java swing中经常要使用到进度条，比如下载文件和拷贝文件时显示进度，如下图所示：

 下载完成之后：

难点在于：在读取输入流的时候，实时更新进度条。 

我自己定了一个规则：

（1） 若输入流的大小小于1024，则字节数组的长度就是输入流的大小。

    （2）获取文件的大小，并平分为100等份，得到商1；

     （3拿每一等份（商1）和1024比较：若小于等于1024，则字节数组大小为商1；

若大于1024，则除以1024，得到商2，则字节数组大小为商1/商2

规定：100%时的颜色为蓝色：copyProgressBar.setForeground(Color.blue);

核心代码：

/**** 在实际使用过程中，应该放在线程中* @param in* @param sourceSize*            : 输入流的长度，即要读取的字节个数* @param targfile*/public static void progress(JProgressBar copyProgressBar, InputStream in,long sourceSize, File targfile) {FileOutputStream target = null;try {int bytesArrLeng = 0;if (sourceSize < SystemHWUtil.BUFF_SIZE_1024) {//bytesArrLeng = (int) sourceSize;} else {long shangOne = sourceSize / SystemHWUtil.NUMBER_100;if (shangOne == 0) {// sourceSize<100shangOne = shangOne + 1;}if (shangOne <= SystemHWUtil.BUFF_SIZE_1024) {bytesArrLeng = (int) shangOne;} else {long shangTwo = shangOne / SystemHWUtil.BUFF_SIZE_1024;if (shangOne % SystemHWUtil.BUFF_SIZE_1024 != 0) {shangTwo = shangTwo + 1L;}bytesArrLeng = (int) (shangOne / shangTwo);}}System.out.println("字节数组的长度是：" + bytesArrLeng);target = new FileOutputStream(targfile);byte[] buffer = new byte[bytesArrLeng];int byteNum;long hasReadByte = 0L;// 已经读取的字节个数float result;int progressSize = 0;while ((byteNum = in.read(buffer)) != SystemHWUtil.NEGATIVE_ONE) {target.write(buffer, 0, byteNum);hasReadByte = hasReadByte + byteNum;result = (float) ((double) hasReadByte / sourceSize);progressSize = Math.round(result * SystemHWUtil.NUMBER_100);// copyProgressBar.setString(progressSize + "%");// copyProgressBar.setValue(progressSize);updateProgress(copyProgressBar, progressSize);}if (progressSize < SystemHWUtil.NUMBER_100) {progressSize = SystemHWUtil.NUMBER_100;updateProgress(copyProgressBar, progressSize);}copyProgressBar.setForeground(Color.blue);// System.out// .println("[SystemUtil:copyFile]:file copy successfully!");// resultTextArea.setText();} catch (Exception e) {e.printStackTrace();// copyFileBtn.setEnabled(true);} finally {if (in != null) {try {in.close();} catch (IOException e) {e.printStackTrace();}in = null;}if (target != null) {try {target.close();} catch (IOException e) {e.printStackTrace();}target = null;}}}/**** 更新进度条上得进度数字* @param copyProgressBar* @param progressSize*/private static void updateProgress(JProgressBar copyProgressBar, int progressSize) {copyProgressBar.setString(progressSize + "%");copyProgressBar.setValue(progressSize);}

 使用进度条的代码：

new Thread(new Runnable() {@Overridepublic void run() {try {HttpSocketUtil.setDetail(true);// HttpSocketUtil.httpRequest(urlTF.getText(), null,// null, true, selectedFile, -1, -1);HttpURLConnection huc = HttpSocketUtil.beforeConnect(httpSenderApp.getUrlTF().getText(), null, null, null, null,SystemHWUtil.NEGATIVE_ONE,SystemHWUtil.NEGATIVE_ONE);InputStream in = huc.getInputStream();int contentLength;String sizeHeadKey = null;if (ValueWidget.isNullOrEmpty(sizeHeadKey)) {// 若header中没有sizecontentLength = huc.getContentLength();} else {contentLength = Integer.parseInt(huc.getHeaderField(sizeHeadKey));}ComponentUtil.progress(httpSenderApp.getCopyProgressBar(), in,contentLength, selectedFile);GUIUtil23.infoDialog("下载成功!size:"+ FileUtils.formatFileSize2(selectedFile.length()));} catch (Exception e) {GUIUtil23.errorDialog(e.getMessage());e.printStackTrace();}}}).start();

依赖的jar：io0007-find_progess-0.0.7.2-SNAPSHOT.jar

demo：http-sender

注意：项目使用maven 构建

参考:

http://hw1287789687.iteye.com/blog/2246665