初探异步 AsyncTask 扫描SD卡指定后缀 .

初探异步 AsyncTask

 

        最基本的异步DEMO,AsyncTask实现扫描SD卡指定后缀类型的文件(递归扫描)

 

 

package allen.test;

import java.io.File;
import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class TestActivity extends Activity
{

    static List txtList;// 文件列表

    EditText editText;

    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        this.setTitle("异步加载DEMO(扫描SD卡指定后缀文件)");
        Button btnPhoto = (Button) findViewById(R.id.button);
        editText = (EditText) findViewById(R.id.edittext);
        txtList = new ArrayList();
        btnPhoto.setOnClickListener(new View.OnClickListener()
        {

            public void onClick(View v)
            {

                new AsyncTask()
                {

                    private ProgressDialog dialog;

                    protected void onPreExecute()
                    {
                        dialog = ProgressDialog.show(TestActivity.this, "",
                                "正在扫描SD卡,请稍候....");
                        super.onPreExecute();
                    }

                    protected String[] doInBackground(Integer... params)
                    {
                        if (!android.os.Environment.getExternalStorageState()
                                .equals(android.os.Environment.MEDIA_MOUNTED))
                        {

                        }
                        else
                        {
                            if (!editText.getText().toString().equals(""))
                            {
                                GetFiles(Environment
                                        .getExternalStorageDirectory());
                            }
                        }
                        return null;
                    }

                    protected void onPostExecute(String[] result)
                    {
                        dialog.dismiss();
                        if (editText.getText().toString().equals(""))
                        {
                            Toast.makeText(TestActivity.this, "请输入有效信息",
                                    Toast.LENGTH_SHORT).show();
                        }
                        else
                        {
                            Toast.makeText(TestActivity.this, "扫描完毕",
                                    Toast.LENGTH_LONG).show();
                            Intent in = new Intent();
                            in.setClass(TestActivity.this, ListOk.class);
                            TestActivity.this.startActivity(in);
                        }
                        super.onPostExecute(result);
                    }
                }.execute(0);
            }
        });

    }

    /**
     * 获取文件列表
     *
     * @param filePath
     */
    public void GetFiles(File filePath)
    {

        File[] files = filePath.listFiles();

        if (files != null)
        {
            for (int i = 0; i < files.length; i++)
            {
                if (files[i].isDirectory())
                {
                    GetFiles(files[i]);
                }
                else
                {
                    if (files[i].getName().toLowerCase()
                            .endsWith("." + editText.getText().toString()))
                    {
                        txtList.add(files[i]);
                    }
                }
            }
        }
    }

}

 显示类

package allen.test;

import java.io.File;
import java.util.ArrayList;
import java.util.List;

import android.app.ListActivity;
import android.os.Bundle;
import android.widget.ArrayAdapter;

public class ListOk extends ListActivity
{

    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);

        ArrayAdapter adapter = new ArrayAdapter(this,
                android.R.layout.simple_list_item_1,
                FileToStr(TestActivity.txtList));
        setListAdapter(adapter);
    }

    /**
     * 把文件列表转换成字符串
     *
     * @param f
     * @return
     */
    public String[] FileToStr(List f)
    {
        ArrayList listStr = new ArrayList();
        for (int i = 0; i < f.size(); i++)
        {
            String nameString = f.get(i).getName();
            listStr.add(nameString);
        }
        return listStr.toArray(new String[0]);
    }
}

 main布局

 

[html] view plaincopyprint?

xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android=""
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <EditText
        android:id="@+id/edittext"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:hint="请输入扫描的文件后缀名(例如mp3)" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="开始扫描SD卡" />

LinearLayout>

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