android——自定义listView

2022-08-18 19:05:56

都知道微信主机面有个界面会一行一一行的聊天记录，那个效果就可以用listview来实现（当然这只是其中的一种）

　　listView是一种比较常见的组件它用来展示列的view，它是根据数据的长度来显示数据，要做出效果还要用到适配器。适配器就是把一些数据给弄得适当，适合以便于在View上显示。可以看作是界面数据绑定的一种理解。它所操纵的数据一般都是一些比较复杂的数据，如数组，链表，数据库，集合等。适配器就像显示器，把复杂的东西按人可以接受的方式来展现，更详细解释请看http://wenku.baidu.com/link?url=SH9GU2Mn2xP-RDcw_RkgIsh59qY-vFGzK7LLj6qwsoThT-Lbae-ro33VdBJBd2qlsh_L8LL6_k5pd2JvehWs2-zb48a-luiIVKbwJ4SToV3（转载）

 package com.example.winxin2;

 import java.sql.SQLException;

 import java.util.ArrayList;

 import java.util.HashMap;

 import java.util.List;

 import java.util.Map;

 import com.example.entity.Message;

 import com.j256.ormlite.dao.Dao;

 import android.app.Activity;

 import android.content.ContentValues;

 import android.database.Cursor;

 import android.database.sqlite.SQLiteDatabase;

 import android.database.sqlite.SQLiteOpenHelper;

 import android.os.Bundle;

 import android.provider.SyncStateContract.Helpers;

 import android.util.Log;

 import android.view.LayoutInflater;

 import android.view.Menu;

 import android.view.MenuItem;

 import android.view.View;

 import android.view.ViewGroup;

 import android.widget.AdapterView;

 import android.widget.AdapterView.OnItemClickListener;

 import android.widget.BaseAdapter;

 import android.widget.ImageView;

 import android.widget.LinearLayout;

 import android.widget.ListView;

 import android.widget.SimpleAdapter;

 import android.widget.TextView;

 import android.widget.Toast;

 public class MainActivity extends Activity {

     private SimpleAdapter sa;

     private ormdatabase DBorm;

     private static SQLiteDatabase db;

     private ListView lv;

     private List<Message> messageList = new ArrayList<Message>();

     private List<Map<String,Object> > messageList2 = new ArrayList<Map<String,Object> >();

     @Override

     protected void onCreate(Bundle savedInstanceState) {

         super.onCreate(savedInstanceState);

         setContentView(R.layout.weixin);

         //模拟读取数据库或者互联网

         for (int i = 0; i < 1000; i++) {

             Message m = new Message();

             m.setTou1("xxx");

             m.setUserName("张三疯"+i);

             m.setLastMessage("今晚有约，一起华山论剑");

             m.setDatetime("11月11日");

             messageList.add(m);//上周

             //定义一个界面与数据的混合体,一个item代表一行记录

             Map<String,Object> item  = new HashMap<String,Object>();

             //一行记录，包含多个控件

             item.put("tou", R.drawable.tou1);

             item.put("userName", "张三疯"+i);

             item.put("lastMessage", "今晚有约，一起华山论剑");

             item.put("datetime","11月11日");

             messageList2.add(item);

         } 

         lv = (ListView)findViewById(R.id.listView1);

         sa = new SimpleAdapter(this,

                 messageList2,//data 不仅仅是数据，而是一个与界面耦合的数据混合体

                 R.layout.listview_item_layout,

                 new String[] {"tou","userName","lastMessage","datetime"},//from 从那来

                 new int[] {R.id.imageView1,R.id.tv_userName,R.id.tv_lastMessage,R.id.tv_datetime}//to 到那里去

                 );

         lv.setAdapter(sa);

         lv.setOnItemClickListener(new OnItemClickListener() {

             @Override

             public void onItemClick(AdapterView<?> parent, View view,

                     int position, long id) {

                 Map<String,Object> item = messageList2.get(position);

                 sa.notifyDataSetChanged();

                 Toast.makeText(MainActivity.this, (String)item.get("userName"), Toast.LENGTH_SHORT).show();

             }

         });

         //简单理解为VC绑在一起

         /*

          * baseAdapter，店长推荐 5星级

         lv.setAdapter( new BaseAdapter(){

             //返回多少条记录

             @Override

             public int getCount() {

                 // TODO Auto-generated method stub

                 return messageList.size();

             }

             //每一个item项，返回一次界面

             @Override

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

                 View view = null;

                 //布局不变，数据变

                 //如果缓存为空，我们生成新的布局作为1个item

                 if(convertView==null){

                     Log.i("info:", "没有缓存，重新生成"+position);

                     LayoutInflater inflater = MainActivity.this.getLayoutInflater();

                     //因为getView()返回的对象，adapter会自动赋给ListView

                     view = inflater.inflate(R.layout.listview_item_layout, null);

                 }else{

                     Log.i("info:", "有缓存，不需要重新生成"+position);

                     view = convertView;

                 }

                 Message m = messageList.get(position);

                 TextView tv_userName = (TextView)view.findViewById(R.id.tv_userName);

                 tv_userName.setText(  m.getUserName()  );

                 tv_userName.setTextSize(15);

                 TextView tv_lastMessage = (TextView)view.findViewById(R.id.tv_lastMessage);

                 tv_lastMessage.setText(  m.getLastMessage()  );

                 tv_lastMessage.setTextSize(12);

                 TextView tv_datetime = (T xtView)view.findViewById(R.id.tv_datetime);

                 tv_datetime.setText( m.getDatetime()  );

                 tv_datetime.setTextSize(12);

                 return view;

             }

             @Override

             public Object getItem(int position) {

                 // TODO Auto-generated method stub

                 return null;

             }

             @Override

             public long getItemId(int position) {

                 // TODO Auto-generated method stub

                 return 0;

             }

         } );

         */

     }

     }

 }

布局文件

　　weixin.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="vertical" >

    <LinearLayout

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_weight="1">

        <include layout="@layout/listview_layout"/>

    </LinearLayout>

</LinearLayout>

listview_item_layout.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:id="@+id/imageView1"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_margin="10dp"/>

    <LinearLayout

        android:layout_weight="1"

        android:layout_width="match_parent"

        android:layout_height="80dp"

        android:orientation="vertical"

        android:layout_margin="5dp"

        >

        <TextView

        android:id="@+id/tv_userName"

         android:layout_width="match_parent"

        android:layout_height="20dp"

         />

         <TextView

        android:id="@+id/tv_lastMessage"

         android:layout_width="match_parent"

        android:layout_height="15dp"

         />

    </LinearLayout>

    <TextView

        android:id="@+id/tv_datetime"

         android:layout_width="150dp"

        android:layout_height="15dp"

         />

</LinearLayout>

listview_layout.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="vertical" >

    <ListView

        android:id="@+id/listView1"

        android:layout_width="match_parent"

        android:layout_height="match_parent" >

    </ListView>

</LinearLayout>

码农公寓

相关文章