Android开发——数据存储之文件存储


通过openFileOutput和openFileInputput方法现。


写文件使用OutStream,可以通过openFileOutput方法 获得OutStream对象。

写文件使用InStream,可以通过openFileInput方法 获得InStream对象。

例子：

程序清单1

File.java

package xiaocool.net.memory;

import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

import android.widget.Toast;

import java.io.InputStream;

import java.io.OutputStream;

/**

* Created by lrenovo G480 on 2015/3/21.

*/

public class FileActivity extends Activity {

private Button bt1,bt2;

private EditText et1,et2;

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.file);

bt1 = (Button) this.findViewById(R.id.button);

bt2 = (Button) this.findViewById(R.id.button2);

et1 = (EditText) this.findViewById(R.id.editText);

et2 = (EditText) this.findViewById(R.id.editText2);

bt1.setOnClickListener(new Button.OnClickListener(){

public void onClick(View v){

write(et1.getText().toString());

Toast.makeText(FileActivity.this, "文件写入成功", Toast.LENGTH_LONG)

.show();

}

});

bt2.setOnClickListener(new Button.OnClickListener(){

public void onClick(View v){

et2.setText(read());

Toast.makeText(FileActivity.this, "文件读取成功", Toast.LENGTH_LONG)

.show();

}

});

}

private void write(String str) {

try {

OutputStream a = openFileOutput("file.txt", Activity.MODE_PRIVATE);

a.write(str.getBytes());

a.close();

}

catch (Exception e) {

}

}

private String read() {

try {

InputStream inputStream = openFileInput("file.txt");

byte[] b = new byte[inputStream.available()];

inputStream.read(b);

return new String(b);

}

catch (Exception e) {

}

return null;

}

}

程序清单2

file.xml

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

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

android:layout_width="match_parent" android:layout_height="match_parent">

<Button

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="写文件"

android:id="@+id/button"

android:layout_weight="1"

android:layout_gravity="center_vertical"

android:layout_below="@+id/editText"

android:layout_centerHorizontal="true"

android:layout_marginTop="48dp" />

<EditText

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:inputType="phone"

android:ems="10"

android:id="@+id/editText"

android:layout_weight="1"

android:layout_alignParentTop="true"

android:layout_centerHorizontal="true"

android:layout_marginTop="57dp" />

<EditText

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:inputType="phone"

android:ems="10"

android:id="@+id/editText2"

android:layout_centerVertical="true"

android:layout_alignLeft="@+id/editText"

android:layout_alignStart="@+id/editText" />

<Button

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="读文件"

android:id="@+id/button2"

android:layout_marginTop="50dp"

android:layout_below="@+id/editText2"

android:layout_alignLeft="@+id/button"

android:layout_alignStart="@+id/button" />

</RelativeLayout>

效果图：