Listview没有优化之前

MainActivity.java

package com.example.listviewdemo4;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

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

public class MainActivity extends Activity {

	ListView listview;
	List<Map<String, Object>> list;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		listview = (ListView) findViewById(R.id.listview);

		// 获取数据
		list = getData();

		listview.setAdapter(new ListViewAdapter(list,MainActivity.this));

	}

	private List<Map<String, Object>> getData() {
		// TODO Auto-generated method stub

		List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();

		Map<String, Object> map = new HashMap<String, Object>();
		map.put("name", "图1");
		map.put("pictrue", R.drawable.tu1);
		list.add(map);

		map = new HashMap<String, Object>();
		map.put("name", "图2");
		map.put("pictrue", R.drawable.tu2);
		list.add(map);
		
		
		map = new HashMap<String, Object>();
		map.put("name", "图3");
		map.put("pictrue", R.drawable.tu3);
		list.add(map);
		
		
		map = new HashMap<String, Object>();
		map.put("name", "图4");
		map.put("pictrue", R.drawable.tu4);
		list.add(map);
		
		return list;
	}

}

ListViewAdapter.java

package com.example.listviewdemo4;

import java.util.List;
import java.util.Map;

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

public class ListViewAdapter extends BaseAdapter{
	
	List<Map<String, Object>> list;
	Context context;
	LayoutInflater layoutInflater;
	ListViewAdapter(List<Map<String, Object>> list,Context context){
		this.list=list;
		this.context=context;
		//使用context上下文获取系统layout_inflater服务
		layoutInflater=(LayoutInflater) context.getSystemService(context.LAYOUT_INFLATER_SERVICE);
		
	}

	@Override
	public int getCount() {
		// TODO Auto-generated method stub
		return list.size();
	}

	@Override
	public Object getItem(int arg0) {
		// TODO Auto-generated method stub
		return list.get(arg0);
	}

	@Override
	public long getItemId(int arg0) {
		// TODO Auto-generated method stub
		return arg0;
	}

	@Override
	public View getView(int position, View contentView, ViewGroup arg2) {
		//layoutInflater 传入list_item会生成一个view
		View view=layoutInflater.inflate(R.layout.list_item, null);
                //在生成的view中寻找控件
		TextView textview=(TextView)view.findViewById(R.id.textview);
                //把控件设置内容
		textview.setText((CharSequence) list.get(position).get("name"));
		
		ImageView imageView=(ImageView)view.findViewById(R.id.imageview);
                //设置图片的资源
		imageView.setImageResource((Integer) list.get(position).get("pictrue"));
		
		return view;
	}

}

配置文件：

 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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />
    
    
    <ListView 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" 
        android:id="@+id/listview"
        ></ListView>
    
    

</RelativeLayout>

 listview_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:orientation="vertical" >
    
    <TextView 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/textview"
        />
    <ImageView 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/imageview"
        />

</LinearLayout>