Question

主要活动：

package com.example.phpmysql;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity {

    private EditText usernameField,passwordField;
    private TextView status,role,method;

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

        usernameField = (EditText)findViewById(R.id.editText1);
        passwordField = (EditText)findViewById(R.id.editText2);

        status = (TextView)findViewById(R.id.textView6);
        role = (TextView)findViewById(R.id.textView7);
        method = (TextView)findViewById(R.id.textView9);
    }



    public void login(View view){
        String username = usernameField.getText().toString();
        String password = passwordField.getText().toString();
        method.setText("Get Method");
        new SigninActivity(this,status,role,0).execute(username,password);

    }

    public void loginPost(View view){
        String username = usernameField.getText().toString();
        String password = passwordField.getText().toString();
        method.setText("Post Method");
        new SigninActivity(this,status,role,1).execute(username,password);
    }
}

SigninActivity：

package com.example.phpmysql;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.URI;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;

import android.content.Context;
import android.os.AsyncTask;
import android.widget.TextView;

public class SigninActivity  extends AsyncTask{



    private TextView statusField,roleField;
    private Context context;
    private int byGetOrPost = 0;

    //flag 0 means get and 1 means post.(By default it is get.)

    public SigninActivity(Context context,TextView statusField,TextView 
      roleField,int flag) {
        this.context = context;
        this.statusField = statusField;
        this.roleField = roleField;
        byGetOrPost = flag;
    }

    protected void onPreExecute(){
    }

    @Override
    protected String doInBackground(String... arg0) {
        if(byGetOrPost == 0){ //means by Get Method

            try{
                String username = (String)arg0[0];
                String password = (String)arg0[1];
                String link = "http://myphpmysqlweb.hostei.com/login.php?username="+username+"& password="+password;

                URL url = new URL(link);
                HttpClient client = new DefaultHttpClient();
                HttpGet request = new HttpGet();
                request.setURI(new URI(link));
                HttpResponse response = client.execute(request);
                BufferedReader in = new BufferedReader(new
                        InputStreamReader(response.getEntity().getContent()));

                StringBuffer sb = new StringBuffer("");
                String line="";

                while ((line = in.readLine()) != null) {
                    sb.append(line);
                    break;
                }

                in.close();
                return sb.toString();
            } catch(Exception e){
                return new String("Exception: " + e.getMessage());
            }
        } else{
            try{
                String username = (String)arg0[0];
                String password = (String)arg0[1];

                String link="http://myphpmysqlweb.hostei.com/loginpost.php";
                String data  = URLEncoder.encode("username", "UTF-8") + "=" +
                        URLEncoder.encode(username, "UTF-8");
                data += "&" + URLEncoder.encode("password", "UTF-8") + "=" +
                        URLEncoder.encode(password, "UTF-8");

                URL url = new URL(link);
                URLConnection conn = url.openConnection();

                conn.setDoOutput(true);
                OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());

                wr.write( data );
                wr.flush();

                BufferedReader reader = new BufferedReader(new
                        InputStreamReader(conn.getInputStream()));

                StringBuilder sb = new StringBuilder();
                String line = null;

                // Read Server Response
                while((line = reader.readLine()) != null) {
                    sb.append(line);
                    break;
                }

                return sb.toString();
            } catch(Exception e){
                return new String("Exception: " + e.getMessage());
            }
        }
    }

    @Override
    protected void onPostExecute(String result){
        this.statusField.setText("Login Successful");
        this.roleField.setText(result);
    }
}

public class SigninActivity extends AsyncTask以红色下划线显示，类SigninActivity必须声明abstract或在doInBackground(Params...)中实现抽象方法AsyncTask？

我尝试添加doInBackground，但它说它从未使用过？我尝试将其设为adbstract，但后来我无法从mainactivity调用该类

Answer 1

您需要提供通用参数

public class SigninActivity  extends AsyncTask<String, Void, String>

否则参数类型为raw-type且签名不匹配

课程＆＃39; SigninActivity＆＃39;必须被宣布为抽象的或实现抽象方法＆＃39; doInBackground（Params ...）＆＃39;在＆＃39; AsyncTask＆＃39;

1 个答案: