java - 安卓 : Getting error "cannot resolve getSharedPreferences(java.lang.String, int)"

Question

我尝试访问非 Activity 类中的 SharedPreferences，但总是收到此错误 cannot parse getSharedPreferences(java.lang.String, int) 。但是当我在正常 Activity 类中使用 getSharedPreferences 时，我不会收到此错误。

有人知道如何解决这个问题吗？

这是我的代码:

public class ConnectionClass {

SharedPreferences pref = getSharedPreferences("MyPrefs", Context.MODE_PRIVATE);
String ip = pref.getString("serverIP", "");

// String ip = "";
// String ip = server_IP;
String classDriver = "net.sourceforge.jtds.jdbc.Driver";
String db = "passoDB";
String un = "sa";
String password = "dhen1234";

@SuppressLint("NewApi")
public Connection CONN(Context context) {

    StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder()
            .permitAll().build();
    StrictMode.setThreadPolicy(policy);
    Connection conn = null;
    String ConnURL = null;
    try {
        Class.forName(classDriver);
        ConnURL = "jdbc:jtds:sqlserver://" + ip + ";"
                + "databaseName=" + db + ";user=" + un + ";password="
                + password + ";";
        conn = DriverManager.getConnection(ConnURL);
    } catch (SQLException se) {
        Log.e("ERRO", se.getMessage());
    } catch (ClassNotFoundException e) {
        Log.e("ERRO", e.getMessage());
    } catch (Exception e) {
        Log.e("ERRO", e.getMessage());
    }
    return conn;
}
}

Answer 1

是的，正如西蒙所说，要访问共享首选项，您需要上下文，因此为了使该代码正常工作，我将添加这一行。

    public class ConnectionClass {


String classDriver = "net.sourceforge.jtds.jdbc.Driver";
String db = "passoDB";
String un = "sa";
String password = "dhen1234";


 String ip = "";


 public ConnectionClass(Context context){
        SharedPreferences prefs = context.getSharedPreferences("MyPrefs", context.MODE_PRIVATE);
        ip = prefs.getString("serverIP", "");

 }


@SuppressLint("NewApi")
public Connection CONN(Context context) {

    StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder()
            .permitAll().build();
    StrictMode.setThreadPolicy(policy);
    Connection conn = null;
    String ConnURL = null;
    try {
        Class.forName(classDriver);
        ConnURL = "jdbc:jtds:sqlserver://" + ip + ";"
                + "databaseName=" + db + ";user=" + un + ";password="
                + password + ";";
        conn = DriverManager.getConnection(ConnURL);
    } catch (SQLException se) {
        Log.e("ERRO", se.getMessage());
    } catch (ClassNotFoundException e) {
        Log.e("ERRO", e.getMessage());
    } catch (Exception e) {
        Log.e("ERRO", e.getMessage());
    }
    return conn;
}
}

我没有正确缩进，希望有帮助。

在调用类时，您应该这样调用:

ConnectionClass connectionClass = new ConnectionClass(YourActivity.this);//if in activity

ConnectionClass connectionClass = new ConnectionClass(getActivity());//if in fragment