在Android中阅读Excel

目前我正在开发android开发.根据要求,应用程序应该能够读取Excel文件以进行数据输入.

正如其他人从这个主题开始,我已经完成了Java Excel Api和Apache POI,但两者都需要进行一些修改以满足我的要求：

JExcel API：
   – 不能支持XLSX

Apache POI：
   – 支持XLS文件
   – 要在Dalvik中支持XLSX,您需要克服64K和javax库,或使用端口版本(即从Andrew Kondratev开始)
   – 文件大小将增加2.4MB

但是我们还有其他选择在Android 4或更低版本中使用Excel文件吗？

解决方法:

对于那些需要使用全功能excel文件(即绘图,VBA等等)的应用程序,你应该使用Apache POI,它很简单,但现在仍然是最好的解决方案.

但是,如果您只需要阅读Excel,那么使用JavaScript解决方案可能会更好.使用js-xlsx库,您可以将Excel文件传输到JSON.库大小很小,只有395KB(仅包括xlsx.core.min.js)

我相信这不是最好的解决方案：
   – WebView需要使用UI Thread,它可能会在读取大型Excel文件时阻止UI.
   – 性能问题
但您可以将其更改为其他JavaScript引擎(如Rhino或V8)以解决这些问题.

这是代码

回调接口：

public interface ExcelReaderListener {
    void onReadExcelCompleted(List<String> stringList);
}

主要活动：

private ProgressDialog progressDialog;

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    new AlertDialog.Builder(MainActivity.this)
            .setMessage("message")
            .setTitle("title")
            .setPositiveButton(R.string.ok, new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    dialog.dismiss();

                    new FileChooser(MainActivity.this, new String[]{"xls", "xlsx"})
                            .setFileListener(new FileChooser.FileSelectedListener() {
                                @Override
                                public void fileSelected(File file) {
                                    progressDialog = new ProgressDialog(MainActivity.this);
                                    progressDialog.setTitle("title");
                                    progressDialog.setMessage("message");
                                    progressDialog.setIndeterminate(true);
                                    progressDialog.setCanceledOnTouchOutside(false);

                                    Toast.makeText(MainActivity.this, file.getName(), Toast.LENGTH_SHORT).show();
                                    String filePath = file.getAbsolutePath();
                                    ExcelReaderListener excelReaderListener = MainActivity.this;

                                    progressDialog.show();
                                    try {
                                        final WebView webView = new WebView(MainActivity.this);
                                        new JSExcelReader(filePath, webView, excelReaderListener);
                                    } catch (Exception ex) {
                                        Log.e("Import excel error", ex.getMessage());
                                    }
                                }
                            })
                            .showDialog();
                }
            })
            .show();
}

@Override
public void onReadExcelCompleted(List<String> stringList) {
    Toast.makeText(MainActivity.this, "Parse Completed", Toast.LENGTH_SHORT).show();

    if (progressDialog != null && progressDialog.isShowing()) {
        progressDialog.dismiss();
    }

    // Write into DB
    ...
}

用户选择excel文件的界面：

https://rogerkeays.com/simple-android-file-chooser

JSExcelReader :(读取excel并将其转换为ArrayList的核心部分)

public class JSExcelReader {

    private ExcelReaderListener callback;

    public JSExcelReader(String filePath, final WebView webView, ExcelReaderListener callback) {
        this.callback = callback;

        File file = new File(filePath);

        try (InputStream is = new FileInputStream(file)) {
            // convert file to Base64
            if (file.length() > Integer.MAX_VALUE)
                Log.e("File too big", "file too big");
            byte[] bytes = new byte[(int) file.length()];

            int offset = 0;
            int numRead;
            while (offset < bytes.length &&
            (numRead = is.read(bytes, offset, bytes.length - offset)) >= 0) {
                offset += numRead;
            }

            if (offset < bytes.length)
                throw new Exception("Could not completely read file");

            final String b64 = Base64.encodeToString(bytes, Base64.NO_WRAP);

            // feed the string into webview and get the result
            WebSettings webSettings = webView.getSettings();
            webSettings.setJavaScriptEnabled(true);
            webView.loadUrl("file:///android_asset/AndroidParseExcel.html");
            webView.setWebViewClient(new WebViewClient() {
                public void onPageFinished(WebView view, String url) {
                    webView.evaluateJavascript("convertFile('" + b64 + "');", new ValueCallback<String>() {
                        @Override
                        public void onReceiveValue(String value) {
                            parseJSON(value);
                        }
                    });
                }
            });
        } catch (Exception ex) {
            Log.e("Convert Excel failure", ex.getMessage());
        }
    }

    private void parseJSON(String jsonString) {
        try {
            // return value is something like "{\n\"Sheet1\":\n[\"title\"...
            // you need to remove those escape character first
            JSONObject jsonRoot = new JSONObject(jsonString.substring(1, jsonString.length() - 1)
                                                            .replaceAll("\\\\n", "")
                                                            .replaceAll("\\\\\"", "\"")
                                                            .replaceAll("\\\\\\\\\"", "'"));
            JSONArray sheet1 = jsonRoot.optJSONArray("Sheet1");
            List<String> stringList = new ArrayList<>();

            JSONObject jsonObject;
            for (int i = 0; i < sheet1.length(); i++) {
                jsonObject = sheet1.getJSONObject(i);

                stringList.add(jsonObject.optString("title"));
            }

            callback.onReadExcelCompleted(stringList);
        } catch (Exception ex) {
            Log.e("Error in parse JSON", ex.getMessage());
        }
    }
}

AndroidParseExcel.html :(你应该把这个和JavaScript库放到资产文件夹中)

<html>
<script src="file:///android_asset/xlsx.core.min.js"></script>
<head></head>
<body>
</body>
<script type ="text/javascript">

    "use strict";

    var X = XLSX;

    function convertFile(b64data) {
        var wb = X.read(b64data, {type: 'base64',WTF: false});

        var result = {};
        wb.SheetNames.forEach(function(sheetName) {
            var roa = X.utils.sheet_to_row_object_array(wb.Sheets[sheetName]);
            if(roa.length > 0){
                result[sheetName] = roa;
            }
        });

        return JSON.stringify(result, 2, 2);
    }
</script>
</html>

标签：jexcelapi,android,excel,apache-poi
来源： https://codeday.me/bug/20190727/1553770.html