Friends using the Windows operating system must not be unfamiliar with Excel, but to use Java language to manipulate the Excel file is not an easy task. Today, the Web is increasingly popular, the demand for the Excel file is increasing through the web, and the current more popular operation is to create a CSV (Comma Separated Values) file in the JSP or Servlet, and will file this file with MIME, TEXT / CSV type returns to the browser, then calls Excel and displays the CSV file. This is just to say that you can access the Excel file, but you can't really manipulate the Excel file. This article will give you a surprise, introduce you to an open source project, Java Excel API, use it, you can easily manipulate the Excel file.
Introduction to Java Excel API
Java Excel is an open source project, which can read the contents of the Excel file through its Java developers, create a new Excel file, update the existing Excel file. Using this API non-Windows operating system can also process the Excel data table by pure Java applications. Because it is written in Java, we can call the API to implement access to the Excel data table in a web application.
The stable version released now is V2.0, providing the following features:
Read the data from the files such as Excel 95, 97, 2000;
Read the Excel formula (you can read the formula after Excel 97);
Generate an Excel data table (format is Excel 97);
Support font, numbers, date formatting;
Support for the shadow operation of the cell, and color operation;
Modify the existing data sheet;
The following features are now also supported, but will soon provide:
Unable to read chart information;
You can read, but you can't generate formulas, any type of formula last calculated value can be read;
Application example
1, read data sheets from the Excel file
The Java Excel API can either a file (.xls) of the local file system, or you can read the Excel data table from the input stream. The first step in reading the Excel data is to create Workbook (Terminology: Working). The following code snippet is explained how to operate: (full code see Excelreading.java)
Import java.io. *; import jxl. *; ... ... ... ... ... ... Try {// Build a Workbook object, read-only Workbook object // Create Workbook from the local file // Create Workbook INPUTSTREAM IS = New FileInputStream from the input stream (Sourcefile ); jxl.workbook rwb = workbook.getworkbook (is);} catch (exception e) {E.PrintStackTrace ();}
Once you have created Workbook, we can access the Excel Sheet by it (Terminology: Worksheet). Refer to the following code segment:
// Get the first Sheet table Sheet RS = rwb.getsheet (0);
We can access it through the name of Sheet, or you can access it by subscript. If you are accessible by the subscript, you should pay attention to the starting mark from 0, just like an array.
Once you get the Sheet, we can access Excel Cell (Terms: Cells) through it. Refer to the following code segment:
/ / Get the first line, the value of the first column Cell C00 = rs.getcell (0, 0); string strc00 = c00.getContents (); // Get the first line, the value Cell C10 = RS of the second column. getcell (1, 0); string strc10 = c10.getContents (); // Get the second line, the second column of the value Cell C11 = rs.getcell (1, 1); string strC11 = c11.getContents (); system .out.println ("Cell (0, 0)" "value:" strc00 "; type:" c00.gettype ()); system.out.println ("Cell (1, 0)" " Value: " strc10 "; type: " c10.gettype ()); system.out.println (" Cell (1, 1) " " value: " strc11 "; type: " C11.Gettype ()) If only the value of Cell is obtained, we can easily return any type of CELL value as a string. Cell (0, 0) in the sample code is text type, Cell (1, 0) is a digital type, Cell (1, 1) is a date type, through getContents (), three types of return values are characters.
If you need to know the exact type of Cell content, the API also provides a range of methods. Refer to the following code segment:
String strc00 = null; double strc10 = 0.00; Date strc11 = NULL; Cell C00 = rs.getcell (0, 0); Cell C10 = rs.getcell (1, 0); Cell C11 = rs.getcell (1, 1) ; if (c00.gettype () == celltype.label) {Labelcell Labelc00 = (labelcell) c00; strc00 = labelc00.getstring ();} if (c10.gettype () == cellType.Number) {nmberCell Numc10 = ( Numbercell) C10; strc10 = Numc10.getValue ();} if (c11.gettype () == cellType.date) {datecell datec11 = (Datecell) C11; strc11 = datec11.getdate ();} system.out.println "Cell (0, 0)" "value:" strc00 "; type:" c00.gettype ()); system.out.println ("Cell (1, 0)" "value:" STRC10 "; type:" c10.gettype ()); System.out.Println ("Cell (1, 1)" "Value:" STRC11 "; TYPE:" C11.Gettype ()); After obtaining the Cell object, the type of the cell can be obtained by getType () method, and then match the basic type provided by the API, forcibly converting into a corresponding type, and finally call the corresponding value method getxxx (), you can get it. Type value. The API provides the following basic types, corresponding to the data format of Excel, as shown below:
For details of each type, see Java Excel API Document.
When you complete the processing of Excel spreadsheet data, you must use the close () method to close the previously created object to release the memory space occupied by the read data table, which is especially important when reading a large amount of data. . Refer to the following code segment:
// When the operation is complete, turn off the object, release the occupied memory space RWB.Close ();
The Java Excel API provides a number of ways to access the Excel data sheet, here I only briefly introduce several common methods, other methods, please refer to Java Excel API Document in the appendix.
Methods for providing Workbook class 1. Int getnumberofsheets ()
Get the number of worksheets (Sheets) in Workbook, examples:
JXL.Workbook RWB = jxl.workbook.getworkbook (new file (source (sourcefile)); int shop = rwb.getnumberofsheets ();
2. Sheet [] getsheets ()
Returns Workbook Worksheet (Sheet) Object Arrse, Example: JXL.Workbook RWB = JXL.Workbook.getWorkbook (New File (SourceFile); Sheet [] Sheets = RWB.Getsheets ();
3. String getversion ()
Returns the version number of the API that is in use, it seems that there is nothing big.
JXL.Workbook RWB = jxl.workbook.getworkbook (new file (sourcefile); string apiversion = rwb.getversion ();
Method provided by the Sheet interface
1) String getName ()
Get the name of Sheet, example:
JXL.Workbook RWB = jxl.workbook.getworkbook (new file (source (sourcefile)); jxl.sheet = rwb.getsheet (0); string sheetname = rs.getName ();
2) INT getColumns ()
Get the total number of columns included in the Sheet table, examples:
JXL.Workbook RWB = jxl.workbook.getworkbook (new file (sourcefile); jxl.sheet = rwb.getsheet (0); int gcolumns = rs.getColumns ();
3) Cell [] getColumn (int column)
Get all the cells of a column, returns a cell object array, example:
JXL.Workbook RWB = jxl.Workbook.getWorkbook (new file (sourcefile); jxl.sheet = rwb.getsheet (0); cell [] cell = rs.getColumn (0);
4) INT getRows ()
Get the total number of lines contained in the Sheet table, examples:
JXL.Workbook RWB = jxl.workbook.getworkbook (new file (sourcefile)); jxl.sheet = rwb.getsheet (0); int gROWS = rs.getrows ();
5) Cell [] GetRow (int Row)
Get all the cells of a certain line, returning the cell object array, an example:
JXL.Workbook RWB = jxl.Workbook.getWorkbook (new file (sourcefile)); jxl.sheet = rwb.getsheet (0); cell [] cell = rs.getrow (0);
6) Cell getcell (int column, int in)
Get the object reference to the specified cell, you need to pay attention to its two parameters, the first is the number of columns, the second is the number of rows, which is different from the usual row, the column combination is somewhat different.
JXL.Workbook RWB = jxl.Workbook.getWorkbook (new file (sourcefile)); jxl.sheet = rwb.getsheet (0); cell cell = rs.getcell (0, 0);
2, generate new Excel work
The following code is mainly to introduce you how to generate a simple Excel worksheet, where the content of the cell is no modified (e.g., font, color, etc.), and all the content is written as a string. (Full code See Excelwriting.java) Similar to reading Excel worksheets, first create a Workbook object using the factory method of the Workbook class, hereby pay attention, can only be provided by the API Method to create Workbook, not to use WritableWorkbook constructor because the constructor of class WritableWorkbook is protected by protected type. The sample code snippet is as follows:
Import java.io. *; import jxl. *; import jxl.write. *; ... ... ... try {// Build a Workbook object, read-only Workbook object // Method 1: Create a writable Excel workbook JXL. write.WritableWorkbook wwb = Workbook.createWorkbook (new File (targetfile)); // Method 2: WritableWorkbook written directly to the output stream / * OutputStream os = new FileOutputStream (targetfile); jxl.write.WritableWorkbook wwb = Workbook.createWorkbook (OS); * /} catch (exception e) {E.PrintStackTrace ();}
The API provides two ways to process the writable output stream. One is to generate a local file. If the file name does not have a full path, the default file is positioned in the current directory, if the file name has a full path The generated Excel file is positioned in the corresponding directory; another is to write the Excel object directly to the output stream, for example: the user accesses the web server through the browser, if the HTTP header is set correctly, the browser is automatically called The client's Excel application displays the dynamically generated Excel spreadsheet.
The next step is to create a worksheet, the method of creating a worksheet is almost the same as the method of creating a work, and the corresponding object is also obtained through the factory mode method. This method requires two parameters, one is the name of the worksheet, the other is The worksheet is in the position of the work, refer to the following code snippet:
// Create an Excel worksheet jxl.write.writablesheet ws = wwb.createsheet ("Test Sheet 1", 0); "This pot is also supported, the material is also ready, you can start the pot!" It is only the EXCEL basic data type provided by the API, and it is possible to add them to the worksheet. Refer to the following code segment: // 1. Add label object jxl.write.label labelc = new JXL.WRITE .Label (0, 0, "this is a label cell"); ws.addcell (labelc); // Add a word formatting object jxl.write.writablefont wf = new jxl.write.writableFont (WritableFont.Times , 18, WritableFont.Bold, True; JXL.WRITE.WRITABECECELLFORMAT WCFF = New JXL.WRITE.WRITABECELLFORMAT (WF); jxl.write.label labelcf = new jxl.write.Label (1, 0, "this is a label Cell ", WCFF); ws.addcell (labelcf); // Add object with font color formatting jxl.write.writablefont wfc = new jxl.write.writablefont (Writablefont.arial, 10, Writablefont.No_Bold, False, underlinestyle .No_underline, jxl.format.colour.red; jxl.write.writablecellformat wcffc = new jxl.write.writablecellFormat (WFC); jxl.write.label labelcfc = new jxl.write.label (1, 0, "this is A label cell ", WCFFC); ws.addcell (labelcf); // 2. Add Number object jxl.write.number labeln = new jxl.wri TE.NUMBER (0, 1, 3.1415926); ws.addcell (labeln); // Add Number object with formatting jxl.write.numberformat nf = new jxl.write.NumberFormat ("#. ##"); JXL .write.writablecellformat wcfn = new jxl.write.writablecellformat (nf); jxl.write.number labelnf = new jxl.write.Number (1, 1, 3.1415926, wcfn); ws.addcell (labelnf); // 3. Add Boolean object jxl.write.Boolean labelb = new jxl.write.boolean (0, 2, false); ws.addcell (labelb); // 4. Add a DateTime object jxl.write.datetime labeldt = new jxl.write. DateTime (0, 3, new java.util.date ()); ws.addcell (labeldt); // Add a DateFormat object with formatting, jxl.write.dateFormat DF =
NEW JXL.WRITE.DATEFORMAT ("DD MM YYYY HH: MM: SS"); jxl.write.writablecellformat wcfdf = new jxl.write.writablecellFormat (DF); jxl.write.datetime labeldtf = new jxl.write.datetime 1, 3, new java.util.date (), wcfdf); ws.addcell (labeldtf); there are two points to causing everyone to pay attention. The first point, when constructing the cell, the location of the cell in the worksheet has been determined. Once created, the location of the cell cannot be changed, although the content of the cell can be changed. In the second point, the positioning of the cell is the following regularity (COLUMN, ROW), and the subscript starts from 0, for example, A1 is stored in (0, 0), B1 is stored (1, 0) .
Finally, don't forget to close the open Excel workmail object to release the occupied memory, see the following code snippet:
// Write an Exel worksheet Wwb.write (); // Close Excel workmail object wwb.close ();
This may have little different from the operation of reading the Excel file. Before shutting down the Excel object, you must call the Write () method first, because the previous operation is stored in the cache, so the content to operate through this method Save in the file. If you turn off the Excel object first, you can only get an empty work.
3, copy, update Excel work thin
Next, I will introduce how to update an existing work, mainly the following two steps, the first step is to construct a read-only Excel work, the second step is to create new writable with the Excel workstorm that has been created. Excel works thin, refer to the following code snippet: (complete code see ExcelModifying.java)
// Create a read-only Excel work thin object jxl.workbook rw = jxl.workbook.getworkbook (new file (sourcefile)); // Create a writable Excel workmail object Jxl.write.writableworkbook wwb = workbook.createworkbook (New file (targetfile), RW); // reads the first workpiece jxl.write.writablesheet WS = wwb.getsheet (0); // Get the first cell object jxl.write.writableCell WC = WS .Getwritablecell (0, 0); // Judgment the type of cell, make corresponding conversion IF (wc.gettype () == cellType.label) {Label L = (label) wc; l.setstring ("The value" ");} // Write an Excel object Wwb.write (); // Close the writable Excel object wwb.close (); // Close the read-only Excel object rw.close ();
The reason why to build an Excel object is completely due to efficiency because the above example is the main application of the API. In order to improve performance, when reading a worksheet, some of the output information related to the data, all format information, such as: font, color, etc. are not processed, because our purpose is to get the value of row data, both There is no modification, nor does it affect the value of the value. The only unfavorable thing is that in memory will save both the same worksheet, so when the worksheet is large, it will occupy a considerable amount of memory, but now the size of memory is not a key factor. Once you have a writable worksheet object, we can update the cell object, where we do not have to call the ADD () method provided by the API, because the cell has been in the worksheet, so we only need To call the corresponding setxxxx () method, you can complete the update operation.
Using the original formatted modification of the cells cannot be removed, we can also add new units to make the content of the cells in different forms.
The newly generated worksheet object is writable. In addition to updating the original unit, you can add a new cell to a worksheet, which is exactly the same as the operation of Example 2.
Finally, don't forget to call the Write () method, write the updated content into the file, then turn off the workmaking object, here there are two working thin objects to be turned off, one is read-only, and the other is writable.
