3.11

可以从数据库查数据

public class MainActivity extends AppCompatActivity {
    private Button button,buttonInsert;
    private TextView textView;
    private static final int TEST_USER_SELECT = 1;
    int i =0;
    @SuppressLint("HandlerLeak")
    private Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            String user;
            switch (msg.what){
                case TEST_USER_SELECT:
                    Test test = (Test) msg.obj;
                    user = test.getName();
                    System.out.println("***********");
                    System.out.println("***********");
                    System.out.println("user:"+user);
                    textView.setText(user);
                    break;
            }
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button = (Button) findViewById(R.id.bt_send);
        textView = (TextView) findViewById(R.id.tv_response);
    }

    @Override
    protected void onStart() {
        super.onStart();
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //执行查询操作
                //通多点击buttoni自增长查询对应id的name
                if (i<=3){//因为数据库我就添加了三个数据条数，所以进行判断使其可以循环查询
                    i++;
                }
                else{
                    i=1;
                }
                //连接数据库进行操作需要在主线程操作
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        Connection conn = null;
                        conn =(Connection) com.example.mysqlconnection1.DBOpenHelper.getConn();
                        String sql = "select name from test_one where id='"+i+"'";
                        Statement st;
                        try {
                            st = (Statement) conn.createStatement();
                            ResultSet rs = st.executeQuery(sql);
                            while (rs.next()){
                                //因为查出来的数据试剂盒的形式，所以我们新建一个javabean存储
                                Test test = new Test();
                                test.setName(rs.getString(1));
                                Message msg = new Message();
                                msg.what =TEST_USER_SELECT;
                                msg.obj = test;
                                handler.sendMessage(msg);
                            }
                            st.close();
                            conn.close();
                        } catch (SQLException e) {
                            e.printStackTrace();
                        }
                    }
                }).start();

            }
        });
        buttonInsert = (Button) findViewById(R.id.bt_insert);
        buttonInsert.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                // 连接数据库进行操作需要在主线程操作
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        Connection conn = null;
                        conn =(Connection) com.example.mysqlconnection1.DBOpenHelper.getConn();
                        String name = "NewName"; // 新数据的名称
                        String sql = "insert into test_one(name) values('"+name+"')";
                        Statement st;
                        try {
                            st = (Statement) conn.createStatement();
                            int rowAffected = st.executeUpdate(sql);
                            if (rowAffected > 0) {
                                // 插入成功，您可以选择显示一个Toast或者执行其他UI更新操作
                            }
                            st.close();
                            conn.close();
                        } catch (SQLException e) {
                            e.printStackTrace();
                        }
                    }
                }).start();
            }
        });

    }
}