Java tutorial
package org.jsoup.nodes; import org.jsoup.SerializationException; import org.jsoup.internal.StringUtil; import org.jsoup.helper.Validate; import java.io.IOException; import java.util.Arrays; import java.util.Map; /** A single key + value attribute. (Only used for presentation.) */ public class Attribute implements Map.Entry<String, String>, Cloneable { private static final String[] booleanAttributes = { "allowfullscreen", "async", "autofocus", "checked", "compact", "declare", "default", "defer", "disabled", "formnovalidate", "hidden", "inert", "ismap", "itemscope", "multiple", "muted", "nohref", "noresize", "noshade", "novalidate", "nowrap", "open", "readonly", "required", "reversed", "seamless", "selected", "sortable", "truespeed", "typemustmatch" }; private String key; private String val; Attributes parent; // used to update the holding Attributes when the key / value is changed via this interface /** * Create a new attribute from unencoded (raw) key and value. * @param key attribute key; case is preserved. * @param value attribute value * @see #createFromEncoded */ public Attribute(String key, String value) { this(key, value, null); } /** * Create a new attribute from unencoded (raw) key and value. * @param key attribute key; case is preserved. * @param val attribute value * @param parent the containing Attributes (this Attribute is not automatically added to said Attributes) * @see #createFromEncoded*/ public Attribute(String key, String val, Attributes parent) { Validate.notNull(key); key = key.trim(); Validate.notEmpty(key); // trimming could potentially make empty, so validate here this.key = key; this.val = val; this.parent = parent; } /** Get the attribute key. @return the attribute key */ public String getKey() { return key; } /** Set the attribute key; case is preserved. @param key the new key; must not be null */ public void setKey(String key) { Validate.notNull(key); key = key.trim(); Validate.notEmpty(key); // trimming could potentially make empty, so validate here if (parent != null) { int i = parent.indexOfKey(this.key); if (i != Attributes.NotFound) parent.keys[i] = key; } this.key = key; } /** Get the attribute value. @return the attribute value */ public String getValue() { return Attributes.checkNotNull(val); } /** Set the attribute value. @param val the new attribute value; must not be null */ public String setValue(String val) { String oldVal = this.val; if (parent != null) { oldVal = parent.get(this.key); // trust the container more int i = parent.indexOfKey(this.key); if (i != Attributes.NotFound) parent.vals[i] = val; } this.val = val; return Attributes.checkNotNull(oldVal); } /** Get the HTML representation of this attribute; e.g. {@code href="index.html"}. @return HTML */ public String html() { StringBuilder sb = StringUtil.borrowBuilder(); try { html(sb, (new Document("")).outputSettings()); } catch (IOException exception) { throw new SerializationException(exception); } return StringUtil.releaseBuilder(sb); } protected static void html(String key, String val, Appendable accum, Document.OutputSettings out) throws IOException { accum.append(key); if (!shouldCollapseAttribute(key, val, out)) { accum.append("=\""); Entities.escape(accum, Attributes.checkNotNull(val), out, true, false, false); accum.append('"'); } } protected void html(Appendable accum, Document.OutputSettings out) throws IOException { html(key, val, accum, out); } /** Get the string representation of this attribute, implemented as {@link #html()}. @return string */ @Override public String toString() { return html(); } /** * Create a new Attribute from an unencoded key and a HTML attribute encoded value. * @param unencodedKey assumes the key is not encoded, as can be only run of simple \w chars. * @param encodedValue HTML attribute encoded value * @return attribute */ public static Attribute createFromEncoded(String unencodedKey, String encodedValue) { String value = Entities.unescape(encodedValue, true); return new Attribute(unencodedKey, value, null); // parent will get set when Put } protected boolean isDataAttribute() { return isDataAttribute(key); } protected static boolean isDataAttribute(String key) { return key.startsWith(Attributes.dataPrefix) && key.length() > Attributes.dataPrefix.length(); } /** * Collapsible if it's a boolean attribute and value is empty or same as name * * @param out output settings * @return Returns whether collapsible or not */ protected final boolean shouldCollapseAttribute(Document.OutputSettings out) { return shouldCollapseAttribute(key, val, out); } protected static boolean shouldCollapseAttribute(final String key, final String val, final Document.OutputSettings out) { return (out.syntax() == Document.OutputSettings.Syntax.html && (val == null || ("".equals(val) || val.equalsIgnoreCase(key)) && Attribute.isBooleanAttribute(key))); } /** * @deprecated */ protected boolean isBooleanAttribute() { return Arrays.binarySearch(booleanAttributes, key) >= 0 || val == null; } /** * Checks if this attribute name is defined as a boolean attribute in HTML5 */ protected static boolean isBooleanAttribute(final String key) { return Arrays.binarySearch(booleanAttributes, key) >= 0; } @Override public boolean equals(Object o) { // note parent not considered if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Attribute attribute = (Attribute) o; if (key != null ? !key.equals(attribute.key) : attribute.key != null) return false; return val != null ? val.equals(attribute.val) : attribute.val == null; } @Override public int hashCode() { // note parent not considered int result = key != null ? key.hashCode() : 0; result = 31 * result + (val != null ? val.hashCode() : 0); return result; } @Override public Attribute clone() { try { return (Attribute) super.clone(); } catch (CloneNotSupportedException e) { throw new RuntimeException(e); } } }