代码中加载ListView

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package com.example.listviewactivity;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 MainActivity 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(MainActivity.this);            } else {                mTextView = (TextView) view;            }            mTextView.setText("Item " + position);            mTextView.setTextSize(20f);            mTextView.setGravity(Gravity.CENTER);            mTextView.setHeight(60);            return mTextView;        }    }}
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