mainActivity如下:

package cn.testcamera;
import java.io.File;
import java.text.SimpleDateFormat;
import java.util.Date;
import android.app.Activity;
import android.content.ContentResolver;
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.provider.MediaStore;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

public class MainActivity extends Activity {
    private Button mButton;
    private ImageView mImageView;
    private File mPhotoFile;
    private String mPhotoPath;
    private Uri mPhotoOnSDCardUri;
    public final static int CAMERA_RESULT=777;
    public final static int CAMERA_RESULT_CUT=888;
    public final static int CAMERA_RESULT_CUT_OVER=999;
    public final static String TAG="xx";
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        mButton = (Button) findViewById(R.id.button);
        mButton.setOnClickListener(new ButtonOnClickListener());
        mImageView = (ImageView) findViewById(R.id.imageView);

    }

    private class ButtonOnClickListener implements View.OnClickListener {
        public void onClick(View v) {
            try {
                Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
                mPhotoPath="mnt/sdcard/DCIM/Camera/"+getPhotoFileName();
                mPhotoFile = new File(mPhotoPath);
                if (!mPhotoFile.exists()) {
                    mPhotoFile.createNewFile();
                }
                mPhotoOnSDCardUri=Uri.fromFile(mPhotoFile);
                intent.putExtra(MediaStore.EXTRA_OUTPUT, mPhotoOnSDCardUri);
                //拍照后显示此图片
                //startActivityForResult(intent,CAMERA_RESULT);
                //拍照后先修改再显示此图片
                startActivityForResult(intent,CAMERA_RESULT_CUT);
            } catch (Exception e) {
            }
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        //1   拍照后显示照片
        if (requestCode==CAMERA_RESULT) {
             Bitmap bitmap = BitmapFactory.decodeFile(mPhotoPath, null);  
             mImageView.setImageBitmap(bitmap);
        }
        //2   拍照后剪切照片,然后显示
        //2.1拍照且剪裁
        if (requestCode == CAMERA_RESULT_CUT) {
            Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE,mPhotoOnSDCardUri);
            sendBroadcast(intent);
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            Uri systemImageUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
            ContentResolver contentResolver = getContentResolver();
            Cursor cursor = contentResolver.query(systemImageUri, null,
                    MediaStore.Images.Media.DISPLAY_NAME + "='"
                            + mPhotoFile.getName() + "'", null, null);
            Uri photoUriInMedia = null;
            if (cursor != null && cursor.getCount() > 0) {
                cursor.moveToLast();
                long id = cursor.getLong(0);
                photoUriInMedia = ContentUris.withAppendedId(systemImageUri, id);
            }
            cursor.close();
            Intent in = new Intent("com.android.camera.action.CROP");
            //需要裁减的图片格式
            in.setDataAndType(photoUriInMedia, "image/*");
            //允许裁减
            in.putExtra("crop", "true");
            //剪裁后ImageView显时图片的宽
            in.putExtra("outputX", 250);
            //剪裁后ImageView显时图片的高
            in.putExtra("outputY", 250);
            //设置剪裁框的宽高比例
            in.putExtra("aspectX", 1);
            in.putExtra("aspectY", 1);
            in.putExtra("return-data", true);
            startActivityForResult(in, CAMERA_RESULT_CUT_OVER);
        }
        //2.2显示
        if (requestCode==CAMERA_RESULT_CUT_OVER) {
            //剪切图片的时候,若"放弃"则回答的data为null
            if (data!=null) {
                Bitmap bitmap = (Bitmap) data.getExtras().get("data");
                mImageView.setImageBitmap(bitmap);
            }
        }
    }

    private String getPhotoFileName() {
        Date date = new Date(System.currentTimeMillis());
        SimpleDateFormat dateFormat = new SimpleDateFormat("'IMG'_yyyyMMdd_HHmmss");
        return dateFormat.format(date) + ".jpg";
    }
}

<RelativeLayout 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" >

    <Button
        android:id="@+id/button"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="点击按钮拍照"
     />
    <ImageView 
        android:id="@+id/imageView"
        android:layout_below="@id/button"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
     />

</RelativeLayout>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="cn.testcamera"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="10" />
    <uses-permission android:name="android.permission.CAMERA"/>
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:launchMode="singleTask"
            android:label="@string/title_activity_main" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>