数据保存到sd卡上

1 关键代码

 

package cn.lee.data;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

import cn.lee.Manager.DataManager;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class AboutDateActivity extends Activity {
 private EditText fileNameEditText;
 private EditText fileContentEditText;
 private EditText readfileContentEditText;
 private Button button;
 private Button readButton;
 private static final String TAGSTRING = "AboutDateActivity";

 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);

  button = (Button) this.findViewById(R.id.button);
  readButton = (Button) this.findViewById(R.id.readButton);
  fileNameEditText = (EditText) this.findViewById(R.id.fileName);
  fileContentEditText = (EditText) this.findViewById(R.id.fileContent);
  readfileContentEditText = (EditText) this
    .findViewById(R.id.readfileContent);

  // 读取
  readButton.setOnClickListener(onClickListener);
  // 保存
  button.setOnClickListener(onClickListener);
 }

 /**
  * 由于这个内部实现类是一个接口的实例 所以这里把他提取出来 作为一个成员变量 2010-04-18
  */
 private View.OnClickListener onClickListener = new View.OnClickListener() {
  /**
   * 由于button的父类是view 所以这里的onclick的参数传来的view v就可以找到这个button
   */
  public void onClick(View v) {
   Button button = (Button) v;// 将父类view强转成子类button
   int info = R.string.sus;  //操作成功
   String fileNameString = fileNameEditText.getText().toString();
   
   /**
    * 判断sd卡是否存在 Environment.getExternalStorageState() 得到sd卡当前的状态
    *
    * getExternalStorageState() returns MEDIA_MOUNTED if the
    * media is present and mounted at its mount point with
    * read/write access. 如果返回 MEDIA_MOUNTED表示外部存储设备存在。并且有读写的权限
    */
   
   if (Environment.getExternalStorageState().equals(
     Environment.MEDIA_MOUNTED)) {
    if ("".equals(fileNameString)) {
     info = R.string.filenamenotnull; //文件名不能为空
    } else {
     FileOutputStream fileOutputStream = null;
     FileInputStream fileInputStream = null;
     try {
      switch (button.getId()) {
      case R.id.button: {// 保存
       String fileContentString = fileContentEditText
         .getText().toString();
       /**
        * Environment.getExternalStorageDirectory();
        * 得到外存储设备的路径
        *
        */
       File file = new File(Environment
         .getExternalStorageDirectory(),
         fileNameString);
       fileOutputStream = new FileOutputStream(file);
       DataManager.saveDate(fileOutputStream,
         fileContentString);
       break;
      }

      case R.id.readButton: {
       fileInputStream = null;
       fileInputStream = AboutDateActivity.this
         .openFileInput(fileNameString);
       String contentString = DataManager
         .readDate(fileInputStream);
       readfileContentEditText.setText(contentString);
       break;
      }
      default:
       break;
      }

     } catch (Exception e) {
      // TODO Auto-generated catch block
      Log.i(TAGSTRING, e.toString());
      info = R.string.infor;
     } finally {
      try {
       if (fileOutputStream != null) {
        fileOutputStream.close();
       }
       if (fileInputStream != null) {
        fileInputStream.close();
       }

      } catch (IOException e) {

       Log.i(TAGSTRING, e.toString());
       info = R.string.infor;
      }
     }

    }
   } else {
    info = R.string.infor;
   }
   Toast.makeText(AboutDateActivity.this, info, 1).show();
  }

 };
}

 

2 资源文件

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="cn.lee.data"
      android:versionCode="1"
      android:versionName="1.0">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
     <uses-library  android:name="android.test.runner" />
        <activity android:name=".AboutDateActivity"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>
    <uses-sdk android:minSdkVersion="7" />
 <instrumentation android:name="android.test.InstrumentationTestRunner" android:targetPackage="cn.lee.data"
 android:label="Test for my app"/>
 <!-- 允许程序访问外部存储设备 -->
 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
 <!-- 允许创建和删除外部存储设备的文件 -->
 <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
</manifest>

 

 

3 业务service

 

package cn.lee.Manager;

import java.io.ByteArrayOutputStream;

import java.io.InputStream;
import java.io.OutputStream;

public class DataManager {
 /**
  * 没有使用成员变量的方法可以定义为静态方法
  * 保存数据的业务逻辑
  * OutputStream 输出流
  * content 文件内容
  * @throws Exception
  */
 public static void saveDate (OutputStream outputStream , String contentString) throws Exception
 {
  outputStream.write(contentString.getBytes());
  outputStream.close();
 }
 /**
  * 读取数据的业务逻辑
  * @param InputStream
  * @param contentString
  * @throws Exception
  */
 public static  String readDate (InputStream inputStream ) throws Exception
 {
  byte [] byte1 = new byte[1024];
  /**
   * 当输入流读到文件的末尾 返回就是－1
   */
  int length = inputStream.read(byte1);
  ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
  if(length!=-1)
  {
   //读到的内容存在内存中ByteArrayOutputStream 这个类用于将byte流存储在内存中
   
   byteArrayOutputStream.write(byte1, 0, length);
  }
  String dateString =   byteArrayOutputStream.toString();
  byteArrayOutputStream.close();
  inputStream.close();
  return dateString;
 }
}