DBUtils的使用

来源：互联网发布：安卓数据恢复编辑：程序博客网时间：2024/06/11 19:53

实体类中必须有id的这个字段

public class MainActivity extends Activity {

   private static final String TAG = "MainActivity";
   private DbUtils dbUtils;

   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);
       dbUtils = DbUtils.create(this, "studentDb");
       try {
           dbUtils.createTableIfNotExist(User.class);
       } catch (DbException e) {
           e.printStackTrace();
       }

   }

   public void add(View v) {
       try {
           dbUtils.save(new User(1, "张三", "男"));
           dbUtils.save(new User(2, "李四", "女"));

       } catch (DbException e) {
           e.printStackTrace();
       }
   }

   public void delete(View v) {
       try {
           // dbUtils.delete(new User(2, "李四", "女"));
           WhereBuilder wb = WhereBuilder.b("name", "=", "张三");// 创建一个WhereBuilder（过滤条件）
           dbUtils.delete(User.class, wb);
           // WhereBuilder whereBuilder;
           // dbUtils.delete(User.class, whereBuilder);
       } catch (DbException e) {
           e.printStackTrace();
       }
   }

   public void update(View v) {
       try {
           WhereBuilder wb = WhereBuilder.b("name", "=", "张三");// 创建一个WhereBuilder（过滤条件）
           dbUtils.update(new User(2, "张三", "女"), wb, null);
       } catch (DbException e) {
           e.printStackTrace();
       }
   }

   public void query(View v) {
       try {
           List<User> user = dbUtils.findAll(User.class);
//           User u = dbUtils.findFirst(User.class);
//           Log.i(TAG, u.getName() + u.getGender() + u.getId());
           WhereBuilder whereBuilder=WhereBuilder.b("name", "==", "张三");
           // Selector selector=Selector.;
           List<User> findAll = dbUtils.findAll(Selector.from(User.class).where(whereBuilder));
           for (User user2 : findAll) {
               Log.i(TAG,
                       "userId" + user2.getId() + "userName" + user2.getName()
                               + "userGender" + user2.getGender());
           }
       } catch (DbException e) {
           e.printStackTrace();
       }

   }
}

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