SharedPreferences

Posted 2020-09-17

使用SharedPreferences将姓名和年龄信息保存到文件，然后再读取，如图所示

主界面代码：

<?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_main"
    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="cn.edu.niit.myapplication5.MainActivity"
    android:orientation="vertical">

    <EditText
        android:id="@+id/name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/name" />
    <EditText
        android:id="@+id/age"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/age"/>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

    </LinearLayout>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:orientation="horizontal">

        <Button
            android:id="@+id/in"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:text="@string/in"
            android:textSize="20sp" />

        <Button
            android:id="@+id/read"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:text="@string/read"
            android:textSize="20sp"/>
    </LinearLayout>
</LinearLayout>
Strings的代码如下：

<resources>
    <string name="app_name">My Application5</string>
    <string name="name">姓名</string>
    <string name="age">年龄</string>
    <string name="in">写入</string>
    <string name="read">读取</string>
</resources>
效果图如下：

Java部分代码如下：

package cn.edu.niit.myapplication5;




        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.Toast;

        import java.io.BufferedReader;
        import java.io.BufferedWriter;
        import java.io.FileInputStream;
        import java.io.FileNotFoundException;
        import java.io.FileOutputStream;
        import java.io.IOException;
        import java.io.InputStreamReader;
        import java.io.OutputStreamWriter;

public class MainActivity extends AppCompatActivity {

    //定义相关组件
    private EditText evname;
    private EditText evage;
    //确定按钮
    private Button in;
    private Button read;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //获取组件
        evname = (EditText) findViewById(R.id.name);
        evage = (EditText) findViewById(R.id.age);
        in= (Button)findViewById(R.id.in);
        //设置按钮监听事件
        in.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String name = evname.getText().toString();
                String age =evage.getText().toString();

                if(saveToFile(name)){
                    Toast.makeText( MainActivity.this,"成功保存" ,Toast.LENGTH_SHORT).show();

                }
            }
        });

        read = (Button)findViewById(R.id.read);
        read.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String username = evname.getText().toString();
                String filename = "data.txt";
                String result = "";
                try{
                    //打开文件，读取数据
                    FileInputStream in = openFileInput( filename );
                    BufferedReader reader = new BufferedReader( new InputStreamReader( in ) );
                    username = reader.readLine();
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                username = evname.getText().toString();
                String age =evage.getText().toString();
                Toast.makeText(MainActivity.this, "输入姓名"+username+",年龄：" + age,Toast.LENGTH_SHORT).show();
            }
        });
    }

    private boolean saveToFile(String userName) {
        try {
            FileOutputStream out = openFileOutput("data.txt",  MODE_PRIVATE );
            BufferedWriter writer = new BufferedWriter( new OutputStreamWriter( out ) );
            writer.write(userName);
            out.close();
            return true;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }