android中SharedPreferences的用法

左手的ㄟ右手 2022-08-05 07:50 115阅读 0赞

SharedPreferences的用法非常简单，因为原理和Map差不多，所以下面给出一个参考程序：

MainActivity.java

import android.content.Context;
    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.TextView;
    
    import java.text.SimpleDateFormat;
    import java.util.Date;
    import java.util.HashSet;
    import java.util.Iterator;
    import java.util.Set;
    
    public class MainActivity extends AppCompatActivity {
        SharedPreferences preferences;
        SharedPreferences.Editor editor;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);
    
            //获取只能被本应用程序读、写的SharedPreferences对象
            preferences = getSharedPreferences("raid", Context.MODE_WORLD_READABLE);
            editor = preferences.edit();
            Button write = (Button)findViewById(R.id.write);
            Button read = (Button)findViewById(R.id.read);
            final TextView txt = (TextView)findViewById(R.id.txt);
            write.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    editor.putBoolean("booleanValue", true);
                    editor.putFloat("floatValue", 12.5f);
                    editor.putInt("intValue", 12);
                    editor.putLong("longValue", 22222222);
                    editor.putString("stringValue", getDateString());
                    Set<String> set = new HashSet<String>();
                    for(int i = 0; i < 3; i++) {
                        set.add("set"+i);
                    }
                    editor.putStringSet("setValue", set);
                    editor.commit();
                }
            });
    
            read.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    StringBuilder sb = new StringBuilder();
                    sb.append(preferences.getBoolean("booleanValue", false) + "\n");
                    sb.append(preferences.getFloat("floatValue", 0.0f) + "\n");
                    sb.append(preferences.getInt("intValue", 0) + "\n");
                    sb.append(preferences.getLong("longValue", 0) + "\n");
                    sb.append(preferences.getString("stringValue", null) + "\n");
                    sb.append("the set is : " + "\n");
                    Set<String> set = preferences.getStringSet("setValue", null);
                    if(set != null) {
                        Iterator<String> iterator = set.iterator();
                        while(iterator.hasNext()) {
                            sb.append(iterator.next() + "\n");
                        }
                    }
                    txt.setText(sb.toString());
                }
            });
        }
    
        private String getDateString() {
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日hh:mm:ss");
            return sdf.format(new Date());
        }
    
    }

main.xml