android编程之代码布局（三）

前两篇介绍了一般常用的布局组件写法，这一次，再来看看其他组件的

一、listview

listview也和大多数组件一样，一般会在这里难住的，就是自定义布局样式的时候。

[java]
view plain
copy

print?

// 创建LinearLayout对象  
LinearLayout mRelativeLayout = new LinearLayout(this);  
mRelativeLayout.setLayoutParams(new LinearLayout.LayoutParams(  
        LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));  
  
//  创建ListView对象  
ListView mListView = new ListView(this);  
mListView.setAdapter(new ListAdapter(this, mVector));  
  
// 添加组件  
mRelativeLayout.addView(mListView, new LayoutParams(  
        LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));  

// 创建LinearLayout对象
LinearLayout mRelativeLayout = new LinearLayout(this);
mRelativeLayout.setLayoutParams(new LinearLayout.LayoutParams(
LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));

//  创建ListView对象
ListView mListView = new ListView(this);
mListView.setAdapter(new ListAdapter(this, mVector));

// 添加组件
mRelativeLayout.addView(mListView, new LayoutParams(
LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));

其中，ListAdapter为继承BaseAdapter的自定义类。

mVector是我们自定义的数据，里面包含了两个名字：小明，小刚。

接下来，我们看看重点的ListAdapter是如何自定义布局的

[java]
view plain
copy

print?

public class ListAdapter extends BaseAdapter {  
    private Vector<String> mVector;  
  
    private Context mContext;  
  
    public ListAdapter(Context mContext, Vector<String> mVector) {  
        this.mContext = mContext;  
        this.mVector = mVector;  
    }  
  
    public Object getItem(int position) {  
        return null;  
    }  
  
    public long getItemId(int position) {  
        return 0;  
    }  
  
    public int getCount() {  
        return mVector.size();  
    }  
  
    class ViewHolder {  
        ImageView head;  
        TextView name;  
    }  
  
    public View getView(int position, View convertView, ViewGroup parent) {  
        ViewHolder holder = null;  
        RelativeLayout rl = null;  
        if (convertView == null) {  
            rl = new RelativeLayout(mContext);  
            rl.setBackgroundDrawable(bitmapDrawable_listitembg);  
  
            // head  
            ImageView head = new ImageView(mContext);  
            head.setId(1);  
              
            RelativeLayout.LayoutParams mLayoutParams = new RelativeLayout.LayoutParams(  
                    64, 64);  
            mLayoutParams.topMargin = 15;  
            mLayoutParams.leftMargin = 10;  
            mLayoutParams.bottomMargin = 15;  
            mLayoutParams.addRule(RelativeLayout.CENTER_VERTICAL);  
            rl.addView(head, mLayoutParams);  
  
            // nickname  
            TextView mTextView = new TextView(mContext);  
            mTextView.setTextSize(20);  
            mTextView.setTextColor(0xff000000);  
            mTextView.setId(2);  
  
            mLayoutParams = new RelativeLayout.LayoutParams(  
                    LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);  
            mLayoutParams.topMargin = 10;  
            mLayoutParams.leftMargin = 10;  
            mLayoutParams.addRule(RelativeLayout.RIGHT_OF, 1);  
            rl.addView(mTextView, mLayoutParams);  
  
              
            holder = new ViewHolder();  
            holder.head = head;  
            holder.name = mTextView;  
            rl.setTag(holder);  
        } else {  
            holder = (ViewHolder) convertView.getTag();  
            rl = (RelativeLayout) convertView;  
        }  
  
        holder.head.setImageDrawable(bitmapDrawable_headimage);  
        holder.name.setText(mVector.elementAt(position));  
  
        return rl;  
    }  
}  

public class ListAdapter extends BaseAdapter {
private Vector<String> mVector;

private Context mContext;

public ListAdapter(Context mContext, Vector<String> mVector) {
this.mContext = mContext;
this.mVector = mVector;
}

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

public long getItemId(int position) {
return 0;
}

public int getCount() {
return mVector.size();
}

class ViewHolder {
ImageView head;
TextView name;
}

public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
RelativeLayout rl = null;
if (convertView == null) {
rl = new RelativeLayout(mContext);
rl.setBackgroundDrawable(bitmapDrawable_listitembg);

// head
ImageView head = new ImageView(mContext);
head.setId(1);

RelativeLayout.LayoutParams mLayoutParams = new RelativeLayout.LayoutParams(
64, 64);
mLayoutParams.topMargin = 15;
mLayoutParams.leftMargin = 10;
mLayoutParams.bottomMargin = 15;
mLayoutParams.addRule(RelativeLayout.CENTER_VERTICAL);
rl.addView(head, mLayoutParams);

// nickname
TextView mTextView = new TextView(mContext);
mTextView.setTextSize(20);
mTextView.setTextColor(0xff000000);
mTextView.setId(2);

mLayoutParams = new RelativeLayout.LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
mLayoutParams.topMargin = 10;
mLayoutParams.leftMargin = 10;
mLayoutParams.addRule(RelativeLayout.RIGHT_OF, 1);
rl.addView(mTextView, mLayoutParams);

holder = new ViewHolder();
holder.head = head;
holder.name = mTextView;
rl.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
rl = (RelativeLayout) convertView;
}

holder.head.setImageDrawable(bitmapDrawable_headimage);
holder.name.setText(mVector.elementAt(position));

return rl;
}
}

如果对之前讲的相对布局看过的话，这里对自定义布局的写法应该不难理解。

定义了一个头像ImageView和一个名字TextView。让头像距离上下左各有一段距离，然后让名字在头像右边显示，并距离头像右一定距离。

关于布局背景图片的设置：rl.setBackgroundDrawable(bitmapDrawable_listitembg);设置的图片是从asset中读取得到的，头像的也是。

最后附上显示效果：