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Android開發(fā)中ListView自定義adapter的封裝

 更新時間：2016年09月08日 10:29:16   作者：生命壹號  
這篇文章主要為大家詳細介紹了android開發(fā)中ListView自定義adapter的封裝，ListView的模板寫法，感興趣的小伙伴們可以參考一下

【引入】 

我們一般編寫listView的時候順序是這樣的：
 •需要展示的數(shù)據(jù)集List<T>
 •為這個數(shù)據(jù)集編寫一個ListView
 •為這個ListView編寫一個Adapter，一般繼承自BaseAdapter
 •在BaseAdapter內(nèi)部編寫一個ViewHolder類，對應ListView里面的item控件，提高控件的查詢效率 

分析：

List<T>:ListView --> Adapter extends BaseAdapter --> ViewHolder 

一般情況下，一個ListView對應一個Adapter類，對應一個ViewHolder類，那如果一個app中有20個ListView，我們豈不是要寫20遍？所以的做法是：
 •抽取ViewHolder，作為公共的類。
 •將Adapter封裝成CommonAdapter，作為公共的類。 

一、傳統(tǒng)方式編寫適配器： 

（1）activity_main.xml: 

<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">

<ListView
 android:id="@+id/listView"
 android:layout_width="match_parent"
 android:layout_height="match_parent"></ListView>

</RelativeLayout>

(2)item_listview.xml:單個item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"
 android:padding="10dp">

 <TextView
 android:id="@+id/titleTv"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:singleLine="true"
 android:text="Android新技能"
 android:textColor="#444"
 android:textSize="16sp" />

 <TextView
 android:id="@+id/descTv"
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:layout_below="@+id/titleTv"
 android:layout_marginTop="10dp"
 android:maxLines="2"
 android:minLines="1"
 android:text="Android為ListView和GridView打造萬能適配器"
 android:textColor="#898989"
 android:textSize="16sp" />

 <TextView
 android:id="@+id/timeTv"
 android:paddingTop="3dp"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_below="@+id/descTv"
 android:layout_marginTop="10dp"
 android:text="2015-05-04"
 android:textColor="#898989"
 android:textSize="12sp" />

 <TextView
 android:padding="2dp"
 android:id="@+id/phoneTv"
 android:gravity="center"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_below="@+id/descTv"
 android:layout_marginTop="10dp"
 android:background="#2ED667"
 android:drawableLeft="@mipmap/phone"
 android:drawablePadding="5dp"
 android:text="10086"
 android:textColor="#ffffff"
 android:textSize="12sp"
 android:layout_alignParentRight="true" />


</RelativeLayout>

其對應的布局效果如下：

（3）Bean.java:ListView的數(shù)據(jù)集

package com.smyhvae.baseadapter.entities;

/**
 * Created by smyhvae on 2015/5/4.
 */
public class Bean {
 private String title;
 private String desc;
 private String time;
 private String phone;

 public Bean() {
 }

 public Bean(String title, String desc, String time, String phone) {
 this.title = title;
 
 this.desc = desc;
 this.time = time;
 this.phone = phone;
 }

 public String getTitle() {
 return title;
 }

 public void setTitle(String title) {
 this.title = title;
 }

 public String getDesc() {
 return desc;
 }

 public void setDesc(String desc) {
 this.desc = desc;
 }

 public String getTime() {
 return time;
 }

 public void setTime(String time) {
 this.time = time;
 }

 public String getPhone() {
 return phone;
 }

 public void setPhone(String phone) {
 this.phone = phone;
 }
}

（4）MyAdapter.java:自定義適配器，繼承自BaseAdapter 

package com.smyhvae.baseadapter;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

import com.smyhvae.baseadapter.entities.Bean;

import java.util.List;

/**
 * Created by smyhvae on 2015/5/4.
 */
public class MyAdapter extends BaseAdapter {
 private LayoutInflater mInflater;
 private List<Bean> mDatas;

 //MyAdapter需要一個Context，通過Context獲得Layout.inflater，然后通過inflater加載item的布局
 public MyAdapter(Context context, List<Bean> datas) {

 mInflater = LayoutInflater.from(context);
 mDatas = datas;
 }

 //返回數(shù)據(jù)集的長度
 @Override
 public int getCount() {
 return mDatas.size();
 }

 @Override
 public Object getItem(int position) {
 return mDatas.get(position);
 }

 @Override
 public long getItemId(int position) {
 return position;
 }

 //這個方法才是重點，我們要為它編寫一個ViewHolder
 @Override
 public View getView(int position, View convertView, ViewGroup parent) {
 ViewHolder holder = null;
 if (convertView == null) {
  convertView = mInflater.inflate(R.layout.item_listview, parent, false); //加載布局
  holder = new ViewHolder();

  holder.titleTv = (TextView) convertView.findViewById(R.id.titleTv);
  holder.descTv = (TextView) convertView.findViewById(R.id.descTv);
  holder.timeTv = (TextView) convertView.findViewById(R.id.timeTv);
  holder.phoneTv = (TextView) convertView.findViewById(R.id.phoneTv);

  convertView.setTag(holder);
 } else { //else里面說明，convertView已經(jīng)被復用了，說明convertView中已經(jīng)設置過tag了，即holder
  holder = (ViewHolder) convertView.getTag();
 }

 Bean bean = mDatas.get(position);
 holder.titleTv.setText(bean.getTitle());
 holder.descTv.setText(bean.getDesc());
 holder.timeTv.setText(bean.getTime());
 holder.phoneTv.setText(bean.getPhone());

 return convertView;
 }

 //這個ViewHolder只能服務于當前這個特定的adapter，因為ViewHolder里會指定item的控件，不同的ListView，item可能不同，所以ViewHolder寫成一個私有的類
 private class ViewHolder {
 TextView titleTv;
 TextView descTv;
 TextView timeTv;
 TextView phoneTv;
 }

}

(5)MainActivity.java: 

package com.smyhvae.baseadapter;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ListView;

import com.smyhvae.baseadapter.entities.Bean;

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

public class MainActivity extends Activity {

 private ListView listView;
 private List<Bean> mDatas;
 private MyAdapter mAdapter;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);

 initView();
 initData();

 }

 //方法：初始化View
 private void initView() {
 listView = (ListView) findViewById(R.id.listView);
 }

 //方法；初始化Data
 private void initData() {
 mDatas = new ArrayList<Bean>();

 //將數(shù)據(jù)裝到集合中去
 Bean bean = new Bean("Android新技能1", "Android為ListView和GridView打造萬能適配器", "2015-05-04", "10086");
 mDatas.add(bean);

 bean = new Bean("Android新技能2", "Android為ListView和GridView打造萬能適配器", "2015-05-04", "10086");
 mDatas.add(bean);

 bean = new Bean("Android新技能3", "Android為ListView和GridView打造萬能適配器", "2015-05-04", "10086");
 mDatas.add(bean);

 bean = new Bean("Android新技能4", "Android為ListView和GridView打造萬能適配器", "2015-05-04", "10086");
 mDatas.add(bean);

 //為數(shù)據(jù)綁定適配器
 mAdapter = new MyAdapter(this,mDatas);

 listView.setAdapter(mAdapter);
 }

}

運行效果如下：

 

【工程文件】 
2015-05-04-BaseAdapter的傳統(tǒng)寫法.rar

二、ListView中自定義adapter的封裝（萬能的寫法來編寫適配器）： 
完整版代碼如下： 

(1)activity_main.xml: 

<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">

<ListView
 android:id="@+id/listView"
 android:layout_width="match_parent"
 android:layout_height="match_parent"></ListView>

</RelativeLayout>

（2）item_listview.xml.xml:（ListView中單個item的布局） 

<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:padding="10dp">

 <TextView
 android:id="@+id/titleTv"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:singleLine="true"
 android:text="Android新技能"
 android:textColor="#444"
 android:textSize="16sp" />

 <TextView
 android:id="@+id/descTv"
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:layout_below="@+id/titleTv"
 android:layout_marginTop="10dp"
 android:maxLines="2"
 android:minLines="1"
 android:text="Android為ListView和GridView打造萬能適配器"
 android:textColor="#898989"
 android:textSize="16sp" />

 <TextView
 android:id="@+id/timeTv"
 android:paddingTop="3dp"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_below="@+id/descTv"
 android:layout_marginTop="10dp"
 android:text="2015-05-04"
 android:textColor="#898989"
 android:textSize="12sp" />

 <TextView
 android:padding="2dp"
 android:id="@+id/phoneTv"
 android:gravity="center"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_below="@+id/descTv"
 android:layout_marginTop="10dp"
 android:background="#2ED667"
 android:drawableLeft="@mipmap/phone"
 android:drawablePadding="5dp"
 android:text="10086"
 android:textColor="#ffffff"
 android:textSize="12sp"
 android:layout_alignParentRight="true" />


</RelativeLayout>

其對應的布局效果如下：

 

（3）Bean.java:數(shù)據(jù)集 

package com.smyhvae.baseadapter.entities;

/**
 * Created by smyhvae on 2015/5/4.
 */
public class Bean {
 private String title;
 private String desc;
 private String time;
 private String phone;

 public Bean() {
 }

 public Bean(String title, String desc, String time, String phone) {
 this.title = title;

 this.desc = desc;
 this.time = time;
 this.phone = phone;
 }

 public String getTitle() {
 return title;
 }

 public void setTitle(String title) {
 this.title = title;
 }

 public String getDesc() {
 return desc;
 }

 public void setDesc(String desc) {
 this.desc = desc;
 }

 public String getTime() {
 return time;
 }

 public void setTime(String time) {
 this.time = time;
 }

 public String getPhone() {
 return phone;
 }

 public void setPhone(String phone) {
 this.phone = phone;
 }
}

（4）【可復用的代碼】ViewHolder.java: 

package com.smyhvae.baseadapter.utils;

import android.content.Context;
import android.util.SparseArray;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
 * Created by smyhvae on 2015/5/4.
 */
public class ViewHolder {

 private SparseArray<View> mViews;
 private int mPosition;
 private View mConvertView;

 public ViewHolder(Context context, ViewGroup parent, int layoutId, int position) {
 this.mPosition = position;
 this.mViews = new SparseArray<View>();

 mConvertView = LayoutInflater.from(context).inflate(layoutId, parent, false);

 mConvertView.setTag(this);

 }

 public static ViewHolder get(Context context, View convertView, ViewGroup parent, int layoutId, int position) {
 if (convertView == null) {
  return new ViewHolder(context, parent, layoutId, position);
 } else {
  ViewHolder holder = (ViewHolder) convertView.getTag();
  holder.mPosition = position; //即使ViewHolder是復用的，但是position記得更新一下
  return holder;
 }
 }

 /*
 通過viewId獲取控件
 */
 //使用的是泛型T,返回的是View的子類
 public <T extends View> T getView(int viewId) {
 View view = mViews.get(viewId);

 if (view == null) {
  view = mConvertView.findViewById(viewId);
  mViews.put(viewId, view);
 }

 return (T) view;
 }

 public View getConvertView() {
 return mConvertView;
 }

}

（5）【可復用的代碼】ListViewAdapter.java:自定義的通用適配器，繼承自BaseAdapter。以后如果是自定義ListView的adapter，繼承它就行了 

package com.smyhvae.baseadapter.utils;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;

import java.util.List;

/**
 * Created by smyhvae on 2015/5/4.
 * 通用的ListView的BaseAdapter，所有的ListView的自定義adapter都可以繼承這個類哦
 */
public abstract class ListViewAdapter<T> extends BaseAdapter {

 //為了讓子類訪問，于是將屬性設置為protected
 protected Context mContext;
 protected List<T> mDatas;
 protected LayoutInflater mInflater;
 private int layoutId; //不同的ListView的item布局肯能不同，所以要把布局單獨提取出來

 public ListViewAdapter(Context context, List<T> datas, int layoutId) {
 this.mContext = context;
 mInflater = LayoutInflater.from(context);
 this.mDatas = datas;
 this.layoutId = layoutId;
 }

 @Override
 public int getCount() {
 return mDatas.size();
 }

 @Override
 public T getItem(int position) {
 return mDatas.get(position);
 }

 @Override
 public long getItemId(int position) {
 return position;
 }

 @Override
 public View getView(int position, View convertView, ViewGroup parent) {
 //初始化ViewHolder,使用通用的ViewHolder，一行代碼就搞定ViewHolder的初始化咯
 ViewHolder holder = ViewHolder.get(mContext, convertView, parent, layoutId, position);//layoutId就是單個item的布局

 convert(holder, getItem(position));
 return holder.getConvertView(); //這一行的代碼要注意了
 }

 //將convert方法公布出去
 public abstract void convert(ViewHolder holder, T t);

}

（6）ListViewAdapterWithViewHolder.java:繼承自ListViewAdapter 

package com.smyhvae.baseadapter;

import android.content.Context;
import android.widget.TextView;

import com.smyhvae.baseadapter.entities.Bean;
import com.smyhvae.baseadapter.utils.ListViewAdapter;
import com.smyhvae.baseadapter.utils.ViewHolder;

import java.util.List;

/**
 * Created by smyhvae on 2015/5/4.
 */
public class ListViewAdapterWithViewHolder extends ListViewAdapter<Bean> {

 //MyAdapter需要一個Context，通過Context獲得Layout.inflater，然后通過inflater加載item的布局
 public ListViewAdapterWithViewHolder(Context context, List<Bean> datas) {
 super(context, datas, R.layout.item_listview);
 }

 @Override
 public void convert(ViewHolder holder, Bean bean) {

 ((TextView) holder.getView(R.id.titleTv)).setText(bean.getTitle());
 ((TextView) holder.getView(R.id.descTv)).setText(bean.getDesc());
 ((TextView) holder.getView(R.id.timeTv)).setText(bean.getTime());
 ((TextView) holder.getView(R.id.phoneTv)).setText(bean.getPhone());

/*
 TextView tv = holder.getView(R.id.titleTv);
 tv.setText(...);

 ImageView view = getView(viewId);
 Imageloader.getInstance().loadImag(view.url);
*/
 }
}

（7）MainActivity.java: 

package com.smyhvae.baseadapter;

import android.app.Activity;
import android.os.Bundle;
import android.widget.ListView;

import com.smyhvae.baseadapter.entities.Bean;

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

public class MainActivity extends Activity {

 private ListView listView;
 private List<Bean> mDatas;

 private ListViewAdapterWithViewHolder listViewAdapterWithViewHolder;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);

 initView();
 initData();
 }


 //方法：初始化View
 private void initView() {
 listView = (ListView) findViewById(R.id.listView);
 }

 //方法；初始化Data
 private void initData() {
 mDatas = new ArrayList<Bean>();

 //將數(shù)據(jù)裝到集合中去
 Bean bean = new Bean("Android新技能1", "Android為ListView和GridView打造萬能適配器", "2015-05-04", "10086");
 mDatas.add(bean);

 bean = new Bean("Android新技能2", "Android為ListView和GridView打造萬能適配器", "2015-05-04", "10086");
 mDatas.add(bean);

 bean = new Bean("Android新技能3", "Android為ListView和GridView打造萬能適配器", "2015-05-04", "10086");
 mDatas.add(bean);

 bean = new Bean("Android新技能4", "Android為ListView和GridView打造萬能適配器", "2015-05-04", "10086");
 mDatas.add(bean);

 //為數(shù)據(jù)綁定適配器
 listViewAdapterWithViewHolder = new ListViewAdapterWithViewHolder(this, mDatas);

 listView.setAdapter(listViewAdapterWithViewHolder);

 }
}

運行效果：

 

這樣的話，以后每寫個ListView，就這么做：直接導入ViewHolder.java和ListViewAdapter，然后寫一個自定義adapter繼承自ListViewAdapter就行了。 

【工程文件】2015-05-04-BaseAdapter的封裝.rar

三、常見問題： 

1、item控件搶占焦點： 

假設item里有一個checkbox，那運行程序之后，發(fā)現(xiàn)只有checkBox能被點擊，而item中的其他位置不能被點擊(包括點擊整個item也沒有反應)，這是由于checkbox搶占了整個item的焦點。辦法是:： 

辦法1：為該checkBox設置屬性：android:focusable = "false"
辦法2：為該item設置屬性：android:descendantFocusability = "blocksDescendants" 

不讓這個item的焦點從上往下傳。 

2、ListView復用導致內(nèi)容錯亂。

以上就是本文的全部內(nèi)容，希望對大家的學習有所幫助，也希望大家多多支持腳本之家。

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