common_helper/src/main/java/com/xiongyingqi/util/xml/TransformerUtils.java
public static void enableIndenting(Transformer transformer, int indentAmount) {
        Assert.notNull(transformer, "Transformer must not be null");
        Assert.isTrue(indentAmount > -1, "The indent amount cannot be less than zero : got " + indentAmount);
        transformer.setOutputProperty(OutputKeys.INDENT, "yes");
        try {
            // Xalan-specific, but this is the most common XSLT engine in any case
            transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", String.valueOf(indentAmount));
        } catch (IllegalArgumentException ignored) {
        }
    }
public static void enableIndenting(Transformer transformer, int indentAmount) {
        Assert.notNull(transformer, "Transformer must not be null");
        Assert.isTrue(indentAmount > -1, "The indent amount cannot be less than zero : got " + indentAmount);
        transformer.setOutputProperty(OutputKeys.INDENT, "yes");
        try {
            // Xalan-specific, but this is the most common XSLT engine in any case
            transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", String.valueOf(indentAmount));
        } catch (IllegalArgumentException ignored) {
        }
    }
Enable indenting for the supplied {@link javax.xml.transform.Transformer}. <p>If the underlying XSLT engine is
Xalan, then the special output key {@code indent-amount} will be also be set to a value of {@link
#DEFAULT_INDENT_AMOUNT} characters.

@param transformer  the target transformer
@param indentAmount the size of the indent (2 characters, 3 characters, etc.)
@see javax.xml.transform.Transformer#setOutputProperty(String, String)
@see javax.xml.transform.OutputKeys#INDENT