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Android开发——数据存储(二)File内部存储
内部存储特点
代码示例
FileStorageActivity的java文件
package com.example.administrator.exercise.datastorage;
import android.content.SharedPreferences;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import com.example.administrator.exercise.R;
import com.example.administrator.exercise.util.ToastUtil;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
public class FileStorageActivity extends AppCompatActivity {
private EditText editText;
private Button button_save,button_display;
private TextView textView;
private final static String filename= "text.txt";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_file_storage);
editText = (EditText) findViewById(R.id.fs_et_input);
textView = (TextView) findViewById(R.id.fs_tv_display);
//连接保存按钮
button_save = (Button) findViewById(R.id.fs_btn_save);
//连接显示按钮
button_display = (Button) findViewById(R.id.fs_btn_display);
button_save.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
writeData(editText.getText().toString());
ToastUtil.showMsg(FileStorageActivity.this,"保存成功");
}
});
button_display.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
textView.setText(readData());
ToastUtil.showMsg(FileStorageActivity.this,"读取成功");
}
});
}
//存储数据
private void writeData(String content){
FileOutputStream fileOutputStream = null;
try {
//创建存储目标
fileOutputStream = openFileOutput(filename,MODE_PRIVATE);
//字节方式存储方法
fileOutputStream.write(content.getBytes());
} catch (IOException e) {
e.printStackTrace();
}
finally {
//关闭流
if(fileOutputStream!=null)
try {
fileOutputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
//读取数据
private String readData(){
FileInputStream fileInputStream = null;
try {
//获取读取文件
fileInputStream = openFileInput(filename);
//设置一次读取字节数
byte[] buff = new byte[1024];
//获取stringBuilder
StringBuilder stringBuilder = new StringBuilder("");
int len = 0;
//循环读取
while((len = fileInputStream.read(buff)) > 0 ){
stringBuilder.append(new String(buff,0,len));
}
//返回读取数据
return stringBuilder.toString();
} catch (IOException e) {
e.printStackTrace();
}
finally {
//关闭流
try {
fileInputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
}
布局文件
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_shared_preferences"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<EditText
android:layout_width="match_parent"
android:layout_height="50dp"
android:hint="请输入数据"
android:id="@+id/fs_et_input"
/>
<Button
android:layout_width="match_parent"
android:layout_height="50dp"
android:text="保存"
android:textSize="16sp"
android:id="@+id/fs_btn_save"/>
<Button
android:layout_width="match_parent"
android:layout_height="50dp"
android:text="显示"
android:textSize="16sp"
android:id="@+id/fs_btn_display"/>
<TextView
android:layout_width="match_parent"
android:layout_height="50dp"
android:id="@+id/fs_tv_display"/>
</LinearLayout>
运行结果图
存储位置
data/data/ApplicationID(包名)/files/文件名