Android本地存储方法浅析介绍

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >
    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/editText"
        android:hint="请输入内容"/>
</LinearLayout>

private fun save(inputText: String) {
    try {
        // 打开输出文件，如果不存在就新建一个
        val output = openFileOutput("data", Context.MODE_PRIVATE)
        // 设置输出流
        val writer = BufferedWriter(OutputStreamWriter(output))
        // 使用use语法，在输出所有内容完毕后就会自动关闭流，不需要手动关闭了！
        writer.use {
            it.write(inputText)
        }
    } catch (e: IOException) {
        e.printStackTrace()
    }
}

private fun load(): String {
    // 存储获取到的文本
    val content = StringBuilder()
    try {
        // 打开文件
        val input = openFileInput("data")
        // 设置输入流
        val reader = BufferedReader(InputStreamReader(input))
        reader.use {
            // 逐行输入到content变量
            reader.forEachLine {
                content.append(it)
            }
        }
    } catch (e: IOException) {
        e.printStackTrace()
    }
    // 返回得到的文字文本数据
    return content.toString()
}

package com.zhiyiyi.listviewdemo
import android.content.Context
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Toast
import kotlinx.android.synthetic.main.activity_main.*
import java.io.*
class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        // activity打开前读取存储的文件，拿出内容
        val inputText = load()
        if (inputText.isNotEmpty()) {
            editText.setText(inputText)
            editText.setSelection(inputText.length)
            Toast.makeText(this, "Restoring succeeded", Toast.LENGTH_SHORT).show()
        }
    }
    // activity销毁前执行存储方法
    override fun onDestroy() {
        super.onDestroy()
        val inputText = editText.text.toString()
        save(inputText)
    }
    // 存储
    private fun save(inputText: String) {
        try {
            val output = openFileOutput("data", Context.MODE_PRIVATE)
            val writer = BufferedWriter(OutputStreamWriter(output))
            writer.use {
                it.write(inputText)
            }
        } catch (e: IOException) {
            e.printStackTrace()
        }
    }
    // 读取
    private fun load(): String {
        val content = StringBuilder()
        try {
            val input = openFileInput("data")
            val reader = BufferedReader(InputStreamReader(input))
            reader.use {
                reader.forEachLine {
                    content.append(it)
                }
            }
        } catch (e: IOException) {
            e.printStackTrace()
        }
        return content.toString()
    }
}