Android數(shù)據(jù)存儲(chǔ)(2)向機(jī)身內(nèi)存(Internal Storage)和SDcard(External Storage)讀寫數(shù)據(jù)實(shí)例

天海544 2014-01-10

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總的來說向內(nèi)存和SDcard中讀寫數(shù)據(jù)和java io操作基本差不多而機(jī)身內(nèi)存讀取和SDcard讀取數(shù)據(jù)有少許差別

機(jī)身內(nèi)存數(shù)據(jù)讀寫

1.機(jī)身內(nèi)存讀取主要用個(gè)兩個(gè)類文件輸入流(FileInputStream)和文件輸出流(FileOutputStream): FileInputStream fileInput = this.openFileInput("test.txt") 第一個(gè)參數(shù)為 data/此程序包名/data/test.txt 文件下的文件名 ;

FileOutputStream fileOut = this.openFileOutput("test.txt",this.MODE_APPEND)第一個(gè)參數(shù)表示文件名第二個(gè)參數(shù)表示打開的方式

2.獲取了文件輸入輸出流之后其后的文件的讀寫和基本的IO操作一樣

SDcard數(shù)據(jù)讀寫

1.SDcard數(shù)據(jù)讀寫需要注定的先要在Androidmainfest.xml文件中注冊(cè)新建刪除和讀寫的權(quán)限 :

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

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

2.讀寫的基本流程就是:

2. 1 通過Environment類的getExternalStorageState()方法來判斷手機(jī)是否有SDcard: Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)

2.2 最通過getExternalStorageDirectory()方法來獲取文件目錄:File file = new File(Environment.getExternalStorageDirectory().getCanonicalPath() + "/test.txt"); 讀寫的文件都在sdcrad文件夾中通過File Explorer可以導(dǎo)出來

2.3 其后就和基本IO操作相同了

2.4還有要注意一點(diǎn)的是在運(yùn)行的模擬器的時(shí)候要附帶虛擬的SDcard時(shí) 要在Run as->Run Configurations 中要關(guān)聯(lián)一下如下圖

機(jī)身內(nèi)存數(shù)據(jù)讀寫實(shí)例

[html] view plain copy

<LinearLayout xmlns:android="http://schemas./apk/res/android"
xmlns:tools="http://schemas./tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center_horizontal"
android:orientation="vertical"
tools:context=".MainActivity" >
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/ed1"
android:inputType="textMultiLine"/>
<Button
android:id="@+id/write"
android:text="寫入"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
<Button
android:id="@+id/read"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="讀入"/>
<EditText
android:id="@+id/ed2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="textMultiLine"/>
<Button
android:id="@+id/delete"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="刪除指定的文件"
/>
<EditText
android:id="@+id/ed3"
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>

[java] view plain copy

package com.android.xiong.fileiotest;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
public class MainActivity extends Activity {
private Button read;
private Button write;
private EditText ed1;
private EditText ed2;
private EditText ed3;
private Button delete;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
read = (Button) findViewById(R.id.read);
write = (Button) findViewById(R.id.write);
delete = (Button) findViewById(R.id.delete);
ed3 = (EditText) findViewById(R.id.ed3);
ed2 = (EditText) findViewById(R.id.ed2);
ed1 = (EditText) findViewById(R.id.ed1);
write.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String str = ed1.getText().toString();
if (!str.equals("")) {
write(str);
}
}
});
read.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
read();
}
});
delete.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String str = ed3.getText().toString();
if (!str.equals("")) {
deleteFiles(str);
} else {
ed3.setText(str + ":該文件輸入錯(cuò)誤或不存在!");
}
}
});
}
private void write(String content) {
try {
// 以追加的方式打開文件輸出流
FileOutputStream fileOut = this.openFileOutput("test.txt",
this.MODE_APPEND);
// 寫入數(shù)據(jù)
fileOut.write(content.getBytes());
// 關(guān)閉文件輸出流
fileOut.close();
} catch (Exception e) {
e.printStackTrace();
}
}
private void read() {
try {
ed2.setText("");
// 打開文件輸入流
FileInputStream fileInput = this.openFileInput("test.txt");
BufferedReader br = new BufferedReader(new InputStreamReader(
fileInput));
String str = null;
StringBuilder stb = new StringBuilder();
while ((str = br.readLine()) !=null ) {
stb.append(str);
}
ed2.setText(stb);
} catch (Exception e) {
e.printStackTrace();
}
}
//刪除指定的文件
private void deleteFiles(String fileName) {
try {
// 獲取data文件中的所有文件列表
List<String> name = Arrays.asList(this.fileList());
if (name.contains(fileName)) {
this.deleteFile(fileName);
ed3.setText(fileName + ":該文件成功刪除！");
} else
ed3.setText(fileName + ":該文件輸入錯(cuò)誤或不存在!");
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}

SDcard數(shù)據(jù)讀寫實(shí)例

[html] view plain copy

<LinearLayout xmlns:android="http://schemas./apk/res/android"
xmlns:tools="http://schemas./tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center_horizontal"
android:orientation="vertical"
tools:context=".MainActivity" >
<EditText
android:id="@+id/ed1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="textMultiLine"/>
<Button
android:id="@+id/write"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="寫入SD卡中"/>
<Button
android:id="@+id/read"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="讀取SD文件"/>
<TextView
android:id="@+id/txt1"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
</LinearLayout>

[html] view plain copy

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas./apk/res/android"
package="com.android.xiong.sdcardtest"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="14"
android:targetSdkVersion="17" />
<uses-permission android:name="android.permission.MOUNT_FORMAT_FILESYSTEMS" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.android.xiong.sdcardtest.MainActivity"
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>
</manifest>

[java] view plain copy

package com.android.xiong.sdcardtest;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends Activity {
private Button write;
private Button read;
private EditText ed1;
private TextView txt1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
write = (Button) findViewById(R.id.write);
read = (Button) findViewById(R.id.read);
ed1 = (EditText) findViewById(R.id.ed1);
txt1 = (TextView) findViewById(R.id.txt1);
write.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
writeSDcard(ed1.getText().toString());
}
});
read.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
txt1.setText(readSDcard());
}
});
}
// 把數(shù)據(jù)寫入SD卡
private void writeSDcard(String str) {
try {
// 判斷是否存在SD卡
if (Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED)) {
// 獲取SD卡的目錄
File file = Environment.getExternalStorageDirectory();
FileOutputStream fileW = new FileOutputStream(file.getCanonicalPath() + "/test.txt");
fileW.write(str.getBytes());
fileW.close();
}
} catch (Exception e) {
e.printStackTrace();
}
}
// 從SD卡中讀取數(shù)據(jù)
private String readSDcard() {
StringBuffer str = new StringBuffer();
try {
// 判斷是否存在SD
if (Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED)) {
File file = new File(Environment.getExternalStorageDirectory()
.getCanonicalPath() + "/test.txt");
// 判斷是否存在該文件
if (file.exists()) {
// 打開文件輸入流
FileInputStream fileR = new FileInputStream(file);
BufferedReader reads = new BufferedReader(
new InputStreamReader(fileR));
String st = null;
while ((st =reads.readLine())!=null ) {
str.append(st);
}
fileR.close();
} else {
txt1.setText("該目錄下文件不存在");
}
}
} catch (Exception e) {
e.printStackTrace();
}
return str.toString();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}

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