如何在Android中缓存/保存自定义类对象？

Question

我想将ArrayList<CustomClass>-object 保存到Android存储中的某个位置以快速检索并在其中显示数据。

这可能吗？如果可以，那么SQLite或外部存储适合哪种技术？

Answer 1

例。

public class MyClass implements Serializable 
{
    private static final long serialVersionUID = 1L;

    public String title;
    public String startTime;
    public String endTime;
    public String day;

    public boolean classEnabled;


    public MyClass(String title, String startTime, boolean enable) {
        this.title = title;
        this.startTime = startTime;
        this.classEnabled = enable;
    }

    public boolean saveObject(MyClass obj) {   
        final File suspend_f=new File(SerializationTest.cacheDir, "test");

        FileOutputStream   fos  = null;
        ObjectOutputStream oos  = null;
        boolean            keep = true;

        try {
            fos = new FileOutputStream(suspend_f);
            oos = new ObjectOutputStream(fos);
            oos.writeObject(obj);
        } catch (Exception e) {
            keep = false;
        } finally {
            try {
                if (oos != null)   oos.close();
                if (fos != null)   fos.close();
                if (keep == false) suspend_f.delete();
        } catch (Exception e) { /* do nothing */ }
        }

        return keep;
    }

    public MyClass getObject(Context c) {
        final File suspend_f=new File(SerializationTest.cacheDir, "test");

        MyClass simpleClass= null;
        FileInputStream fis = null;
        ObjectInputStream is = null;

        try {
            fis = new FileInputStream(suspend_f);
            is = new ObjectInputStream(fis);
            simpleClass = (MyClass) is.readObject();
        } catch(Exception e) {
            String val= e.getMessage();
        } finally {
            try {
                if (fis != null)   fis.close();
                if (is != null)   is.close();
            } catch (Exception e) { }
        }

        return simpleClass;  
    }

并从活动中致电

if(android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED))
    cacheDir=new File(android.os.Environment.getExternalStorageDirectory(),"MyCustomObject");
else
    cacheDir= getCacheDir();
if(!cacheDir.exists())
    cacheDir.mkdirs();

MyClass m = new MyClass("umer", "asif", true);
boolean result = m.saveObject(m);

if(result)
    Toast.makeText(this, "Saved object", Toast.LENGTH_LONG).show();
else
    Toast.makeText(this, "Error saving object", Toast.LENGTH_LONG).show();

MyClass m = new MyClass();
MyClass c = m.getObject(this);

if(c!= null)
    Toast.makeText(this, "Retrieved object", Toast.LENGTH_LONG).show();
else
    Toast.makeText(this, "Error retrieving object", Toast.LENGTH_LONG).show();

不要忘记在清单文件中使用write_external_storage权限。