测试 ListView 的效率 1 [原创]

测试 ListView 的效率

为了亲自测试 ListView 的使用效率, 做如下测试:

package cn.powerise.test01;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import android.app.ListActivity;
import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

/**
 * 测试 ListView 的效率
 * @author R9(QQ:34351088)
 */
public class List_Efficiency_1 extends ListActivity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        List<HashMap<String, Object>> data = null;
        MyAdapter adapter = null;

        data = getData();

        adapter = new MyAdapter(this, data, R.layout.efficiency_item);
        setListAdapter(adapter);
    }

    private List<HashMap<String, Object>> getData() {
        List<HashMap<String, Object>> data = null;
        HashMap<String, Object> item = null;

        data = new ArrayList<HashMap<String, Object>>();
        for (int i = 10; i < 40; i++) {
            item = new HashMap<String, Object>();
            item.put("image", R.drawable.icon);
            item.put("id", i);
            item.put("name", "Name" + i);
            item.put("age", "Age" + i);
            item.put("phone", "139073100" + i);
            data.add(item);
        }

        return data;
    }

    class MyAdapter extends BaseAdapter {

        private List<HashMap<String, Object>> mData;
        private LayoutInflater mInflater;
        private int mResource;

        public MyAdapter(Context context, List<HashMap<String, Object>> data, int resource) {
            mData = data;
            mResource = resource;
            mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {

            View view = null;

            view = mInflater.inflate(mResource, null);
            /**
             * 测试效率(普通情况)
             */
            System.out.println("-->" + position + " :: ");

            ImageView imageView = (ImageView) view.findViewById(R.id.iv_image);
            TextView idTextView = (TextView) view.findViewById(R.id.txt_id);
            TextView nameTextView = (TextView) view.findViewById(R.id.txt_name);
            TextView ageTextView = (TextView) view.findViewById(R.id.txt_age);
            TextView phoneTextView = (TextView) view.findViewById(R.id.txt_phone);

            HashMap<String, Object> dataSet = mData.get(position);

            imageView.setImageResource(R.drawable.icon);
            idTextView.setText(dataSet.get("id").toString());
            nameTextView.setText(dataSet.get("name").toString());
            ageTextView.setText(dataSet.get("age").toString());
            phoneTextView.setText(dataSet.get("phone").toString());

            return view;
        }

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

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

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

    }
}

item 的布局文件: efficiency_item.xml

<?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:gravity="center_vertical"
    android:orientation="horizontal" >

    <ImageView
        android:id="@+id/iv_image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >

        <TextView
            android:id="@+id/txt_id"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />

        <TextView
            android:id="@+id/txt_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />

        <TextView
            android:id="@+id/txt_age"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />

        <TextView
            android:id="@+id/txt_phone"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />
    </LinearLayout>

</LinearLayout>

如下图所示:

在控制台打印输出:

上面是初始状态情况, 下面, 不停的往下, 或往上拖拉 ListView. 控制台打印出如下所示:

也就是说, 每一个 item 进入可视区域后, 都会调用 getView 方法, 并且会重新构造一个 view. 这样的写法最直接, 直观, 但是效率最低, 因为每次都要重新构造一次.