代码添加ProgressBar 进度条

  大家好 今天为大家分享代码中添加ProgressBar的例子 。当我们需要初始化程序或者联网获取数据 在数据库中查找数据时，这些需要耗费些时间的操作就需要进度条来提示用户有任务在进行，以免造成程序界面假死。 为什么要在代码中添加而不在布局里面添加呢，因为在代码里添加可以重复多次利用，免得没用到时就得在布局里添加，麻烦。

    好了，下面我们来做个简单的Demo熟悉一下，

    第一步：首先创建工程ProgressBarInsertLayoutinCode。

    第二步：创建XMl 布局文件  我们就用自动创建的main.xml （在这里面只添加了一个Button）用来启动ProgressBar，代码如下：

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1.    <?xmlversion="1.0"encoding="utf-8"?> 
2. <RelativeLayoutxmlns:android="http://schemas.android.com/apk/res/android" 
3. android:id="@+id/relative" 
4. android:layout_width="fill_parent" 
5. android:layout_height="fill_parent" 
6. > 
7. <Buttonandroid:id="@+id/button" 
8. android:text="Click me" 
9. android:layout_width="fill_parent" 
10. android:layout_height="wrap_content"/> 
11. </RelativeLayout> 

   <?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"android:id="@+id/relative"android:layout_width="fill_parent"android:layout_height="fill_parent"><Button android:id="@+id/button"android:text="Click me"android:layout_width="fill_parent"android:layout_height="wrap_content"/></RelativeLayout>

        第三步：修改ProgressBarInsertLayoutinCodeActivity代码，如下：（这里我们用到了Handler和Thread，用来更新ProgressBar的进度，这样就可以到一定是消除ProgressBar）

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1. package cn.li.progressbardemo; 
2.  
3. import android.app.Activity; 
4. import android.os.Bundle; 
5. import android.view.View; 
6. import android.widget.Button; 
7.  
8. public class ProgressBarInsertLayoutinCodeActivity extends Activity { 
9. /** Called when the activity is first created. */ 
10. private Button btn; 
11. private InsertProgressBar bar; 
12. @Override 
13. public void onCreate(Bundle savedInstanceState) { 
14. super.onCreate(savedInstanceState); 
15. setContentView(R.layout.main); 
16. bar = new InsertProgressBar(ProgressBarInsertLayoutinCodeActivity.this); 
17. btn = (Button)findViewById(R.id.button); 
18. btn.setOnClickListener(new View.OnClickListener() { 
19.  
20. @Override 
21. public void onClick(View v) { 
22. // TODO Auto-generated method stub 
23. bar.insertBar(); 
24. } 
25. }); 
26. } 
27. } 

package cn.li.progressbardemo;import android.app.Activity;import android.os.Bundle;import android.view.View;import android.widget.Button;public class ProgressBarInsertLayoutinCodeActivity extends Activity {/** Called when the activity is first created. */private Button btn;private InsertProgressBar bar;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);bar = new InsertProgressBar(ProgressBarInsertLayoutinCodeActivity.this);btn = (Button)findViewById(R.id.button);btn.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubbar.insertBar();}});}}

第四步：创建InsertProgressBar.java 此类创建了ProgressBar

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1. package cn.li.progressbardemo; 
2.  
3. import android.content.Context; 
4. import android.os.Handler; 
5. import android.os.Message; 
6. import android.view.View; 
7. import android.widget.ProgressBar; 
8. import android.widget.RelativeLayout; 
9. import android.widget.RelativeLayout.LayoutParams; 
10.  
11. public class InsertProgressBar { 
12.  
13. private RelativeLayout relative ; 
14. private ProgressBar bar; 
15. private ProgressBarInsertLayoutinCodeActivity context; 
16. private int rate = 0; 
17.  
18. protected static final int STOP = 0; 
19. protected static final int NEXT =1; 
20.  
21. public InsertProgressBar(Context c) { 
22. super(); 
23. context = (ProgressBarInsertLayoutinCodeActivity) c; 
24. relative = (RelativeLayout)context.findViewById(R.id.relative); 
25. bar = new ProgressBar(context); 
26. //设置ProgressBar的高宽和显示位置 
27. RelativeLayout.LayoutParams params =new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT); 
28. params.getRules()[RelativeLayout.CENTER_IN_PARENT] = RelativeLayout.TRUE; 
29. bar.setLayoutParams(params); 
30. } 
31.  
32. public void insertBar() { 
33. bar.setProgress(0); 
34. //当ProgressBar正在运行时就不再创建ProgressBar 
35. if(!bar.isShown()){ 
36. bar.setVisibility(View.VISIBLE); 
37. relative.addView(bar); 
38. new MyThread().start(); 
39. } 
40.  
41. } 
42.  
43. class MyThread extends Thread{ 
44.  
45. @Override 
46. public void run() { 
47. super.run(); 
48.  
49. try { 
50. for(int i=0;i<25;i++){ 
51. rate = (i+1)*4; 
52. if(i!=24){ 
53. Message msg = new Message(); 
54. msg.what = NEXT; 
55. myhandler.sendMessage(msg); 
56. }else{ 
57. Message msg = new Message(); 
58. msg.what = STOP; 
59. myhandler.sendMessage(msg); 
60. } 
61. MyThread.sleep(200); 
62. } 
63. } catch (Exception e) { 
64. } 
65.  
66. } 
67.  
68. } 
69. //创建一个Handle 接收消息 
70. private Handler myhandler = new Handler(){ 
71.  
72. @Override 
73. public void handleMessage(Message msg) { 
74. super.handleMessage(msg); 
75. switch (msg.what) { 
76. case STOP: 
77. bar.setVisibility(View.GONE); 
78. relative.removeView(bar); 
79. Thread.currentThread().interrupt(); 
80. break; 
81. case NEXT: 
82. bar.setProgress(rate); 
83. break; 
84. } 
85. }  
86. }; 
87. } 

package cn.li.progressbardemo;import android.content.Context;import android.os.Handler;import android.os.Message;import android.view.View;import android.widget.ProgressBar;import android.widget.RelativeLayout;import android.widget.RelativeLayout.LayoutParams;public class InsertProgressBar {private RelativeLayout relative ;private ProgressBar bar;private ProgressBarInsertLayoutinCodeActivity context;private int rate = 0;protected static final int STOP = 0;protected static final int NEXT = 1;public InsertProgressBar(Context c) {super();context = (ProgressBarInsertLayoutinCodeActivity) c;relative = (RelativeLayout)context.findViewById(R.id.relative);bar = new ProgressBar(context);//设置ProgressBar的高宽和显示位置RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);params.getRules()[RelativeLayout.CENTER_IN_PARENT] = RelativeLayout.TRUE;bar.setLayoutParams(params);}public void insertBar() {bar.setProgress(0);//当ProgressBar正在运行时就不再创建ProgressBarif(!bar.isShown()){bar.setVisibility(View.VISIBLE);relative.addView(bar);new MyThread().start();}}class MyThread extends Thread{@Overridepublic void run() {super.run();try {for(int i=0;i<25;i++){rate = (i+1)*4;if(i!=24){Message msg = new Message();msg.what = NEXT;myhandler.sendMessage(msg);}else{Message msg = new Message();msg.what = STOP;myhandler.sendMessage(msg);}MyThread.sleep(200);}} catch (Exception e) {}}}//创建一个Handle 接收消息private Handler myhandler = new Handler(){@Overridepublic void handleMessage(Message msg) {super.handleMessage(msg);switch (msg.what) {case STOP:bar.setVisibility(View.GONE);relative.removeView(bar);Thread.currentThread().interrupt();break;case NEXT:bar.setProgress(rate);break;}} };}

OK，运行工程 效果如图