ListView是在程序开发中经常要用到。在开发之中被用来做列表的设计实现。根据需求的列表中可能有很多数据，数据加载中原始的方法

1.一次全部加载数据，这肯定很耗内存，也影响性能，更好的方法

2.加载页面显示的数据，更优化的方法

3.使用复用技术，加载页面的数据。

方法一的实现：在布局文件中加入视图

布局文件activity_main.xml

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="fill_parent"

android:layout_height="fill_parent" >

<LinearLayout

android:id="@+id/linearlayout"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:orientation="vertical" >

</LinearLayout>

</ScrollView>

主程序MainActivity.java

public class MainActivity extends ActionBarActivity {

private LinearLayout layout ;

private TextView textView;

private List<Person> list;

private ImageView  p_w_picpathView;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

layout = (LinearLayout)findViewById(R.id.linearlayout);

list = addPerson();

//界面中显示多条数据

for(int i = 0  ; i< 1000; i++){

textView = new TextView(this);

p_w_picpathView = new ImageView(this);

p_w_picpathView.setBackgroundResource(R.drawable.ic_launcher);

textView.setTextColor(Color.BLUE);

textView.setText(list.get(i).toString());

//    在LinearLayout中加入View

layout.addView(p_w_picpathView);

layout.addView(textView);

}

}

private List<Person> addPerson() {

List<Person> list1 = new ArrayList<Person>();

Person person;

for(int i = 0 ; i < 100000 ; i++){

person = new Person("hhh", "zhangwwww", i);

list1.add(person);

}

return list1;

}

}

这个是简单列表简单的实现，Person类是个学生类包括name,info,age,三个字段。自定义了toString()方法，用于显示学生的姓名，信息和年龄。

在测试中，当把循环次数增到很大的时候，不能全部加载出所有的项，超出的不会显示。性能是最低的。

方法二：在布局中加入view性能很低，我们用ListView控件实现系统给BaseAdapter，SimpleAdapter，ArrayAdapter等等。实现性能的优化。它是在通过页面显示的个数，调用getView方法多少次来绘制界面，滑动的时候在重绘。

布局文件activity_main.xml

<LinearLayout 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:orientation="vertical"

>

<ListView

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:id="@+id/list"

/>

</LinearLayout>

主程序MainActivity.java

public class MainActivity extends ActionBarActivity {

private ListView listView;

MyAdapter myAdapter;

private List<Person> list;

Button button;

private int pressedId = -1;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

listView = (ListView)findViewById(R.id.list);

button = (Button)findViewById(R.id.button);

list = getListData();

myAdapter = new MyAdapter(this,list);

listView.setAdapter(myAdapter);

}

private List<Person> getListData() {

List<Person> list1  = new ArrayList<Person>();

Person person;

for(int i = 0 ; i < 100 ; i++){

person = new Person("hhhh","ssss",i);

list1.add(person);

}

return list1;

}

}

   MyAdapte是继承BaseAdapter的类，重写public View getView(int arg0, View arg1, ViewGroup arg2) 方法。在这个方法中设置ListView控件中每行要显示的数据。简单的实现：

@Override

public View getView(int arg0, View arg1, ViewGroup arg2) {

//布局文件LinearLayout的id

linear = new LinearLayout(context);

//图片视图的ID

p_w_picpathView = new ImageView(context);

p_w_picpathView.setBackgroundResource(R.drawable.ic_launcher);

//加入到布局中

linear.addView(p_w_picpathView);

textView = new TextView(context);

textView.setTextColor(Color.BLUE);

textView.setText(person.get(arg0).toString());

linear.addView(textView);

//返回视图

return linear;

}

方法三：是在方法二的基础上改进。加入了item布局文件，独立控件ID的获取，判断视图是否在内存中存在。

item布局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:orientation="horizontal"

android:descendantFocusability="blocksDescendants">

<ImageView

android:id="@+id/imgView_1"

android:layout_width="wrap_content"

android:layout_height="wrap_content" />

<TextView android:id="@+id/textViewName_1"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

/>

<TextView android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:id="@+id/textViewInfo_1"></TextView>

<Button

android:id="@+id/load_1"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:background="@drawable/selector_bt_load"

></Button>

</LinearLayout>

ListView布局：

<LinearLayout 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="com.feiliu.fllistview_2.MainActivity$PlaceholderFragment" >

<ListView

android:id="@+id/listView"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

></ListView>

</LinearLayout>

在MyAdapter中加入独立获取控件的ID的方法.

//view的声明在类的成员变量中声明

public void getViewId(){

imgView_1 = (ImageView) convertView.findViewById(R.id.imgView_1);

textViewName_1 = (TextView) convertView.findViewById(R.id.textViewName_1);

textViewInfo_1 = (TextView) convertView.findViewById(R.id.textViewInfo_1);

load_1 = (Button)convertView.findViewById(R.id.load_1);

}

在MyAdapter构造方法中调用一次，接下来是重写getView(int arg0, View arg1, ViewGroup arg2)方法。

protected View getView(int position, View convertView) {

//convertView是每一项的视图，判断是否为空，不为空就不重加载

if (convertView == null) {

convertView = mLayoutInflater.inflate(getResourceId(), null);

}

imgView_1.setBackgroundResource((Integer)arrayList.get(position).get("imgView"));

textViewName_1.setText((String)arrayList.get(position).get("imgName"));

textViewInfo_1.setText(arrayList.get(position).get("imgInfo").toString());

load_1.setText("下载");

return convertView;

}

主程序MainActivity.java

public class MainActivity extends ActionBarActivity {

private ArrayList<HashMap<String, Object>> arrayList;

private ListViewAdapter<HashMap<String, Object>> listViewAdapter;

private ListView listView;

String[] imgNames = new String[] { "刀塔传奇", "群星斗地主", "二战前线", "剑圣传奇首发",

"消灭星星", "黄金矿工3", "放开那三国", "3D捕鱼达人", "全民打飞机",

};

String[] imgInfos = new String[] { "互动网游|128.1M", "×××桌游|5.5M", "飞行射击|5.3M",

"互动网游|90.1M", "休闲趣味|3.6M", "休闲趣味|7.5M", "互动网游|95.0M", "休闲趣味|26.6M",

"飞行射击|5.4M", " };

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.listview);

arrayList = getData();

listView = (ListView) findViewById(R.id.listView);

listViewAdapter = new ListViewAdapter<HashMap<String, Object>>(this, this.arrayList);

listView.setAdapter(listViewAdapter);

}

private ArrayList<HashMap<String, Object>> getData() {

ArrayList<HashMap<String, Object>> arrayList = new ArrayList<HashMap<String, Object>>();

HashMap<String, Object> map;

for (int j = 0; j < 9; j++) {

map = new HashMap<String, Object>();

map.put("imgView", R.drawable.ic_launcher);

map.put("imgName", imgNames[j * 3]);

map.put("imgInfo", imgInfos[j * 3]);

map.put("imgView1", R.drawable.ic_launcher);

map.put("imgName1", imgNames[j * 3 + 1]);

map.put("imgInfo1", imgInfos[j * 3 + 1]);

map.put("imgView2", R.drawable.ic_launcher);

map.put("imgName2", imgNames[j * 3 + 2]);

map.put("imgInfo2", imgInfos[j * 3 + 2]);

arrayList.add(map);

}

return arrayList;

}

}

ListView在开发中占的比重还是很重的。本人也是初学，有什么不当的请谅解。