spring FormTag 源码
spring FormTag 代码
文件路径：/spring-webmvc/src/main/java/org/springframework/web/servlet/tags/form/FormTag.java
/*
* Copyright 2002-2018 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.web.servlet.tags.form;
import java.nio.charset.UnsupportedCharsetException;
import java.util.Map;
import jakarta.servlet.ServletRequest;
import jakarta.servlet.ServletResponse;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.jsp.JspException;
import jakarta.servlet.jsp.PageContext;
import org.springframework.beans.PropertyAccessor;
import org.springframework.core.Conventions;
import org.springframework.http.HttpMethod;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.CollectionUtils;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.support.RequestDataValueProcessor;
import org.springframework.web.util.HtmlUtils;
import org.springframework.web.util.UriUtils;
/**
* The {@code <form>} tag renders an HTML 'form' tag and exposes a binding path to
* inner tags for binding.
*
* <p>Users should place the form object into the
* {@link org.springframework.web.servlet.ModelAndView ModelAndView} when
* populating the data for their view. The name of this form object can be
* configured using the {@link #setModelAttribute "modelAttribute"} property.
*
* <p>
* <table>
* <caption>Attribute Summary</caption>
* <thead>
* <tr>
* <th class="colFirst">Attribute</th>
* <th class="colOne">Required?</th>
* <th class="colOne">Runtime Expression?</th>
* <th class="colLast">Description</th>
* </tr>
* </thead>
* <tbody>
* <tr class="altColor">
* <td><p>acceptCharset</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>Specifies the list of character encodings for input data that is accepted
* by the server processing this form. The value is a space- and/or comma-delimited
* list of charset values. The client must interpret this list as an exclusive-or
* list, i.e., the server is able to accept any single character encoding per
* entity received.</p></td>
* </tr>
* <tr class="rowColor">
* <td><p>action</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Required Attribute</p></td>
* </tr>
* <tr class="altColor">
* <td><p>cssClass</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Optional Attribute</p></td>
* </tr>
* <tr class="rowColor">
* <td><p>cssStyle</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Optional Attribute</p></td>
* </tr>
* <tr class="altColor">
* <td><p>dir</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Standard Attribute</p></td>
* </tr>
* <tr class="rowColor">
* <td><p>enctype</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Optional Attribute</p></td>
* </tr>
* <tr class="altColor">
* <td><p>htmlEscape</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>Enable/disable HTML escaping of rendered values.</p></td>
* </tr>
* <tr class="rowColor">
* <td><p>id</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Standard Attribute</p></td>
* </tr>
* <tr class="altColor">
* <td><p>lang</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Standard Attribute</p></td>
* </tr>
* <tr class="rowColor">
* <td><p>method</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Optional Attribute</p></td>
* </tr>
* <tr class="altColor">
* <td><p>methodParam</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>The parameter name used for HTTP methods other then GET and POST.
* Default is '_method'.</p></td>
* </tr>
* <tr class="rowColor">
* <td><p>modelAttribute</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>Name of the model attribute under which the form object is exposed.
* Defaults to 'command'.</p></td>
* </tr>
* <tr class="altColor">
* <td><p>name</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Standard Attribute - added for backwards compatibility cases</p></td>
* </tr>
* <tr class="rowColor">
* <td><p>onclick</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Event Attribute</p></td>
* </tr>
* <tr class="altColor">
* <td><p>ondblclick</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Event Attribute</p></td>
* </tr>
* <tr class="rowColor">
* <td><p>onkeydown</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Event Attribute</p></td>
* </tr>
* <tr class="altColor">
* <td><p>onkeypress</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Event Attribute</p></td>
* </tr>
* <tr class="rowColor">
* <td><p>onkeyup</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Event Attribute</p></td>
* </tr>
* <tr class="altColor">
* <td><p>onmousedown</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Event Attribute</p></td>
* </tr>
* <tr class="rowColor">
* <td><p>onmousemove</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Event Attribute</p></td>
* </tr>
* <tr class="altColor">
* <td><p>onmouseout</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Event Attribute</p></td>
* </tr>
* <tr class="rowColor">
* <td><p>onmouseover</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Event Attribute</p></td>
* </tr>
* <tr class="altColor">
* <td><p>onmouseup</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Event Attribute</p></td>
* </tr>
* <tr class="rowColor">
* <td><p>onreset</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Event Attribute</p></td>
* </tr>
* <tr class="altColor">
* <td><p>onsubmit</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Event Attribute</p></td>
* </tr>
* <tr class="rowColor">
* <td><p>servletRelativeAction</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>Action reference to be appended to the current servlet path</p></td>
* </tr>
* <tr class="altColor">
* <td><p>target</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Optional Attribute</p></td>
* </tr>
* <tr class="rowColor">
* <td><p>title</p></td>
* <td><p>false</p></td>
* <td><p>true</p></td>
* <td><p>HTML Standard Attribute</p></td>
* </tr>
* </tbody>
* </table>
*
* @author Rob Harrop
* @author Juergen Hoeller
* @author Scott Andrews
* @author Rossen Stoyanchev
* @since 2.0
*/
@SuppressWarnings("serial")
public class FormTag extends AbstractHtmlElementTag {
/** The default HTTP method using which form values are sent to the server: "post". */
private static final String DEFAULT_METHOD = "post";
/** The default attribute name: "command". */
public static final String DEFAULT_COMMAND_NAME = "command";
/** The name of the '{@code modelAttribute}' setting. */
private static final String MODEL_ATTRIBUTE = "modelAttribute";
/**
* The name of the {@link jakarta.servlet.jsp.PageContext} attribute under which the
* form object name is exposed.
*/
public static final String MODEL_ATTRIBUTE_VARIABLE_NAME =
Conventions.getQualifiedAttributeName(AbstractFormTag.class, MODEL_ATTRIBUTE);
/** Default method parameter, i.e. {@code _method}. */
private static final String DEFAULT_METHOD_PARAM = "_method";
private static final String FORM_TAG = "form";
private static final String INPUT_TAG = "input";
private static final String ACTION_ATTRIBUTE = "action";
private static final String METHOD_ATTRIBUTE = "method";
private static final String TARGET_ATTRIBUTE = "target";
private static final String ENCTYPE_ATTRIBUTE = "enctype";
private static final String ACCEPT_CHARSET_ATTRIBUTE = "accept-charset";
private static final String ONSUBMIT_ATTRIBUTE = "onsubmit";
private static final String ONRESET_ATTRIBUTE = "onreset";
private static final String AUTOCOMPLETE_ATTRIBUTE = "autocomplete";
private static final String NAME_ATTRIBUTE = "name";
private static final String VALUE_ATTRIBUTE = "value";
private static final String TYPE_ATTRIBUTE = "type";
@Nullable
private TagWriter tagWriter;
private String modelAttribute = DEFAULT_COMMAND_NAME;
@Nullable
private String name;
@Nullable
private String action;
@Nullable
private String servletRelativeAction;
private String method = DEFAULT_METHOD;
@Nullable
private String target;
@Nullable
private String enctype;
@Nullable
private String acceptCharset;
@Nullable
private String onsubmit;
@Nullable
private String onreset;
@Nullable
private String autocomplete;
private String methodParam = DEFAULT_METHOD_PARAM;
/** Caching a previous nested path, so that it may be reset. */
@Nullable
private String previousNestedPath;
/**
* Set the name of the form attribute in the model.
* <p>May be a runtime expression.
*/
public void setModelAttribute(String modelAttribute) {
this.modelAttribute = modelAttribute;
}
/**
* Get the name of the form attribute in the model.
*/
protected String getModelAttribute() {
return this.modelAttribute;
}
/**
* Set the value of the '{@code name}' attribute.
* <p>May be a runtime expression.
* <p>Name is not a valid attribute for form on XHTML 1.0. However,
* it is sometimes needed for backward compatibility.
*/
public void setName(String name) {
this.name = name;
}
/**
* Get the value of the '{@code name}' attribute.
*/
@Override
@Nullable
protected String getName() throws JspException {
return this.name;
}
/**
* Set the value of the '{@code action}' attribute.
* <p>May be a runtime expression.
*/
public void setAction(@Nullable String action) {
this.action = (action != null ? action : "");
}
/**
* Get the value of the '{@code action}' attribute.
*/
@Nullable
protected String getAction() {
return this.action;
}
/**
* Set the value of the '{@code action}' attribute through a value
* that is to be appended to the current servlet path.
* <p>May be a runtime expression.
* @since 3.2.3
*/
public void setServletRelativeAction(@Nullable String servletRelativeAction) {
this.servletRelativeAction = servletRelativeAction;
}
/**
* Get the servlet-relative value of the '{@code action}' attribute.
* @since 3.2.3
*/
@Nullable
protected String getServletRelativeAction() {
return this.servletRelativeAction;
}
/**
* Set the value of the '{@code method}' attribute.
* <p>May be a runtime expression.
*/
public void setMethod(String method) {
this.method = method;
}
/**
* Get the value of the '{@code method}' attribute.
*/
protected String getMethod() {
return this.method;
}
/**
* Set the value of the '{@code target}' attribute.
* <p>May be a runtime expression.
*/
public void setTarget(String target) {
this.target = target;
}
/**
* Get the value of the '{@code target}' attribute.
*/
@Nullable
public String getTarget() {
return this.target;
}
/**
* Set the value of the '{@code enctype}' attribute.
* <p>May be a runtime expression.
*/
public void setEnctype(String enctype) {
this.enctype = enctype;
}
/**
* Get the value of the '{@code enctype}' attribute.
*/
@Nullable
protected String getEnctype() {
return this.enctype;
}
/**
* Set the value of the '{@code acceptCharset}' attribute.
* <p>May be a runtime expression.
*/
public void setAcceptCharset(String acceptCharset) {
this.acceptCharset = acceptCharset;
}
/**
* Get the value of the '{@code acceptCharset}' attribute.
*/
@Nullable
protected String getAcceptCharset() {
return this.acceptCharset;
}
/**
* Set the value of the '{@code onsubmit}' attribute.
* <p>May be a runtime expression.
*/
public void setOnsubmit(String onsubmit) {
this.onsubmit = onsubmit;
}
/**
* Get the value of the '{@code onsubmit}' attribute.
*/
@Nullable
protected String getOnsubmit() {
return this.onsubmit;
}
/**
* Set the value of the '{@code onreset}' attribute.
* <p>May be a runtime expression.
*/
public void setOnreset(String onreset) {
this.onreset = onreset;
}
/**
* Get the value of the '{@code onreset}' attribute.
*/
@Nullable
protected String getOnreset() {
return this.onreset;
}
/**
* Set the value of the '{@code autocomplete}' attribute.
* May be a runtime expression.
*/
public void setAutocomplete(String autocomplete) {
this.autocomplete = autocomplete;
}
/**
* Get the value of the '{@code autocomplete}' attribute.
*/
@Nullable
protected String getAutocomplete() {
return this.autocomplete;
}
/**
* Set the name of the request param for non-browser supported HTTP methods.
*/
public void setMethodParam(String methodParam) {
this.methodParam = methodParam;
}
/**
* Get the name of the request param for non-browser supported HTTP methods.
* @since 4.2.3
*/
protected String getMethodParam() {
return this.methodParam;
}
/**
* Determine if the HTTP method is supported by browsers (i.e. GET or POST).
*/
protected boolean isMethodBrowserSupported(String method) {
return ("get".equalsIgnoreCase(method) || "post".equalsIgnoreCase(method));
}
/**
* Writes the opening part of the block '{@code form}' tag and exposes
* the form object name in the {@link jakarta.servlet.jsp.PageContext}.
* @param tagWriter the {@link TagWriter} to which the form content is to be written
* @return {@link jakarta.servlet.jsp.tagext.Tag#EVAL_BODY_INCLUDE}
*/
@Override
protected int writeTagContent(TagWriter tagWriter) throws JspException {
this.tagWriter = tagWriter;
tagWriter.startTag(FORM_TAG);
writeDefaultAttributes(tagWriter);
tagWriter.writeAttribute(ACTION_ATTRIBUTE, resolveAction());
writeOptionalAttribute(tagWriter, METHOD_ATTRIBUTE, getHttpMethod());
writeOptionalAttribute(tagWriter, TARGET_ATTRIBUTE, getTarget());
writeOptionalAttribute(tagWriter, ENCTYPE_ATTRIBUTE, getEnctype());
writeOptionalAttribute(tagWriter, ACCEPT_CHARSET_ATTRIBUTE, getAcceptCharset());
writeOptionalAttribute(tagWriter, ONSUBMIT_ATTRIBUTE, getOnsubmit());
writeOptionalAttribute(tagWriter, ONRESET_ATTRIBUTE, getOnreset());
writeOptionalAttribute(tagWriter, AUTOCOMPLETE_ATTRIBUTE, getAutocomplete());
tagWriter.forceBlock();
if (!isMethodBrowserSupported(getMethod())) {
assertHttpMethod(getMethod());
String inputName = getMethodParam();
String inputType = "hidden";
tagWriter.startTag(INPUT_TAG);
writeOptionalAttribute(tagWriter, TYPE_ATTRIBUTE, inputType);
writeOptionalAttribute(tagWriter, NAME_ATTRIBUTE, inputName);
writeOptionalAttribute(tagWriter, VALUE_ATTRIBUTE, processFieldValue(inputName, getMethod(), inputType));
tagWriter.endTag();
}
// Expose the form object name for nested tags...
String modelAttribute = resolveModelAttribute();
this.pageContext.setAttribute(MODEL_ATTRIBUTE_VARIABLE_NAME, modelAttribute, PageContext.REQUEST_SCOPE);
// Save previous nestedPath value, build and expose current nestedPath value.
// Use request scope to expose nestedPath to included pages too.
this.previousNestedPath =
(String) this.pageContext.getAttribute(NESTED_PATH_VARIABLE_NAME, PageContext.REQUEST_SCOPE);
this.pageContext.setAttribute(NESTED_PATH_VARIABLE_NAME,
modelAttribute + PropertyAccessor.NESTED_PROPERTY_SEPARATOR, PageContext.REQUEST_SCOPE);
return EVAL_BODY_INCLUDE;
}
private String getHttpMethod() {
return (isMethodBrowserSupported(getMethod()) ? getMethod() : DEFAULT_METHOD);
}
private void assertHttpMethod(String method) {
for (HttpMethod httpMethod : HttpMethod.values()) {
if (httpMethod.name().equalsIgnoreCase(method)) {
return;
}
}
throw new IllegalArgumentException("Invalid HTTP method: " + method);
}
/**
* Autogenerated IDs correspond to the form object name.
*/
@Override
protected String autogenerateId() throws JspException {
return resolveModelAttribute();
}
/**
* {@link #evaluate Resolves} and returns the name of the form object.
* @throws IllegalArgumentException if the form object resolves to {@code null}
*/
protected String resolveModelAttribute() throws JspException {
Object resolvedModelAttribute = evaluate(MODEL_ATTRIBUTE, getModelAttribute());
if (resolvedModelAttribute == null) {
throw new IllegalArgumentException(MODEL_ATTRIBUTE + " must not be null");
}
return (String) resolvedModelAttribute;
}
/**
* Resolve the value of the '{@code action}' attribute.
* <p>If the user configured an '{@code action}' value then the result of
* evaluating this value is used. If the user configured an
* '{@code servletRelativeAction}' value then the value is prepended
* with the context and servlet paths, and the result is used. Otherwise, the
* {@link org.springframework.web.servlet.support.RequestContext#getRequestUri()
* originating URI} is used.
* @return the value that is to be used for the '{@code action}' attribute
*/
protected String resolveAction() throws JspException {
String action = getAction();
String servletRelativeAction = getServletRelativeAction();
if (StringUtils.hasText(action)) {
action = getDisplayString(evaluate(ACTION_ATTRIBUTE, action));
return processAction(action);
}
else if (StringUtils.hasText(servletRelativeAction)) {
String pathToServlet = getRequestContext().getPathToServlet();
if (servletRelativeAction.startsWith("/") &&
!servletRelativeAction.startsWith(getRequestContext().getContextPath())) {
servletRelativeAction = pathToServlet + servletRelativeAction;
}
servletRelativeAction = getDisplayString(evaluate(ACTION_ATTRIBUTE, servletRelativeAction));
return processAction(servletRelativeAction);
}
else {
String requestUri = getRequestContext().getRequestUri();
String encoding = this.pageContext.getResponse().getCharacterEncoding();
try {
requestUri = UriUtils.encodePath(requestUri, encoding);
}
catch (UnsupportedCharsetException ex) {
// shouldn't happen - if it does, proceed with requestUri as-is
}
ServletResponse response = this.pageContext.getResponse();
if (response instanceof HttpServletResponse) {
requestUri = ((HttpServletResponse) response).encodeURL(requestUri);
String queryString = getRequestContext().getQueryString();
if (StringUtils.hasText(queryString)) {
requestUri += "?" + HtmlUtils.htmlEscape(queryString);
}
}
if (StringUtils.hasText(requestUri)) {
return processAction(requestUri);
}
else {
throw new IllegalArgumentException("Attribute 'action' is required. " +
"Attempted to resolve against current request URI but request URI was null.");
}
}
}
/**
* Process the action through a {@link RequestDataValueProcessor} instance
* if one is configured or otherwise returns the action unmodified.
*/
private String processAction(String action) {
RequestDataValueProcessor processor = getRequestContext().getRequestDataValueProcessor();
ServletRequest request = this.pageContext.getRequest();
if (processor != null && request instanceof HttpServletRequest) {
action = processor.processAction((HttpServletRequest) request, action, getHttpMethod());
}
return action;
}
/**
* Closes the '{@code form}' block tag and removes the form object name
* from the {@link jakarta.servlet.jsp.PageContext}.
*/
@Override
public int doEndTag() throws JspException {
RequestDataValueProcessor processor = getRequestContext().getRequestDataValueProcessor();
ServletRequest request = this.pageContext.getRequest();
if (processor != null && request instanceof HttpServletRequest) {
writeHiddenFields(processor.getExtraHiddenFields((HttpServletRequest) request));
}
Assert.state(this.tagWriter != null, "No TagWriter set");
this.tagWriter.endTag();
return EVAL_PAGE;
}
/**
* Writes the given values as hidden fields.
*/
private void writeHiddenFields(@Nullable Map<String, String> hiddenFields) throws JspException {
if (!CollectionUtils.isEmpty(hiddenFields)) {
Assert.state(this.tagWriter != null, "No TagWriter set");
this.tagWriter.appendValue("<div>\n");
for (Map.Entry<String, String> entry : hiddenFields.entrySet()) {
this.tagWriter.appendValue("<input type=\"hidden\" ");
this.tagWriter.appendValue("name=\"" + entry.getKey() + "\" value=\"" + entry.getValue() + "\" ");
this.tagWriter.appendValue("/>\n");
}
this.tagWriter.appendValue("</div>");
}
}
/**
* Clears the stored {@link TagWriter}.
*/
@Override
public void doFinally() {
super.doFinally();
this.pageContext.removeAttribute(MODEL_ATTRIBUTE_VARIABLE_NAME, PageContext.REQUEST_SCOPE);
if (this.previousNestedPath != null) {
// Expose previous nestedPath value.
this.pageContext.setAttribute(NESTED_PATH_VARIABLE_NAME, this.previousNestedPath, PageContext.REQUEST_SCOPE);
}
else {
// Remove exposed nestedPath value.
this.pageContext.removeAttribute(NESTED_PATH_VARIABLE_NAME, PageContext.REQUEST_SCOPE);
}
this.tagWriter = null;
this.previousNestedPath = null;
}
/**
* Override resolve CSS class since error class is not supported.
*/
@Override
protected String resolveCssClass() throws JspException {
return ObjectUtils.getDisplayString(evaluate("cssClass", getCssClass()));
}
/**
* Unsupported for forms.
* @throws UnsupportedOperationException always
*/
@Override
public void setPath(String path) {
throw new UnsupportedOperationException("The 'path' attribute is not supported for forms");
}
/**
* Unsupported for forms.
* @throws UnsupportedOperationException always
*/
@Override
public void setCssErrorClass(String cssErrorClass) {
throw new UnsupportedOperationException("The 'cssErrorClass' attribute is not supported for forms");
}
}
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