Android数据库选择查询 - 不显示所有记录

Question

您好我是android的初学者。我想在我的电脑上建立数据库连接到mssql服务器。我在网上找到了例子。 我想我连接有问题。因为我的User表中有两条记录。但是这段代码只给了我表中的第一条记录。

这是ConnectionClass.java：

import android.annotation.SuppressLint;
import android.os.StrictMode;
import android.util.Log;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class ConnectionClass {
String ip = "127.0.0.1:1433";
String classs = "net.sourceforge.jtds.jdbc.Driver";
String db = "DBAndroid1";
String un = "TestUser";
String password = "123";
 @SuppressLint("NewApi")
public Connection CONN() {
    StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder()
            .permitAll().build();
    StrictMode.setThreadPolicy(policy);
    Connection conn = null;
    String ConnURL = null;
    try {

        Class.forName(classs).newInstance();
        ConnURL = "jdbc:jtds:sqlserver://" + ip + ";"
                + "databaseName=" + db + ";user=" + un + ";password="
                + password + ";";
        conn = DriverManager.getConnection(ConnURL);
    } catch (SQLException se) {
        Log.e("ERRO0", se.getMessage());
    } catch (ClassNotFoundException e) {
        Log.e("ERRO1", e.getMessage());
    } catch (Exception e) {
        Log.e("ERRO2", e.getMessage());
    }
    return conn;
}
}

这是我的MainActivity.java。

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.Toast;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

ConnectionClass connectionClass;
EditText edtuserid, edtpass;
Button btnlogin;
ProgressBar pbbar;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    connectionClass = new ConnectionClass();
    edtuserid = (EditText) findViewById(R.id.et_username);
    edtpass = (EditText) findViewById(R.id.et_password);
    btnlogin = (Button) findViewById(R.id.btn_Login);
    pbbar = (ProgressBar) findViewById(R.id.pbbar);
    pbbar.setVisibility(View.GONE);

    btnlogin.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            DoLogin  doLogin = new DoLogin();
            doLogin.execute("");

        }
    });

}


public class DoLogin extends AsyncTask<String,String,String>
{
    String z = "";
    Boolean isSuccess = false;

    String userid = edtuserid.getText().toString();
    String password = edtpass.getText().toString();


    @Override
    protected void onPreExecute() {
        pbbar.setVisibility(View.VISIBLE);
    }

    @Override
    protected void onPostExecute(String r) {
        pbbar.setVisibility(View.GONE);
        Toast.makeText(MainActivity.this,r,Toast.LENGTH_SHORT).show();

        if(isSuccess) {
            Toast.makeText(MainActivity.this,r,Toast.LENGTH_SHORT).show();
        }

    }

    @Override
    protected String doInBackground(String... params) {
        if(userid.trim().equals("")|| password.trim().equals(""))
            z = "Please enter User Id and Password";
        else
        {
            try {
                Connection con = connectionClass.CONN();
                if (con == null) {
                    z = "Error in connection with SQL server";
                } else {
                    String query = "select Username from [User]";
                    Statement stmt = con.createStatement();
                    ResultSet rs = stmt.executeQuery(query);
                    int columnCount = rs.getMetaData().getColumnCount();

                    System.out.println("Eleman sayisi: "+ columnCount);
                    if(rs.next())
                    {
                        String lastName = rs.getString("Username");
                        z = "Login successfull";
                        z = z + " " + lastName;
                        isSuccess=true;
                    }
                    else
                    {
                        z = "Invalid Credentials";
                        isSuccess = false;
                    }

                }
            }
            catch (Exception ex)
            {
                isSuccess = false;
                z = "Exceptions burda mi "+ ex;
            }
        }
        return z;
    }
}
}

我希望你能提供帮助。谢谢。

Answer 1

您在表中有两条记录但是您使用if（rs.next（））来获取仅返回单条记录的记录。 使用循环或while循环来获取所有记录并循环迭代结果集。