java web从零单排第七期《struts2》用ActionSupport类验证提交表单

struts2中ActionSupport类具有验证表单的功能，可以将一些错误信息显示在jsp页面上。

ActionSupport的父类是Object，实现了六个接口，分别是：Action，LocalProvider，TextProvider，Validateble，ValidateAware，Serializable。

由于ActionSupport类实现了Action接口，可以确定ActionSupport拥有Action的5个常量值，在此基础上ActionSupport对功能进行了许多拓展，如具有验证功能。

我们先找一下validateble接口，点开Web App libraries 下的 xwork-core jar包

双击之后把源代码添加进去：

代码如下：

/*
 * Copyright 2002-2006,2009 The Apache Software Foundation.
 * 
 * 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
 * 
 *      http://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 com.opensymphony.xwork2;

import com.opensymphony.xwork2.inject.Container;
import com.opensymphony.xwork2.inject.Inject;
import com.opensymphony.xwork2.util.ValueStack;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.logging.LoggerFactory;

import java.io.Serializable;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.ResourceBundle;


/**
 * Provides a default implementation for the most common actions.
 * See the documentation for all the interfaces this class implements for more detailed information.
 */
public class ActionSupport implements Action, Validateable, ValidationAware, TextProvider, LocaleProvider, Serializable {

    protected static Logger LOG = LoggerFactory.getLogger(ActionSupport.class);

    private final ValidationAwareSupport validationAware = new ValidationAwareSupport();

    private transient TextProvider textProvider;
    private Container container;

    public void setActionErrors(Collection<String> errorMessages) {
        validationAware.setActionErrors(errorMessages);
    }

    public Collection<String> getActionErrors() {
        return validationAware.getActionErrors();
    }

    public void setActionMessages(Collection<String> messages) {
        validationAware.setActionMessages(messages);
    }

    public Collection<String> getActionMessages() {
        return validationAware.getActionMessages();
    }

    /**
     * @deprecated Use {@link #getActionErrors()}.
     */
    @Deprecated
    public Collection<String> getErrorMessages() {
        return getActionErrors();
    }

    /**
     * @deprecated Use {@link #getFieldErrors()}.
     */
    @Deprecated
    public Map<String, List<String>> getErrors() {
        return getFieldErrors();
    }

    public void setFieldErrors(Map<String, List<String>> errorMap) {
        validationAware.setFieldErrors(errorMap);
    }

    public Map<String, List<String>> getFieldErrors() {
        return validationAware.getFieldErrors();
    }

    public Locale getLocale() {
        ActionContext ctx = ActionContext.getContext();
        if (ctx != null) {
            return ctx.getLocale();
        } else {
            if (LOG.isDebugEnabled()) {
        	LOG.debug("Action context not initialized");
            }
            return null;
        }
    }

    public boolean hasKey(String key) {
        return getTextProvider().hasKey(key);
    }

    public String getText(String aTextName) {
        return getTextProvider().getText(aTextName);
    }

    public String getText(String aTextName, String defaultValue) {
        return getTextProvider().getText(aTextName, defaultValue);
    }

    public String getText(String aTextName, String defaultValue, String obj) {
        return getTextProvider().getText(aTextName, defaultValue, obj);
    }

    public String getText(String aTextName, List<?> args) {
        return getTextProvider().getText(aTextName, args);
    }

    public String getText(String key, String[] args) {
        return getTextProvider().getText(key, args);
    }

    public String getText(String aTextName, String defaultValue, List<?> args) {
        return getTextProvider().getText(aTextName, defaultValue, args);
    }

    public String getText(String key, String defaultValue, String[] args) {
        return getTextProvider().getText(key, defaultValue, args);
    }

    public String getText(String key, String defaultValue, List<?> args, ValueStack stack) {
        return getTextProvider().getText(key, defaultValue, args, stack);
    }

    public String getText(String key, String defaultValue, String[] args, ValueStack stack) {
        return getTextProvider().getText(key, defaultValue, args, stack);
    }

    /**
     * Dedicated method to support I10N and conversion errors
     *
     * @param key message which contains formatting string
     * @param expr that should be formatted
     * @return formatted expr with format specified by key
     */
    public String getFormatted(String key, String expr) {
        Map<String, Object> conversionErrors = ActionContext.getContext().getConversionErrors();
        if (conversionErrors.containsKey(expr)) {
            String[] vals = (String[]) conversionErrors.get(expr);
            return vals[0];
        } else {
            final ValueStack valueStack = ActionContext.getContext().getValueStack();
            final Object val = valueStack.findValue(expr);
            return getText(key, Arrays.asList(val));
        }
    }

    public ResourceBundle getTexts() {
        return getTextProvider().getTexts();
    }

    public ResourceBundle getTexts(String aBundleName) {
        return getTextProvider().getTexts(aBundleName);
    }

    public void addActionError(String anErrorMessage) {
        validationAware.addActionError(anErrorMessage);
    }

    public void addActionMessage(String aMessage) {
        validationAware.addActionMessage(aMessage);
    }

    public void addFieldError(String fieldName, String errorMessage) {
        validationAware.addFieldError(fieldName, errorMessage);
    }

    public String input() throws Exception {
        return INPUT;
    }

    public String doDefault() throws Exception {
        return SUCCESS;
    }

    /**
     * A default implementation that does nothing an returns "success".
     * <p/>
     * Subclasses should override this method to provide their business logic.
     * <p/>
     * See also {@link com.opensymphony.xwork2.Action#execute()}.
     *
     * @return returns {@link #SUCCESS}
     * @throws Exception can be thrown by subclasses.
     */
    public String execute() throws Exception {
        return SUCCESS;
    }

    public boolean hasActionErrors() {
        return validationAware.hasActionErrors();
    }

    public boolean hasActionMessages() {
        return validationAware.hasActionMessages();
    }

    public boolean hasErrors() {
        return validationAware.hasErrors();
    }

    public boolean hasFieldErrors() {
        return validationAware.hasFieldErrors();
    }

    /**
     * Clears field errors. Useful for Continuations and other situations
     * where you might want to clear parts of the state on the same action.
     */
    public void clearFieldErrors() {
        validationAware.clearFieldErrors();
    }

    /**
     * Clears action errors. Useful for Continuations and other situations
     * where you might want to clear parts of the state on the same action.
     */
    public void clearActionErrors() {
        validationAware.clearActionErrors();
    }

    /**
     * Clears messages. Useful for Continuations and other situations
     * where you might want to clear parts of the state on the same action.
     */
    public void clearMessages() {
        validationAware.clearMessages();
    }

    /**
     * Clears all errors. Useful for Continuations and other situations
     * where you might want to clear parts of the state on the same action.
     */
    public void clearErrors() {
        validationAware.clearErrors();
    }

    /**
     * Clears all errors and messages. Useful for Continuations and other situations
     * where you might want to clear parts of the state on the same action.
     */
    public void clearErrorsAndMessages() {
        validationAware.clearErrorsAndMessages();
    }

    /**
     * A default implementation that validates nothing.
     * Subclasses should override this method to provide validations.
     */
    public void validate() {
    }

    @Override
    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }

    /**
     * <!-- START SNIPPET: pause-method -->
     * Stops the action invocation immediately (by throwing a PauseException) and causes the action invocation to return
     * the specified result, such as {@link #SUCCESS}, {@link #INPUT}, etc.
     * <p/>
     * <p/>
     * The next time this action is invoked (and using the same continuation ID), the method will resume immediately
     * after where this method was called, with the entire call stack in the execute method restored.
     * <p/>
     * <p/>
     * Note: this method can <b>only</b> be called within the {@link #execute()} method.
     * <!-- END SNIPPET: pause-method -->
     *
     * @param result the result to return - the same type of return value in the {@link #execute()} method.
     */
    public void pause(String result) {
    }

    /**
     * If called first time it will create {@link com.opensymphony.xwork2.TextProviderFactory},
     * inject dependency (if {@link com.opensymphony.xwork2.inject.Container} is accesible) into in,
     * then will create new {@link com.opensymphony.xwork2.TextProvider} and store it in a field
     * for future references and at the returns reference to that field
     *
     * @return reference to field with TextProvider
     */
    private TextProvider getTextProvider() {
        if (textProvider == null) {
            TextProviderFactory tpf = new TextProviderFactory();
            if (container != null) {
                container.inject(tpf);
            }
            textProvider = tpf.createInstance(getClass(), this);
        }
        return textProvider;
    }

    @Inject
    public void setContainer(Container container) {
        this.container = container;
    }

}

 

 Validateable接口只有一个方法，即validate(),必须覆盖该方法来实现自定义的验证功能。

下面将实现继承自ActionSupport类的实例，是action控制层具有验证功能。

将上一节中的Login.java添加validate方法，具体代码如下：

package controller;

import com.opensymphony.xwork2.ActionSupport;

public class Login extends ActionSupport{
	private String username;
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		System.out.println("username setting");
		this.username = username;
	}

	public void setPassword(String password) {
		System.out.println("password setting");
		this.password = password;
	}
	
	public String getPassword() {
		return password;
	}
	private String password;
	
	@Override
	public void validate() {
		// TODO Auto-generated method stub
		super.validate();
		if("".equals(this.getUsername()))
		{
			this.addFieldError("usernname", "用户名不能为空");
		}
		if("".equals(this.getPassword()))
		{
			this.addFieldError("password", "密码不能为空");
		}
	}
	public String execute()
	{
		if(username.equals("hello")&&password.equals("struts2"))
		{
			return "success";
		}
		else
		{
			return "false";
		}
	}
}

validate方法是在execute方法之前执行的。

如果表单的内容为空，则执行this.addFieldError()方法：

this.addFieldError("usernname", "用户名不能为空");
this.addFieldError("password", "密码不能为空");

将出错的信息显示在jsp页面名称为username和password的s:textfield标签中，然后就可以查看login.jsp页面的变化：

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ taglib uri="/struts-tags" prefix="s" %>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>  
  <body>
  <form action="login.action" method="post" name="login">
   <s:textfield name="username" label="账号"></s:textfield>
   <s:textfield name=password“" label="密码"></s:textfield>
   <br>
   <s:submit value="提交"></s:submit>
  </form>  
  </body>
</html>

在新的jsp页面中使用了struts2表单标签库，s:textfield是在浏览器显示单行文本域，而s:textfield name的属性值一定要和Login.java类中的属性名相同，这样才可以上实现自动填充，label属性是标签内的文本提示内容。

最后还需要配置struts.xml文件，并显示错误提示，等待重新输入：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN" "http://struts.apache.org/dtd/struts-2.0.dtd">
<struts>

   <package name="Maybe" extends="struts-default">
   
     <action name="login" class="controller.Login">
       <result name="success">/true.jsp</result>
       <result name="false">/false.jsp</result>
       <result name="input">/login.jsp</result>
   </action>
   </package>
</struts>

其中result name=“inout”是当出现错误自动转到重新输入的状态。

我们来查看一下Action这个类：

/*
 * Copyright 2002-2007,2009 The Apache Software Foundation.
 * 
 * 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
 * 
 *      http://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 com.opensymphony.xwork2;

/**
 * All actions <b>may</b> implement this interface, which exposes the <code>execute()</code> method.
 * <p/>
 * However, as of XWork 1.1, this is <b>not</b> required and is only here to assist users. You are free to create POJOs
 * that honor the same contract defined by this interface without actually implementing the interface.
 */
public interface Action {

    /**
     * The action execution was successful. Show result
     * view to the end user.
     */
    public static final String SUCCESS = "success";

    /**
     * The action execution was successful but do not
     * show a view. This is useful for actions that are
     * handling the view in another fashion like redirect.
     */
    public static final String NONE = "none";

    /**
     * The action execution was a failure.
     * Show an error view, possibly asking the
     * user to retry entering data.
     */
    public static final String ERROR = "error";

    /**
     * The action execution require more input
     * in order to succeed.
     * This result is typically used if a form
     * handling action has been executed so as
     * to provide defaults for a form. The
     * form associated with the handler should be
     * shown to the end user.
     * <p/>
     * This result is also used if the given input
     * params are invalid, meaning the user
     * should try providing input again.
     */
    public static final String INPUT = "input";

    /**
     * The action could not execute, since the
     * user most was not logged in. The login view
     * should be shown.
     */
    public static final String LOGIN = "login";


    /**
     * Where the logic of the action is executed.
     *
     * @return a string representing the logical result of the execution.
     *         See constants in this interface for a list of standard result values.
     * @throws Exception thrown if a system level exception occurs.
     *                   <b>Note:</b> Application level exceptions should be handled by returning
     *                   an error value, such as <code>Action.ERROR</code>.
     */
    public String execute() throws Exception;

}

可以看到在Action中定义了许多常量字符串INPUT就是其中之一，如果运行了Login.java中的validate方法，addFieldError方法就会返回到login.jsp页面，显示出错误信息。

 

运行一下，若不输入用户名和密码，运行结果如图所示：