Android存储 SD卡或者文件存储实现。

Android实现SD卡和实现内存文件存储的做法基本是一样的。只是取得文件路径的方法不一样，基本上跟java的文件操作是一致的，下面是程序的代码。配置取的位置和实现有所不同，其他是一样的，下面是代码：

main.xml:

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

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

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    android:orientation="vertical" 

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    android:layout_width="fill_parent" 

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    android:layout_height="fill_parent"> 

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<EditText android:id="@+id/edit1" 

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    android:layout_width="fill_parent" 

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    android:layout_height="wrap_content" 

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    android:lines="4"/> 

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<Button android:id="@+id/write" 

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    android:layout_width="wrap_content" 

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    android:layout_height="wrap_content"  

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    android:text="@string/write"/> 

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<EditText android:id="@+id/edit2" 

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    android:layout_width="fill_parent" 

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    android:layout_height="wrap_content" 

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    android:editable="false" 

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    android:cursorVisible="false" 

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    android:lines="4"/>       

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<Button android:id="@+id/read" 

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    android:layout_width="wrap_content" 

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    android:layout_height="wrap_content"  

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    android:text="@string/read"/> 

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</LinearLayout>

在AndroidManifest清单文件中要对SD卡读取进行支持。代码如下：

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<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/> 

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<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

在String.xml中添加两个内容:

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<string name="read">读取</string> 

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lt;string name="write">写入</string>

下面是文件实现的代码：

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package cn.jason.io;

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import java.io.FileInputStream;

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import java.io.FileOutputStream;

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import java.io.IOException;

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import java.io.PrintStream;

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import android.app.Activity;

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import android.os.Bundle;

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import android.view.View;

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import android.view.View.OnClickListener;

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import android.widget.Button;

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import android.widget.EditText;

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public class FileTestActivity extends Activity {

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    final String FILE = "jason.bin";

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    @Override

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    public void onCreate(Bundle savedInstanceState) {

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        super.onCreate(savedInstanceState);

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        setContentView(R.layout.main);

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        Button read = (Button) findViewById(R.id.read);

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        Button write = (Button) findViewById(R.id.write);

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        final EditText edit1 = (EditText) findViewById(R.id.edit1);

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        final EditText edit2 = (EditText) findViewById(R.id.edit2);

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        write.setOnClickListener(new OnClickListener() {

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            @Override

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            public void onClick(View v) {

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                write(edit1.getText().toString());

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                edit1.setText("");

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            }

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        });

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        read.setOnClickListener(new OnClickListener() {

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            @Override

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            public void onClick(View v) {

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                edit2.setText(read());

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            }

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        });

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    }

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    private String read() {

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        try {

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            FileInputStream fis = openFileInput(FILE);

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            byte[] buffer = new byte[1024];

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            int hasRead = 0;

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            StringBuilder sb = new StringBuilder("");

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            while ((hasRead = fis.read(buffer)) > 0) {

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                sb.append(new String(buffer, 0, hasRead));

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            }

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            return sb.toString();

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        } catch (IOException e) {

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            e.printStackTrace();

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        }

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        return null;

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    }

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    private void write(String content)

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    {

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        try

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        {

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            // 以追加模式打开文件输出流

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            FileOutputStream fos = openFileOutput(FILE, MODE_APPEND);

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            // 将FileOutputStream包装成PrintStream

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            PrintStream ps = new PrintStream(fos);

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            // 输出文件内容

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            ps.println(content);

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            ps.close();

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        }

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        catch (Exception e)

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        {

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            e.printStackTrace();

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        }

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    }

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}

下面是sd卡存储实现的代码：

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package cn.jason.io;

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import java.io.BufferedReader;

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import java.io.File;

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import java.io.FileInputStream;

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import java.io.FileNotFoundException;

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import java.io.IOException;

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import java.io.InputStreamReader;

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import java.io.RandomAccessFile;

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import java.net.ContentHandler;

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import android.app.Activity;

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import android.os.Bundle;

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import android.os.Environment;

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import android.view.View;

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import android.view.View.OnClickListener;

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import android.widget.Button;

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import android.widget.EditText;

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public class SDCardTestActivity extends Activity {

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    final String FILE = "/jason.bin";

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    @Override

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    public void onCreate(Bundle savedInstanceState) {

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        super.onCreate(savedInstanceState);

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        setContentView(R.layout.main);

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        Button read = (Button) findViewById(R.id.read);

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        Button write = (Button) findViewById(R.id.write);

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        // 获取两个文本框

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        final EditText edit1 = (EditText) findViewById(R.id.edit1);

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        final EditText edit2 = (EditText) findViewById(R.id.edit2);

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        // 为write按钮绑定事件监听器

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        write.setOnClickListener(new OnClickListener() {

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            @Override

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            public void onClick(View source) {

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                // 将edit1中的内容写入文件中

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                write(edit1.getText().toString());

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                edit1.setText("");

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            }

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        });

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        read.setOnClickListener(new OnClickListener() {

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            @Override

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            public void onClick(View v) {

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                // 读取指定文件中的内容，并显示出来

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                edit2.setText(read());

49
            }

50
        });

51
    }

52
     
53
    private String read() {

54
        // 如果手机插入了SD卡，而且应用程序具有访问SD的权限

55
         
56
        try {

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            if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {

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                // 获取SD卡的目录

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                File sdDirFile = Environment.getExternalStorageDirectory();

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                //获取指定文件对应的输入流

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                FileInputStream fis = newFileInputStream(sdDirFile.getCanonicalPath()+ FILE);

62
                //将指定输入流包装成BufferedReader

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                BufferedReader br = new BufferedReader(new InputStreamReader(fis));

64
                 
65
                StringBuilder sb = new StringBuilder("");

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                String line = null;

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                while ((line =br.readLine())!=null) {

68
                    sb.append(line);

69
                }

70
                return sb.toString();

71
            }

72
        } catch (FileNotFoundException e) {

73
            e.printStackTrace();

74
        } catch (IOException e) {

75
            e.printStackTrace();

76
        }

77
        return null;

78
    }

79
 
80
    private void write(String context){

81
        try {

82
            if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){

83
                File sdDir = Environment.getExternalStorageDirectory();

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                File targetFile = new File(sdDir.getCanonicalPath()+ FILE);

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                RandomAccessFile raf = new RandomAccessFile(targetFile, "rw");

86
                raf.seek(targetFile.length());

87
                raf.write(context.getBytes());

88
                raf.close();

89
            }

90
        } catch (Exception e) {

91
        }

92
    }

93
}

转自：http://blog.csdn.net/jasonchris/article/details/7619468