MergeAdapte+listView实现复杂布局

MergeAdapter对ListView的自定制非常有效，用来实现一些复杂的布局。首先先看下面两个类：

MergeAdapter.java

[java] view plain copy
/*
Copyright (c) 2008-2009 CommonsWare, LLC
Portions (c) 2009 Google, Inc.

Licensed under the Apache License, Version 2.0 (the "License"); you may 
not use this file except in compliance with the License. You may obtain 
a copy of the License at 
    http://www.apache.org/licenses/LICENSE-2.0 
Unless required by applicable law or agreed to in writing, software 
distributed under the License is distributed on an "AS IS" BASIS, 
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
See the License for the specific language governing permissions and 
limitations under the License. 

*/

package com.commonsware.cwac.merge;

import android.database.DataSetObserver;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListAdapter;
import android.widget.SectionIndexer;
import java.util.ArrayList;
import java.util.List;
import com.commonsware.cwac.sacklist.SackOfViewsAdapter;

/**
* Adapter that merges multiple child adapters and views
* into a single contiguous whole.
*
* Adapters used as pieces within MergeAdapter must
* have view type IDs monotonically increasing from 0. Ideally,
* adapters also have distinct ranges for their row ids, as
* returned by getItemId().
*
*/
public class MergeAdapter extends BaseAdapter implements SectionIndexer {
private ArrayList pieces=new ArrayList();

/** 
    * Stock constructor, simply chaining to the superclass. 
*/  
public MergeAdapter() {  
    super();  
}  

/** 
    * Adds a new adapter to the roster of things to appear 
    * in the aggregate list. 
    * @param adapter Source for row views for this section 
*/  
public void addAdapter(ListAdapter adapter) {  
    pieces.add(adapter);  
    adapter.registerDataSetObserver(new CascadeDataSetObserver());  
}  

/** 
    * Adds a new View to the roster of things to appear 
    * in the aggregate list. 
    * @param view Single view to add 
*/  
public void addView(View view) {  
    addView(view, false);  
}  

/** 
    * Adds a new View to the roster of things to appear 
    * in the aggregate list. 
    * @param view Single view to add 
    * @param enabled false if views are disabled, true if enabled 
*/  
public void addView(View view, boolean enabled) {  
    ArrayList list=new ArrayList(1);  

    list.add(view);  

    addViews(list, enabled);  
}  

/** 
    * Adds a list of views to the roster of things to appear 
    * in the aggregate list. 
    * @param views List of views to add 
*/  
public void addViews(List views) {  
    addViews(views, false);  
}  

/** 
    * Adds a list of views to the roster of things to appear 
    * in the aggregate list. 
    * @param views List of views to add 
    * @param enabled false if views are disabled, true if enabled 
*/  
public void addViews(List views, boolean enabled) {  
    if (enabled) {  
        addAdapter(new EnabledSackAdapter(views));  
    }  
    else {  
        addAdapter(new SackOfViewsAdapter(views));  
    }  
}  

/** 
    * Get the data item associated with the specified 
    * position in the data set. 
    * @param position Position of the item whose data we want 
*/  
@Override  
public Object getItem(int position) {  
    for (ListAdapter piece : pieces) {  
        int size=piece.getCount();  

        if (position sections=new ArrayList