activity_data1.xml

<?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: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="com.hanqi.test5.DataActivity1"
android:orientation="vertical"> <EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/et_1"
android:hint="key"/> <EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/et_2"
android:hint="value"/> <LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"> <Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="保存"
android:layout_weight="1"
android:onClick="bt1_OnClick"/> <Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="读取"
android:layout_weight="1"
android:onClick="bt2_OnClick"/>
</LinearLayout> <EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/et_3"
android:hint="要存储的内容"/> <EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/et_4"
android:hint="从文件中读取的内容"/> <LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"> <Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="保存"
android:layout_weight="1"
android:onClick="bt3_OnClick"/> <Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="读取"
android:layout_weight="1"
android:onClick="bt4_OnClick"/>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"> <Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="保存文件"
android:layout_weight="1"
android:onClick="bt5_OnClick"/> <Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="读取文件"
android:layout_weight="1"
android:onClick="bt6_OnClick"/>
</LinearLayout>
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/vipflower"
android:id="@+id/iv_4"/>
</LinearLayout>

DataActivity1.java

package com.hanqi.test5;

import android.content.SharedPreferences;
import android.content.res.AssetManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast; import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.PrintStream; public class DataActivity1 extends AppCompatActivity { EditText et_1;
EditText et_2; EditText et_3;
EditText et_4; ImageView iv_4; SharedPreferences sp; @Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_data1); et_1 = (EditText)findViewById(R.id.et_1);
et_2 = (EditText)findViewById(R.id.et_2); et_3 = (EditText)findViewById(R.id.et_3);
et_4 = (EditText)findViewById(R.id.et_4); iv_4 = (ImageView)findViewById(R.id.iv_4); //1.获取sp实例,指定了文件名和操作模式
sp = getSharedPreferences("mydata",MODE_PRIVATE); } //操作assets内的文件
public void bt5_OnClick(View v)
{
//1.获取AssetManager管理器
AssetManager am = getAssets(); try
{
//2.打开文件,获取输入流
InputStream is = am.open("yuantu.png"); //3.获取输出流
FileOutputStream fos = openFileOutput("yuantu.png",MODE_PRIVATE); //4.边读边写
byte[] b = new byte[1024]; int i =0; while ((i = is.read(b))>0)
{
fos.write(b,0,i);
}
fos.close();
is.close(); Toast.makeText(DataActivity1.this, "保存成功", Toast.LENGTH_SHORT).show(); }
catch (Exception e)
{
e.printStackTrace();
Toast.makeText(DataActivity1.this, "保存失败", Toast.LENGTH_SHORT).show();
}
} //从手机内部存储读图片文件
public void bt6_OnClick(View v)
{
//改变ImageView的图片来源,指向手机存储空间 //1.获取文件存储的绝对路径
String filepath = getFilesDir().getAbsolutePath(); //2.组合图片文件的完整路径
filepath += "/yuantu.png"; //3.生成位图实例
Bitmap bm = BitmapFactory.decodeFile(filepath); //4.改变ImageView的图片来源
iv_4.setImageBitmap(bm);
} //文件名
final String FILENAME = "test.txt";
public void bt3_OnClick(View v)
{
//1.获取要存储的内容
String content = et_3.getText().toString();
//2.获取输出流
try
{
FileOutputStream fos_1 = openFileOutput(FILENAME,MODE_APPEND); //3.构造PrintStream
PrintStream pm = new PrintStream(fos_1); //4.写入内容
pm.println(content); //5.关闭
pm.close(); fos_1.close(); Toast.makeText(DataActivity1.this, "保存成功", Toast.LENGTH_SHORT).show();
}
catch (Exception e)
{
e.printStackTrace(); Toast.makeText(DataActivity1.this, "保存失败", Toast.LENGTH_SHORT).show();
}
} public void bt4_OnClick(View v)
{
try
{
//1.获取输入流
FileInputStream fis = openFileInput(FILENAME); //2.定义读取的数组
byte[] b = new byte[1024]; //3.读出的数据的长度
int i =0; StringBuilder sb_1 = new StringBuilder(); while ((i=fis.read(b))>0)
{
sb_1.append(new String(b,0,i) );
}
fis.close(); //设置显示读出内容
et_4.setText(sb_1); Toast.makeText(DataActivity1.this, "读取成功", Toast.LENGTH_SHORT).show();
}
catch (Exception e)
{
e.printStackTrace();
Toast.makeText(DataActivity1.this, "读取失败", Toast.LENGTH_SHORT).show();
}
} //保存
public void bt1_OnClick(View v) {
//1.获取key和value
String key = et_1.getText().toString();
String value = et_2.getText().toString(); if (key.length() == 0 || value.length() == 0) {
Toast.makeText(DataActivity1.this, "key或value不能为空", Toast.LENGTH_SHORT).show();
}
else {
//2.取得Editor
SharedPreferences.Editor editor = sp.edit(); //3.放入键值对
editor.putString(key, value); //4.提交保存
boolean b = editor.commit(); if (b) {
Toast.makeText(DataActivity1.this, "保存成功", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(DataActivity1.this, "保存失败", Toast.LENGTH_SHORT).show();
}
}
}
//读取
public void bt2_OnClick(View v)
{ //1.获取要读的key
String key = et_1.getText().toString(); //2.读并设置文本框
et_2.setText(sp.getString(key, "没有发现key")); } }

数据存储总结之思维导图:

Android课程---关于数据存储的学习-LMLPHP

05-11 14:03