Android从SD卡中加载图片或读取信息

 package com.xplus.mytxttest;

 import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;

 import android.app.Activity;
 import android.content.Context;
 import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
 import android.os.Bundle;
 import android.os.Environment;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.Button;
 import android.widget.EditText;
 import android.widget.ImageView;
 import android.widget.TextView;
 import android.widget.Toast;

 public class ActivitySdCard extends Activity {

     private Button btn_write;
     private Button btn_read;
     private EditText edit_write;
     private TextView view_read;
     private TextView text_info;

     private ImageView img_image1;
     private ImageView img_image2;
     private ImageView img_image3;
     private ImageView img_image4;
     private ImageView img_image5;
     private TextView text_image1;
     private TextView text_image2;
     private TextView text_image3;
     private TextView text_image4;
     private TextView text_image5;
     private int flag = 0;


     @Override
     protected void onCreate(Bundle savedInstanceState) {
         // TODO Auto-generated method stub
         super.onCreate(savedInstanceState);
         setContentView(R.layout.main_sd);
         init();

         System.out.println("CodeEncoding:" + getCodeEncoding());

         if (Environment.getExternalStorageState().equals(
                 Environment.MEDIA_MOUNTED)) {
             File file = new File(Environment.getExternalStorageDirectory(),
                     "my.txt");
             try {
                 FileInputStream inStream = new FileInputStream(file);
                 // 内存中开辟一段缓冲区
                 byte[] buffer = new byte[1024];
                 // 创建一个字节输出流
                 ByteArrayOutputStream outStream = new ByteArrayOutputStream();
                 // 读取出来的数据首先放入缓冲去，，满了之后再写到字符输出流
                 int len;
                 while ((len = inStream.read(buffer)) != -1) {
                     outStream.write(buffer, 0, len);
                 }
                 inStream.close();
                 outStream.close();
                 System.out.println(outStream.toString());
                 String[] arrStr = outStream.toString().split("-");
                 queryPic(arrStr);
             }
             catch (Exception e) {
                 // TODO: handle exception
             }


             btn_read.setOnClickListener(new OnClickListener() {
                 @Override
                 public void onClick(View v) {
                     try {
                         File sdCardDir = Environment
                                 .getExternalStorageDirectory();
                         System.out.println(sdCardDir.toString());
                         if (Environment.getExternalStorageState().equals(
                                 Environment.MEDIA_MOUNTED)) {
                             File readFile = new File(sdCardDir, "my.txt");
                             FileInputStream istream = new FileInputStream(
                                     readFile);
                             // 内存中开辟一段缓冲区
                             byte[] buffer = new byte[1024];
                             // 创建一个字节输出流
                             ByteArrayOutputStream ostream = new ByteArrayOutputStream();
                             // 读取出来的数据首先放入缓冲去，，满了之后再写到字符输出流
                             int len;
                             while ((len = istream.read(buffer)) != -1) {
                                 ostream.write(buffer, 0, len);
                             }
                             ostream.close();
                             istream.close();
                             String txtStr = ostream.toString();
                             view_read.setText(txtStr);
                         }
                     } catch (FileNotFoundException e) {
                         // TODO Auto-generated catch block
                         e.printStackTrace();
                     } catch (IOException e) {
                         // TODO Auto-generated catch block
                         e.printStackTrace();
                     }
                 }
             });

             btn_write.setOnClickListener(new OnClickListener() {
                 @Override
                 public void onClick(View v) {
                     try {
                         System.out.println("write");
                         File sdCardDir = Environment
                                 .getExternalStorageDirectory();
                         System.out.println(Environment
                                 .getExternalStorageState());
                         if (Environment.getExternalStorageState().equals(
                                 Environment.MEDIA_MOUNTED)) {
                             System.out.println("write");
                             File saveFile = new File(sdCardDir, "my.txt");
                             FileOutputStream fos = new FileOutputStream(
                                     saveFile);
                             fos.write(edit_write.getText().toString()
                                     .getBytes());

                             fos.close();
                             Toast.makeText(ActivitySdCard.this, "写入成功",
                                     Toast.LENGTH_SHORT).show();
                         }

                     } catch (FileNotFoundException e) {
                         // TODO Auto-generated catch block
                         e.printStackTrace();
                     } catch (IOException e) {
                         // TODO Auto-generated catch block
                         e.printStackTrace();
                     }

                 }
             });
         }

     }

     private void init() {
         btn_read = (Button) findViewById(R.id.button_sd_read);
         btn_write = (Button) findViewById(R.id.button_sd_write);
         edit_write = (EditText) findViewById(R.id.editText_sd_edit);
         view_read = (TextView) findViewById(R.id.textView_sd_text);
         text_info = (TextView) findViewById(R.id.textView_sd_info);

         img_image1 = (ImageView) findViewById(R.id.imageView_sd_image1);
         img_image2 = (ImageView) findViewById(R.id.imageView_sd_image2);
         img_image3 = (ImageView) findViewById(R.id.imageView_sd_image3);
         img_image4 = (ImageView) findViewById(R.id.imageView_sd_image4);
         img_image5 = (ImageView) findViewById(R.id.imageView_sd_image5);
         text_image1 = (TextView)findViewById(R.id.textView_sd_text1);
         text_image2 = (TextView)findViewById(R.id.textView_sd_text2);
         text_image3 = (TextView)findViewById(R.id.textView_sd_text3);
         text_image4 = (TextView)findViewById(R.id.textView_sd_text4);
         text_image5 = (TextView)findViewById(R.id.textView_sd_text5);

     }

     private void queryPic(String[] str){
         img_image1.setImageBitmap(BitmapFactory.decodeFile(str[flag]));
         text_image1.setText("名称："+str[++flag]+"\n价格："+str[++flag]);
         img_image2.setImageBitmap(BitmapFactory.decodeFile(str[++flag]));
         text_image2.setText("名称："+str[++flag]+"\n价格："+str[++flag]);
         img_image3.setImageBitmap(BitmapFactory.decodeFile(str[++flag]));
         text_image3.setText("名称："+str[++flag]+"\n价格："+str[++flag]);
         img_image4.setImageBitmap(BitmapFactory.decodeFile(str[++flag]));
         text_image4.setText("名称："+str[++flag]+"\n价格："+str[++flag]);
         img_image5.setImageBitmap(BitmapFactory.decodeFile(str[++flag]));
         text_image5.setText("名称："+str[++flag]+"\n价格："+str[++flag]);
     }

     private String getCodeEncoding() {
         String code = "gb2312";
         try {
             InputStream inputStream = new FileInputStream(
                     Environment.getExternalStorageDirectory() + "/my.txt");
             byte[] head = new byte[3];
             inputStream.read(head);
             if (head[0] == -1 && head[1] == -2) {
                 code = "UTF-16";
             }
             if (head[0] == -2 && head[1] == -1) {
                 code = "Unicode";
             }
             if (head[0] == -17 && head[1] == -69 && head[2] == -65) {
                 code = "UTF-8";
             }

         } catch (FileNotFoundException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         } catch (IOException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }

         return code;
     }

     @Override
     protected void onDestroy() {
         // TODO Auto-generated method stub
         super.onDestroy();
     }

 }

xml

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent"
     android:orientation="vertical" >
     <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content" >
         <Button
             android:id="@+id/button_sd_write"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:text="write" />
         <Button
             android:id="@+id/button_sd_read"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:text="read" />
     </LinearLayout>
     <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content" >
         <EditText
             android:id="@+id/editText_sd_edit"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:layout_weight="1"
             android:ems="10"
             android:inputType="textPersonName" >
             <requestFocus />
         </EditText>
     </LinearLayout>
     <TextView
         android:id="@+id/textView_sd_text"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:text="读取的内容" />
     <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:orientation="vertical" >
         <TableLayout
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:layout_gravity="center" >
             <TableRow
                 android:id="@+id/tableRow1"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content" >
                 <ImageView
                     android:id="@+id/imageView_sd_image1"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
                     android:src="@drawable/ic_action_search" />
                 <ImageView
                     android:id="@+id/imageView_sd_image2"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
                     android:src="@drawable/ic_action_search" />
                 <ImageView
                     android:id="@+id/imageView_sd_image3"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
                     android:src="@drawable/ic_action_search" />
                 <ImageView
                     android:id="@+id/imageView_sd_image4"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
                     android:src="@drawable/ic_action_search" />
                 <ImageView
                     android:id="@+id/imageView_sd_image5"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
                     android:src="@drawable/ic_action_search" />
             </TableRow>
             <TableRow
                 android:id="@+id/tableRow2"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content" >
                 <TextView
                     android:id="@+id/textView_sd_text1"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
                     android:layout_gravity="center"
                     android:text="1"
                     android:textSize="20dip" />
                 <TextView
                     android:id="@+id/textView_sd_text2"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
                     android:layout_gravity="center"
                     android:text="2"
                     android:textSize="20dip" />
                 <TextView
                     android:id="@+id/textView_sd_text3"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
                     android:layout_gravity="center"
                     android:text="3"
                     android:textSize="20dip" />
                 <TextView
                     android:id="@+id/textView_sd_text4"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
                     android:layout_gravity="center"
                     android:text="4"
                     android:textSize="20dip" />
                 <TextView
                     android:id="@+id/textView_sd_text5"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
                     android:layout_gravity="center"
                     android:text="5"
                     android:textSize="20dip" />
             </TableRow>
         </TableLayout>
     </LinearLayout>
     <TextView
         android:id="@+id/textView_sd_info"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_gravity="center"
         android:text="图片描述信息" />

 </LinearLayout>

如果要读取txt中的信息，可以用BufferedReader实现一行一行的读取，然后将读取的数据添加到一个List中，再通过List获取需要的数据即可。

 File file = new File(firstPath + secondPath + thirdPath[flag],
                         "/akinndo.txt");

                 BufferedReader reader = new BufferedReader(new FileReader(file));
                 String r = reader.readLine();
                 while (r != null) {
                     String[] informations = r.split(",");
                     Map<String, String> map = new HashMap<String, String>();
                     map.put("dir", firstPath + informations[0]);
                     map.put("description", informations[1]);
                     list.add(map);
                     r = reader.readLine();
                 }