android listView 分批加载

当我们浏览空间到末尾时，数据它会自己加载或者需要我们点击按钮之类的继续加载新的数据。下面我们就介绍如何在ListView中实现数据的分批次加载。

首先创建一个布局文件foot.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="40dp"

    android:orientation="horizontal" >

  <Button    

      android:id="@+id/bt_load"    

      android:layout_width="wrap_content"    

      android:layout_height="match_parent"  

      android:gravity="center_vertical"

      android:text="加载更多数据" /> 

  <ProgressBar

      android:id="@+id/pg"

      android:layout_weight="1"

      android:layout_width="wrap_content"

      android:layout_height="wrap_content"

      android:layout_gravity="center_horizontal"

   

      />

</LinearLayout>

xml文件创建成功后我们来看下代码

public class MainActivity extends Activity {

public static  ListView listView;

AdapterTest adapterTest;

public static   View foot;

private Boolean isBoolean = false;

private Button Btn;

private ProgressBar progressBar;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

foot = getLayoutInflater().inflate(R.layout.list_foot, null);

progressBar = (ProgressBar) foot.findViewById(R.id.pg);

Btn = (Button) foot.findViewById(R.id.bt_load);

//手动加载时需要设置

progressBar.setVisibility(View.GONE);

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

adapterTest = new AdapterTest(this);

listView.addFooterView(foot);

listView.setAdapter(adapterTest);

//手动加载时设置的监听

Btn.setOnClickListener(new OnClickListener() {

@Override

public void onClick(View v) {

progressBar.setVisibility(View.VISIBLE);

adapterTest.handler.postDelayed(new Runnable() {

@Override

public void run() {

adapterTest.handler.sendEmptyMessage(0);

progressBar.setVisibility(View.GONE);

}

}, 2000);

}

});

 

listView.setOnScrollListener(new OnScrollListener() {

@Override

public void onScrollStateChanged(AbsListView view, int scrollState) {

}

@Override

public void onScroll(AbsListView view, int firstVisibleItem,

int visibleItemCount, int totalItemCount) {

Log.d("onScroll", (listView.getCount() - 1)

+ "firstVisibleItem="

+ (firstVisibleItem + visibleItemCount - 1));

//实现自动加载

/* if (listView.getCount() - 1 == (firstVisibleItem

+ visibleItemCount - 1)) {

if (isBoolean) {

adapterTest.handler.postDelayed(new Runnable() {

@Override

public void run() {

adapterTest.handler.sendEmptyMessage(0);

}

}, 2000);

isBoolean = false;

return;

}

} else {

isBoolean = true;

}*/

}

});

}

}

适配器AdapterTest.java文件：

public class AdapterTest extends BaseAdapter {

private ArrayList<String> strings;

private Context mContext;

//设置ListView加载最大条目

private int max = 55;

public AdapterTest(Context context) {

strings = new ArrayList<String>();

this.mContext = context;

setStrigs(0, 20);

}

private void setStrigs(int start, int length) {

if (start < max - 1) {

if (start + length <= max) {

for (int i = start; i < start + length; i++) {

strings.add("项目" + (i + 1));

}

this.notifyDataSetChanged();

} else if (start + length > max) {

for (int i = start; i <max; i++) {

strings.add("项目" + (i + 1));

}

this.notifyDataSetChanged();

MainActivity.listView.removeFooterView(MainActivity.foot);

}

}else if (start == max ) {

Toast.makeText(mContext, "无数据啦", 1).show();

}

}

@Override

public int getCount() {

// TODO Auto-generated method stub

return strings.size();

}

@Override

public Object getItem(int position) {

// TODO Auto-generated method stub

return null;

}

@Override

public long getItemId(int position) {

// TODO Auto-generated method stub

return 0;

}

@Override

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

TextView view = new TextView(mContext);

view.setTextSize(20);

view.setText(strings.get(position));

return view;

}

public Handler handler = new Handler() {

public void handleMessage(android.os.Message msg) {

setStrigs(strings.size(), 10);

};

};

}