Android学习笔记之数据的内部存储方式实习数据的读写、存储到Cache实现读写
（1）目录结构
（2） 布局文件：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<EditText
android:id="@+id/editText1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginLeft="28dp"
android:layout_marginTop="17dp"
android:ems="10" />
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/editText1"
android:layout_below="@+id/editText1"
android:layout_marginTop="54dp"
android:text="保存信息" />
</RelativeLayout>
（3）保存数据、读取数据的工具类：FileService.java
package com.example.data_storage_interal.file;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import android.content.Context;
/**
* 使用内部存储的方式，可以使应用卸载的时候清除所有的相关信息
*
* @author piaodangdehun
*
*/
public class FileService {
private Context context;
public FileService(Context context) {
this.context = context;
}
/**
* 保存内容到文件中
*
* @param fileName
* : 文件名
* @param mode
* :模式
* @param data
* :数据的缓冲区
* @return 返回真假值
*/
public boolean saveContentToFile(String fileName, int mode, byte[] data) {
boolean flag = false;
FileOutputStream outputStream = null;
try {
outputStream = context.openFileOutput(fileName, mode);
try {
outputStream.write(data, 0, data.length);
} catch (IOException e) {
e.printStackTrace();
}
flag = true;
} catch (FileNotFoundException e) {
e.printStackTrace();
} finally {
if (outputStream != null) {
try {
outputStream.close();
} catch (Exception e2) {
}
}
}
return true;
}
/**
* 读取数据
*
* @param fileName
* @return
*/
public String readContentFromFile(String fileName) {
String result = "";
FileInputStream fileInputStream = null;
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
try {
fileInputStream = context.openFileInput(fileName);
int len = 0;
byte[] data = new byte[1024];
while ((len = fileInputStream.read(data)) != -1) {
outputStream.write(data, 0, len);
}
return new String(outputStream.toByteArray());
} catch (Exception e) {
e.printStackTrace();
}
return "";
}
/*
* 保存文件到Chace中
*/
public boolean saveCacheFile(String fileName, byte[] data) {
boolean flag = false;
File file = context.getFilesDir();
FileOutputStream outputStream = null;
try {
File folderFile = new File(file.getAbsoluteFile() + "/txt");
if (!folderFile.exists()) {
folderFile.mkdirs();// 创建目录
}
// context.openFileOutput("my.txt", context.MODE_WORLD_READABLE);
outputStream = new FileOutputStream(folderFile.getAbsolutePath()
+ "/" + fileName);
try {
outputStream.write(data, 0, data.length);
} catch (IOException e) {
e.printStackTrace();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} finally {
if (outputStream != null) {
try {
outputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
// System.out.println("-->>"+file.getAbsolutePath());
return flag;
}
/*
* 获得文件的完整路径
*/
public void listCacheFile() {
/*
* String[] strings = context.fileList(); for (int i = 0; i <
* strings.length; i++) { System.out.println("-->>" + strings); }
*/
File file = context.getFilesDir();
File root = new File(file.getAbsoluteFile() + "/txt");
File[] listFiles = root.listFiles();
for (File file2 : listFiles) {
System.err.println("--->>" + file2.getAbsolutePath());
}
}
}
（4）MainActivity.java
package com.example.data_storage_interal;
import com.example.data_storage_interal.file.FileService;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends Activity {
private Button button;
private EditText editText;
private FileService fileService;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = (Button) this.findViewById(R.id.button1);
editText = (EditText) this.findViewById(R.id.editText1);
fileService = new FileService(this);
/*
* 按钮点击的时候存放到文件中
*/
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String valueString = editText.getText().toString().trim();
boolean flag = fileService.saveContentToFile("bb.txt",
Context.MODE_APPEND, valueString.getBytes());
if (flag) {
Toast.makeText(MainActivity.this, "保存成功！",
Toast.LENGTH_SHORT).show();
}
}
});
}
@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;
}
}
（5）测试类（要在资源文件中添加相应的信息、这里不说）
package com.example.data_storage_interal;
import com.example.data_storage_interal.file.FileService;
import android.app.Service;
import android.content.Context;
import android.test.AndroidTestCase;
import android.util.Log;
public class MyTest extends AndroidTestCase {
private static final String TAG = "MyTest";
/*
* 保存数据
*/
public void save() {
FileService fileService = new FileService(getContext());
boolean flag = fileService.saveContentToFile("aa.txt",
Context.MODE_PRIVATE + Context.MODE_APPEND, "nihao".getBytes());
Log.i(TAG, "--->>" + flag);
}
/*
* 保存数据
*/
public void read() {
FileService fileService = new FileService(getContext());
String msg = fileService.readContentFromFile("bb.txt");
Log.i(TAG, "--->>" + msg);
}
public void testChaceFile() {
FileService fileService = new FileService(getContext());
fileService.saveCacheFile("hello.txt", "hello world!".getBytes());
}
public void testListFile() {
FileService fileService = new FileService(getContext());
fileService.listCacheFile();
}
}
保存成功后会在data-data-apk的安装目录下找到相应的文件：
