网上取图片（Fragment）用viewpager显示侧滑

Mike 发表于 2021-7-11 12:10:29

　　实现功能：通过地址网上去多张图片，然后显示viewpager上，可以实现侧滑。
　　首先新建MainImageDetailActivityy继承FragmentActivity
　　package com.example.httpviewpagerfragmnet;

import android.os.Bundle;
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.view.ViewPager;

public class MainImageDetailActivityy extends FragmentActivity {
ViewPager mViewPager;
private ImagePagerAdapter mAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_image_detail_activityy);
mViewPager=(ViewPager) findViewById(R.id.viewpagerone);

mAdapter = new ImagePagerAdapter(getSupportFragmentManager(),Constances.imageThumbUrls);
mViewPager.setAdapter(mAdapter);
mViewPager.setOffscreenPageLimit(3);//ViewPager预加载页设置

}
public class ImagePagerAdapter extends FragmentStatePagerAdapter{
private String[] mImageUrls;
private final int mSize;
public ImagePagerAdapter(FragmentManager fm,String[] mn) {
super(fm);
mImageUrls = mn;

mSize = mImageUrls.length;
}

@Override
public Fragment getItem(int arg0) {

return ImageDetailFragment.newInstance(mImageUrls);
}

@Override
public int getCount() {

return mSize;}

}
}

　　对应的XML：
<?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" >

<android.support.v4.view.ViewPager
   android:id="@+id/viewpagerone"
   android:layout_width="match_parent"
   android:layout_height="match_parent" >
</android.support.v4.view.ViewPager>

</LinearLayout>

　　第二步：
　　package com.example.httpviewpagerfragmnet;

import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Binder;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.ProgressBar;

import com.example.httpviewpagerfragmnet.AsyncImageLoader.ImageCallbackForBitmap;

public class ImageDetailFragment extends Fragment {
private static final String IMAGE_DATA_EXTRA = "extra_image_data";
private String mImageUr;
private ImageView mImageView;
private ProgressBar mProgressBar;

public static ImageDetailFragment newInstance(String imageUrl) {
ImageDetailFragment f = new ImageDetailFragment();

final Bundle args = new Bundle();
args.putString(IMAGE_DATA_EXTRA, imageUrl);
f.setArguments(args);
return f;

}

@Override
public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);
mImageUr = getArguments() != null ? getArguments().getString(
IMAGE_DATA_EXTRA) : null;
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {

final View v = inflater.inflate(R.layout.image_detail_fragment,
container, false);
mImageView = (ImageView) v.findViewById(R.id.imageView);
mProgressBar = (ProgressBar) v.findViewById(R.id.progressBarone);
return v;

}
@Override
public void onActivityCreated(Bundle savedInstanceState) {

super.onActivityCreated(savedInstanceState);
AsyncImageLoader asyncImageLoader = new AsyncImageLoader();
mProgressBar.setVisibility(View.VISIBLE);

mProgressBar.setVisibility(View.GONE);
final Handler handle=new Handler(){
@Override
public void handleMessage(Message msg) {
// TODO Auto-generated method stub
mImageView.setImageBitmap((Bitmap)msg.obj);
mProgressBar.setVisibility(View.GONE);
}
};

// }

Bundle b=new Bundle();
b=getArguments();
final String path=b.getString(IMAGE_DATA_EXTRA);
new Thread(){
public void run() {

URL url=null;
InputStream is=null;
try {
url=new URL(path);
is=url.openStream();
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Bitmap bitmap=BitmapFactory.decodeStream(is);
handle.sendMessage(handle.obtainMessage(0,bitmap));

};

}.start();
}
@Override
public void onDestroy() {

super.onDestroy();
if (mImageView != null) {
mImageView.setImageDrawable(null);
}
}
}

　　XML：
　　显示图片和转圈的两个空间
<?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" >

<ImageView
   android:id="@+id/imageView"
   android:layout_width="match_parent"
   android:layout_height="match_parent" />

<ProgressBar
   android:id="@+id/progressBarone"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_marginTop="80dp"
   android:layout_marginLeft="50dp"/>

</LinearLayout>
　　-------------------------------------------------------------------------------------------------------
　　这是一个网络取图片的封装工具类，也可以自己写：
　　package com.example.httpviewpagerfragmnet;

import java.io.InputStream;
import java.net.URL;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Handler;
import android.os.Message;
import android.util.LruCache;

public class AsyncImageLoader {
/**
* 图片缓存技术的核心类，用于缓存所有下载好的图片，在程序内存达到设定值时会将最少最近使用的图片移除掉。
*/
private LruCache<String, Bitmap> mMemoryCache;

public AsyncImageLoader() {
// 获取应用程序最大可用内存
int maxMemory = (int) Runtime.getRuntime().maxMemory();
int cacheSize = maxMemory / 8;
// 设置图片缓存大小为程序最大可用内存的1/8
mMemoryCache = new LruCache<String, Bitmap>(cacheSize) {
@Override
protected int sizeOf(String key, Bitmap bitmap) {
return bitmap.getByteCount();
}
};
}
/**
* 将一张图片存储到LruCache中。
*
* @param key
* LruCache的键，这里传入图片的URL地址。
* @param bitmap
* LruCache的键，这里传入从网络上下载的Bitmap对象。
*/
public void addBitmapToMemoryCache(String key, Bitmap bitmap) {
if (getBitmapFromMemoryCache(key) == null) {
mMemoryCache.put(key, bitmap);
}
}

/**
* 从LruCache中获取一张图片，如果不存在就返回null。
*
* @param key
* LruCache的键，这里传入图片的URL地址。
* @return 对应传入键的Bitmap对象，或者null。
*/
public Bitmap getBitmapFromMemoryCache(String key) {
return mMemoryCache.get(key);
}

public Bitmap loadBitmap(final String imageUrl,final ImageCallbackForBitmap callback) {

if (imageUrl == null) {
return null;
}

final Handler handler = new Handler() {
@Override
public void handleMessage(Message msg) {
callback.imageLoaded((Bitmap) msg.obj, imageUrl);
}
};

Bitmap bitmap = getBitmapFromMemoryCache(imageUrl);
if( bitmap != null){

return bitmap;
}

new Thread() {
public void run() {

Bitmap bitmap = loadImageBitmapFromUrl(imageUrl);
addBitmapToMemoryCache(imageUrl,bitmap);
if (bitmap != null) {
handler.sendMessage(handler.obtainMessage(0, bitmap));
}
}
}.start();

return null;
}

protected Bitmap loadImageBitmapFromUrl(String imageUrl) {
try {
URL rul = new URL(imageUrl);
InputStream is = rul.openStream();
Bitmap bitmap = BitmapFactory.decodeStream(is);
return bitmap;
} catch (Exception e) {
e.printStackTrace();
return null;
}
}

public interface ImageCallbackForBitmap {
public void imageLoaded(Bitmap bitmap, String imageUrl);
}
}

　　------------------------------------------------------------------------------------------------------
　　这里把网络取图片的地址一并附上，还是封装：
　　package com.example.httpviewpagerfragmnet;

public class Constances {
public static final String ACTION_PLAYER = "action.scxh.android.receiver.MyBroadCastReceiver.play";
public static final String ACTION_STOP = "action.scxh.android.receiver.MyBroadCastReceiver.stop";
public static final String BASE_URL = "http://192.168.1.127:8080";
public static String tag = "UIDemo";

public final static String[] imageThumbUrls = new String[] {
"https://img-my.csdn.net/uploads/201407/26/1406383299_1976.jpg",
"https://img-my.csdn.net/uploads/201407/26/1406383291_6518.jpg",
"https://img-my.csdn.net/uploads/201407/26/1406383291_8239.jpg",
"https://img-my.csdn.net/uploads/201407/26/1406383290_9329.jpg",
"https://img-my.csdn.net/uploads/201407/26/1406383290_1042.jpg",
"https://img-my.csdn.net/uploads/201407/26/1406383275_3977.jpg",
"https://img-my.csdn.net/uploads/201407/26/1406383265_8550.jpg",
"https://img-my.csdn.net/uploads/201407/26/1406383264_3954.jpg",
"https://img-my.csdn.net/uploads/201407/26/1406383264_4787.jpg", };
}

　　这样一个简单地功能就实现了

　　
文档来源：51CTO技术博客https://blog.51cto.com/u_14397532/3035647

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网上取图片（Fragment）用viewpager显示侧滑