ProgressDialog错误

Question

我的代码如下：

           package com.android.skiptvad;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.protocol.HTTP;
import org.apache.http.util.EntityUtils;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.Activity;
import android.app.Dialog;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.Window;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import com.android.skiptvad.*;

public class Login extends Activity {
    private static final int DIALOG_LOADING = 0;
    /** Called when the activity is first created. */
    TextView tvuser;
    String sessionid;
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.login);


        tvuser = (TextView) findViewById(R.id.tvuser);
        TextView tvpw = (TextView) findViewById(R.id.tvpw);
        final EditText etuser = (EditText) findViewById(R.id.etuser);
        final EditText etpw = (EditText) findViewById(R.id.etpw);
        Button btlogin = (Button)findViewById(R.id.btlogin);
        btlogin.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {

                if (etuser.getText() != null && etpw.getText()!= null)
                {
                    showDialog(DIALOG_LOADING);
                    try
                    {
                    //download(etuser.getText().toString(), md5(etpw.getText().toString()));
                    HttpClient client = new DefaultHttpClient();  
                    String postURL = "http://surfkid.redio.de/login";
                    HttpPost post = new HttpPost(postURL); 
                        List<NameValuePair> params = new ArrayList<NameValuePair>();
                        params.add(new BasicNameValuePair("username", etuser.getText().toString()));
                        params.add(new BasicNameValuePair("password", md5(etpw.getText().toString())));
                        UrlEncodedFormEntity ent = new UrlEncodedFormEntity(params,HTTP.UTF_8);
                        post.setEntity(ent);

                        HttpResponse responsePOST = client.execute(post);  
                        HttpEntity resEntity = responsePOST.getEntity();
                        final JSONObject jObject = new JSONObject(EntityUtils.toString(resEntity));
                        JSONObject menuObject = jObject.getJSONObject("responseData");

                        if (jObject.getInt("responseStatus")== 200 && jObject.get("responseDetails")!= null)
                        {
                            sessionid = menuObject.getString("session_id");


                        }   

                        else
                        {

                             if (jObject.getInt("responseStatus")== 500)
                             {
                                 throw new Exception("Server Error");
                             }
                             else if (jObject.getInt("responseStatus")== 400)
                             {
                                 throw new Exception("Wrong User/Password");
                             }
                             else
                             {
                                 throw new Exception();
                             }
                        }

                    }
                    catch (Exception e)
                    {
                        Log.d("error", "error");
                    }
                    finally{
                        dismissDialog(DIALOG_LOADING);
                    }
                }

            }
        });


    }

    public void download (final String user, final String pw)
    {



    }
    private String md5(String in) {

        MessageDigest digest;

        try {

            digest = MessageDigest.getInstance("MD5");

            digest.reset();        

            digest.update(in.getBytes());

            byte[] a = digest.digest();

            int len = a.length;

            StringBuilder sb = new StringBuilder(len << 1);

            for (int i = 0; i < len; i++) {

                sb.append(Character.forDigit((a[i] & 0xf0) >> 4, 16));

                sb.append(Character.forDigit(a[i] & 0x0f, 16));

            }

            return sb.toString();

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

        return null;

    }
    @Override
    protected Dialog onCreateDialog(int id) {
        Dialog dialog = null;
        switch (id) {
        case DIALOG_LOADING:
            dialog = new ProgressDialog(this);
            ((ProgressDialog) dialog).setMessage("Loading, please wait...");
            break;
        }
        return dialog;
    }




}

不显示任何对话框！

Answer 1

不能直接从后台线程对UI执行更新。

如果您一定要使用Thread，那么可以使用onCreateDialog来准备新的对话框，让它正常工作。然后调用showDialog(int)和dismissDialog(int)来显示/隐藏对话框：

private static final int DIALOG_LOADING = 0;

...
@Override
protected Dialog onCreateDialog(int id) {
    Dialog dialog;
    switch (id) {
    case DIALOG_LOADING:
        dialog = new ProgressDialog(this);
        ((ProgressDialog) dialog).setMessage("Loading, please wait...");
        break;
    }
    return dialog;
}

btlogin.setOnClickListener(new OnClickListener() {
    @Override
    public void onClick(View v) {
        if (etuser.getText() != null && etpw.getText()!= null)
        {
            showDialog(DIALOG_LOADING);
            Thread t = new Thread() {
                public void run(){
                    try{
                        download(etuser.getText().toString(), md5(etpw.getText().toString()));
                    } catch(Exception e) {
                        Log.e("TAG","Exception caught in thread:"+e.toString());
                        e.printStackTrace();
                    } finally {
                        try{
                            dismissDialog(DIALOG_LOADING);
                        } catch (IllegalArgumentException e) {
                            Log.w("TAG","Dialog does not exist");
                        }
                    }
                    //finish();  
                }
            };
            t.start();
        }
    }
});

Answer 2

您正试图在UI线程之外调用与UI相关的API函数-在本例中，假定为pd.dismiss()。任何与UI有关的事情都需要在主线程上运行--一个简单的实现方法是通过Activity.runOnUiThread()。

Answer 3

我同意@EboMike的观点，无论你尝试了什么，都可能是错误的。

但我的建议是，使用AsyncTask是一种更干净的方式来做你想要做的事情。