docs.sheetjs.com/docz/docs/03-demos/42-engines/03-rhino.md

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---
title: Java + Rhino
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pagination_prev: demos/bigdata/index
pagination_next: solutions/input
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---
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import current from '/version.js';
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import CodeBlock from '@theme/CodeBlock';
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Rhino is an ES3+ engine in Java.
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The [SheetJS Standalone scripts](/docs/getting-started/installation/standalone)
can be parsed and evaluated in a Rhino context.
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This demo wraps workbooks and sheets into separate Java classes. The final
result is a JAR.
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:::caution pass
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Rhino does not support Uint8Array, so certain formats like NUMBERS cannot be
parsed or written from Rhino JS code!
:::
## Integration Details
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:::caution pass
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Due to code generation errors, optimization must be turned off:
```java
Context context = Context.enter();
context.setOptimizationLevel(-1);
```
:::
Binary strings can be passed back and forth.
_Initialize Rhino_
Rhino does not provide a `global` variable. It can be created:
```java
Context cx = Context.enter();
Scriptable scope = cx.initStandardObjects();
/* Disable optimization */
cx.setOptimizationLevel(-1);
/* Initialize `global` variable */
// highlight-start
String s = "var global = (function(){ return this; }).call(null);";
cx.evaluateString(scope, s, "<cmd>", 1, null);
// highlight-end
```
_Load SheetJS Scripts_
The main library can be loaded by reading the scripts from the Java Archive and
evaluating in the Rhino context:
```java
/* pull source from JAR */
String s = new Scanner(
SheetJS.class.getResourceAsStream("/xlsx.full.min.js")
).useDelimiter("\\Z").next();
/* evaluate */
cx.evaluateString(scope, s, "<cmd>", 1, null);
```
To confirm the library is loaded, `XLSX.version` can be inspected:
```swift
/* get handle to XLSX */
Object XLSX = scope.get("XLSX", scope);
if(XLSX == Scriptable.NOT_FOUND) throw new Exception("XLSX not found");
/* get the version string */
String version = ((NativeObject)XLSX).get("version", scope).toString();
System.out.println("SheetJS version " + version);
```
### Reading Files
A binary string can be generated from a `byte` array:
```java
static String read_file(String file) throws IOException {
/* read file -> array of bytes */
byte[] b = Files.readAllBytes(Paths.get(file));
/* construct binary string */
StringBuilder sb = new StringBuilder();
for(int i = 0; i < b.length; ++i) sb.append(Character.toString((char)(b[i] < 0 ? b[i] + 256 : b[i])));
return sb.toString();
}
```
This string can be loaded into the JS engine and processed:
```java
/* options argument */
String os = "q = {'type':'binary', 'WTF':1};";
NativeObject o = (NativeObject)cx.evaluateString(scope, os, "<cmd>", 2, null);
/* set up function arguments */
String data = read_file(path_to_file);
Object args[] = {data, o};
/* call read -> wb workbook */
NativeObject nXLSX = (NativeObject)XLSX;
Function readfunc = (Function)XLSX.get("read", scope);
NativeObject wb = (NativeObject)readfunc.call(cx, scope, nXLSX, args);
```
`wb` will be a reference to the JS workbook object.
## Complete Example
:::note
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This demo was tested on 2023-07-26 using Rhino 1.7.14.
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:::
0) Ensure Java is installed. Create a folder for the project, download the
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[JAR](https://repo1.maven.org/maven2/org/mozilla/rhino/1.7.14/rhino-1.7.14.jar)
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and rename to `rhino.jar`:
```bash
mkdir sheetjs-java
cd sheetjs-java
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curl -L -o rhino.jar https://repo1.maven.org/maven2/org/mozilla/rhino/1.7.14/rhino-1.7.14.jar
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```
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1) Download the SheetJS Standalone script and the test file. Save both files in
the project directory:
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<ul>
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<li><a href={`https://cdn.sheetjs.com/xlsx-${current}/package/dist/xlsx.full.min.js`}>xlsx.full.min.js</a></li>
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<li><a href="https://sheetjs.com/pres.xlsx">pres.xlsx</a></li>
</ul>
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<CodeBlock language="bash">{`\
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curl -LO https://cdn.sheetjs.com/xlsx-${current}/package/dist/xlsx.full.min.js
curl -LO https://sheetjs.com/pres.xlsx`}
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</CodeBlock>
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2) Download [`SheetJSRhino.zip`](pathname:///rhino/SheetJSRhino.zip) and unzip
```bash
curl -LO https://docs.sheetjs.com/rhino/SheetJSRhino.zip
unzip SheetJSRhino.zip
```
3) Save the following code to `SheetJSRhino.java`:
```java title="SheetJSRhino.java"
/* sheetjs (C) 2013-present SheetJS -- https://sheetjs.com */
/* vim: set ts=2: */
import com.sheetjs.SheetJS;
import com.sheetjs.SheetJSFile;
import com.sheetjs.SheetJSSheet;
public class SheetJSRhino {
public static void main(String args[]) throws Exception {
try {
SheetJS sjs = new SheetJS();
/* open file */
SheetJSFile xl = sjs.read_file(args[0]);
/* get sheetnames */
String[] sheetnames = xl.get_sheet_names();
System.err.println(sheetnames[0]);
/* convert to CSV */
SheetJSSheet sheet = xl.get_sheet(0);
String csv = sheet.get_csv();
System.out.println(csv);
} catch(Exception e) { throw e; } finally { SheetJS.close(); }
}
}
```
4) Assemble `SheetJS.jar` from the demo code:
```bash
javac -cp .:rhino.jar SheetJSRhino.java
jar -cf SheetJS.jar SheetJSRhino.class com/sheetjs/*.class xlsx.full.min.js
```
5) Test the program:
```bash
java -cp .:SheetJS.jar:rhino.jar SheetJSRhino pres.xlsx
```
If successful, a CSV will be printed to console.