Android—万能ListView适配器
吴泽乐
8年前
<p>ListView是开发中最常用的控件了，但是总是会写重复的代码，浪费时间又没有意义。</p> <p>最近参考一些资料，发现一个万能ListView适配器，代码量少，节省时间，总结一下分享给大家。</p> <p>首先有一个自定义的Adapter继承于BaseAdapter，下面是自定义的Adapter，精华在getView()方法中</p> <pre> <code class="language-java">package com.example.mylistview.util; import java.util.List; import android.content.Context; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; public abstract class CommonAdapter<T> extends BaseAdapter { /** * 上下文 */ private Context mContext; /** * 实体类集合 */ private List<T> mDatas; private LayoutInflater mInflater; /** * 控件id */ private int mlayoutId; public CommonAdapter(Context context, List<T> datas, int layoutId) { this.mContext = context; this.mDatas = datas; this.mlayoutId = layoutId; mInflater = LayoutInflater.from(context); } @Override public int getCount() { // TODO Auto-generated method stub return mDatas.size(); } @Override public T getItem(int arg0) { // TODO Auto-generated method stub return mDatas.get(arg0); } @Override public long getItemId(int arg0) { // TODO Auto-generated method stub return arg0; } @Override public View getView(int arg0, View arg1, ViewGroup arg2) { // TODO Auto-generated method stub ViewHolder holder = ViewHolder.get(mContext, arg1, arg2, mlayoutId, arg0); convert(holder, getItem(arg0)); return holder.getConvertView(); } public abstract void convert(ViewHolder holder, T t); } </code></pre> <p>以上的抽象方法convert(ViewHolder holder, T t)；就相当于以前通用代码中的</p> <p>viewHolder.mTextView = (TextView) convertView .findViewById(R.id.id_tv_title);</p> <p>viewHolder.mTextView.setText(Bean.getName());</p> <p>找到控件的id再去设施setText等重复的代码方法中的参数ViewHolder holder, T t holder就相当于以前通用代码中的viewHolder，t就相当于一个自己定义的实体类Bean。</p> <p>以上代码中getView()方法中有一个ViewHolder是需要自己声明的，以下是代码以及详细注释：</p> <pre> <code class="language-java">package com.example.mylistview.util; import android.content.Context; import android.graphics.Bitmap; import android.renderscript.Type; import android.util.SparseArray; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.ImageView; import android.widget.TextView; public class ViewHolder { /** * SparseArray类存放View集合 */ private SparseArray<View> mViews; /** * */ private int mPosition; /** * 布局文件 */ private View mConvertView; public View getConvertView() { return mConvertView; } public ViewHolder(Context context, ViewGroup parent, int layoutId, int position) { this.mViews = new SparseArray<View>(); this.mPosition = position; this.mConvertView = LayoutInflater.from(context).inflate(layoutId, parent, false); this.mConvertView.setTag(this); } /** * 拿到一个ViewHolder对象 * @param context * @param convertView * @param parent * @param layoutId * @param position * @return */ public static ViewHolder get(Context context, View convertView, ViewGroup parent, int layoutId, int position) { if (null == convertView) { return new ViewHolder(context, parent, layoutId, position); } else { ViewHolder holder = (ViewHolder) convertView.getTag(); holder.mPosition = position; return holder; } } /** * 通过控件的id获取对应的控件，如果没有则加入views * @param viewId * @return */ public <T extends View> T getView(int viewId) { View view = mViews.get(viewId); if (null == view) { view = mConvertView.findViewById(viewId); mViews.put(viewId, view); } return (T) view; } /** * 为TextView设置字符串 * @param viewId * @param text * @return */ public ViewHolder setText(int viewId, String text) { TextView tv = getView(viewId); tv.setText(text); return this; } /** * 为ImageView设置图片 * * @param viewId * @param drawableId * @return */ public ViewHolder setImageResource(int viewId, int drawableId) { ImageView view = getView(viewId); view.setImageResource(drawableId); return this; } public int getPosition() { return mPosition; } } </code></pre> <p>再写一个Adapter继承于万能适配器CommonAdapter，还是要写一个自己的Adapter,因为一个项目可能会有多个ListView，但是每个的item元素，布局都会有所不同的，这个泪用来区分不同的ListView与自己所对应的item.这个代码量较少完全可以写成内部类在Activity.java中.</p> <pre> <code class="language-java">package com.example.mylistview.adapter; import java.util.List; import android.content.Context; import android.view.View; import android.view.View.OnClickListener; import android.widget.CheckBox; import com.example.mylistview.R; import com.example.mylistview.domain.Bean; import com.example.mylistview.util.CommonAdapter; import com.example.mylistview.util.ViewHolder; public class MyAdapter extends CommonAdapter<Bean> { public MyAdapter(Context context, List<Bean> datas, int layoutId) { super(context, datas, layoutId); // TODO Auto-generated constructor stub } @Override public void convert(ViewHolder holder, final Bean bean) { // TODO Auto-generated method stub holder.setText(R.id.tv_title, bean.getTitle()) .setText(R.id.tv_desc, bean.getDesc()) .setText(R.id.tv_time, bean.getTime()) .setText(R.id.tv_phone, bean.getPhone()); /** * 防止CheckBox混乱 */ final CheckBox cBox = (CheckBox)(holder.getView(R.id.cb)); if (cBox != null) { cBox.setChecked(bean.isChecked()); cBox.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { bean.setChecked(cBox.isChecked()); } }); } } } </code></pre> <p>优化之后用适配器的时候就简单多了下面是实体类,item和MainActivity.java中的代码：</p> <p>实体类：</p> <pre> <code class="language-java">package com.example.mylistview.domain; public class Bean { private String title; private String desc; private String time; private String phone; private boolean isChecked; public boolean isChecked() { return isChecked; } public void setChecked(boolean isChecked) { this.isChecked = isChecked; } /** * @param title * @param desc * @param time * @param phone */ 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; } } </code></pre> <p>MainActivity.java：</p> <p>重点代码：</p> <pre> <code class="language-java">参数有上下文，集合，和自己对应的item就可以了</code></pre> <pre> <code class="language-java"> adapter = new MyAdapter(this, mDatas, R.layout.item); </code></pre> <pre> <code class="language-java">package com.example.mylistview.ui; import java.util.ArrayList; import java.util.List; import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.view.View; import android.widget.AdapterView; import android.widget.AdapterView.OnItemClickListener; import android.widget.ListView; import com.example.mylistview.R; import com.example.mylistview.adapter.MyAdapter; import com.example.mylistview.domain.Bean; public class MainActivity extends Activity { private ListView listView; private List<Bean> mDatas; /** * 适配器 */ private MyAdapter adapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initView(); initData(); listener(); } private void listener() { // TODO Auto-generated method stub listView.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) { // TODO Auto-generated method stub startActivity(new Intent(MainActivity.this, SecondActivity.class)); } }); } private void initData() { // TODO Auto-generated method stub mDatas = new ArrayList<Bean>(); Bean bean = new Bean("Android新技能 Get", "Android-打造万能的ListView和GridView适配器", "2015-08-05", "10086"); mDatas.add(bean); bean = new Bean("捡到权志龙一个", "在星巴克捡到权志龙一个", "2015-08-06", "10086"); mDatas.add(bean); bean = new Bean("GetTOP一个", "在韩国首尔捡到TOP一个", "2015-08-07", "10086"); mDatas.add(bean); adapter = new MyAdapter(this, mDatas, R.layout.item); listView.setAdapter(adapter); } private void initView() { // TODO Auto-generated method stub listView = (ListView) findViewById(R.id.listView); } } </code></pre> <p>item布局：</p> <pre> <code class="language-java"><?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="wrap_content" android:padding="10dp" > <CheckBox android:focusable="false" android:id="@+id/cb" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentRight="true" android:layout_centerInParent="true" /> <TextView android:id="@+id/tv_title" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginTop="10dp" android:singleLine="true" android:text="Android新技能 Get" /> <TextView android:id="@+id/tv_desc" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_below="@id/tv_title" android:layout_marginTop="10dp" android:layout_toLeftOf="@id/cb" android:maxLines="2" android:text="Android-打造万能的ListView和GridView适配器" android:textColor="#898989" /> <TextView android:id="@+id/tv_time" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@id/tv_desc" android:layout_marginTop="10dp" android:text="2015-08-05" android:textColor="#898989" android:textSize="12sp" /> <TextView android:id="@+id/tv_phone" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentRight="true" android:layout_below="@id/tv_desc" android:layout_marginTop="10dp" android:background="#20793D" android:maxLines="1" android:text="10086" android:padding="4dp" android:textColor="#FFF" /> </RelativeLayout> </code></pre> <p>效果图：</p> <p><img src="https://simg.open-open.com/show/89593689838c5efe45bb4d7ce3098f3e.png"></p> <p>用这个去适配另一个不同的布局：</p> <p>新布局的Adapter一样继承自己的万能adapter:CommonAdapter</p> <pre> <code class="language-java">package com.example.mylistview.adapter; import java.util.List; import java.util.Map; import android.content.Context; import com.example.mylistview.R; import com.example.mylistview.util.CommonAdapter; import com.example.mylistview.util.ViewHolder; public class SecondAdapter extends CommonAdapter<Map<String, String>> { public SecondAdapter(Context context, List<Map<String, String>> datas, int layoutId) { super(context, datas, layoutId); // TODO Auto-generated constructor stub } @Override public void convert(ViewHolder holder, Map<String, String> t) { // TODO Auto-generated method stub holder.setText(R.id.tv_item2values, t.get("values")); } } </code></pre> <p>Activity.java代码：</p> <pre> <code class="language-java">package com.example.mylistview.ui; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import android.app.Activity; import android.os.Bundle; import android.widget.ListView; import com.example.mylistview.R; import com.example.mylistview.adapter.MyAdapter; import com.example.mylistview.adapter.SecondAdapter; public class SecondActivity extends Activity { private ListView listView_second; private SecondAdapter secondAdapter; private List<Map<String, String>> lists = new ArrayList<Map<String, String>>(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_second); initView(); initData(); } private void initData() { // TODO Auto-generated method stub for (int i = 0; i < 4; i++) { Map map = new HashMap<String, String>(); map.put("values", "条目" + i); lists.add(map); } secondAdapter = new SecondAdapter(this, lists, R.layout.item2); listView_second.setAdapter(secondAdapter); } private void initView() { // TODO Auto-generated method stub listView_second = (ListView) findViewById(R.id.listView_second); } } </code></pre> <p>item：</p> <pre> <code class="language-java"><?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" > <TextView android:id="@+id/tv_item2values" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center" android:text="ffffff" android:layout_margin="16dp" android:gravity="center" /> </LinearLayout> </code></pre> <p>效果图：</p> <p><img src="https://simg.open-open.com/show/2d305cbee087d7db89acb28647428ba6.png"></p> <p>备忘，希望能给大家带来帮助。</p> <p> </p> <p>来自：http://www.cnblogs.com/yunfang/p/5777014.html</p> <p> </p> <p><span style="background:rgb(189, 8, 28) url("data:image/svg+xml; 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