将 pojo 列表复制到剪贴板

Question

郎：Java

我们正在尝试以 table 格式将 pojo 列表复制到剪贴板。

要点：我们正在努力实现的目标：

1.将 pojo 列表转换为 table 格式

2。如果用户在某些 excel sheet 中复制它，那么它应该很容易复制，或者即使用户尝试在记事本中复制它也应该以 table 格式打印。

3。将一些元数据添加到剪贴板以确定我们将再次导入 table 时的 pojo。

为了将 pojo 列表转换为 table 格式，我使用了 jtable 但我无法导出所有 jtable 内容到剪贴板。

任何人都可以建议我是否应该遵循 jtable 方法并将 table 复制到剪贴板或任何其他解决方案也可用。

更新：正如评论中所建议的，我尝试使用 flavours

public class ClipboardTest implements ClipboardOwner {
    public static void main(String[] args) {
        ClipboardTest clipboardTest = new ClipboardTest();
        clipboardTest.copyToClipboard();
        //clipboardTest.getFromClipboard();

    }

    public void copyToClipboard() {
        Clipboard clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();
        Pojo data = new Pojo("1", "2", "ame2", "2", "2");
        MyObjectSelection dataSelection = new MyObjectSelection(data);
        StringSelection selection = new StringSelection("testing string");
        clipboard.setContents(dataSelection, ClipboardTest.this);
        System.out.println("copied to clipboard");
    }

    public void getFromClipboard() {
        Clipboard clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();
        Transferable clipboardContent = clipboard.getContents(this);

        DataFlavor[] flavors = clipboardContent.getTransferDataFlavors();
        System.out.println("flavors.length = " + flavors.length);
        for (int i = 0; i < flavors.length; i++) {
            System.out.println("flavor[" + i + "] = " + flavors[i]);
        }
    }

    // ClipboardOwner implementation

    @Override
    public void lostOwnership(Clipboard clipboard, Transferable transferable) {
        System.out.println("ClipboardTest: Lost ownership");
    }

}


---
myobjectselection.java


public class MyObjectSelection implements Transferable, ClipboardOwner {
    private static DataFlavor dmselFlavor = new DataFlavor(Pojo.class,
            "Test data flavor");
    private Pojo selection;

    public MyObjectSelection(Pojo selection) {
        this.selection = selection;
    }

    // Transferable implementation

    @Override
    public DataFlavor[] getTransferDataFlavors() {
        System.out.println("getTransferDataFlavors");
        DataFlavor[] ret = { dmselFlavor };
        return ret;
    }

    @Override
    public boolean isDataFlavorSupported(DataFlavor flavor) {
        return dmselFlavor.equals(flavor);
    }

    @Override
    public synchronized Object getTransferData(DataFlavor flavor)
            throws UnsupportedFlavorException {
        if (isDataFlavorSupported(flavor)) {
            return this.selection;
        } else {
            throw new UnsupportedFlavorException(dmselFlavor);
        }
    }

    // ClipboardOwner implementation

    @Override
    public void lostOwnership(Clipboard clipboard, Transferable transferable) {
        System.out.println("MyObjectSelection: Lost ownership");
    }

}

-- pojo.java

public class Pojo  implements Serializable{
/**
     * 
     */
    private static final long serialVersionUID = 1L;
private String name;
private String name1;
private String name2;
private String name3;
    private String name4;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getName1() {
        return name1;
    }

    public void setName1(String name1) {
        this.name1 = name1;
    }

    public String getName2() {
        return name2;
    }

    public void setName2(String name2) {
        this.name2 = name2;
    }

    public String getName3() {
        return name3;
    }

    public void setName3(String name3) {
        this.name3 = name3;
    }

    public String getName4() {
        return name4;
    }

    public void setName4(String name4) {
        this.name4 = name4;
    }

    public Pojo(String name, String name1, String name2, String name3,
            String name4) {
        super();
        this.name = name;
        this.name1 = name1;
        this.name2 = name2;
        this.name3 = name3;
        this.name4 = name4;
    }

}

当我试图将字符串值复制到剪贴板时，它正在工作，但是当我试图复制 pojo 时，它是否不起作用。

Answer 1

对于您想要支持的每种风格，您必须提供方法以指定格式对对象进行编码。

这意味着您可能需要为纯文本提供编码器，html 和 CVS 来涵盖基础知识。

所以，基于你的Pojo，我写了一个Transferable支持：

List（共 Pojo 秒）
HTML
CVS
纯文本
并连载（作为对List的补充，但本质上是一样的）

`PojoTransferable`

public class PojoTransferable implements Transferable {

    public static final DataFlavor POJO_LIST_DATA_FLAVOR = new DataFlavor(List.class, "application/x-java-pojo-list;class=java.util.List");
    public static final DataFlavor HTML_DATA_FLAVOR = new DataFlavor("text/html", "HTML");
    public static final DataFlavor CSV_DATA_FLAVOR = new DataFlavor("text/csv", "CVS");
    public static final DataFlavor PLAIN_DATA_FLAVOR = new DataFlavor("text/plain", "Plain text");
    public static final DataFlavor SERIALIZED_DATA_FLAVOR = new DataFlavor(Pojo.class, "application/x-java-serialized-object; Pojo");

    private static String[] HEADERS = new String[]{"name", "name1", "name2", "name3", "name4"};
    private static Pojo POJO_HEADER = new Pojo("name", "name1", "name2", "name3", "name4");

    private List<Pojo> pojos;

    public PojoTransferable(List<Pojo> pojos) {
        this.pojos = pojos;
    }

    @Override
    public DataFlavor[] getTransferDataFlavors() {
        return new DataFlavor[]{POJO_LIST_DATA_FLAVOR, HTML_DATA_FLAVOR, CSV_DATA_FLAVOR, SERIALIZED_DATA_FLAVOR, PLAIN_DATA_FLAVOR};
    }

    @Override
    public boolean isDataFlavorSupported(DataFlavor flavor) {
        boolean supported = false;
        for (DataFlavor mine : getTransferDataFlavors()) {
            if (mine.equals(flavor)) {
                supported = true;
                break;
            }
        }
        return supported;
    }

    @Override
    public Object getTransferData(DataFlavor flavor) throws UnsupportedFlavorException, IOException {
        Object data = null;
        if (POJO_LIST_DATA_FLAVOR.equals(flavor)) {
            data = pojos;
        } else if (HTML_DATA_FLAVOR.equals(flavor)) {
            data = new ByteArrayInputStream(formatAsHTML().getBytes());
        } else if (SERIALIZED_DATA_FLAVOR.equals(flavor)) {
            data = pojos;
        } else if (CSV_DATA_FLAVOR.equals(flavor)) {
            data = new ByteArrayInputStream(formatAsCVS().getBytes());
        } else if (PLAIN_DATA_FLAVOR.equals(flavor)) {
            data = new ByteArrayInputStream(formatAsPlainText().getBytes());
        } else {
            throw new UnsupportedFlavorException(flavor);
        }
        return data;
    }

    protected String formatAsCVS(Pojo pojo) {
        StringJoiner sj = new StringJoiner(",");
        sj.add(pojo.getName());
        sj.add(pojo.getName2());
        sj.add(pojo.getName3());
        sj.add(pojo.getName4());
        return sj.toString();
    }

    public String formatAsCVS() {
        StringBuilder sb = new StringBuilder(128);
        sb.append(formatAsCVS(POJO_HEADER));
        for (Pojo pojo : pojos) {
            sb.append(formatAsCVS(pojo));
        }
        return "";
    }

    protected Map<Integer, Integer> columnWidthsFor(Pojo pojo) {
        Map<Integer, Integer> columnWidths = new HashMap<>();
        columnWidths.put(0, pojo.getName().length());
        columnWidths.put(1, pojo.getName1().length());
        columnWidths.put(2, pojo.getName2().length());
        columnWidths.put(3, pojo.getName3().length());
        columnWidths.put(4, pojo.getName4().length());
        return columnWidths;
    }

    protected void apply(Map<Integer, Integer> pojoWidths, Map<Integer, Integer> columnWidths) {
        for (int index = 0; index < 5; index++) {
            int currentWidth = 2;
            if (columnWidths.containsKey(index)) {
                currentWidth = columnWidths.get(index);
            }
            int columnWidth = 2;
            if (pojoWidths.containsKey(index)) {
                columnWidth = pojoWidths.get(index);
            }
            columnWidths.put(index, Math.max(currentWidth, columnWidth));
        }
    }

    protected String formatAsPlainText(Pojo pojo, String format) {
        return String.format(format, pojo.getName(), pojo.getName1(), pojo.getName2(), pojo.getName3(), pojo.getName4());
    }

    public static String fill(int padding) {
        return String.format("%" + padding + "s", "").replace(" ", "-");
    }

    public String formatAsPlainText() {
        Map<Integer, Integer> columnWidths = new HashMap<>();

        apply(columnWidthsFor(POJO_HEADER), columnWidths);
        for (Pojo pojo : pojos) {
            apply(columnWidthsFor(pojo), columnWidths);
        }

        StringJoiner sjFormat = new StringJoiner("|");
        StringJoiner sjSep = new StringJoiner("+");
        for (int index = 0; index < 5; index++) {
            int currentWidth = 0;
            if (columnWidths.containsKey(index)) {
                currentWidth = columnWidths.get(index);
            }
            sjFormat.add(" %-" + currentWidth + "s ");
            sjSep.add(fill(currentWidth + 2));
        }
        sjFormat.add("%n");
        sjSep.add("\n");

        String seperator = sjSep.toString();
        String format = sjFormat.toString();
        StringBuilder sb = new StringBuilder(128);
        sb.append(formatAsPlainText(POJO_HEADER, format));
        for (Pojo pojo : pojos) {
            sb.append(seperator);
            sb.append(formatAsPlainText(pojo, format));
        }
        return sb.toString();
    }

    public String formatAsHTML() {
        StringBuilder sb = new StringBuilder(128);
        sb.append("<html><body>");
        sb.append("<table border='1'>");
        sb.append("<tr>");
        for (String header : HEADERS) {
            sb.append("<th>").append(header).append("</th>");
        }
        sb.append("</tr>");
        for (Pojo pojo : pojos) {
            sb.append("<tr>");
            sb.append("<td>").append(pojo.getName()).append("</td>");
            sb.append("<td>").append(pojo.getName1()).append("</td>");
            sb.append("<td>").append(pojo.getName2()).append("</td>");
            sb.append("<td>").append(pojo.getName3()).append("</td>");
            sb.append("<td>").append(pojo.getName4()).append("</td>");
            sb.append("</tr>");
        }
        sb.append("</table>");

        return sb.toString();
    }
}

测试...

然后我写了一个非常简单的测试...

List<Pojo> pojos = new ArrayList<>(25);
pojos.add(new Pojo("one", "two", "three", "four", "five"));

PojoTransferable pt = new PojoTransferable(pojos);
Clipboard cb = Toolkit.getDefaultToolkit().getSystemClipboard();
cb.setContents(pt, new ClipboardOwner() {
    @Override
    public void lostOwnership(Clipboard clipboard, Transferable contents) {
        System.out.println("Lost");
    }
});
try {
    Object data = cb.getData(PojoTransferable.POJO_LIST_DATA_FLAVOR);
    if (data instanceof List) {
        List listOfPojos = (List)data;
        System.out.println("listOfPojos contains " + listOfPojos.size());
        for (Object o : listOfPojos) {
            System.out.println(o);
        }
    }
} catch (UnsupportedFlavorException ex) {
    Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
} catch (IOException ex) {
    Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
}

当我运行它时，它打印出来...

listOfPojos contains 1
test.Pojo@5b480cf9

告诉用户 List 风格有效（满足我们的需要），但随后我打开了文本编辑器、Word 和 Excel 并将内容粘贴到其中...

nb: Excel 使用了 HTML 格式，看图

将 pojo 列表复制到剪贴板

Copy the list of pojo to clipboard

java

clipboard

jtable

pojo

PojoTransferable

测试...

`PojoTransferable`