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

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1. // 创建LinearLayout对象  
2. LinearLayout mRelativeLayout = new LinearLayout(this);  
3. mRelativeLayout.setLayoutParams(new LinearLayout.LayoutParams(  
4.         LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));  
5.   
6. //  创建ListView对象  
7. ListView mListView = new ListView(this);  
8. mListView.setAdapter(new ListAdapter(this, mVector));  
9.   
10. // 添加组件  
11. mRelativeLayout.addView(mListView, new LayoutParams(  
12.         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

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1. public class ListAdapter extends BaseAdapter {  
2.     private Vector<String> mVector;  
3.   
4.     private Context mContext;  
5.   
6.     public ListAdapter(Context mContext, Vector<String> mVector) {  
7.         this.mContext = mContext;  
8.         this.mVector = mVector;  
9.     }  
10.   
11.     public Object getItem(int position) {  
12.         return null;  
13.     }  
14.   
15.     public long getItemId(int position) {  
16.         return 0;  
17.     }  
18.   
19.     public int getCount() {  
20.         return mVector.size();  
21.     }  
22.   
23.     class ViewHolder {  
24.         ImageView head;  
25.         TextView name;  
26.     }  
27.   
28.     public View getView(int position, View convertView, ViewGroup parent) {  
29.         ViewHolder holder = null;  
30.         RelativeLayout rl = null;  
31.         if (convertView == null) {  
32.             rl = new RelativeLayout(mContext);  
33.             rl.setBackgroundDrawable(bitmapDrawable_listitembg);  
34.   
35.             // head  
36.             ImageView head = new ImageView(mContext);  
37.             head.setId(1);  
38.               
39.             RelativeLayout.LayoutParams mLayoutParams = new RelativeLayout.LayoutParams(  
40.                     64, 64);  
41.             mLayoutParams.topMargin = 15;  
42.             mLayoutParams.leftMargin = 10;  
43.             mLayoutParams.bottomMargin = 15;  
44.             mLayoutParams.addRule(RelativeLayout.CENTER_VERTICAL);  
45.             rl.addView(head, mLayoutParams);  
46.   
47.             // nickname  
48.             TextView mTextView = new TextView(mContext);  
49.             mTextView.setTextSize(20);  
50.             mTextView.setTextColor(0xff000000);  
51.             mTextView.setId(2);  
52.   
53.             mLayoutParams = new RelativeLayout.LayoutParams(  
54.                     LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);  
55.             mLayoutParams.topMargin = 10;  
56.             mLayoutParams.leftMargin = 10;  
57.             mLayoutParams.addRule(RelativeLayout.RIGHT_OF, 1);  
58.             rl.addView(mTextView, mLayoutParams);  
59.   
60.               
61.             holder = new ViewHolder();  
62.             holder.head = head;  
63.             holder.name = mTextView;  
64.             rl.setTag(holder);  
65.         } else {  
66.             holder = (ViewHolder) convertView.getTag();  
67.             rl = (RelativeLayout) convertView;  
68.         }  
69.   
70.         holder.head.setImageDrawable(bitmapDrawable_headimage);  
71.         holder.name.setText(mVector.elementAt(position));  
72.   
73.         return rl;  
74.     }  
75. }  

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);// headImageView 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);// nicknameTextView 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：