Android中ListView的具体应用

package com.example.android_day10_two;


import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.app.ProgressDialog;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ListView;
import android.widget.TextView;


public class MainActivity extends Activity {
private ListView listView;
private TextView empty;
private List<Map<String, Object>> data=new ArrayList<Map<String,Object>>();
private MyAdapter myAdapter;
private boolean isBottom=false;
public static final String  PATH = "http://chanyouji.com/api/articles.json?page=";
private int page=1;


@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView=(ListView) findViewById(R.id.listView);
empty=(TextView) findViewById(R.id.empty);
listView.setEmptyView(empty);
myAdapter=new MyAdapter(data, this);
listView.setAdapter(myAdapter);
new MyTask().execute(PATH+page);
listView.setOnScrollListener(new OnScrollListener() {

@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
// TODO Auto-generated method stub
if (isBottom&&scrollState==OnScrollListener.SCROLL_STATE_IDLE) {
page++;
new MyTask().execute(PATH+page);
}
}


@Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
// TODO Auto-generated method stub
isBottom=((firstVisibleItem+visibleItemCount)==totalItemCount);
}
});
}
class MyTask extends AsyncTask<String,Void,List<Map<String,Object>>>{
private ProgressDialog dialog;
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
dialog=new ProgressDialog(MainActivity.this);
dialog.setTitle("提示：");
dialog.setMessage("正在加载中......");
dialog.setCanceledOnTouchOutside(false);
dialog.show();
}
@Override
protected List<Map<String, Object>> doInBackground(String... params) {
// TODO Auto-generated method stub
return Tools.parserJson(Tools.getString(params[0]));
}
@Override
protected void onPostExecute(List<Map<String, Object>> result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
if (result!=null) {
data.addAll(result);
myAdapter.notifyDataSetChanged();
}
dialog.dismiss();
}
}

}

package com.example.android_day10_two;


import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Bitmap;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;


public class MyAdapter extends BaseAdapter{
private List<Map<String, Object>> data;
private Context context;
private Map<String, Bitmap> mapImage=new HashMap<String, Bitmap>();


public MyAdapter(List<Map<String, Object>> data,Context context) {
// TODO Auto-generated constructor stub
this.data=data;
this.context=context;
}


@Override
public int getCount() {
// TODO Auto-generated method stub
return data!=null? data.size():0;
}


@Override
public Map<String, Object> getItem(int position) {
// TODO Auto-generated method stub
return data.get(position);
}


@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}


@SuppressLint("SimpleDateFormat")
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
ViewHolder holder=null;
if (convertView==null) {
convertView=LayoutInflater.from(context).inflate(R.layout.itemlayout,parent,false);
holder=new ViewHolder();
holder.imageView=(ImageView) convertView.findViewById(R.id.image);
holder.name=(TextView) convertView.findViewById(R.id.name);
holder.title=(TextView) convertView.findViewById(R.id.title);
holder.time=(TextView) convertView.findViewById(R.id.time);
convertView.setTag(holder);
}else {
holder=(ViewHolder) convertView.getTag();
}
Map<String, Object> map=data.get(position);
holder.name.setText(map.get("name").toString());
holder.title.setText(map.get("title").toString());
if (mapImage.containsKey(map.get("image_url").toString())) {
Bitmap bitmap=mapImage.get(map.get("image_url").toString());
holder.imageView.setImageBitmap(bitmap);
//Log.e("Bitmap", "正在下载。。。。。。"+mapImage.get(map.get("image_url").toString()));
}else {
new ImageTask(holder.imageView,mapImage).execute(map.get("image_url").toString());
}
long time=Long.parseLong(map.get("updated_at").toString());
SimpleDateFormat format=new SimpleDateFormat("yyyy-MM-dd HH-mm-ss");
String text=format.format(new Date(time*1000));
holder.time.setText(text);
return convertView;
}
class ViewHolder{
ImageView imageView;
TextView name;
TextView title;
TextView time;
}


}

package com.example.android_day10_two;


import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.json.JSONArray;
import org.json.JSONObject;


import android.graphics.Bitmap;
import android.graphics.BitmapFactory;


public class Tools {
public static String getString(String path) {
ByteArrayOutputStream outputStream=null;

try {
URL url= new URL(path);
HttpURLConnection conn=(HttpURLConnection) url.openConnection();
conn.setReadTimeout(5000);
if (conn.getResponseCode()==200) {
InputStream inputStream=conn.getInputStream();
outputStream=new ByteArrayOutputStream();
byte[] buffer=new byte[8*1024];
int len=0;
while ((len=inputStream.read(buffer))!=-1) {
outputStream.write(buffer,0,len);
outputStream.flush();
}
return outputStream.toString();
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
try {
if (outputStream!=null) {
outputStream.close();
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

return "";
}
public static List<Map<String, Object>> parserJson(String json) {
List<Map<String, Object>> data=new ArrayList<Map<String,Object>>();
JSONArray jsonArray;
try {
jsonArray = new JSONArray(json);
for (int i = 0; i < jsonArray.length(); i++) {
Map<String, Object> map=new HashMap<String, Object>();
JSONObject jsonObject=jsonArray.getJSONObject(i);
map.put("name", jsonObject.getString("name"));
map.put("title", jsonObject.getString("title"));
map.put("image_url", jsonObject.getString("image_url"));
map.put("updated_at", jsonObject.getString("updated_at"));
data.add(map);
}
return data;
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
public static Bitmap getBitmap(String path) {
ByteArrayOutputStream outputStream=null;
URL url;
try {
url = new URL(path);
HttpURLConnection conn=(HttpURLConnection) url.openConnection();
conn.setReadTimeout(5000);
if (conn.getResponseCode()==200) {
InputStream inputStream=conn.getInputStream();
outputStream=new ByteArrayOutputStream();
byte[] buffer=new byte[8*1024];
int len=0;
while ((len=inputStream.read(buffer))!=-1) {
outputStream.write(buffer,0,len);
outputStream.flush();
}
return BitmapFactory.decodeByteArray(outputStream.toByteArray(), 0, outputStream.toByteArray().length);
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
try {
if (outputStream!=null) {
outputStream.close();
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

return null;
}


}