JAVA獲取系統中的變量

通過System類可以獲取系統中的變量。可以獲取env和System Property。獲取到之後存到D盤的SystemProperties.xls中。具體需要用到什麼系統變量以後就可以在這個xls中查詢了。

程序需要用到POI，我的版本是3.10。如果沒有的話可以在這下載：poi_3.10_FINAL

不想使用POI的童鞋吧for循環裏面的代碼改成System.out.println();輸出即可。

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Properties;
import java.util.Set;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.util.CellRangeAddress;


public class TestJava {
	static Map<String , String> env = System.getenv();
	static Map<String , String> properties = new HashMap<String , String>();
	public static void main(String[] args) {
		/*
		 * Get properties in System and write to XLS File
		 */
		File file = new File("D:/SystemProperties.xls");
		if (file.exists()) {
			file.delete();
		}
		Workbook wb = null;
		OutputStream os = null;
		try {
			file.createNewFile();
			os = new FileOutputStream(file);
			wb = new HSSFWorkbook();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} 
		Sheet sheet = wb.createSheet("env");
		CellRangeAddress cra = new CellRangeAddress(0,0,0,1);
		sheet.addMergedRegion(cra);
		Row row = sheet.createRow(0);
		row.createCell(0).setCellValue("env");
		row = sheet.createRow(1);
		row.createCell(0).setCellValue("Name");
		row.createCell(1).setCellValue("Value");
		int rownum=2;
		Set<Entry<String, String>>  set = env.entrySet();		
		for (Entry<String, String> entry : set) {
			row = sheet.createRow(rownum);
			row.createCell(0).setCellValue(entry.getKey());
			row.createCell(1).setCellValue(entry.getValue());
			rownum++;
		}
		sheet = wb.createSheet("SystemProperties");
		sheet.addMergedRegion(cra);
		row = sheet.createRow(0);
		row.createCell(0).setCellValue("SystemProperties");
		row = sheet.createRow(1);
		row.createCell(0).setCellValue("Name");
		row.createCell(1).setCellValue("Value");;
		Properties p = System.getProperties();
		Set<String> names =  p.stringPropertyNames();
		rownum=2;
		for (String name : names) {
			row = sheet.getRow(rownum);
			if (row == null) {
				row = sheet.createRow(rownum);
			}
			row.createCell(0).setCellValue(name);
			row.createCell(1).setCellValue(p.getProperty(name));
			rownum++;
		}
		try {
			wb.write(os);
			os.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}