直接应用项目中的Android图片缓存技术
前不久搞的Android图片缓存,刚开始引入开源的框架,用着还行,但是在开发中遇到问题,就比如universal-image-loader-1.9.5.jar这个框架吧,在加载图片的时候自定义imageview无法加载,可能是存在以下问题吧,况且导入框架导致开发的项目包越来越大,基于上面的这几种情况,于是我就想自己写一个图片三级缓存的工具。
简要分析:刚开始想,图片的加载显示无非是先检查内存里面有没有,没就去文件里面找,若是文件里面没有的话就去开启网络下载,这样也符合开发中的大部分需求,而且效率肯定要高一点,在某些场合如快速滑动listview时从文件中加载图片就没有从内存中加载得快。先来看看效果吧!
这是第一次加载出来的图片,当然是网上的一张图片:
图片加载出来了,我们要看看日志,日志不会说谎,我截图的日志
刚才是本地和内存都没有那就的去网络下载了,所有日志打印的是开启网络下载
然而第二次进入应用的时候呢?还回去开启网络下载吗?那肯定不会的,要不这样要它有啥用呢?
看看吧这就是第二次进入应用的时候的日志
从文件中加载图片,不在需要开启网络下载直接从文件中获取,好了,这样问题就来了,从文件中读取肯定效率不好呀,没有直接从内存中读取快吧!我们调用系统维护好的一个算法,最近最少使用算法,这个算法是在我学操作系统的时候学到的,当时老师讲了一下,不过还好,能在项目中用到老师讲的东西,对此,以为就这个就完了?我们应该把文件中的图片读取到内存中,这样防止像listview这样的快速滑动产生的错位bug。下面看看我在快速滑动时的效果:
加载的图片都是从内存中获取,这样在效果上面就很好的啦!
好的,这么好的图片三级缓存,那到底怎么实现的呢以及到底怎么用的呢?下面就贴出我写的代码吧!让小伙伴看看,顺便优化优化!
package com.example.util;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.CompressFormat;
import android.graphics.BitmapFactory;
import android.os.Handler;
import android.os.Message;
import android.support.v4.util.LruCache;
import android.util.Log;
public class ImageCachceUitl {
public static final int SUCCSEE = 0;
public static final int FAIL = 1;
private Context context;
private LruCache<String, Bitmap> cache;//lru算法集合,string是图片的url,bitmap为图片的值类型
private File cacheDir;
Handler handler;
private ExecutorService executorService;//维护线性池
public ImageCachceUitl(Context context ,Handler handler){
this.context=context;
this.handler=handler;
cacheDir=context.getCacheDir();//获得cache文件夹
//维护几个网络线程下载图片
executorService=Executors.newFixedThreadPool(5);
int maxSize=(int) (Runtime.getRuntime().maxMemory()/8);//获得运行环境的内存大小的1/8
cache=new LruCache<String, Bitmap>(maxSize){
// TODO 每存储一张图片的大小(作用于内存溢出丢图片)
@Override
protected int sizeOf(String key, Bitmap value) {
//返回当前一行所占的字节数*高度,就是图片的大小
return value.getRowBytes()*value.getHeight();
}
};//当前图片缓存总数的大小
}
public Bitmap getBitmapFromUrl(String url,int position){
//1内存中获取图片LRU算法
Bitmap bitmap=cache.get(url);
//内存中有指定图片
if (bitmap!=null) {
Log.i("从内存中获得图片", "从内存中获得图片"+url);
return bitmap;
}
//2文件中获取图片
bitmap=getBitmapFromFile(url);
if (bitmap!=null) {
Log.i("从文件中获得图片", "从文件中获得图片"+url);
return bitmap;
}
//3开启网络下载
Log.i("从网络中获得图片", "从网络中获得图片"+url);
getBitmapFromNet(url,position);
return null;
}
private void getBitmapFromNet(String url, int position) {
//开启任务
executorService.execute(new RunnableTask(url,position));
}
//任务接口
class RunnableTask implements Runnable{
String imageUrl;
int position;
private HttpURLConnection httpURLConnection;
public RunnableTask(String imageUrl, int position) {
this.position=position;
this.imageUrl=imageUrl;
}
@Override
public void run() {
//子线程的操作,开启网络下载图片
try {
URL url=new URL(imageUrl);
//请求对象
httpURLConnection=(HttpURLConnection) url.openConnection();
//网络请求的方式
httpURLConnection.setRequestMethod("GET");
//超时的时间,
httpURLConnection.setConnectTimeout(5000);
//读取超时的时间
httpURLConnection.setReadTimeout(5000);
//httpURLConnection.getResponseCode()拿到最新数据
if (httpURLConnection.getResponseCode()==200) {
//success get data from net;get tape
InputStream inputStream=httpURLConnection.getInputStream();
//将流转化成bitmap图片
Bitmap bitmap=BitmapFactory.decodeStream(inputStream);
//利用handler机制放入主线程中显示
Message msg=new Message();
//需要在主线程中显示的图片msg.obj
msg.obj=bitmap;
msg.arg1=position;
//为msg设置标记
msg.what=SUCCSEE;
handler.sendMessage(msg);
//一,将下载完后的图片保存到内存中
cache.put(imageUrl, bitmap);
//二,将下载完后的图片保存到文件中
writeToLoce(imageUrl,bitmap);
return;
}
} catch (Exception e) {
e.printStackTrace();
}
//关闭请求
finally{
//断开服务器
if (httpURLConnection!=null) {
httpURLConnection.disconnect();
}
}
//发送一个空消息
handler.obtainMessage(FAIL).sendToTarget();
}
}
private void writeToLoce(String imageUrl, Bitmap bitmap) {
try {
String bitmapefilename=MD5Encoder.encode(imageUrl).substring(10);
Log.i("bitmapefilename", bitmapefilename);
File file=new File(cacheDir, bitmapefilename);
FileOutputStream fileOutputStream =new FileOutputStream(file);
//写入文件的操作(1图片类型2图片质量当为100时表示不压缩3文件流)
bitmap.compress(CompressFormat.JPEG, 100, fileOutputStream);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private Bitmap getBitmapFromFile(String url) {
try {
//使用Md5工具加密截取前10个字符串
String bitmapefilename=MD5Encoder.encode(url).substring(10);
File file=new File(cacheDir, bitmapefilename);
// file.mkdir();
//FileInputStream fileInputStream=new FileInputStream(file);
Bitmap bitmap=BitmapFactory.decodeFile(file.getPath());//完整文件路径
//Log.i("文件路径", file.getPath().toString());
//2读取之后放入内存,提高效率
cache.put(url, bitmap);
return bitmap;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}
下面就是一个使用demo了,其实很简单
package com.example.do0me;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.security.PublicKey;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import org.ksoap2.SoapEnvelope;
import org.ksoap2.serialization.MarshalBase64;
import org.ksoap2.serialization.SoapObject;
import org.ksoap2.serialization.SoapSerializationEnvelope;
import org.ksoap2.transport.HttpTransportSE;
import org.xmlpull.v1.XmlPullParserException;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.drawable.BitmapDrawable;
import android.os.Bundle;
import android.os.Handler;
import android.util.Base64;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.view.ViewTreeObserver.OnPreDrawListener;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.Toast;
import com.example.util.AgbcApi;
import com.example.util.ClippingPicture;
import com.example.util.FastBlur;
import com.example.util.ImageCachceUitl;
import com.tencent.connect.avatar.c;
public class MainActivity4 extends Activity {
private ImageCachceUitl imageCachceUitl;
private List<String> urlList=new ArrayList<String>();
private Runnable runnable;
private Handler handler =new Handler(){
public void handleMessage(android.os.Message msg) {
switch (msg.what) {
case ImageCachceUitl.SUCCSEE:
Bitmap bitmap=(Bitmap) msg.obj;
int psition=msg.arg1;
//通过TAg加载当前的limageview
ImageView imageView=(ImageView) listview.findViewWithTag(psition);
if (null!=bitmap&&null!=imageView) {
imageView.setImageBitmap(bitmap);
}
break;
case ImageCachceUitl.FAIL:
Toast.makeText(getApplicationContext(), "下载错误", Toast.LENGTH_LONG).show();
default:
break;
}
};
};
private ListView listview;
private SoapObject request;
private ExecutorService executorService;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main4);
listview=(ListView) findViewById(R.id.imageviewlist);
imageCachceUitl=new ImageCachceUitl(getApplicationContext(), handler);
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");urlList.add("http://ww4.sinaimg.cn/large/90bd89ffjw1eqvmd6o8r6j20go0p5ju2.jpg");
listview.setAdapter(new myListAdapt());
executorService=Executors.newFixedThreadPool(5);
executorService.execute(new Runnable() {
@Override
public void run() {
getImageromSdk();
}
});
}
public String getImageFromAndroid(String arg0,String arg1, String arg2){
Log.i("进入端口方法", "进入端口方法");
final String methodName="getImageFromAndroid";
final String soapAction=AgbcApi.NAMESPACE+methodName;
request = new SoapObject(AgbcApi.NAMESPACE, methodName);
request.addProperty("arg0",arg1);
request.addProperty("arg1",arg2);
SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11);
(new MarshalBase64()).register(envelope);
envelope.bodyOut = request;
envelope.dotNet=false;
envelope.setOutputSoapObject(request);
HttpTransportSE ht = new HttpTransportSE(AgbcApi.TASKSERVICEURL);
ht.debug=true;
try {
ht.call(soapAction, envelope);
Log.i("请求", envelope.bodyIn.toString());
} catch (IOException | XmlPullParserException e) {
e.printStackTrace();
}
return arg1;
};
@SuppressLint("SdCardPath")
public void getImageromSdk(){
Log.i("进入获取图片方法", "进入获取图片方法");
try{
String class="lazy" data-srcUrl = "/sdcard/"; //路径
String fileName = "1.png"; //文件名
String filrName2="2.jpg";
List<String>imageList=new ArrayList<>();
imageList.add(fileName);
imageList.add(filrName2);
for (int i = 0; i < imageList.size(); i++) {
FileInputStream fis = new FileInputStream(class="lazy" data-srcUrl + imageList.get(i));
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buffer = new byte[4096];
int count = 0;
while((count = fis.read(buffer)) >= 0){
baos.write(buffer, 0, count);
}
String uploadBuffer = new String(Base64.encode(baos.toByteArray(), Base64.DEFAULT)); //进行Base64编码
String methodName = "uploadImage";
getImageFromAndroid(methodName,imageList.get(i), uploadBuffer); //调用webservice
Log.i("connectWebService", "start");
fis.close();
}
}catch(Exception e){
e.printStackTrace();
}
}
class myListAdapt extends BaseAdapter{
private LayoutInflater layoutInflater;
ImageView list_imag;
Button list_but;
@Override
public int getCount() {
// TODO Auto-generated method stub
return urlList.size();
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return urlList.get(position);
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
@SuppressLint({ "InflateParams", "ViewHolder" })
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
layoutInflater=LayoutInflater.from(getApplication());
//if (layoutInflater==null) {
convertView = layoutInflater.inflate(R.layout.image_list_item, null);
// }
list_but=(Button) convertView.findViewById(R.id.list_but);
list_imag=(ImageView) convertView.findViewById(R.id.list_imag);
list_imag.setTag(position);
final Bitmap bitmap=imageCachceUitl.getBitmapFromUrl(urlList.get(position), position);
if (null!=bitmap) {
list_imag.setImageBitmap(bitmap);
}
list_imag.setVisibility(View.VISIBLE);
list_but.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
//urlList.get(position);
Log.i("获取点击焦点", "获取点击焦点");
// getImageromSdk();
//startRun();
new Thread(new Runnable() {
@Override
public void run() {
getImageromSdk();
}
}).start();
}
});
return convertView;
}
}
}
就为大家介绍到这吧,大家慢慢消化,希望文章对大家有或多或少的帮助。
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