java 清空打印队列

Java中清空打印队列可以通过以下步骤实现：

1. 获取打印服务对象：`PrintService printService = PrintServiceLookup.lookupDefaultPrintService();`

2. 获取打印队列：`DocPrintJob printJob = printService.createPrintJob();`

3. 创建一个空的Doc对象：`Doc emptyDoc = new SimpleDoc(new byte[0], DocFlavor.BYTE_ARRAY.AUTOSENSE, null);`

4. 调用打印队列的cancel方法，将空的Doc对象传递给它：`printJob.cancel(emptyDoc);`

完整示例代码如下：

import javax.print.Doc;
import javax.print.DocFlavor;
import javax.print.DocPrintJob;
import javax.print.PrintService;
import javax.print.PrintServiceLookup;
import javax.print.SimpleDoc;

public class ClearPrintQueueExample {

    public static void main(String[] args) {
        PrintService printService = PrintServiceLookup.lookupDefaultPrintService();
        DocPrintJob printJob = printService.createPrintJob();
        Doc emptyDoc = new SimpleDoc(new byte[0], DocFlavor.BYTE_ARRAY.AUTOSENSE, null);
        printJob.cancel(emptyDoc);
        System.out.println("Print queue cleared.");
    }

}