2022-10-28学习内容

1.SharedPreferences用法

1.1activity_share_write.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="5dp">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/tv_name"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:gravity="center"
            android:text="姓名："
            android:textColor="@color/black"
            android:textSize="17sp" />

        <EditText
            android:id="@+id/et_name"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:layout_marginTop="3dp"
            android:layout_marginBottom="3dp"
            android:background="@drawable/editext_selector"
            android:hint="请输入姓名"
            android:inputType="text"
            android:maxLength="12"
            android:textColor="@color/black"
            android:textSize="17sp" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/tv_age"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:gravity="center"
            android:text="年龄："
            android:textColor="@color/black"
            android:textSize="17sp" />

        <EditText
            android:id="@+id/et_age"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:layout_marginTop="3dp"
            android:layout_marginBottom="3dp"
            android:background="@drawable/editext_selector"
            android:hint="请输入年龄"
            android:inputType="number"
            android:maxLength="2"
            android:textColor="@color/black"
            android:textSize="17sp" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/tv_height"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:gravity="center"
            android:text="身高："
            android:textColor="@color/black"
            android:textSize="17sp" />

        <EditText
            android:id="@+id/et_height"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:layout_marginTop="3dp"
            android:layout_marginBottom="3dp"
            android:background="@drawable/editext_selector"
            android:hint="请输入身高"
            android:inputType="number"
            android:maxLength="3"
            android:textColor="@color/black"
            android:textSize="17sp" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/tv_weight"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:gravity="center"
            android:text="体重："
            android:textColor="@color/black"
            android:textSize="17sp" />

        <EditText
            android:id="@+id/et_weight"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:layout_marginTop="3dp"
            android:layout_marginBottom="3dp"
            android:background="@drawable/editext_selector"
            android:hint="请输入体重"
            android:inputType="numberDecimal"
            android:maxLength="5"
            android:textColor="@color/black"
            android:textSize="17sp" />

    </LinearLayout>

    <CheckBox
        android:id="@+id/ck_married"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:checked="false"
        android:gravity="center"
        android:text="已婚"
        android:textColor="@color/black"
        android:textSize="17sp" />

    <Button
        android:id="@+id/btn_save"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="保存到共享参数"
        android:textColor="@color/black"
        android:textSize="17sp" />

</LinearLayout>

1.2ShareWriteActivity.java

package com.example.chapter06;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.widget.CheckBox;
import android.widget.EditText;

public class ShareWriteActivity extends AppCompatActivity implements View.OnClickListener {

    private EditText et_name;
    private EditText et_age;
    private EditText et_height;
    private EditText et_weight;
    private CheckBox ck_married;
    private SharedPreferences preferences;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_share_write);
        et_name = findViewById(R.id.et_name);
        et_age = findViewById(R.id.et_age);
        et_height = findViewById(R.id.et_height);
        et_weight = findViewById(R.id.et_weight);
        ck_married = findViewById(R.id.ck_married);

        findViewById(R.id.btn_save).setOnClickListener(this);

        preferences = getSharedPreferences("config", Context.MODE_PRIVATE);
        reload();
    }

    private void reload() {
        String name = preferences.getString("name", null);
        if (name != null) {
            et_name.setText(name);
        }
        int age = preferences.getInt("age", 0);
        if (age != 0) {
            et_age.setText(String.valueOf(age));
        }
        float height = preferences.getFloat("height", 0f);
        if (height != 0f) {
            et_height.setText(String.valueOf(height));
        }
        float weight = preferences.getFloat("weight", 0f);
        if (height != 0f) {
            et_weight.setText(String.valueOf(weight));
        }
        boolean married = preferences.getBoolean("married", false);
        ck_married.setChecked(married);
    }

    @Override
    public void onClick(View v) {
        String name = et_name.getText().toString();
        String age = et_age.getText().toString();
        String height = et_height.getText().toString();
        String weight = et_weight.getText().toString();

        SharedPreferences.Editor editor = preferences.edit();
        editor.putString("name", name);
        editor.putInt("age", Integer.parseInt(age));
        editor.putFloat("height", Float.parseFloat(height));
        editor.putFloat("weight", Float.parseFloat(weight));
        editor.putBoolean("married", ck_married.isChecked());
        editor.commit();

    }
}

1.3效果：

 退出应用，重新进入，从SharedPreferences中读取：

 

 SharedPreferences文件位置：

 

 

 

 1.4config.xml

<?xml version='1.0' encoding='utf-8' standalone='yes' ?>
<map>
    <string name="name">ceshi</string>
    <float name="weight" value="110.0" />
    <boolean name="married" value="true" />
    <int name="age" value="27" />
    <float name="height" value="170.0" />
</map>