ListView布局之View复用原理举例

Posted blfbuaa

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1.简单介绍:

ListView是android开发中经常使用的控件,系统自带的那些样式,我就不列举了。

今天主要看一下。一个模仿系统历史通话记录的ListView。

效果例如以下:

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上面ListView的样式还能够更复杂。首先看一下这个简单的ListView的Item的布局文件:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/contacts_items"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="#ffffff"
    android:orientation="vertical" >

    <View
        android:id="@+id/topLine"
        android:layout_width="fill_parent"
        android:layout_height="1dp"
        android:background="#ff474745" />

    <RelativeLayout
        android:layout_width="fill_parent"
        android:layout_height="60dp"
        android:gravity="center_vertical"
        android:paddingRight="1.0dip" >

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:layout_alignParentLeft="true"
            android:layout_centerVertical="true"
            android:gravity="center_vertical"
            android:orientation="horizontal" >

            <ImageView
                android:id="@+id/imgHead"
                android:layout_width="wrap_content"
                android:layout_height="fill_parent"
                android:layout_marginLeft="15dp"
                android:layout_marginRight="10dp"
                android:contentDescription="" />

            <LinearLayout
                android:layout_width="wrap_content"
                android:layout_height="fill_parent"
                android:gravity="center_vertical"
                android:orientation="vertical" >

                <TextView
                    android:id="@+id/tvName"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_gravity="center_vertical"
                    android:ellipsize="end"
                    android:singleLine="true"
                    android:textSize="14.0sp" />

                <TextView
                    android:id="@+id/tvTelephone"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_gravity="center_vertical"
                    android:layout_marginTop="4.0dip"
                    android:ellipsize="end"
                    android:singleLine="true"
                    android:textColor="#ffcccccc"
                    android:textSize="12sp" />

                <TextView
                    android:id="@+id/tvDate"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginRight="0.2dip"
                    android:layout_marginTop="0dip"
                    android:ellipsize="end"
                    android:singleLine="true"
                    android:textColor="#ffcccccc"
                    android:textSize="12sp" />
            </LinearLayout>
        </LinearLayout>

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:layout_alignParentRight="true"
            android:layout_centerVertical="true"
            android:gravity="center_vertical"
            android:orientation="horizontal" >

            <Button
                android:id="@+id/btnCall"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginRight="0.2dip"
                android:layout_marginTop="0dip"
                android:ellipsize="end"
                android:singleLine="true"
                android:textColor="#ff0000ff"
                android:focusable="false"
                android:textSize="12sp" />
        </LinearLayout>
    </RelativeLayout>

    <View
        android:id="@+id/bottomLine"
        android:layout_width="fill_parent"
        android:layout_height="1dp"
        android:background="#ff1c1c1b" />

    <View
        android:id="@+id/lastLine"
        android:layout_width="fill_parent"
        android:layout_height="1dp"
        android:background="#ff474745"
        android:visibility="gone" />

</LinearLayout>

没什么问题吧?可是你一定要注意Button的一个属性:android:focusable="false",假设不加这个属性,会使得ListView的OnItemClick被屏蔽。

因为是模仿通话记录,那么Item里面的这个属性。我们还是封装到一个类里面吧。

/*
 * $filename: Model.java,v $
 * $Date: 2014-4-27  $
 * Copyright (C) ZhengHaibo, Inc. All rights reserved.
 * This software is Made by Zhenghaibo.
 */
package com.example.testaa;

import org.androidannotations.annotations.EBean;

/*
 *@author: ZhengHaibo  
 *web:     http://blog.csdn.net/nuptboyzhb
 *mail:    [email protected]
 *2014-4-27  Nanjing,njupt,China
 */
@EBean
public class Model {
	private int imgHead;//头像资源ID
	private String name;//姓名
	private String telephone;//电话号码
	private String date;//日期
	public int getImgHead() {
		return imgHead;
	}
	public void setImgHead(int imgHead) {
		this.imgHead = imgHead;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getTelephone() {
		return telephone;
	}
	public void setTelephone(String telephone) {
		this.telephone = telephone;
	}
	public String getDate() {
		return date;
	}
	public void setDate(String date) {
		this.date = date;
	}
	
}

接下来。思路非常清晰。就是继承BaseAdapter类,重写它的几个重要方法:

@Override
			public View getView(int position, View convertView, ViewGroup parent) {
				// TODO Auto-generated method stub
				return null;
			}
			
			@Override
			public long getItemId(int position) {
				// TODO Auto-generated method stub
				return 0;
			}
			
			@Override
			public Object getItem(int position) {
				// TODO Auto-generated method stub
				return null;
			}
			
			@Override
			public int getCount() {
				// TODO Auto-generated method stub
				return 0;
			}

依照我们的需求,我们必须在getView类中,为Item布局中的每个View进行关联。设置对应的參数。而对于Button,还要设置对应的事件监听器。我们必须注意的是:在设置事件监听器的时候。我们必须将当前的Item的位置信息position传递给监听器。否则的话,onClick方法无法知道当前按下的是哪个button。因此,我们写了一个内部类,实现OnClickListener接口,这个类的须要有一个属性来保存Item的位置。

因此,我们的BaseAdapter1代码例如以下:

/*
 * $filename: BaseAdapter1.java,v $
 * $Date: 2014-4-27  $
 * Copyright (C) ZhengHaibo, Inc. All rights reserved.
 * This software is Made by Zhenghaibo.
 */
package com.example.testaa;

import java.util.ArrayList;
import java.util.List;

import android.content.Context;
import android.graphics.BitmapFactory;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

/*
 *@author: ZhengHaibo  
 *web:     http://blog.csdn.net/nuptboyzhb
 *mail:    [email protected]
 *2014-4-27  Nanjing,njupt,China
 */
public class BaseAdapter1 extends BaseAdapter {
	
	private Context context;
	
	private List<Model> listViewData;
	
	private int layoutResId;//ListView每个Item的布局文件
	
	public BaseAdapter1(Context context,int layoutResId) {
		this.context = context;
		this.layoutResId = layoutResId;
		listViewData = new ArrayList<Model>();
	}
	
	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
        convertView = LayoutInflater.from(context).inflate(layoutResId,null);
        Model model = listViewData.get(position);
        ImageView imageView = (ImageView)convertView.findViewById(R.id.imgHead);
        imageView.setImageBitmap(BitmapFactory.decodeResource(context.getResources(), model.getImgHead()));
        TextView tvName = (TextView)convertView.findViewById(R.id.tvName);
        tvName.setText(model.getName());
        TextView tvTelephone = (TextView)convertView.findViewById(R.id.tvTelephone);
        tvTelephone.setText(model.getTelephone());
        TextView tvDate = (TextView)convertView.findViewById(R.id.tvDate);
        tvDate.setText(model.getDate());
        Button btnCall = (Button) convertView.findViewById(R.id.btnCall);
        btnCall.setText("拨打电话");
        btnCall.setOnClickListener(new ListViewButtonOnClickListener(position) );
		return convertView;
	}
	
	@Override
	public long getItemId(int position) {
		// TODO Auto-generated method stub
		return position;
	}
	
	@Override
	public Object getItem(int position) {
		// TODO Auto-generated method stub
		return listViewData.get(position);
	}
	
	@Override
	public int getCount() {
		// TODO Auto-generated method stub
		if(null == listViewData){
			return 0;
		}
		return listViewData.size();
	}
	
	/**
	 * 加入一条记录
	 * @param model
	 */
	public void addModel(Model model){
		listViewData.add(model);
	}
	/**
	 * 获取一条记录
	 * @param i
	 * @return
	 */
	public Model getModel(int i){
		if(i<0||i>listViewData.size()-1){
			return null;
		}
		return listViewData.get(i);
	}
	/**
	 * 清除全部数据
	 */
	public void clear(){
		listViewData.clear();
	}
	
	class ListViewButtonOnClickListener implements OnClickListener{
		private int position;//记录ListView中Button所在的Item的位置
		public ListViewButtonOnClickListener(int position) {
			this.position = position;
		}
		@Override
		public void onClick(View v) {
			Toast.makeText(context,listViewData.get(position).getTelephone(), Toast.LENGTH_SHORT).show();
		}
	}
}

由此可见,假设我们须要定制Item的布局,我们仅仅须要改动的地方除了Item的布局文件以外,还要将Adapter里的getView方法进行对应的改动。

接下来看一下Activity的測试代码

package com.example.testaa;

import java.text.SimpleDateFormat;
import java.util.Date;

import org.androidannotations.annotations.AfterViews;
import org.androidannotations.annotations.EActivity;
import org.androidannotations.annotations.ViewById;

import android.app.Activity;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
import android.widget.Toast;
@EActivity(R.layout.activity_list_1)
public class ActivityList1 extends Activity implements OnItemClickListener{
	
	@ViewById
	ListView listView;
	//ListView的设配器
	private BaseAdapter1 baseAdapter1;
	@AfterViews
	void afterViewInitList(){
		baseAdapter1 = new BaseAdapter1(this,R.layout.listview1);
		listView.setAdapter(baseAdapter1);
		listView.setOnItemClickListener(this);
		for(int i=0;i<10;i++){
			Model model = new Model();
			model.setImgHead(R.drawable.ic_launcher);
			model.setName("Name"+i);
			model.setTelephone("手机  1311111111"+i);
			model.setDate(new SimpleDateFormat().format(new Date()).toString());
			baseAdapter1.addModel(model);
		}
		baseAdapter1.notifyDataSetChanged();
		
	}
	@Override
	public void onItemClick(AdapterView<?> arg0, View arg1, int position, long arg3) {
		// TODO Auto-generated method stub
		Log.d("ItemClick", "pos="+position);
		String string = "clicked item"+position+"content="+baseAdapter1.getModel(position).getTelephone();
		Toast.makeText(this, string, Toast.LENGTH_SHORT).show();
	}
}

此时。就完毕了我们想要的功能。

Item的点击事件和Button的点击事件互不冲突。

问题二:

向微信,QQ,易信等聊天界面的ListView则有所不同。

我们上述的样例是:Item仅仅有一个布局。而聊天界面其中ListView的Item布局有多种,比方显示文字的布局,显示图片的布局,显示语音的布局等等。除此之外。我们还要依据消息的发送者,将其左右分开。在这里,仅仅演示左右的文本。原理都是都是一样的。

先看一下布局文件

左右文本的布局文件:

<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"
     >

    <ImageView
        android:id="@+id/imgHead"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_margin="5dip"
        android:src="@drawable/ic_launcher"
         />
    
    <Button 
        android:id="@+id/btn_left_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_toRightOf="@+id/imgHead"
        android:layout_marginTop="5dip"
        android:layout_marginBottom="5dip"
        android:textColor="#404040"
        android:textSize="16sp"
        android:gravity="center"
        android:focusable="false"
        android:background="@drawable/chatfrom_bg_normal"
        />

</RelativeLayout>

右边的布局文件:

<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"
     >

    <ImageView
        android:id="@+id/imgHead"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:layout_margin="5dip"
        android:src="@drawable/ic_launcher"
         />
    
    <Button 
        android:id="@+id/btn_right_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_toLeftOf="@+id/imgHead"
        android:layout_marginTop="5dip"
        android:layout_marginBottom="5dip"
        android:textColor="#404040"
        android:textSize="16sp"
        android:gravity="center"
        android:focusable="false"
        android:background="@drawable/chatto_bg_normal"
        />

</RelativeLayout>

再看一下适配器,基本和上一个样例一样,不一样无非就是getView方法的差异。

/*
 * $filename: BaseAdapter1.java,v $
 * $Date: 2014-4-27  $
 * Copyright (C) ZhengHaibo, Inc. All rights reserved.
 * This software is Made by Zhenghaibo.
 */
package com.example.testaa;

import java.util.ArrayList;
import java.util.List;

import android.content.Context;
import android.graphics.BitmapFactory;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

/*
 *@author: ZhengHaibo  
 *web:     http://blog.csdn.net/nuptboyzhb
 *mail:    [email protected]
 *2014-4-27  Nanjing,njupt,China
 */
public class ChatBaseAdapter extends BaseAdapter {
	
	private Context context;
	
	private List<Msg> listViewData;
	
	public ChatBaseAdapter(Context context) {
		this.context = context;
		listViewData = new ArrayList<Msg>();
	}
	
	/**
	 * 依据发送消息的类型进行分类,不同的消息类型不同的布局
	 */
	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		Msg msg = listViewData.get(position);
		if(msg.isSelf()){//自己发送的消息
			convertView = LayoutInflater.from(context).inflate(R.layout.list_item_right_text,null);
			ImageView imgHead =(ImageView) convertView.findViewById(R.id.imgHead);
			imgHead.setImageBitmap(BitmapFactory.decodeResource(context.getResources(), R.drawable.ic_launcher));
			Button btn = (Button)convertView.findViewById(R.id.btn_right_text);
			btn.setText(msg.getContent());
			btn.setOnClickListener(new ListViewButtonOnClickListener(position));
		}else {//对方发送的消息
			convertView = LayoutInflater.from(context).inflate(R.layout.list_item_left_text,null);
			ImageView imgHead =(ImageView) convertView.findViewById(R.id.imgHead);
			imgHead.setImageBitmap(BitmapFactory.decodeResource(context.getResources(), R.drawable.ic_launcher));
			Button btn = (Button)convertView.findViewById(R.id.btn_left_text);
			btn.setText(msg.getContent());
			btn.setOnClickListener(new ListViewButtonOnClickListener(position));
		}
		return convertView;
	}
	
	@Override
	public long getItemId(int position) {
		// TODO Auto-generated method stub
		return position;
	}
	
	@Override
	public Object getItem(int position) {
		// TODO Auto-generated method stub
		return listViewData.get(position);
	}
	
	@Override
	public int getCount() {
		// TODO Auto-generated method stub
		if(null == listViewData){
			return 0;
		}
		return listViewData.size();
	}
	
	/**
	 * 加入一条记录
	 * @param Msg
	 */
	public void addMsg(Msg Msg){
		listViewData.add(Msg);
	}
	/**
	 * 获取一条记录
	 * @param i
	 * @return
	 */
	public Msg getMsg(int i){
		if(i<0||i>listViewData.size()-1){
			return null;
		}
		return listViewData.get(i);
	}
	/**
	 * 清除全部数据
	 */
	public void clear(){
		listViewData.clear();
	}
	
	class ListViewButtonOnClickListener implements OnClickListener{
		private int position;//记录ListView中Button所在的Item的位置
		public ListViewButtonOnClickListener(int position) {
			this.position = position;
		}
		@Override
		public void onClick(View v) {
			Toast.makeText(context,listViewData.get(position).getContent(), Toast.LENGTH_SHORT).show();
		}
	}
}

Activity的代码为:

package com.example.testaa;

import org.androidannotations.annotations.AfterViews;
import org.androidannotations.annotations.EActivity;
import org.androidannotations.annotations.ViewById;

import android.app.Activity;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
import android.widget.Toast;
@EActivity(R.layout.activity_list_2)
public class ActivityList2 extends Activity implements OnItemClickListener{
	
	@ViewById
	ListView listView;
	
	private ChatBaseAdapter chatBaseAdapter;
	@AfterViews
	void afterViewInitList(){
		chatBaseAdapter = new ChatBaseAdapter(this);
		listView.setAdapter(chatBaseAdapter);
		listView.setOnItemClickListener(this);
		for(int i=0;i<10;i++){
			Msg msg = new Msg();
			if(i%2==0){
				msg.setSelf(false);
			}else {
				msg.setSelf(true);			
			}
			msg.setContent("abc"+i);
			chatBaseAdapter.addMsg(msg);
		}
		chatBaseAdapter.notifyDataSetChanged();
		
	}
	@Override
	public void onItemClick(AdapterView<?> arg0, View arg1, int position, long arg3) {
		// TODO Auto-generated method stub
		Log.d("ItemClick", "pos="+position);
		String string = "clicked item"+position+"content="+chatBaseAdapter.getMsg(position).getContent();
		Toast.makeText(this, string, Toast.LENGTH_SHORT).show();
	}
}

效果:

技术分享


关于聊天界面的很多其它内容可參考博文:http://blog.csdn.net/xyz_lmn/article/details/13745489

原理基本一样。

注意:整个项目的代码使用的是AndroidAnnotation框架,本博客的代码下载:http://download.csdn.net/detail/nuptboyzhb/7260915

















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