ListView实现多种item布局的方法和注意事项

这篇文章的效果也是大家常见的，各种通讯应用的对话列表都是这种方式，像微信、whatsapp、易信、米聊等。我们这篇文章也权当为回忆，形成简单的笔记。这篇文章参考了2009年Google IO中的《TurboChargeYourUI-How to make your AndroidUI fast and efficient》和2010年Google IO中的《The World of List View》。像2009年Google IO的资料还是很前沿的，那会Android开发资料很少，最重要的就是参考google发布的各种资料。

    在《TurboChargeYourUI-How to make your AndroidUI fast and efficient》介绍了怎样提高listview的性能，优化了listview的加载速度。这里的item使用的是单一布局，能够实现view的重用和回收，那么多种布局文件的怎么办呢，如果再使用上面的方法，view的重用会出现问题，Android使用的BaseAdapter提供了解决多种布局文件的重用方法。

1）重写 getViewTypeCount() – 该方法返回多少个不同的布局

2）重写 getItemViewType(int) – 根据position返回相应的Item

/**
 * 比原来的多了getItemViewType和getViewTypeCount这两个方法，
 *
 * */
public class ChatAdapter extends BaseAdapter {

    public static final String KEY = "key";
    public static final String VALUE = "value";

    public static final int VALUE_TIME_TIP = 0;// 7种不同的布局
    public static final int VALUE_LEFT_TEXT = 1;
    public static final int VALUE_LEFT_IMAGE = 2;
    public static final int VALUE_LEFT_AUDIO = 3;
    public static final int VALUE_RIGHT_TEXT = 4;
    public static final int VALUE_RIGHT_IMAGE = 5;
    public static final int VALUE_RIGHT_AUDIO = 6;
    private LayoutInflater mInflater;

    private List<Message> myList;

    public ChatAdapter(Context context, List<Message> myList) {
        this.myList = myList;

        mInflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public int getCount() {
        return myList.size();
    }

    @Override
    public Object getItem(int arg0) {
        return myList.get(arg0);
    }

    @Override
    public long getItemId(int arg0) {
        return arg0;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup arg2) {

        Message msg = myList.get(position);
        int type = getItemViewType(position);
        ViewHolderTime holderTime = null;
        ViewHolderRightText holderRightText = null;
        ViewHolderRightImg holderRightImg = null;
        ViewHolderRightAudio holderRightAudio = null;
        ViewHolderLeftText holderLeftText = null;
        ViewHolderLeftImg holderLeftImg = null;
        ViewHolderLeftAudio holderLeftAudio = null;

        if (convertView == null) {
            switch (type) {
            case VALUE_TIME_TIP:
                holderTime = new ViewHolderTime();
                convertView = mInflater.inflate(R.layout.list_item_time_tip,
                        null);
                holderTime.tvTimeTip = (TextView) convertView
                        .findViewById(R.id.tv_time_tip);
                holderTime.tvTimeTip.setText(msg.getValue());
                convertView.setTag(holderTime);
                break;
            // 左边
            case VALUE_LEFT_TEXT:
                holderLeftText = new ViewHolderLeftText();
                convertView = mInflater.inflate(R.layout.list_item_left_text,
                        null);
                holderLeftText.ivLeftIcon = (ImageView) convertView
                        .findViewById(R.id.iv_icon);
                holderLeftText.btnLeftText = (Button) convertView
                        .findViewById(R.id.btn_left_text);
                holderLeftText.btnLeftText.setText(msg.getValue());
                convertView.setTag(holderLeftText);
                break;

            case VALUE_LEFT_IMAGE:
                holderLeftImg = new ViewHolderLeftImg();
                convertView = mInflater.inflate(R.layout.list_item_left_iamge,
                        null);
                holderLeftImg.ivLeftIcon = (ImageView) convertView
                        .findViewById(R.id.iv_icon);
                holderLeftImg.ivLeftImage = (ImageView) convertView
                        .findViewById(R.id.iv_left_image);
                holderLeftImg.ivLeftImage.setImageResource(R.drawable.test);
                convertView.setTag(holderLeftImg);
                break;

            case VALUE_LEFT_AUDIO:
                holderLeftAudio = new ViewHolderLeftAudio();
                convertView = mInflater.inflate(R.layout.list_item_left_audio,
                        null);
                holderLeftAudio.ivLeftIcon = (ImageView) convertView
                        .findViewById(R.id.iv_icon);
                holderLeftAudio.btnLeftAudio = (Button) convertView
                        .findViewById(R.id.btn_left_audio);
                holderLeftAudio.tvLeftAudioTime = (TextView) convertView
                        .findViewById(R.id.tv_left_audio_time);
                holderLeftAudio.tvLeftAudioTime.setText(msg.getValue());
                convertView.setTag(holderLeftAudio);
                break;
            // 右边
            case VALUE_RIGHT_TEXT:
                holderRightText= new ViewHolderRightText();
                convertView = mInflater.inflate(R.layout.list_item_right_text,
                        null);
                holderRightText.ivRightIcon = (ImageView) convertView
                        .findViewById(R.id.iv_icon);
                holderRightText.btnRightText = (Button) convertView
                        .findViewById(R.id.btn_right_text);
                holderRightText.btnRightText.setText(msg.getValue());
                convertView.setTag(holderRightText);
                break;

            case VALUE_RIGHT_IMAGE:
                holderRightImg= new ViewHolderRightImg();
                convertView = mInflater.inflate(R.layout.list_item_right_iamge,
                        null);
                holderRightImg.ivRightIcon = (ImageView) convertView
                        .findViewById(R.id.iv_icon);
                holderRightImg.ivRightImage = (ImageView) convertView
                        .findViewById(R.id.iv_right_image);
                holderRightImg.ivRightImage.setImageResource(R.drawable.test);
                convertView.setTag(holderRightImg);
                break;

            case VALUE_RIGHT_AUDIO:
                holderRightAudio=new ViewHolderRightAudio();
                convertView = mInflater.inflate(R.layout.list_item_right_audio,
                        null);
                holderRightAudio.ivRightIcon = (ImageView) convertView
                        .findViewById(R.id.iv_icon);
                holderRightAudio.btnRightAudio = (Button) convertView
                        .findViewById(R.id.btn_right_audio);
                holderRightAudio.tvRightAudioTime = (TextView) convertView
                        .findViewById(R.id.tv_right_audio_time);
                holderRightAudio.tvRightAudioTime.setText(msg.getValue());
                convertView.setTag(holderRightAudio);
                break;

            default:
                break;
            }

        } else {
            Log.d("baseAdapter", "Adapter_:"+(convertView == null) );
            switch (type) {
            case VALUE_TIME_TIP:
                holderTime=(ViewHolderTime)convertView.getTag();
                holderTime.tvTimeTip.setText(msg.getValue());
                break;
            case VALUE_LEFT_TEXT:
                holderLeftText=(ViewHolderLeftText)convertView.getTag();
                holderLeftText.btnLeftText.setText(msg.getValue());
                break;
            case VALUE_LEFT_IMAGE:
                holderLeftImg=(ViewHolderLeftImg)convertView.getTag();
                holderLeftImg.ivLeftImage.setImageResource(R.drawable.test);
                break;
            case VALUE_LEFT_AUDIO:
                holderLeftAudio=(ViewHolderLeftAudio)convertView.getTag();
                holderLeftAudio.tvLeftAudioTime.setText(msg.getValue());
                break;
            case VALUE_RIGHT_TEXT:
                holderRightText=(ViewHolderRightText)convertView.getTag();
                holderRightText.btnRightText.setText(msg.getValue());
                break;
            case VALUE_RIGHT_IMAGE:
                holderRightImg=(ViewHolderRightImg)convertView.getTag();
                holderRightImg.ivRightImage.setImageResource(R.drawable.test);
                break;
            case VALUE_RIGHT_AUDIO:
                holderRightAudio=(ViewHolderRightAudio)convertView.getTag();
                holderRightAudio.tvRightAudioTime.setText(msg.getValue());
                break;

            default:
                break;
            }

            //holder = (ViewHolder) convertView.getTag();
        }
        return convertView;
    }

    /**
     * 根据数据源的position返回需要显示的的layout的type
     *
     * type的值必须从0开始
     *
     * */
    @Override
    public int getItemViewType(int position) {

        Message msg = myList.get(position);
        int type = msg.getType();
        Log.e("TYPE:", "" + type);
        return type;
    }

    /**
     * 返回所有的layout的数量
     *
     * */
    @Override
    public int getViewTypeCount() {
        return 7;
    }

    class ViewHolderTime {
        private TextView tvTimeTip;// 时间
    }

    class ViewHolderRightText {
        private ImageView ivRightIcon;// 右边的头像
        private Button btnRightText;// 右边的文本
    }

    class ViewHolderRightImg {
        private ImageView ivRightIcon;// 右边的头像
        private ImageView ivRightImage;// 右边的图像
    }

    class ViewHolderRightAudio {
        private ImageView ivRightIcon;// 右边的头像
        private Button btnRightAudio;// 右边的声音
        private TextView tvRightAudioTime;// 右边的声音时间
    }

    class ViewHolderLeftText {
        private ImageView ivLeftIcon;// 左边的头像
        private Button btnLeftText;// 左边的文本
    }

    class ViewHolderLeftImg {
        private ImageView ivLeftIcon;// 左边的头像
        private ImageView ivLeftImage;// 左边的图像
    }

    class ViewHolderLeftAudio {
        private ImageView ivLeftIcon;// 左边的头像
        private Button btnLeftAudio;// 左边的声音
        private TextView tvLeftAudioTime;// 左边的声音时间
    }

}

分享两张微信、易信的图，你也可以做成这样子。

     

注意：

使用Listview显示多样视图时，用到了getItemViewType和getViewTypeCount，但是我一运行程序就会报数组越界异常，经过查资料发现，getItemViewType的值一定要从0开始，我开始设置的type类型是从1开始的，结果就悲催了，app一直崩溃，报Java.lang.ArrayIndexOutOfBoundsException。最后把type类型改成从0开始就好了，最后注意一点，getViewTypeCount返回值一定要大于等于getItemViewType的个数。