用Adapter實(shí)現(xiàn)聊天ListView

聊天界面會(huì)展示至少兩種布局，即收到消息和發(fā)送消息。這樣一個(gè)ListView與平時(shí)使用的ListView的最大不同，在于它有兩個(gè)不同的布局：收到的布局和發(fā)送的布局。需要利用Adapter實(shí)現(xiàn)這樣的效果。即需要在獲取布局的時(shí)候判斷該獲取哪個(gè)布局。

public abstract class BaseAdapter extends Object
implements ListAdapter SpinnerAdapter java.lang.Object ???? android.widget.BaseAdapter

BaseAdapter這個(gè)類中提供了兩個(gè)方法：

public intgetItemViewType (int position) Added in API level 1

Get the type of View that will be created by getView(int, View, ViewGroup) for the specified item.

ParametersThe position of the item within the adapter's data set whose view type we want. Returns? 返回第position個(gè)Item是何種類型 An integer representing the type of View. Two views should share the same type if one can be converted to the other ingetView(int, View, ViewGroup). Note: Integers must be in the range 0 togetViewTypeCount() - 1. IGNORE_ITEM_VIEW_TYPE can also be returned.

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public intgetViewTypeCount () Added in API level 1

Returns the number of types of Views that will be created by getView(int, View, ViewGroup). Each type represents a set of views that can be converted ingetView(int, View, ViewGroup). If the adapter always returns the same type of View for all items, this method should return 1.

This method will only be called when when the adapter is set on the the AdapterView.

Returns 返回不同布局的數(shù)目 The number of types of Views that will be created by this adapter

首先需要實(shí)現(xiàn)兩個(gè)布局——發(fā)送和接收

chat_item_itemin.xml

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chat_item_itemout.xml

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為了封裝聊天內(nèi)容，便于在Adapter中獲取數(shù)據(jù)信息，封裝一個(gè)Bean類來保存聊天信息。編寫javabean就是編寫一個(gè)java的類，所以只要會(huì)寫類就能編寫一個(gè)bean，這個(gè)類創(chuàng)建的一個(gè)對(duì)象稱做一個(gè)bean。為了能讓使用這個(gè)bean的應(yīng)用程序構(gòu)建工具（比如JSP引擎）知道這個(gè)bean的屬性和方法，只需在類的方法命名上遵守以下規(guī)則：

1． 如果類的成員變量的名字是xxx，那么為了更改或獲取成員變量的值，即更改或獲取屬性，在類中可以使用兩個(gè)方法：

getXxx()，用來獲取屬性xxx。

setXxx()，用來修改屬性xxx。

2． 對(duì)于boolean類型的成員變量，即布爾邏輯類型的屬性，允許使用"is"代替上面的"get"和"set"。

3． 類中方法的訪問屬性都必須是public的。

4． 類中如果有構(gòu)造方法，那么這個(gè)構(gòu)造方法也是public的并且是無參數(shù)的。

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ChatItemListViewBean.java

package?sunny.example.ahfourlistviewchat;

//封裝一個(gè)Bean來保存聊天信息
import?android.graphics.Bitmap;
public?class?ChatItemListViewBean?{

	private?int?type;
	private?String?text;
	private?Bitmap?icon;
	
	public?ChatItemListViewBean(){
		
	}
	
	public?int?getType(){
		return?type;
	}
	//在使用時(shí)setType?如bean1.setType(0);
	public?void?setType(int?type){
		this.type?=?type;
	}
	
	public?String?getText(){
		return?text;
	}
	
	public?void?setText(String?text){
		this.text?=?text;
	}
	
	public?Bitmap?getIcon(){
		return?icon;
	}
	
	public?void?setIcon(Bitmap?icon){
		this.icon?=?icon;
	}
}

activity_main.xml

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ChatItemListViewTest.java

package?sunny.example.ahfourlistviewchat;

import?android.support.v7.app.ActionBarActivity;
import?android.widget.ListView;
import?android.graphics.BitmapFactory;
import?android.os.Bundle;
import?java.util.List;
import?java.util.ArrayList;
public?class?ChatItemListViewTest?extends?ActionBarActivity{

	private?ListView?mListView;
	protected?void?onCreate(Bundle?savedInstanceState){
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		mListView?=?(ListView)findViewById(R.id.listView_chat);
		ChatItemListViewBean?bean1?=?new?ChatItemListViewBean();
		bean1.setType(0);
		bean1.setIcon(BitmapFactory.decodeResource(getResources(),?R.drawable.ic_launcher));
		bean1.setText("Hello.?How?are?you?");
		
		ChatItemListViewBean?bean2?=?new?ChatItemListViewBean();
		bean2.setType(1);
		bean2.setIcon(BitmapFactory.decodeResource(getResources(),?R.drawable.ic_launcher));
		bean2.setText("Fine.?Thank?you");
		
		Listdata?=?new?ArrayList();
		data.add(bean1);
		data.add(bean2);
		mListView.setAdapter(new?ChatItemListViewAdapter(this,data));
	}
}

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