads.documents".equals(uri.getAuthority())) { 
Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"), 
Long.valueOf(docId)); 
imagePath = getImagePath(contentUri, null); 
} 
} 
else if ("content".equals(uri.getScheme())) { 
// 如果不是document类型的Uri，则使用普通方式处理 
imagePath = getImagePath(uri, null); 
} 
// 根据图片路径显示图片 
displayImage(imagePath); 
} 
private String getImagePath(Uri uri, String selection) { 
String path = null; 
// 通过Uri和selection来获取真实图片路径 
Cursor cursor = getContentResolver().query(uri, null, selection, null, null); 
if (cursor != null) { 
if (cursor.moveToFirst()) { 
path = cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.DATA)); 
} 
cursor.close(); 
} 
return path; 
} 
private void displayImage(String imagePath) { 
if (imagePath != null) { 
Bitmap bitmap = BitmapFactory.decodeFile(imagePath); 
picture.setImageBitmap(bitmap); 
} 
else { 
Toast.makeText(this, "failed to get image", Toast.LENGTH_SHORT).show(); 
} 
} 
}