Android 內(nèi)部存儲(chǔ)

保存到內(nèi)部存儲(chǔ)

下面的代碼顯示了如何將文件保存到內(nèi)部存儲(chǔ)。

主布局文件

<?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" >

 <TextView
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
     android:text="Please enter some text" />

 <EditText
     android:id="@+id/txtText1"
     android:layout_width="fill_parent"
     android:layout_height="wrap_content" />

 <Button
     android:id="@+id/btnSave"
     android:text="Save"
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
     android:onClick="onClickSave" />

 <Button
     android:id="@+id/btnLoad"
     android:text="Load"
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
     android:onClick="onClickLoad" />

</LinearLayout>

MainActivity.java文件

package cn.w3cschool.myapplication3.app;
// m.o2fo.com
import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

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

public class MainActivity extends Activity {
    EditText textBox;
    static final int READ_BLOCK_SIZE = 100;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textBox = (EditText) findViewById(R.id.txtText1);
    }

    public void onClickSave(View view) {
        String str = textBox.getText().toString();
        try {
            //SD Card Storage
            File sdCard = Environment.getExternalStorageDirectory();
            File directory = new File(sdCard.getAbsolutePath() +
                    "/MyFiles");
            directory.mkdirs();
            File file = new File(directory, "textfile.txt");
            FileOutputStream fOut = new FileOutputStream(file);
            OutputStreamWriter osw = new
                    OutputStreamWriter(fOut);
            osw.write(str);
            osw.flush();
            osw.close();

            Toast.makeText(getBaseContext(),
                    "File saved successfully!",
                    Toast.LENGTH_SHORT).show();
            textBox.setText("");
        } catch (IOException ioe) {
            ioe.printStackTrace();
        }
    }
}

注意1

上述代碼使用getExternalStorageDirectory()方法返回外部存儲(chǔ)的完整路徑。

通常，它應(yīng)該返回真實(shí)設(shè)備的“/sdcard”路徑，以及Android模擬器的“/mnt/sdcard”路徑。

你不應(yīng)該嘗試硬編碼到SD的路徑卡，因?yàn)橹圃焐炭赡苓x擇為SD卡分配不同的路徑名稱(chēng)。

注意2

為了寫(xiě)入外部存儲(chǔ)，你需要在AndroidManifest.xml文件中添加WRITE_EXTERNAL_STORAGE的權(quán)限:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="cn.w3cschool.Files"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="14" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:label="@string/app_name"
            android:name=".FilesActivity" >
            <intent-filter >
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

從內(nèi)部存儲(chǔ)寫(xiě)入和讀取

下面的代碼顯示了如何從內(nèi)部存儲(chǔ)寫(xiě)入和讀取。

主布局xml文件

<?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">

    <TextView
        android:id="@+id/internal_storage_label"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="10px"
        android:text="Enter some text to write on the internal storage, then read back:" />

    <EditText
        android:id="@+id/internal_storage_input"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="10px" />

    <Button
        android:id="@+id/internal_storage_write_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Write" />

    <Button
        android:id="@+id/internal_storage_read_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Read" />

    <TextView
        android:id="@+id/internal_storage_output"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="10px" />


</LinearLayout>

主Activity Java代碼

// m.o2fo.com
package cn.w3cschool.myapplication3.app;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Scanner;

public class MainActivity extends Activity {
    private static final String LINE_SEP = System.getProperty("line.separator");

    private EditText input;
    private TextView output;
    private Button write;
    private Button read;

    @Override
    public void onCreate(final Bundle icicle) {
        super.onCreate(icicle);
        this.setContentView(R.layout.activity_main);

        this.input = (EditText) findViewById(R.id.internal_storage_input);
        this.output = (TextView) findViewById(R.id.internal_storage_output);

        this.write = (Button) findViewById(R.id.internal_storage_write_button);
        this.write.setOnClickListener(new OnClickListener() {
            public void onClick(final View v) {
                write();
            }
        });

        this.read = (Button) findViewById(R.id.internal_storage_read_button);
        this.read.setOnClickListener(new OnClickListener() {
            public void onClick(final View v) {
                read();
            }
        });
    }

    private void write() {
        FileOutputStream fos = null;
        try {
            // note that there are many modes you can use
            fos = openFileOutput("test.txt", Context.MODE_PRIVATE);
            fos.write(input.getText().toString().getBytes());
            Toast.makeText(this, "File written", Toast.LENGTH_SHORT).show();
            input.setText("");
            output.setText("");
        } catch (FileNotFoundException e) {
            Log.e("m.o2fo.com", "File not found", e);
        } catch (IOException e) {
            Log.e("m.o2fo.com", "IO problem", e);
        } finally {
            try {
                fos.close();
            } catch (IOException e) {
                // ignore, and take the verbosity punch from Java ;)
            }
        }
    }

    private void read() {
        FileInputStream fis = null;
        Scanner scanner = null;
        StringBuilder sb = new StringBuilder();
        try {
            fis = openFileInput("test.txt");
            // scanner does mean one more object, but it"s easier to work with
            scanner = new Scanner(fis);
            while (scanner.hasNextLine()) {
                sb.append(scanner.nextLine() + LINE_SEP);
            }
            Toast.makeText(this, "File read", Toast.LENGTH_SHORT).show();
        } catch (FileNotFoundException e) {
            Log.e("m.o2fo.com", "File not found", e);
        } finally {
            if (fis != null) {
                try {
                    fis.close();
                } catch (IOException e) {
                    // ignore, and take the verbosity punch from Java ;)
                }
            }
            if (scanner != null) {
                scanner.close();
            }
        }
        output.setText(sb.toString());
    }
}