Android 存储方式之文件存储

本人以后附上代码的顺序依次为xml布局文件,AndroidManifest.src文件

xml布局文件,

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/filename"
/>

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

<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/filecontent"
/>

<EditText
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:minLines="3"
android:id="@+id/filecontent"
/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/buttton"
android:id="@+id/button"
/>
</LinearLayout>

AndroidManifest文件

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="cn.itcast.file"
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=".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>
<uses-sdk android:minSdkVersion="8" />

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

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

<instrumentation android:name="android.test.InstrumentationTestRunner"
android:targetPackage="cn.itcast.file" android:label="Tests for My App" />
</manifest>

src文件

package cn.itcast.file;

import cn.itcast.service.FileService;
import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {
private static final String TAG = "MainActivity";
private EditText filenameText;
private EditText filecontentText;
private FileService service;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

service = new FileService(this);

filenameText = (EditText)this.findViewById(R.id.filename);
filecontentText = (EditText)this.findViewById(R.id.filecontent);
Button button = (Button)this.findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String filename = filenameText.getText().toString();
String content = filecontentText.getText().toString();
try {
if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
service.saveToSDCard(filename, content);
Toast.makeText(MainActivity.this, R.string.success, 1).show();
}else{
Toast.makeText(MainActivity.this, R.string.sdcarderror, 1).show();
}
} catch (Exception e) {
Log.e(TAG, e.toString());
Toast.makeText(MainActivity.this, R.string.error, 1).show();
}
}
});
}
}

package cn.itcast.service;

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

import android.content.Context;
import android.os.Environment;

public class FileService {
private Context context;

public FileService(Context context) {
this.context = context;
}

public void saveToSDCard(String filename, String content) throws Exception{
File file = new File(Environment.getExternalStorageDirectory(), filename);
FileOutputStream outStream = new FileOutputStream(file);
outStream.write(content.getBytes());
outStream.close();
}

public void save(String filename, String content) throws Exception{
FileOutputStream outStream = context.openFileOutput(filename, Context.MODE_PRIVATE);
outStream.write(content.getBytes());
outStream.close();
}

public void saveAppend(String filename, String content) throws Exception{// ctrl+shift+y
FileOutputStream outStream = context.openFileOutput(filename, Context.MODE_APPEND);
outStream.write(content.getBytes());
outStream.close();
}

public void saveReadable(String filename, String content) throws Exception{
FileOutputStream outStream = context.openFileOutput(filename, Context.MODE_WORLD_READABLE);
outStream.write(content.getBytes());
outStream.close();
}

public void saveWriteable(String filename, String content) throws Exception{
FileOutputStream outStream = context.openFileOutput(filename, Context.MODE_WORLD_WRITEABLE);
outStream.write(content.getBytes());
outStream.close();
}

public void saveRW(String filename, String content) throws Exception{
FileOutputStream outStream = context.openFileOutput(filename, Context.MODE_WORLD_WRITEABLE + Context.MODE_WORLD_READABLE);
outStream.write(content.getBytes());
outStream.close();
}

public String getContent(String filename) throws Exception{
FileInputStream inStream = context.openFileInput(filename);
ByteArrayOutputStream outStream = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = 0;
while( (len = inStream.read(buffer)) != -1){
outStream.write(buffer, 0, len);
}
byte[] data = outStream.toByteArray();
inStream.close();
outStream.close();
return new String(data);
}
}

测试类：

package cn.itcast.file;

import cn.itcast.service.FileService;
import android.test.AndroidTestCase;
import android.util.Log;

public class FileServiceTest extends AndroidTestCase {
private static final String TAG = "FileServiceTest";

public void testReadFile() throws Throwable{
FileService service = new FileService(this.getContext());
String content = service.getContent("itcast.txt");
Log.i(TAG, content);
}

public void testSaveAppend() throws Throwable{
FileService service = new FileService(this.getContext());
service.saveAppend("append.txt", ",http://www.sohu.com");
}

public void testSaveReadable() throws Throwable{
FileService service = new FileService(this.getContext());
service.saveReadable("readable.txt", ",http://www.csdn.com");
}

public void testSaveWriteable() throws Throwable{
FileService service = new FileService(this.getContext());
service.saveWriteable("writeable.txt", "http://www.babasport.com");
}

public void testSaveRW() throws Throwable{
FileService service = new FileService(this.getContext());
service.saveRW("rw.txt", "http://www.sina.com");
}
}

看懂代码基本上文件保存就没太大问题，可以的话自己写个Demo，可能会因为代码的不熟悉碰到一些问题，不过没关系。

I0的流操作，在不懂的情况下可以查询API，毕竟IO流的操作类还是比较多的。但是流的思维方式是必须有的。

还有就是注意下权限问题

FileOutputStream outStream = context.openFileOutput(filename, Context.MODE_WORLD_WRITEABLE);

MODE_WORLD_WRITEABLE，还有代码其他几种权限这里不多做解释，相信看英文也能明白。

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