challenge（五）内容-ListView使用

￡神魔★判官ぃ 2022-08-21 02:18 150阅读 0赞

重写ListView的adapter方法：

public class ListAdapter extends BaseAdapter{
    	
    	public class ViewHolder{
    		public ImageView head;
    		public TextView title;
    		public TextView info;
    	}
    
    	private List<Map<String, Object>> datas;
    	private LayoutInflater inflater;
    	
    	public ListAdapter(List<Map<String, Object>> datas, Context context){
    		this.datas = datas;
    		this.inflater = LayoutInflater.from(context);
    	}
    
    	@Override
    	public int getCount() {
    		//在此适配器中所代表的数据集中的条目数
    		return datas.size();
    	}
    
    	@Override
    	public Object getItem(int position) {
    		//获取数据集中与指定索引对应的数据项
    		return position;
    	}
    
    	@Override
    	public long getItemId(int position) {
    		//获取在列表中与指定索引对应的行id
    		return position;
    	}
    
    	@Override
    	public View getView(int position, View convertView, ViewGroup parent) {
    		ViewHolder viewHolder = null;
    		if (convertView == null) {
    			viewHolder = new ViewHolder();
    			convertView = inflater.inflate(R.layout.list_item, null);
    			viewHolder.head  = (ImageView) convertView.findViewById(R.id.head);
    			viewHolder.title = (TextView) convertView.findViewById(R.id.title);
    			viewHolder.info  = (TextView) convertView.findViewById(R.id.info);
    			convertView.setTag(viewHolder);
    		} else {
    			viewHolder = (ViewHolder) convertView.getTag();
    		}
    		viewHolder.head.setBackgroundResource((Integer) datas.get(position).get("head"));
    		viewHolder.title.setText((CharSequence) datas.get(position).get("title"));
    		// 加粗，这种方式才能将中文加粗
    		TextPaint paint = viewHolder.title.getPaint();
    		paint.setFakeBoldText(true);
    		viewHolder.info.setText((CharSequence) datas.get(position).get("info"));
    		
    		return convertView;
    	}
    }

主activity使用ListAdapter：

// 数据
    		List<Map<String, Object>> datas = getDatas();
    		ListAdapter listAdapter = new ListAdapter(datas, MainActivity.this);
    		listView = (ListView) findViewById(R.id.list_view);
    		listView.setAdapter(listAdapter);

构造数据，后续从网络获取数据：

/**
    	 * 假设数据
    	 * @return
    	 */
    	public List<Map<String, Object>> getDatas(){
    		List<Map<String, Object>> datas = new ArrayList<Map<String,Object>>();
    		
    		for (int i = 0; i < 10; i++) {
    			Map<String, Object> map = new HashMap<String, Object>();
    			map.put("head", R.drawable.ic_launcher);
    			map.put("title", "这是我的挑战项目");
    			map.put("info", "这是我的挑战项目的描述，谢谢大家观赏！");
    			datas.add(map);
    		}
    		
    		return datas;
    	}

Item布局：

<?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="match_parent"
        	android:layout_margin="10dip"
        	android:orientation="horizontal"
            >
            
            <RelativeLayout 
            android:layout_width="0dip"
        	android:layout_height="match_parent"
        	android:layout_weight="1"
            >
        
    	    <ImageView 
    	        android:id="@+id/head"
    	        android:layout_width="match_parent"
    	    	android:layout_height="match_parent"
    	    	android:background="@drawable/ic_launcher"
    	        />
    	    </RelativeLayout>
    	    
             <LinearLayout 
    	        android:layout_width="0dip"
    	    	android:layout_height="match_parent"
    	    	android:layout_weight="3"
    	    	android:orientation="vertical"
    	        >
    	    
    		    <TextView 
    		        android:id="@+id/title"
    		        android:layout_width="match_parent"
    		    	android:layout_height="0dip"
    		    	android:layout_weight="1"
    		    	android:text="标题"
    		        />
    		    
    		    <TextView 
    		        android:id="@+id/info"
    		        android:layout_width="match_parent"
    		    	android:layout_height="0dip"
    		    	android:layout_weight="2"
    		    	android:text="介绍信息"
    		        />
    	     </LinearLayout>
        </LinearLayout>
    
    </LinearLayout>

效果图（720\*1280分辨率）：

![Center][]

效果图（1080\*1920分辨率）：

![Center 1][]

我们看到两个不同分辨率下显示会有所偏差，下章我们解决分辨率兼容问题。

[Center]: /images/20220731/3ff10f6d63e54e1d9c0f2eacc4d6058e.png
[Center 1]: /images/20220731/3f5dd56258214ed38d0f17655ee69970.png