ListView数据异步加载图片和使用AsyncTask优化
2014-12-25 16:57
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从web端解析并加载其中的图片及文字到android端。
采用异步加载技术提高图片加载效率：
下面第一个是部署在web端的一个list.xml文件：
其中注意src的图片路径，更换下ip地址及工程名称即可。
目的就是就是解析该xml文件读取相应的图片及文字到android端。
android端:
布局:
主布局
部分功能代码:
MainActivity.java:
适配器ContactAdapter.java:
进一步优化，如果数据量太多，线程开的太多，会导致程序崩溃的，优化采用AsyncTask(Handler+Thread+线程池)实现。
修改ContactAdapter.java:
采用异步加载技术提高图片加载效率：
下面第一个是部署在web端的一个list.xml文件：
<?xml version="1.0" encoding="utf-8"?> <contacts> <contact id="1"> <name>张飞</name> <image src="http://192.168.1.106:8080/SecondaryMarket/images/new-pic1.jpg"></image> </contact> <contact id="2"> <name>关羽</name> <image src="http://192.168.1.106:8080/SecondaryMarket/images/i1.jpg"></image> </contact> <contact id="3"> <name>小宁</name> <image src="http://192.168.1.106:8080/SecondaryMarket/images/i2.jpg"></image> </contact> <contact id="4"> <name>拉刘</name> <image src="http://192.168.1.106:8080/SecondaryMarket/images/i3.jpg"></image> </contact> <contact id="5"> <name>张三</name> <image src="http://192.168.1.106:8080/SecondaryMarket/images/i4.jpg"></image> </contact> <contact id="6"> <name>李四</name> <image src="http://192.168.1.106:8080/SecondaryMarket/images/i5.jpg"></image> </contact> <contact id="7"> <name>张飞</name> <image src="http://192.168.1.106:8080/SecondaryMarket/images/i6.jpg"></image> </contact> <contact id="8"> <name>小宋</name> <image src="http://192.168.1.106:8080/SecondaryMarket/images/i1.jpg"></image> </contact> <contact id="9"> <name>妹子</name> <image src="http://192.168.1.106:8080/SecondaryMarket/images/i2.jpg"></image> </contact> </contacts>
其中注意src的图片路径，更换下ip地址及工程名称即可。
目的就是就是解析该xml文件读取相应的图片及文字到android端。
android端:
布局:
主布局
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context="com.example.dataasync.MainActivity" > <ListView android:layout_width="fill_parent" android:layout_height="fill_parent" android:id="@+id/listView" /> </RelativeLayout>每一个listview中选项的布局:listview_item.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="horizontal" > <ImageView android:layout_width="120dp" android:layout_height="120dp" android:id="@+id/imageView" /> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:textSize="18sp" android:textColor="#000000" android:id="@+id/textView" /> </LinearLayout>
部分功能代码:
MainActivity.java:
package com.example.dataasync;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.widget.ListView;
import android.widget.Toast;
import cn.example.domain.Contact;
import com.example.adpter.ContactAdpter;
import com.example.service.ContactService;
public class MainActivity extends ActionBarActivity {
private ListView listView;
File cache;
Handler handler = new Handler(){
@Override
public void handleMessage(Message msg) {
listView.setAdapter(new ContactAdpter(MainActivity.this,(List<Contact>)msg.obj,
R.layout.listview_item,cache));
};
};//Handler的用法就是用于子线程与UI主线程通讯
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) this.findViewById(R.id.listView);
cache = new File(Environment.getExternalStorageDirectory(),"cache");
if(!cache.exists()){
cache.mkdirs();
}
//采用异步方式得到联系人数据
new Thread(new Runnable() {
@Override
public void run() {
try {
List<Contact> data = ContactService.getContacts();
handler.sendMessage(handler.obtainMessage(22, data));
} catch (Exception e) {
e.printStackTrace();
}
}
}).start();
}
@Override
protected void onDestroy() {
for(File file:cache.listFiles()){
file.delete();
}
cache.delete();
super.onDestroy();
}
}适配器ContactAdapter.java:
package com.example.adpter;
import java.io.File;
import java.util.List;
import com.example.dataasync.R;
import com.example.service.ContactService;
import cn.example.domain.Contact;
import android.content.Context;
import android.net.Uri;
import android.os.Handler;
import android.os.Message;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
public class ContactAdpter extends BaseAdapter{
private List<Contact> data;
private int listviewItem;
private File cache;
LayoutInflater layoutInflater;
public ContactAdpter(Context context,List<Contact> data, int listviewItem, File cache) {
this.data = data;
this.listviewItem = listviewItem;
this.cache = cache;
layoutInflater = (LayoutInflater) context.getSystemService(context.LAYOUT_INFLATER_SERVICE);
}
@Override
public int getCount() {
return data.size();
}
@Override
public Object getItem(int position) {
return data.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
TextView textView;
if(convertView == null){
convertView = layoutInflater.inflate(listviewItem, null);
imageView = (ImageView) convertView.findViewById(R.id.imageView);
textView = (TextView) convertView.findViewById(R.id.textView);
convertView.setTag(new DataWraper(imageView, textView));
}else{
DataWraper dataWraper = (DataWraper) convertView.getTag();
imageView = dataWraper.imageView;
textView = dataWraper.textView;
}
Contact contact = data.get(position);
System.out.println(contact.name+":"+contact.image);
textView.setText(contact.name);//这是设置textview控件
//设置imageview控件
asycImageLoad(imageView,contact.image);
return convertView;
}
private void asycImageLoad(final ImageView imageView, final String path) {
//执行在主线程中，往主线程中的队列中添加消息
final Handler handler = new Handler(){//
@Override
public void handleMessage(Message msg) {
Uri uri = (Uri) msg.obj;
if(uri!=null && imageView!=null){
imageView.setImageURI(uri);
}
}
};
Runnable runnable = new Runnable() {
@Override
public void run() {
try {
System.out.println("tdw");
Uri uri = ContactService.getImage(path, cache);
System.out.println("uri"+uri);
//在子线程中通过handler往主线程添加消息
handler.sendMessage(handler.obtainMessage(10,uri));
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
};
new Thread(runnable).start();
}
public final class DataWraper{
public ImageView imageView;
public TextView textView;
public DataWraper(ImageView imageView, TextView textView) {
this.imageView = imageView;
this.textView = textView;
}
}
}进一步优化，如果数据量太多，线程开的太多，会导致程序崩溃的，优化采用AsyncTask(Handler+Thread+线程池)实现。
修改ContactAdapter.java:
package com.example.adpter;
import java.io.File;
import java.util.List;
import com.example.dataasync.R;
import com.example.service.ContactService;
import cn.example.domain.Contact;
import android.content.Context;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Handler;
import android.os.Message;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
public class ContactAdpter extends BaseAdapter{
private List<Contact> data;
private int listviewItem;
private File cache;
LayoutInflater layoutInflater;
public ContactAdpter(Context context,List<Contact> data, int listviewItem, File cache) {
this.data = data;
this.listviewItem = listviewItem;
this.cache = cache;
layoutInflater = (LayoutInflater) context.getSystemService(context.LAYOUT_INFLATER_SERVICE);
}
@Override
public int getCount() {
return data.size();
}
@Override
public Object getItem(int position) {
return data.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
TextView textView;
if(convertView == null){
convertView = layoutInflater.inflate(listviewItem, null);
imageView = (ImageView) convertView.findViewById(R.id.imageView);
textView = (TextView) convertView.findViewById(R.id.textView);
convertView.setTag(new DataWraper(imageView, textView));
}else{
DataWraper dataWraper = (DataWraper) convertView.getTag();
imageView = dataWraper.imageView;
textView = dataWraper.textView;
}
Contact contact = data.get(position);
System.out.println(contact.name+":"+contact.image);
textView.setText(contact.name);//这是设置textview控件
//设置imageview控件
asycImageLoad(imageView,contact.image);
return convertView;
}
//采用AsyncTask(Handler+Thread+线程池)
private void asycImageLoad(ImageView imageView, String path) {
AsyncImageTask asyncImageTask = new AsyncImageTask(imageView);
asyncImageTask.execute(path);
}
public final class AsyncImageTask extends AsyncTask<String, Integer, Uri>{
private ImageView imageView;
public AsyncImageTask(ImageView imageView) {
this.imageView = imageView;
}
@Override
protected Uri doInBackground(String... params) {//运行在子线程中
try {
return ContactService.getImage(params[0], cache);
} catch (Exception e) {
e.printStackTrace();
};
return null;
}
//处理后的结果传给该方法进行处理
@Override
protected void onPostExecute(Uri result) {//运行在主线程中个，该机制内部自带线程数和handler对象
if(result!=null && imageView!=null){
imageView.setImageURI(result);
}
}
}
/*
private void asycImageLoad(final ImageView imageView, final String path) {
//执行在主线程中，往主线程中的队列中添加消息
final Handler handler = new Handler(){//
@Override
public void handleMessage(Message msg) {
Uri uri = (Uri) msg.obj;
if(uri!=null && imageView!=null){
imageView.setImageURI(uri);
}
}
};
Runnable runnable = new Runnable() {
@Override
public void run() {
try {
System.out.println("tdw");
Uri uri = ContactService.getImage(path, cache);
System.out.println("uri"+uri);
//在子线程中通过handler往主线程添加消息
handler.sendMessage(handler.obtainMessage(10,uri));
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
};
new Thread(runnable).start();
}*/
public final class DataWraper{
public ImageView imageView;
public TextView textView;
public DataWraper(ImageView imageView, TextView textView) {
this.imageView = imageView;
this.textView = textView;
}
}
}
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