android - 显示图像的 fragment 中的内存问题

Question

我正在使用 fragment 来显示图像/页面。我有一个包含所有 fragment 的 Activity(Main)。

package com.example.hscroll.demo;

import android.os.Bundle;
import android.preference.PreferenceManager;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.app.ListFragment;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;

import com.crittercism.app.Crittercism;
import com.example.hscroll.customer.BitmapWeakReference;
import com.example.hscroll.customer.PromotionalPriceListAdditionsDataAdaptor;
import com.example.hscroll.customer.PromotionalPriceListDataAdaptor;
import com.example.hscroll.library.imagezoom.ImageViewTouch;

public class MainAct extends FragmentActivity{

private ImageViewTouch  mImageView;
MyPagerAdapter mPagerAdapter;
ViewPager viewPager;
 static final int NUM_ITEMS = 58;

@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState); 
    Crittercism.init(getApplicationContext(), "4f391d0fb09315319d00048d");
    PreferenceManager.setDefaultValues(this, R.xml.preference, false);

    setContentView(R.layout.viewpager_layout);

    mPagerAdapter = new MyPagerAdapter(getSupportFragmentManager());

    viewPager = (ViewPager)findViewById(R.id.viewpager);
    viewPager.setAdapter(mPagerAdapter);
}


public static class MyPagerAdapter extends FragmentStatePagerAdapter {
    public MyPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public int getCount() {
        return NUM_ITEMS;
    }

    @Override
    public Fragment getItem(int position) {
            return newInstance(position);
    }


}

static Fragment newInstance(int position) {

    Fragment data = null;
    switch(position){

    case 0 :
        data = new Fragment1();
    break;

    case 1 :
        data = new FragmentSignupForm();
    break;

    case 2 :
        data = new Fragment2();
    break;

    case 3 :
        data = new Fragment3();
    break;

    case 4 :
        data = new Fragment4();
    break;

    case 5:
        data = new Fragment5();
    break;

    case 6 :
        data = new Fragment6();
    break;

    case 7 :
        data = new Fragment7();
    break;

    case 8 :
        data = new Fragment8();
    break;

    case 9 :
        data = new Fragment9();
    break;

    case 10 :
        data = new MyMapFragment();
    break;

    case 11:
        data = new FragmentQuestionaire();
        break;

    case 12:
        data = new Fragment10();
        break;

    case 13:
        data = new Fragment11();
        break;

    case 14:
        data = new Fragment12();
        break;

    case 15:
        data = new Fragment13();
        break;

    case 16:
        data = new Fragment14();
        break;

    case 17:
        data = new Fragment15();
        break;

    case 18:
        data = new Fragment16();
        break;

    case 19:
        data = new Fragment17();
        break;

    case 20:
        data = new Fragment18();
        break;

    case 21:
        data = new Fragment19();
        break;

    case 22:
        data = new Fragment20();
        break;

    case 23:
        data = new Fragment21();
        break;

    case 24:
        data = new Fragment22();
        break;

    case 25:
        data = new Fragment23();
        break;

    case 26:
        data = new Fragment24();
        break;

    case 27:
        data = new Fragment25();
        break;

    case 28:
        data = new Fragment26();
        break;

    case 29:
        data = new Fragment27();
        break;

    case 30:
        data = new Fragment28();
        break;

    case 31:
        data = new Fragment29();
        break;

    case 32:
        data = new Fragment30();
        break;

    case 33:
        data = new Fragment31();
        break;

    case 34:
        data = new Fragment32();
        break;

    case 35:
        data = new Fragment33();
        break;

    case 36:
        data = new Fragment34();
        break;

    case 37:
        data = new Fragment35();
        break;

    case 38:
        data = new Fragment36();
        break;

    case 39:
        data = new Fragment37();
        break;

    case 40:
        data = new Fragment38();
        break;

    case 41:
        data = new Fragment39();
        break;

    case 42:
        data = new Fragment40();
        break;

    case 43:
        data = new Fragment41();
        break;

    case 44:
        data = new Fragment42();
        break;

    case 45:
        data = new Fragment43();
        break;

    case 46:
        data = new Fragment44();
        break;

    case 47:
        data = new Fragment45();
        break;

    case 48:
        data = new Fragment46();
        break;

    case 49:
        data = new Fragment47();
        break;

    case 50:
        data = new Fragment48();
        break;

    case 51:
        data = new Fragment49();
        break;

    case 52:
        data = new Fragment50();
        break;

    case 53:
        data = new Fragment51();
        break;

    case 54:
        data = new Fragment52();
        break;

    case 55:
        data = new Fragment53();
        break;

    case 56:
        data = new Fragment54();
        break;

    case 57:
        data = new Fragment55();
        break;

    default :
        data = new FragmentQuestionaire();
    break;  

    }

        return data;
}

@Override
protected void onDestroy() {
    super.onDestroy();
    FragmentSignupForm.CUSTOMER_ADDRESS = "";
    FragmentSignupForm.CUSTOMER_ADDRESS1 = "";
    FragmentSignupForm.CUSTOMER_ADDRESS2 = "";
    FragmentSignupForm.CUSTOMER_EMAIL = "";
    FragmentSignupForm.CUSTOMER_ID = "";
    FragmentSignupForm.CUSTOMER_POSTCODE = "";
    FragmentSignupForm.CUSTOMER_NAME = "";
    FragmentSignupForm.Telephone = "";
    Fragment50.Total = "0";
    Fragment47.amount2 = 0;
    Fragment47.systemSize = "";
    PromotionalPriceListAdditionsDataAdaptor.TotalAdditionalPrice = 0;
    PromotionalPriceListDataAdaptor.TotalPrice = 0;
    PromotionalPriceListDataAdaptor.Capacity = "";
    PromotionalPriceListDataAdaptor.NumberOfPanels = "";
    PromotionalPriceListDataAdaptor.PanelSize = "";
    PromotionalPriceListDataAdaptor.PanelCapacity = "";
    PromotionalPriceListDataAdaptor.SurfaceAreaReuired = "";
    PromotionalPriceListDataAdaptor.Price = "";
    PromotionalPriceListDataAdaptor.PromotionalOffer = "";
    PromotionalPriceListDataAdaptor.TotalOfferPrice = "";
   }

   }

这是 fragment 类中的代码 -

package com.example.hscroll.demo;

import java.io.BufferedInputStream;
import java.io.FileInputStream;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;

import com.example.hscroll.customer.BitmapWeakReference;
 import com.example.hscroll.library.imagezoom.ImageViewTouch;

public class Fragment2 extends Fragment{

ImageViewTouch imgview ;
LayoutInflater inflater;
FileInputStream in;
BufferedInputStream buf;
BitmapWeakReference bitmap;
ViewGroup con;

private final String  PATH = "/mnt/sdcard/Ideal Solar/Layout_1.png";

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstance)
{
    this.inflater = inflater;
    if(container == null)return null;
    container = (LinearLayout)inflater.inflate(R.layout.fragment0_layout, container, false);
    con = container;
    imgview= (ImageViewTouch)container.findViewById(R.id.imageView1);
    bitmap = new BitmapWeakReference(imgview.selectImage(inflater.getContext(), PATH));
    if(bitmap!=null)
        imgview.setImageBitmapReset( bitmap.get(), true );

    return container;
}   

/* @Override
    public void onResume() {

        if(bitmap == null)
        {
            bitmap = SelectImageFunctions.selectImage(inflater.getContext(), PATH);
        }
        super.onResume();
    }*/

 @Override
public void onDestroyView() {
     super.onDestroyView();
        imgview.setImageBitmap(null);
        bitmap.clear();
        bitmap = null;
        Fragment1.unbindDrawables(con.findViewById(R.id.ll));
        System.gc();
    }

   }

每次当我移动到下一个 fragment 时，前一个 fragment 的 onDestroyView() 被调用并且我正在删除位图和 ImageView 的所有引用但仍然没有释放位图或可绘制对象的内存并且内存不断增加。最后它在大约 50MB 时崩溃。

有人可以帮忙吗？我正在为 galaxy tab 开发这个应用程序。

更新 - 动态页面代码 -

 package com.example.hscroll.demo;


   import java.io.BufferedReader;
   import java.io.IOException;
   import java.io.InputStream;
   import java.io.InputStreamReader;
   import java.util.ArrayList;

   import org.apache.http.HttpEntity;
   import org.apache.http.HttpResponse;
   import org.apache.http.NameValuePair;
   import org.apache.http.client.HttpClient;
   import org.apache.http.client.entity.UrlEncodedFormEntity;
   import org.apache.http.client.methods.HttpPost;
   import org.apache.http.impl.client.DefaultHttpClient;
   import org.apache.http.message.BasicNameValuePair;
   import org.json.JSONArray;
   import org.json.JSONObject;

   import android.content.Context;
   import android.os.AsyncTask;
   import android.os.Bundle;
   import android.support.v4.app.Fragment;
   import android.view.LayoutInflater;
   import android.view.View;
   import android.view.ViewGroup;
   import android.view.inputmethod.InputMethodManager;
   import android.widget.Button;
   import android.widget.EditText;
   import android.widget.LinearLayout;
   import android.widget.ScrollView;
   import android.widget.Toast;


   public class FragmentSignupForm extends Fragment {

LayoutInflater inflater;
String result = null;
InputStream is = null;
StringBuilder sb = null;
JSONArray jArray;
EditText c_nameText;
EditText c_addressText;
EditText c_postcodeText;
EditText c_emailText;
EditText s_nameText;
EditText c_addressLine2Text;
EditText telephone_Text;
public static String CUSTOMER_NAME = "";
public static String CUSTOMER_ADDRESS = "";
public static String CUSTOMER_ADDRESS1 = "";
public static String CUSTOMER_ADDRESS2 = "";
public static String CUSTOMER_POSTCODE = "";
public static String CUSTOMER_ID;
public static String CUSTOMER_EMAIL = "";
public static String SALES_CONTACT = "";
public static String Telephone = "";

String output = null;

ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
ViewGroup con;


public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstance)
{
    this.inflater = inflater;
    if(container == null)return null;
    container = (ScrollView)inflater.inflate(R.layout.signup_form_layout, container, false);
    con = container;
    ScrollView sv = (ScrollView)container.findViewById(R.id.SV);
    sv.setBackgroundDrawable(AssestUtil.getBitmapFromAsset(inflater.getContext(), "bg.jpg"));

    LinearLayout ll = (LinearLayout)container.findViewById(R.id.ll);
    ll.setBackgroundDrawable(AssestUtil.getBitmapFromAsset(inflater.getContext(), "formbg2.png"));

    c_nameText = (EditText)container.findViewById(R.id.cust_name);
    c_nameText.setText(CUSTOMER_NAME);
    c_addressText = (EditText)container.findViewById(R.id.cust_address);
    c_addressText.setText(CUSTOMER_ADDRESS1);
    c_addressLine2Text = (EditText)container.findViewById(R.id.cust_Address2);
    c_addressLine2Text.setText(CUSTOMER_ADDRESS2);
    c_postcodeText = (EditText)container.findViewById(R.id.postcode);
    c_postcodeText.setText(CUSTOMER_POSTCODE);
    c_emailText = (EditText)container.findViewById(R.id.cust_email);
    c_emailText.setText(CUSTOMER_EMAIL);
    s_nameText = (EditText)container.findViewById(R.id.sales_name);
    s_nameText.setText(SALES_CONTACT);
    telephone_Text = (EditText)container.findViewById(R.id.telephone);
    telephone_Text.setText(Telephone);             

        Button save = (Button)container.findViewById(R.id.save_btn);
        Button Reset = (Button)container.findViewById(R.id.reset_btn);
        final Context context = inflater.getContext();
          //Send form data to server on click action
       save.setOnClickListener(new View.OnClickListener()
       {

            public void onClick(View v) {

                CUSTOMER_NAME = c_nameText.getText().toString();
                System.out.println(CUSTOMER_NAME);
                CUSTOMER_ADDRESS = c_addressText.getText().toString() + ","+ c_addressLine2Text.getText().toString()+","+c_postcodeText.getText().toString();;
                CUSTOMER_POSTCODE = c_postcodeText.getText().toString();
                Telephone = telephone_Text.getText().toString();

                new SendDataToServer().execute(c_nameText.getText().toString(),c_addressText.getText().toString(),c_addressLine2Text.getText().toString(),c_postcodeText.getText().toString(),c_emailText.getText().toString(),s_nameText.getText().toString(),telephone_Text.getText().toString());
                InputMethodManager imm = (InputMethodManager)context.getSystemService(Context.INPUT_METHOD_SERVICE);
              imm.hideSoftInputFromWindow(s_nameText.getWindowToken(), 0);
            }
       });

     Reset.setOnClickListener(new View.OnClickListener()
       {

            public void onClick(View v) {

                c_nameText.setText(""); 
                c_addressText.setText("");
                c_addressLine2Text.setText("");
                c_postcodeText.setText("");
                c_emailText.setText("");
                s_nameText.setText("");
                telephone_Text.setText("");
            }
       });

    return container;
}

private class SendDataToServer extends AsyncTask<String, Void, String>
{

    @Override
    protected String doInBackground(String... params) {

        try
        {                   
        nameValuePairs.add(new BasicNameValuePair("cust_name",params[0]));
        nameValuePairs.add(new BasicNameValuePair("cust_address",params[1]+","+params[2]));
        nameValuePairs.add(new BasicNameValuePair("cust_postcode",params[3]));
        nameValuePairs.add(new BasicNameValuePair("cust_email",params[4]));
        nameValuePairs.add(new BasicNameValuePair("sales_name",params[5]));
        nameValuePairs.add(new BasicNameValuePair("pvgis_data", params[6]));    

             HttpClient httpclient = new DefaultHttpClient();
              HttpPost httppost = new HttpPost("http://ideal.contrastgroup.info/idealsolar/initializeCustomer.php");
                httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
                HttpResponse response = httpclient.execute(httppost);
                HttpEntity entity = response.getEntity();
                is = entity.getContent();

                JSONObject myAway = new JSONObject(read(is));
                CUSTOMER_ID = myAway.getString("custID");
                output = myAway.getString("message");


        }
        catch(Exception e)
        {
            output = "null";

        }
        return output;
    }

    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);
        if(result.equalsIgnoreCase("success"))
        {
        Toast.makeText(inflater.getContext(), "Database updated", Toast.LENGTH_SHORT).show();
        }
        else
        {
            Toast.makeText(inflater.getContext(), "Error in Connection", Toast.LENGTH_SHORT).show();
        }
    }

}

public static String read(InputStream in) throws IOException {
    StringBuilder sb = new StringBuilder();
    BufferedReader r = new BufferedReader(new InputStreamReader(in));

    for (String line = r.readLine(); line != null; line = r.readLine()) {
        sb.append(line);
    }

    in.close();
    System.out.println(sb.toString());
    return sb.toString();
}


@Override
public void onDestroyView() {
    super.onDestroyView();

    Fragment1.unbindDrawables(con.findViewById(R.id.SV));
    System.gc();
}

     public static void unbindDrawables(View view) {
        if (view.getBackground() != null) {
        view.getBackground().setCallback(null);
        }
        if (view instanceof ViewGroup) {
            for (int i = 0; i < ((ViewGroup) view).getChildCount(); i++) {
            unbindDrawables(((ViewGroup) view).getChildAt(i));
            }
        ((ViewGroup) view).removeAllViews();
        }

Answer 1

来自谷歌:

Fragment State Pager Support Demonstrates the use of the support class ViewPager with a FragmentStatePagerAdapter to build a user interface where the user can fling left or right to switch between fragments. This versions of the adapter doesn't keep around the fragment instances that ViewPager has destroyed.

http://developer.android.com/resources/samples/Support4Demos/src/com/example/android/supportv4/app/FragmentStatePagerSupport.html

与普通分页器的不同之处在于它扩展了 FragmentStatePagerAdapter。

编辑:在谷歌代码中，你在适配器中有这个:

public static class MyAdapter extends FragmentStatePagerAdapter {
    public MyAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public int getCount() {
        return NUM_ITEMS;
    }

    @Override
    public Fragment getItem(int position) {
        return ArrayListFragment.newInstance(position);
    }
}

注意 getItem() 的实现。我们按需获得一个新 fragment ，因此我们不会在需要之前创建 fragment 。这与您创建所有 fragment 并将它们添加到矢量的方法形成对比。 (java 更喜欢 arraylists btw。)使用您的方法， fragment 不会从内存中删除，因为总会有对 fragment 的引用。

编辑 2:再具体一点。在以下内容中:

@Override
public Fragment getItem(int position) {
    return ArrayListFragment.newInstance(position);
}

你可以这样做:

    @Override
    public Fragment getItem(int position) {
if(position == 1) {
return Fragment1.newInstance(position);
} else {
return Fragment2.newInstance(position);
}

    }