Android ListView用EditText实现搜索功能效果

在查阅资料以后，发现其实Android中已经帮我们实现了这个功能，如果你的ListView使用的是系统的ArrayAdapter，那么恭喜你，下面的事情就很简单了，你只需要调用下面的代码就可以实现了：

searchEdittext.addTextChangedListener(new TextWatcher() {
 @Override
 public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {
 // When user change the text
 mAdapter.getFilter().filter(cs);
 }

@Override
 public void beforeTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {
 //
 }
@Override
 public void afterTextChanged(Editable arg0) {
 //
 }
 });
 

你没看错，就一行 mAdapter.getFilter().filter(cs);便可以实现这个搜索功能。不过我相信大多数Adapter都是自定义的，基于这个需求，我去分析了下ArrayAdapter，发现它实现了Filterable接口，那么接下来的事情就比较简单了，就让我们自定的Adapter也去实现Filterable这个接口，不久可以实现这个需求了吗。下面贴出ArrayAdapter中显示过滤功能的关键代码：

public class ArrayAdapter extends BaseAdapter implements Filterable {
 /**


Contains the list of objects that represent the data of this ArrayAdapter.
The content of this list is referred to as "the array" in the documentation.
 */
 private List mObjects;

/**

Lock used to modify the content of {@link #mObjects}. Any write operation
performed on the array should be synchronized on this lock. This lock is also
used by the filter (see {@link #getFilter()} to make a synchronized copy of
the original array of data.
 */
 private final Object mLock = new Object();

// A copy of the original mObjects array, initialized from and then used instead as soon as
 // the mFilter ArrayFilter is used. mObjects will then only contain the filtered values.
 private ArrayList mOriginalValues;
 private ArrayFilter mFilter;
...
public Filter getFilter() {
 if (mFilter == null) {
 mFilter = new ArrayFilter();
 }
 return mFilter;
 }
/**

An array filter constrains the content of the array adapter with
a prefix. Each item that does not start with the supplied prefix
 
is removed from the list.
 */
 private class ArrayFilter extends Filter {
 @Override
 protected FilterResults performFiltering(CharSequence prefix) {
 FilterResults results = new FilterResults();
 
if (mOriginalValues == null) {
 synchronized (mLock) {
 mOriginalValues = new ArrayList(mObjects);
 }
 }
 
if (prefix == null || prefix.length() == 0) {
 ArrayList list;
 synchronized (mLock) {
 list = new ArrayList(mOriginalValues);
 }
 results.values = list;
 results.count = list.size();
 } else {
 String prefixString = prefix.toString().toLowerCase();
 
ArrayList values;
 synchronized (mLock) {
 values = new ArrayList(mOriginalValues);
 }
 
final int count = values.size();
 final ArrayList newValues = new ArrayList();
 
for (int i = 0; i < count; i++) {
 final T value = values.get(i);
 final String valueText = value.toString().toLowerCase();
 
 // First match against the whole, non-splitted value
 if (valueText.startsWith(prefixString)) {
   newValues.add(value);
 } else {
   final String[] words = valueText.split(" ");
   final int wordCount = words.length;

   // Start at index 0, in case valueText starts with space(s)
   for (int k = 0; k < wordCount; k++) {
     if (words[k].startsWith(prefixString)) {
       newValues.add(value);
       break;
     }
   }
 }
 
}
 
results.values = newValues;
 results.count = newValues.size();
 }
 
return results;
 }
 

@Override
protected void publishResults(CharSequence constraint, FilterResults results) {
  //noinspection unchecked
  mObjects = (List) results.values;
  if (results.count > 0) {
    notifyDataSetChanged();
  } else {
    notifyDataSetInvalidated();
  }
}

}
 }

实现

首先写了一个Model（User）模拟数据

public class User {
 private int avatarResId;
 private String name;

public User(int avatarResId, String name) {
 this.avatarResId = avatarResId;
 this.name = name;
 }
public int getAvatarResId() {
 return avatarResId;
 }
public void setAvatarResId(int avatarResId) {
 this.avatarResId = avatarResId;
 }
public String getName() {
 return name;
 }
public void setName(String name) {
 this.name = name;
 }
 }

自定义一个Adapter（UserAdapter）继承自BaseAdapter，实现了Filterable接口，Adapter一些常见的处理，我都去掉了，这里主要讲讲Filterable这个接口。

/**


Contains the list of objects that represent the data of this Adapter.
Adapter数据源
 */
 private List mDatas;

//过滤相关
 /**

This lock is also used by the filter
(see {@link #getFilter()} to make a synchronized copy of
the original array of data.
过滤器上的锁可以同步复制原始数据。
 

*/
 private final Object mLock = new Object();
// A copy of the original mObjects array, initialized from and then used instead as soon as
 // the mFilter ArrayFilter is used. mObjects will then only contain the filtered values.
 //对象数组的备份，当调用ArrayFilter的时候初始化和使用。此时，对象数组只包含已经过滤的数据。
 private ArrayList mOriginalValues;
 private ArrayFilter mFilter;
@Override
 public Filter getFilter() {
 if (mFilter == null) {
 mFilter = new ArrayFilter();
 }
 return mFilter;
 }

写一个ArrayFilter类继承自Filter类，我们需要两个方法：

//执行过滤的方法
 protected FilterResults performFiltering(CharSequence prefix);

//得到过滤结果
 protected void publishResults(CharSequence prefix, FilterResults results);

贴上完整的代码，注释已经写的不能再详细了

 /**


过滤数据的类
 /
 /*
An array filter constrains the content of the array adapter with
a prefix. Each item that does not start with the supplied prefix
is removed from the list.


 
一个带有首字母约束的数组过滤器，每一项不是以该首字母开头的都会被移除该list。
 */
 private class ArrayFilter extends Filter {
 //执行刷选
 @Override
 protected FilterResults performFiltering(CharSequence prefix) {
 FilterResults results = new FilterResults();//过滤的结果
 //原始数据备份为空时，上锁，同步复制原始数据
 if (mOriginalValues == null) {
 synchronized (mLock) {
 mOriginalValues = new ArrayList<>(mDatas);
 }
 }
 //当首字母为空时
 if (prefix == null || prefix.length() == 0) {
 ArrayList list;
 synchronized (mLock) {//同步复制一个原始备份数据
 list = new ArrayList<>(mOriginalValues);
 }
 results.values = list;
 results.count = list.size();//此时返回的results就是原始的数据，不进行过滤
 } else {
 String prefixString = prefix.toString().toLowerCase();//转化为小写
 
ArrayList values;
 synchronized (mLock) {//同步复制一个原始备份数据
 values = new ArrayList<>(mOriginalValues);
 }
 final int count = values.size();
 final ArrayList newValues = new ArrayList<>();
 
for (int i = 0; i < count; i++) {
 final User value = values.get(i);//从List中拿到User对象
 // final String valueText = value.toString().toLowerCase();
 final String valueText = value.getName().toString().toLowerCase();//User对象的name属性作为过滤的参数
 // First match against the whole, non-splitted value
 if (valueText.startsWith(prefixString) || valueText.indexOf(prefixString.toString()) != -1) {//第一个字符是否匹配
 newValues.add(value);//将这个item加入到数组对象中
 } else {//处理首字符是空格
 final String[] words = valueText.split(" ");
 final int wordCount = words.length;
 
   // Start at index 0, in case valueText starts with space(s)
   for (int k = 0; k < wordCount; k++) {
     if (words[k].startsWith(prefixString)) {//一旦找到匹配的就break，跳出for循环
       newValues.add(value);
       break;
     }
   }
 }
 
}
 results.values = newValues;//此时的results就是过滤后的List数组
 results.count = newValues.size();
 }
 return results;
 }
 

//刷选结果
@Override
protected void publishResults(CharSequence prefix, FilterResults results) {
  //noinspection unchecked
  mDatas = (List) results.values;//此时，Adapter数据源就是过滤后的Results
  if (results.count > 0) {
    notifyDataSetChanged();//这个相当于从mDatas中删除了一些数据，只是数据的变化，故使用notifyDataSetChanged()
  } else {
    /**
     * 数据容器变化 ----> notifyDataSetInValidated

     容器中的数据变化 ----> notifyDataSetChanged
     */
    notifyDataSetInvalidated();//当results.count<=0时，此时数据源就是重新new出来的，说明原始的数据源已经失效了
  }
}

}

特别说明

//User对象的name属性作为过滤的参数
 final String valueText = value.getName().toString().toLowerCase();

这个地方是，你要进行搜索的关键字，比如我这里使用的是User对象的Name属性，就是把用户名当作关键字来进行过滤筛选的。这里要根据你自己的具体逻辑来进行设置。

复制代码

代码如下:

if (valueText.startsWith(prefixString) || valueText.indexOf(prefixString.toString()) != -1)

在这里进行关键字匹配，如果你只想使用第一个字符匹配，那么你只需要使用这行代码就可以了：

//首字符匹配
 valueText.startsWith(prefixString)

如果你的需求是只要输入的字符出现在ListView列表中，那么该item就要显示出来，那么你就需要这行代码了：

//你输入的关键字包含在了某个item中，位置不做考虑，即可以不是第一个字符
 valueText.indexOf(prefixString.toString()) != -1

这样就完成了一个EditText + ListView实现搜索的功能。