Android 异步任务中的日志应用程序

我是android的新手，我正在尝试制作一个用于日志记录的小应用程序。我找到了一个，但它对我不起作用，因为我必须在asynk任务中执行它。我已尝试进行一些修改，但没有任何效果：（.这是我的代码：

import org.json.JSONException;
import org.json.JSONObject;

import android.app.Activity;

import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

import android.widget.TextView;

import com.example.androidhive.library.DatabaseHandler;
import com.example.androidhive.library.UserFunctions;


public class LoginActivity extends Activity {
Button btnLogin;
Button btnLinkToRegister;
EditText inputEmail;
EditText inputPassword;
TextView loginErrorMsg;

// JSON Response node names
private static String KEY_SUCCESS = "success";
private static String KEY_ERROR = "error";
private static String KEY_ERROR_MSG = "error_msg";
private static String KEY_UID = "uid";
private static String KEY_NAME = "name";
private static String KEY_EMAIL = "email";
private static String KEY_CREATED_AT = "created_at";

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.login);

    // Importing all assets like buttons, text fields
    inputEmail = (EditText) findViewById(R.id.loginEmail);
    inputPassword = (EditText) findViewById(R.id.loginPassword);
    btnLogin = (Button) findViewById(R.id.btnLogin);
    btnLinkToRegister = (Button) findViewById(R.id.btnLinkToRegisterScreen);
    loginErrorMsg = (TextView) findViewById(R.id.login_error);

    // Login button Click Event
    btnLogin.setOnClickListener(new View.OnClickListener() {

        public void onClick(View view) {
            new LogTask().execute();    
        }

    });

    // Link to Register Screen
    btnLinkToRegister.setOnClickListener(new View.OnClickListener() {

        public void onClick(View view) {
            Intent i = new Intent(getApplicationContext(),RegisterActivity.class);
            startActivity(i);
            finish();
        }
    });
}

private class LogTask extends AsyncTask<String, String, String> {


    protected String doInBackground(String... args) {
        String email = inputEmail.getText().toString();
        String password = inputPassword.getText().toString();
        UserFunctions userFunction = new UserFunctions();
        Log.d("Button", "Login");
        JSONObject json = userFunction.loginUser(email, password);

        // check for login response
        try {
            if (json.getString(KEY_SUCCESS) != null) {
                loginErrorMsg.setText("");
                String res = json.getString(KEY_SUCCESS); 
                if(Integer.parseInt(res) == 1){
                    // user successfully logged in
                    // Store user details in SQLite Database
                    DatabaseHandler db = new DatabaseHandler(getApplicationContext());
                    JSONObject json_user = json.getJSONObject("user");

                    // Clear all previous data in database
                    userFunction.logoutUser(getApplicationContext());
                    db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_EMAIL), json.getString(KEY_UID), json_user.getString(KEY_CREATED_AT));                        


                }else{
                    // Error in login
                    return null;
                }
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }

        return "done";
    }


    protected void onPostExecute(String file_url) {

        if(file_url==null) {
              loginErrorMsg.setText("Incorrect username/password");
       } else if(file_url.equals("done")) {
              Intent dashboard = new Intent(getApplicationContext(), DashboardActivity.class);
              dashboard.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
              startActivity(dashboard);
              finish();
       }

    }

}

---

尝试将与UI相关的代码移动到

onPostExecute（）

，如下所示：

private class LogTask extends AsyncTask<String, String, String> {
    String email, password.

    protected void onPreExecute() {
        email = inputEmail.getText().toString();
        password = inputPassword.getText().toString();
    }
    protected String doInBackground(String... args) {
        UserFunctions userFunction = new UserFunctions();
        Log.d("Button", "Login");
        JSONObject json = userFunction.loginUser(email, password);

        // check for login response
        try {
            if (json.getString(KEY_SUCCESS) != null) {

                String res = json.getString(KEY_SUCCESS); 
                if(Integer.parseInt(res) == 1){
                    // user successfully logged in
                    // Store user details in SQLite Database
                    DatabaseHandler db = new DatabaseHandler(getApplicationContext());
                    JSONObject json_user = json.getJSONObject("user");

                    // Clear all previous data in database
                    userFunction.logoutUser(getApplicationContext());
                    db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_EMAIL), json.getString(KEY_UID), json_user.getString(KEY_CREATED_AT));                        


                }else{
                    // Error in login
                    return null;
                }
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }

        return "done;
    }

---

可以使用Log.e，当从与异步任务一起运行时，它将输出到LogCat窗口

Log.e => Error Logs
Log.d => Debug logs
Log.w => Warning Logs, etc

---

我按照你的建议做了，但是没有用，下面是错误：01-20 09:59:58.685:E/JSON（2243）：{“tag”：“login”，“success”：1，“error”：0，“uid”：“50ee5c6c65dd38.71886880”，“user”：{“name”：“s”，“email”：“s”，“created_at”：“2013-01-10 07:15:08”，“updated__at”：null}01-20 09:59:58.735:W/dalvikvm（2243）：threadid=11:线程退出，但未捕获异常（group=0x409c01f8）01-20 09:59:58.805:E/AndroidRuntime（2243）：致命异常：AsyncTask#1您已决定在实际错误之前剪切错误日志。请尝试编辑问题以包括it01-20 10:10:24.985:E/AndroidRuntime（2285）：在java.lang.Thread.run（Thread.java:856）01-20 10:10:24.985:E/AndroidRuntime（2285）：原因：android.view.ViewRootImpl$CalledFromErrorThreadException:只有创建视图层次结构的原始线程才能接触其视图。@user1994330查看我的编辑。我在try-catch中的if语句之后又删除了一行

protected void onPostExecute(String file_url) {

       if(file_url==null) {
              loginErrorMsg.setText("Incorrect username/password");
       } else if)file_url.equals("done") {
              Intent dashboard = new Intent(getApplicationContext(), DashboardActivity.class);
              dashboard.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
              startActivity(dashboard);
              finish();
       }
}

Log.e => Error Logs
Log.d => Debug logs
Log.w => Warning Logs, etc