<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"

    android:layout_height="wrap_content"

    android:orientation="vertical" >

    <LinearLayout

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:orientation="horizontal" >

        <AutoCompleteTextView

            android:id="@+id/auto"

            android:layout_width="0dp"

            android:layout_height="wrap_content"

            android:layout_weight="1"

            android:completionHint="最近5条记录"

            android:completionThreshold="1"

            />

        <Button

            android:id="@+id/search"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:text="搜索" />

    </LinearLayout>

    <LinearLayout

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:orientation="vertical" >

        <Button

            android:id="@+id/clean"

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:text="清除历史记录"

            android:onClick="cleanHistory"

            />

    </LinearLayout>

</LinearLayout>

public class TestActivity extends Activity {

    private AutoCompleteTextView auto;

    private Button searchbtn;

    private ArrayAdapter<String> arr_adapter;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.test);

        // 初始化

        auto = (AutoCompleteTextView) findViewById(R.id.auto);

        searchbtn = (Button) findViewById(R.id.search);

        // 获取搜索记录文件内容

        SharedPreferences sp = getSharedPreferences("search_history", 0);

        String history = sp.getString("history", "暂时没有搜索记录");

        // 用逗号分割内容返回数组

        String[] history_arr = history.split(",");

        // 新建适配器，适配器数据为搜索历史文件内容

        arr_adapter = new ArrayAdapter<String>(this,

                android.R.layout.simple_dropdown_item_1line, history_arr);

        // 保留前50条数据

        if (history_arr.length > 50) {

            String[] newArrays = new String[50];

            // 实现数组之间的复制

            System.arraycopy(history_arr, 0, newArrays, 0, 50);

            arr_adapter = new ArrayAdapter<String>(this,

                    android.R.layout.simple_dropdown_item_1line, history_arr);

        }

        // 设置适配器

        auto.setAdapter(arr_adapter);

        // 设置监听事件，点击搜索写入搜索词

        searchbtn.setOnClickListener(new Button.OnClickListener() {

            @Override

            public void onClick(View v) {

                // TODO Auto-generated method stub

                save();

            }

        });

    }

    public void save() {

        // 获取搜索框信息

        String text = auto.getText().toString();

        SharedPreferences mysp = getSharedPreferences("search_history", 0);

        String old_text = mysp.getString("history", "暂时没有搜索记录");

        // 利用StringBuilder.append新增内容，逗号便于读取内容时用逗号拆分开

        StringBuilder builder = new StringBuilder(old_text);

        builder.append(text + ",");

        // 判断搜索内容是否已经存在于历史文件，已存在则不重复添加

        if (!old_text.contains(text + ",")) {

            SharedPreferences.Editor myeditor = mysp.edit();

            myeditor.putString("history", builder.toString());

            myeditor.commit();

            Toast.makeText(this, text + "添加成功", Toast.LENGTH_SHORT).show();

        } else {

            Toast.makeText(this, text + "已存在", Toast.LENGTH_SHORT).show();

        }

    }

    //清除搜索记录

    public void cleanHistory(View v){

        SharedPreferences sp =getSharedPreferences("search_history",0);

        SharedPreferences.Editor editor=sp.edit();

        editor.clear();

        editor.commit();

        Toast.makeText(this, "清除成功", Toast.LENGTH_SHORT).show();

        super.onDestroy();

    }

}