图片加载展示

package bwei.com.day_0514_demo156;

import android.app.Application;
import android.content.Context;
import android.graphics.Bitmap;
import android.os.Environment;
import android.os.Handler;
import android.util.Log;

import com.nostra13.universalimageloader.cache.disc.impl.UnlimitedDiskCache;
import com.nostra13.universalimageloader.cache.disc.naming.HashCodeFileNameGenerator;
import com.nostra13.universalimageloader.cache.memory.impl.LruMemoryCache;
import com.nostra13.universalimageloader.core.DisplayImageOptions;
import com.nostra13.universalimageloader.core.ImageLoader;
import com.nostra13.universalimageloader.core.ImageLoaderConfiguration;
import com.nostra13.universalimageloader.core.assist.ImageScaleType;
import com.nostra13.universalimageloader.core.assist.QueueProcessingType;
import com.nostra13.universalimageloader.core.display.FadeInBitmapDisplayer;
import com.nostra13.universalimageloader.core.display.SimpleBitmapDisplayer;
import com.nostra13.universalimageloader.core.download.BaseImageDownloader;

import java.io.File;

public class MyApp extends Application {

    private static final String TAG = "---MyApp";
    private Context context;

    @Override
    public void onCreate() {
        super.onCreate();
        context = this;
        Log.d(TAG, "应用创建---");
        initImageLoader();
    }

    private void initImageLoader() {
        //Configuration 配置
        //Builder 建造者模式
        //存到images
        String sdcardPath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/images";
        File file = new File(sdcardPath);
        ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(context)
                //内存配置
                .memoryCacheExtraOptions(480, 800) // default = device screen dimensions
                //磁盘缓存
//                .diskCacheExtraOptions(480, 800, Bitmap.CompressFormat.JPEG, 75, null)
                .threadPoolSize(3) // 线程池里面线程的数量
                .threadPriority(Thread.NORM_PRIORITY - 1) // 线程优先级
                .tasksProcessingOrder(QueueProcessingType.FIFO) // default
                .memoryCache(new LruMemoryCache(2 * 1024 * 1024))//内存缓存的大小
                .memoryCacheSize(2 * 1024 * 1024)
                .diskCache(new UnlimitedDiskCache(file)) // 指sdcard的缓存路径
                .diskCacheSize(50 * 1024 * 1024)//指sdcard的缓存大小
//                .diskCacheFileCount(100)//指sdcard的缓存文件数量
                .diskCacheFileNameGenerator(new HashCodeFileNameGenerator()) // default
                .imageDownloader(new BaseImageDownloader(context)) // default
//                .imageDecoder(new BaseImageDecoder()) // 图片解码
                .defaultDisplayImageOptions(DisplayImageOptions.createSimple()) // default
                .writeDebugLogs()
                .build();
        //记得配置到ImageLoader
        ImageLoader.getInstance().init(config);
    }
    //加载图片时候的配置
    public static DisplayImageOptions getOptions() {
        DisplayImageOptions options = new DisplayImageOptions.Builder()
                .showImageOnLoading(R.mipmap.ic_launcher) // 加载过程中显示的图片
                .showImageForEmptyUri(R.mipmap.ic_launcher) //当地址为空的时候显示的图片
                .showImageOnFail(R.mipmap.ic_launcher) // 加载错误时显示的图片
                .resetViewBeforeLoading(true)  // 加载前重置视图
                .cacheInMemory(true) // 启动内存缓存
                .cacheOnDisk(true) // 启动磁盘缓存
                .imageScaleType(ImageScaleType.IN_SAMPLE_POWER_OF_2) // default
                .bitmapConfig(Bitmap.Config.ARGB_8888) // default
                .displayer(new SimpleBitmapDisplayer()) // default
                .displayer(new FadeInBitmapDisplayer(100))
                .handler(new Handler()) // default
                .build();
        return options;
    }
}

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

//下个页面
package com.daydayup.day07_imageloaderdemo;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ListView;

import com.nostra13.universalimageloader.core.ImageLoader;

import java.util.ArrayList;
import java.util.List;

/**
 * 1.熟悉ImageLoader  ---  加载一张图片
 * 2.列表里面的图片 ImageLoader ----  图片错乱
 *
 *  1.导包
 *      github
 *  2.配置
 *  3.使用
 *
 * ----三级缓存
 * 1.多线程加载，加载效率高
 * 2.可扩展性强。可以自定义配置
 * 3.使用三级缓存。
 *
 *      应用的启动流程。---
 *
 */
public class MainActivity extends AppCompatActivity {

    private static String pic_url = "http://pic22.photophoto.cn/20120113/0036036848061774_b.jpg";
    private static String pic1="http://img.zcool.cn/community/0381de85949053ca8012193a3339cc5.jpg";
    private static String pic2 = "http://img.zcool.cn/community/038c0ee5744f9a500000025ae5acd2a.jpg";
    private static String pic3 = "http://i1.hdslb.com/bfs/archive/763293ce06bf1e684ef0ea3da43ae5008d8564b8.jpg";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final List<String> images = new ArrayList<>();
        images.add(pic_url);
        images.add(pic1);
        images.add(pic2);
        images.add(pic3);

        Button load_pic = findViewById(R.id.load_pic);
        final ImageView imageView=findViewById(R.id.pic);

        final ListView listView=findViewById(R.id.listview);

        load_pic.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //点击开始使用Imageloader加载图片
//                ImageLoader.getInstance().displayImage(pic_url,imageView);
                //listview加载图片
                MyAdapter myAdapter = new MyAdapter(MainActivity.this, images);
                listView.setAdapter(myAdapter);
            }
        });
    }
}

//适配器

package bwei.com.day_0514_demo156.adapter;

import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;

import com.nostra13.universalimageloader.core.ImageLoader;

import java.util.List;

import bwei.com.day_0514_demo156.MyApp;
import bwei.com.day_0514_demo156.R;

public class MyBase extends BaseAdapter {

   private Context context;
   private List<String> list;

    public MyBase(Context context, List<String> list) {
        this.context = context;
        this.list = list;
    }

    @Override
    public int getCount() {
        return list.size();
    }

    @Override
    public Object getItem(int position) {
        return list.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        ViewHolder holder;

       if (convertView==null){

           convertView=View.inflate(context, R.layout.mybase,null);

            holder = new ViewHolder();

            holder.image=(ImageView) convertView.findViewById(R.id.my_image);
            convertView.setTag(holder);

       }else{
           holder=(ViewHolder) convertView.getTag();
       }


        String pic_url=list.get(position%list.size());
       ImageLoader.getInstance().displayImage(pic_url,holder.image, MyApp.getOptions());
        return convertView;
    }

    class ViewHolder{
        ImageView image;
    }
}