ListView动态加载数据模板（使用代码布局）
对于做Android应用程序来说，ListView一定用得非常多，经常解析xml文件然后在ListView中显示，往往我们需要让它动态地加载内容，也就是不一次性地加载完成，对于手机来说，这点很重要！
笔者之前也是弄的不明白，用的时候直接在网上找代码，复制粘贴，再修改一下就是自己的了，笔者的这个小Demo灵感来自于新浪或者腾讯微博手机客户端，比如第一页加载十条Item，当翻到最后一个Item的时候，会出来一个Button，当点击Button的时候就会继续加载更多的，当然如果不点，就不会加载的，节约用户流量，先看效果图
OK，如果觉得满意的话就继续看下面的代码吧，笔者这里没有用到main.xml文件，全部在java文件中定义的，如果理解了的话自己可以在xml文件里面写布局
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中加载数据
private final LayoutParams mLayoutParams = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.WRAP_CONTENT,
LinearLayout.LayoutParams.WRAP_CONTENT);
int scrollState;// 全局变量，用来记录ScrollView的滚动状态，1表示开始滚动，2表示正在滚动，0表示滚动停止
int visibleItemCount;// 当前可见页面中的Item总数
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
/**
* "加载项"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);
/*
* 当点击按钮的时候显示这个View，此View使用水平方式布局，左边是一个进度条，右边是文本，默认设为不可见
*/
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);// 为布局添加进度条
TextView mTipContent = new TextView(this);
mTipContent.setText("加载中...");
mProgressLoadLayout.addView(mTipContent, mLayoutParams);// 为布局添加文本
mProgressLoadLayout.setVisibility(View.GONE);// 默认设为不可见，注意View.GONE和View.INVISIBLE的区别
mLoadLayout.addView(mProgressLoadLayout);// 把之前的布局以View对象添加进来
final Button button = new Button(this);
button.setText("加载更多");
// 添加按钮
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) {
// 当点击时把带进度条的Layout设为可见，把Button设为不可见
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);
// 获取数据成功时把Layout设为不可见，把Button设为可见
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;
}
}
}
