呼叫：NewUtils .getInstance(content).方法名呼叫其中的方法

    package com.example.renzhili20181106;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.util.LruCache;

import com.google.gson.Gson;

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpUriRequest;
import org.apache.http.client.methods.RequestBuilder;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;


public class NewUtils {
    //單例
    private static  NewUtils instance;
    private  LruCache<String,Bitmap> cache;
    private File saveDir;


    private NewUtils(Context context) {
        int size= (int) (Runtime.getRuntime().freeMemory()*0.3);
        cache=new LruCache<>(size);
        //圖片檔案快取目錄
        saveDir = new File(context.getCacheDir(), "img_cache");
        //不存在,建立
        if(!saveDir.exists()) {
            saveDir.mkdirs();
        }
    }

    public static NewUtils getInstance(Context context) {
        if (instance==null){
            instance=new NewUtils(context);
        }
        return instance;
    }
    //介面
    public  interface  RequeryCallBack<T>{
       void Requery(T o);
   }
    //網路資料介面回撥的方法
   public void getRequery(String url, final Class clazz, final RequeryCallBack callBack){
       @SuppressLint("StaticFieldLeak") AsyncTask<String,Void,Object> asyncTask = new AsyncTask<String, Void, Object>() {
           @Override
           protected Object doInBackground(String... strings) {
               return getGson(strings[0],clazz);
           }
           @Override
           protected void onPostExecute(Object o) {
               callBack.Requery(o);
           }
       }.execute(url);

   }
   //解析json網路資料
   public static <E> E getGson(String url,Class clazz){
        String getdata = getdata(url);
        E e = (E) new Gson().fromJson(getdata,clazz);
        return e;
    }
    //HttpClient獲取網路資料的方法
    public static String getdata(String url){
        try {
            HttpClient client = HttpClients.createDefault();
            HttpUriRequest request = RequestBuilder
                    .get()
                    .setUri(url)
                    .build();
            HttpResponse execute =client.execute(request);
            int statusCode = execute.getStatusLine().getStatusCode();
            if (statusCode==200){
                String s = EntityUtils.toString(execute.getEntity());
                return s;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }
    //解析
    public static <E> E getGsondata(String url,Class clazz){
        String requery = getRequery(url);
        E e = (E) new Gson().fromJson(requery, clazz);
        return e;
    }

//HttpURLConnection獲取網路資料的方法
    public  static String getRequery(String url){
        String s="";
        try {
            URL url1 = new URL(url);
            HttpURLConnection urlConnection = (HttpURLConnection) url1.openConnection();
            urlConnection.setRequestMethod("GET");
            urlConnection.setConnectTimeout(5000);
            urlConnection.setReadTimeout(5000);
            int responseCode = urlConnection.getResponseCode();
            if (responseCode==200){
                s = getstrarn2string(urlConnection.getInputStream());
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
         return s;
    }
    //轉換位元組流為字元流
    private static String getstrarn2string(InputStream inputStream) throws IOException {
        StringBuilder builder = new StringBuilder();
        BufferedReader br = new BufferedReader(new InputStreamReader(inputStream));
        for (String tmp = br.readLine();tmp!=null;tmp=br.readLine()){
            builder.append(tmp);
        }
        return builder.toString();
    }


    //介面
    public  interface  CallBack{
        void loadimage(String url ,Bitmap bitmap);
    }
    //介面回撥
    public  void loadimage(final String urlimage, final CallBack callBack){
        @SuppressLint("StaticFieldLeak") AsyncTask<String,Void,Bitmap> asyncTask =  new AsyncTask<String, Void, Bitmap>() {
            @Override
            protected Bitmap doInBackground(String... strings) {
                return getBitmap(strings[0]);
            }

            @Override
            protected void onPostExecute(Bitmap bitmap) {
                callBack.loadimage(urlimage,bitmap);
            }
        }.execute(urlimage);

    }
    //獲取圖片三級快取
    public  Bitmap getBitmap(String urlimage){
       Bitmap bitmap=null;
       //從記憶體中獲取圖片
       bitmap=cache.get(url2Key(urlimage));
       if (bitmap!=null){
           return bitmap;
       }
       //從sd中獲取
        bitmap=getBitmapForFile(urlimage);
       if (bitmap!=null){
           //緩衝到記憶體中
           cache.put(url2Key(urlimage),bitmap);
           return bitmap;
       }
       //從網路中獲取圖片
        bitmap=loadimage(urlimage);
       if (bitmap!=null){
           //存入磁碟
           saveBitmap2File(urlimage, bitmap);
           //存入記憶體
           cache.put(url2Key(urlimage),bitmap);
       }
        return bitmap;
    }
    //網磁碟寫檔案
    private void saveBitmap2File(String urlimage, Bitmap bitmap) {
        FileOutputStream fileOutputStream=null;
        try {
             fileOutputStream = new FileOutputStream(new File(saveDir, url2Key(urlimage)));
            bitmap.compress(Bitmap.CompressFormat.JPEG,100,fileOutputStream);

        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            if(fileOutputStream!=null){
                try {
                    fileOutputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    //從檔案讀取圖片
    private Bitmap getBitmapForFile(String urlStr) {///////
        //解碼檔案為bitmap圖片
        return BitmapFactory.decodeFile(new File(saveDir, url2Key(urlStr)).getAbsolutePath());
    }

    //將url轉換成key
    //url 做key: 太長;如果作為檔名,不允許/ ?
    private String url2Key(String url) {
        //MD5 摘要方法
        //MessageDigest
        return String.valueOf(url.hashCode());
    }
    //獲取網路圖片
    public  static Bitmap loadimage(String urlimage){
        try {
            URL url1 = new URL(urlimage);
            HttpURLConnection urlConnection = (HttpURLConnection) url1.openConnection();
            urlConnection.setRequestMethod("GET");
            urlConnection.setConnectTimeout(5000);
            urlConnection.setReadTimeout(5000);
            int responseCode = urlConnection.getResponseCode();
            if (responseCode==200){
                Bitmap bitmap = BitmapFactory.decodeStream(urlConnection.getInputStream());
                return  bitmap;
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
        return  null;
    }
}