對于做Android應(yīng)用程序來說，ListView一定用得非常多，經(jīng)常解析xml文件然后在ListView中顯示，往往我們需要讓它動態(tài)地加載內(nèi)容，也就是不一次性地加載完成，對于手機來說，這點很重要！

　　筆者之前也是弄的不明白，用的時候直接在網(wǎng)上找代碼，復(fù)制粘貼，再修改一下就是自己的了，筆者的這個小Demo靈感來自于新浪或者騰訊微博手機客戶端，比如第一頁加載十條Item，當(dāng)翻到最后一個Item的時候，會出來一個Button，當(dāng)點擊Button的時候就會繼續(xù)加載更多的，當(dāng)然如果不點，就不會加載的，節(jié)約用戶流量，先看效果圖

　　如果覺得滿意的話就繼續(xù)看下面的代碼吧，筆者這里沒有用到main.xml文件，全部在java文件中定義的，如果理解了的話自己可以在xml文件里面寫布局

package com.focus.loading;

import android.app.ListActivity;
import android.os.Bundle;
import android.os.Handler;
import android.view.Gravity;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.TextView;

public class ListViewActivity extends ListActivity implements OnScrollListener {
private LinearLayout mLoadLayout;
private LinearLayout mProgressLoadLayout;
private ListView mListView;
private ListViewAdapter mListViewAdapter = new ListViewAdapter();
private int mLastItem = 0;
private int mCount = 41;
private final Handler mHandler = new Handler();// 在Handler中加載數(shù)據(jù)
private final LayoutParams mLayoutParams = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.WRAP_CONTENT,
LinearLayout.LayoutParams.WRAP_CONTENT);
int scrollState;// 全局變量，用來記錄ScrollView的滾動狀態(tài)，1表示開始滾動，2表示正在滾動，0表示滾動停止
int visibleItemCount;// 當(dāng)前可見頁面中的Item總數(shù)

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
/**
* "加載項"布局，此布局被添加到ListView的Footer中。
*/
mLoadLayout = new LinearLayout(this);
mLoadLayout.setMinimumHeight(30);
mLoadLayout.setGravity(Gravity.CENTER);
mLoadLayout.setOrientation(LinearLayout.VERTICAL);

/*
* 當(dāng)點擊按鈕的時候顯示這個View，此View使用水平方式布局，左邊是一個進度條，右邊是文本，默認設(shè)為不可見
*/
mProgressLoadLayout = new LinearLayout(this);
mProgressLoadLayout.setMinimumHeight(30);
mProgressLoadLayout.setGravity(Gravity.CENTER);
mProgressLoadLayout.setOrientation(LinearLayout.HORIZONTAL);

ProgressBar mProgressBar = new ProgressBar(this);
mProgressBar.setPadding(0, 0, 15, 0);
mProgressLoadLayout.addView(mProgressBar, mLayoutParams);
// 為布局添加進度條

TextView mTipContent = new TextView(this);
mTipContent.setText("加載中...");
mProgressLoadLayout.addView(mTipContent, mLayoutParams);
// 為布局添加文本
mProgressLoadLayout.setVisibility(View.GONE);// 默認設(shè)為不可見，注意View.GONE和View.INVISIBLE的區(qū)別

mLoadLayout.addView(mProgressLoadLayout);
/ 把之前的布局以View對象添加進來
final Button button = new Button(this);
button.setText("加載更多");
// 添加按鈕
mLoadLayout.addView(button, new LayoutParams
(LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT));
button.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
if (mLastItem == mListViewAdapter.count
&& scrollState == OnScrollListener.SCROLL_STATE_IDLE) {
// 當(dāng)點擊時把帶進度條的Layout設(shè)為可見，把Button設(shè)為不可見
mProgressLoadLayout.setVisibility(View.VISIBLE);
button.setVisibility(View.GONE);
if (mListViewAdapter.count <= mCount) {
mHandler.postDelayed(new Runnable() {
@Override
public void run() {
mListViewAdapter.count += 10;
mListViewAdapter.notifyDataSetChanged();
mListView.setSelection(mLastItem
- visibleItemCount + 1);
// 獲取數(shù)據(jù)成功時把Layout設(shè)為不可見，把Button設(shè)為可見
mProgressLoadLayout.setVisibility(View.GONE);
button.setVisibility(View.VISIBLE);
}
}, 2000);
}
}
}
});

mListView = getListView();
mListView.addFooterView(mLoadLayout);
setListAdapter(mListViewAdapter);
mListView.setOnScrollListener(this);
}

@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
this.visibleItemCount = visibleItemCount;
mLastItem = firstVisibleItem + visibleItemCount - 1;
if (mListViewAdapter.count > mCount) {
mListView.removeFooterView(mLoadLayout);
}
}

@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
this.scrollState = scrollState;

}

class ListViewAdapter extends BaseAdapter {
int count = 10;

public int getCount() {
return count;
}

public Object getItem(int position) {
return position;
}

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

public View getView(int position, View view, ViewGroup parent) {
TextView mTextView;
if (view == null) {
mTextView = new TextView(ListViewActivity.this);
} else {
mTextView = (TextView) view;
}
mTextView.setText("Item " + position);
mTextView.setTextSize(20f);
mTextView.setGravity(Gravity.CENTER);
mTextView.setHeight(60);
return mTextView;
}
}
}

基本上的注釋都有，對于里面的幾個int型數(shù)據(jù)，不理解的自己logcat一下