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📜  Android ProgressBar示例

📅  最后修改于: 2020-09-29 02:46:03             🧑  作者: Mango

Android ProgressBar示例

我们可以显示android进度条对话框以显示正在完成的工作状态，例如下载文件，分析工作状态等。

在此示例中，我们将显示虚拟文件下载操作的进度对话框。

在这里，我们使用android.app.ProgressDialog类显示进度条。 Android ProgressDialog是AlertDialog类的子类。

ProgressDialog类提供在进度条上工作的方法，例如setProgress()，setMessage()，setProgressStyle()，setMax()，show()等。“进度对话框”的进度范围是0到10000。

让我们看一个简单的示例，在android中显示进度条。

ProgressDialog progressBar = new ProgressDialog(this);
progressBar.setCancelable(true);//you can cancel it by pressing back button
progressBar.setMessage("File downloading ...");
progressBar.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
progressBar.setProgress(0);//initially progress is 0
progressBar.setMax(100);//sets the maximum value 100
progressBar.show();//displays the progress bar

ProgressDialog的Android进度栏示例

让我们看一个使用ProgressDialog类创建进度条的简单示例。

activity_main.xml

从面板上拖动一个按钮，现在activity_main.xml文件将如下所示：

示例：

让我们编写代码以显示进度栏对话框。

package example.javatpoint.com.progressbar;

import android.app.ProgressDialog;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {
    Button btnStartProgress;
    ProgressDialog progressBar;
    private int progressBarStatus = 0;
    private Handler progressBarHandler = new Handler();
    private long fileSize = 0;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        addListenerOnButtonClick();
    }
    public void addListenerOnButtonClick() {
        btnStartProgress = findViewById(R.id.button);
        btnStartProgress.setOnClickListener(new View.OnClickListener(){

            @Override
            public void onClick(View v) {
                // creating progress bar dialog
                progressBar = new ProgressDialog(v.getContext());
                progressBar.setCancelable(true);
                progressBar.setMessage("File downloading ...");
                progressBar.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
                progressBar.setProgress(0);
                progressBar.setMax(100);
                progressBar.show();
                //reset progress bar and filesize status
                progressBarStatus = 0;
                fileSize = 0;

                new Thread(new Runnable() {
                    public void run() {
                        while (progressBarStatus < 100) {
                            // performing operation
                            progressBarStatus = doOperation();
                            try {
                                Thread.sleep(1000);
                            } catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                            // Updating the progress bar
                            progressBarHandler.post(new Runnable() {
                                public void run() {
                                    progressBar.setProgress(progressBarStatus);
                                }
                            });
                        }
                        // performing operation if file is downloaded,
                        if (progressBarStatus >= 100) {
                            // sleeping for 1 second after operation completed
                            try {
                                Thread.sleep(1000);
                            } catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                            // close the progress bar dialog
                            progressBar.dismiss();
                        }
                    }
                }).start();
            }//end of onClick method
        });
    }
    // checking how much file is downloaded and updating the filesize
    public int doOperation() {
        //The range of ProgressDialog starts from 0 to 10000
        while (fileSize <= 10000) {
            fileSize++;
            if (fileSize == 1000) {
                return 10;
            } else if (fileSize == 2000) {
                return 20;
            } else if (fileSize == 3000) {
                return 30;
            } else if (fileSize == 4000) {
                return 40; // you can add more else if 
            } 
         /* else {
                return 100;
            }*/
        }//end of while
            return 100;
    }//end of doOperation
}

输出：