一、基本介绍
- 属于一个轻量级的存储框架
- 以key-value形式保存
- 保存在data/data/package name/shared_prefs目录下
- 可以保存的数据类型：booleans, floats, ints, longs,strings
二、步骤
- 获取SharedPreferences对象
- 通过SharedPreferences对象读取数据
- 通过SharedPreferences对象存储数据
public class MainActivity extends AppCompatActivity {
private String TAG = "MainActivity";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//取值
SharedPreferences settings = getSharedPreferences("login", 0);
String username = settings.getString("username","");
Long password = settings.getLong("password",0);
float salary = settings.getFloat("salary",0f);
Boolean sex = settings.getBoolean("sex",false);
Log.i(TAG,"--------"+username);
Log.i(TAG,"--------"+password);
Log.i(TAG,"--------"+salary);
Log.i(TAG,"--------"+sex);
}
@Override
protected void onStop(){
super.onStop();
//写值
Map<String,Object> map = new HashMap<>();
map.put("username","zhangsan");
map.put("password",123456l);
map.put("salary",1234.34f);
map.put("sex",false);
//文件名不需要后缀名，默认xml
savaSharedPreferences("login",map);
}
public Boolean savaSharedPreferences(String fileName, Map<String,Object> map){
//获取SharedPreferences对象
SharedPreferences preferences = getSharedPreferences(fileName,Context.MODE_PRIVATE);
SharedPreferences.Editor edit = preferences.edit();
for (Map.Entry<String,Object> entry:map.entrySet()){
String key = entry.getKey();
Object values = entry.getValue();
if (values instanceof String){
edit.putString(key,(String)values);
} else if(values instanceof Boolean){
edit.putBoolean(key,(Boolean)values);
} else if(values instanceof Long){
edit.putLong(key,(Long)values);
} else if (values instanceof Float){
edit.putFloat(key,(Float)values);
}else if(values instanceof Integer){
edit.putInt(key,(Integer)values);
}
}
//提交
boolean commit = edit.commit();
return commit;
}
}
保存的文件格式如下：
<?xml version='1.0' encoding='utf-8' standalone='yes' ?>
<map>
<string name="password">1236</string>
<boolean name="isRemember" value="true" />
<boolean name="forget" value="false" />
<string name="userName">张三</string>
</map>
三、案例
案例描述：当我们输入用户名和密码后，点击记住密码，那我们下次登录时账号密码就会默认显示，不勾选记住密码则下次登录则需要自己输入
效果图如下：
代码如下：
<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:orientation="vertical"
tools:context=".MainActivity">
<EditText
android:id="@+id/editTextuserName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:hint="用户名"
android:inputType="text" />
<EditText
android:id="@+id/editTextPassword"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:hint="密码"
android:inputType="textPassword" />
<CheckBox
android:id="@+id/isRemember"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="记住密码" />
<Button
android:id="@+id/btnLogin"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="登录" />
<Button
android:id="@+id/btnRegister"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="注册" />
</LinearLayout>
public class MainActivity extends PreferenceActivity {
private String TAG = "MainActivity";
private EditText edtUserName,edtPassWord;
private Button btnLogin,btnRegister;
private CheckBox isRemember;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
findView();
//获取文件数据
Map<String, ?> map = getSharePreference();
if (map != null && !map.isEmpty()){
String userName = map.get("userName").toString().trim();
String password = map.get("password").toString().trim();
Boolean isBeRe = (Boolean) map.get("isRemember");
Boolean isforget = (Boolean) map.get("forget");
edtUserName.setText(userName);
edtPassWord.setText(password);
isRemember.setChecked(isBeRe);
}
//登录点击事件
btnLogin.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Map<String,Object> map = new HashMap<>();
//是否勾选记住密码
if (isRemember.isChecked()){
map.put("userName",edtUserName.getText().toString());
map.put("password",edtPassWord.getText().toString());
map.put("isRemember",isRemember.isChecked());
savaSharePreference(map);
}else{
map.put("userName","");
map.put("password","");
map.put("isRemember",isRemember.isChecked());
savaSharePreference(map);
}
}
});
}
public void findView(){
edtUserName = findViewById(R.id.editTextuserName);
edtPassWord = findViewById(R.id.editTextPassword);
btnLogin = findViewById(R.id.btnLogin);
isRemember = findViewById(R.id.isRemember);
}
/**
* 将数据保存到文件
* @param map 数据内容
* @return
*/
public boolean savaSharePreference(Map<String,Object> map){
//获取SharedPreferences对象
SharedPreferences preferences = getSharedPreferences("login",MODE_PRIVATE);
SharedPreferences.Editor edit = preferences.edit();
for (Map.Entry<String,Object> entry:map.entrySet()){
String key = entry.getKey();
Object values = entry.getValue();
if (values instanceof String){
edit.putString(key,(String)values);
} else if(values instanceof Boolean){
edit.putBoolean(key,(Boolean)values);
} else if(values instanceof Long){
edit.putLong(key,(Long)values);
} else if (values instanceof Float){
edit.putFloat(key,(Float)values);
}else if(values instanceof Integer){
edit.putInt(key,(Integer)values);
}
}
boolean flag = edit.commit();
return flag;
}
/*
获取文件内容
*/
public Map<String, ?> getSharePreference(){
SharedPreferences preferences = getSharedPreferences("login",MODE_PRIVATE);
Map<String, ?> map = preferences.getAll();
return map;
}
}