StrutsResultSupport的使用

在有特殊情况时；如果没有异常信息，但是有错误并且有错误信息等内容；此时也需要进行友好的错误处理的话，那么可以借助StrutsResultSupport 返回结果类型来实现特定处理。此种方式先需要继承StrutsResultSupport ，然后可以在子类中获取本次请求的相关信息，再根据相关信息进行结果处理：

package commons.struts2;
import <a href="http://lib.csdn.net/base/java" class='replace_word' title="Java 知识库" target='_blank' style='color:#df3434; font-weight:bold;'>Java</a>.io.PrintWriter;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts2.dispatcher.StrutsResultSupport;
import com.opensymphony.xwork2.ActionInvocation;
/**
 * result type for output string in action
 *
 * @author songwei,yaolei <b>Example:</b>
 *
 * <pre>
 * <!-- START SNIPPET: example -->
 * <result name="success" type="string">
 *   <param name="stringName">stringName</param>
 * </result>
 * <!-- END SNIPPET: example -->
 * </pre>
 *
 */
public class StringResultType extends StrutsResultSupport {
    private static final long serialVersionUID = 1L;
    private String contentTypeName;
    private String stringName = "";
    public StringResultType() {
        super();
    }
    public StringResultType(String location) {
        super(location);
    }
    protected void doExecute(String finalLocation, ActionInvocation invocation)
            throws Exception {
        HttpServletResponse response = (HttpServletResponse) invocation
                .getInvocationContext().get(HTTP_RESPONSE);
        // String contentType = (String)
        // invocation.getStack().findValue(conditionalParse(contentTypeName,
        // invocation));
        String contentType = conditionalParse(contentTypeName, invocation);
        if (contentType == null) {
            contentType = "text/plain; charset=UTF-8";
        }
        response.setContentType(contentType);
        PrintWriter out = response.getWriter();
        // String result = conditionalParse(stringName, invocation);
        String result = (String) invocation.getStack().findValue(stringName);
        out.println(result);
        out.flush();
        out.close();
    }
    public String getContentTypeName() {
        return contentTypeName;
    }
    public void setContentTypeName(String contentTypeName) {
        this.contentTypeName = contentTypeName;
    }
    public String getStringName() {
        return stringName;
    }
    public void setStringName(String stringName) {
        this.stringName = stringName;
    }
} 

package test;
import com.opensymphony.xwork2.ActionSupport;
public class MyAction extends ActionSupport{
    String  result="abc";
    public String ajax() {
        return "ajaxResponse";
    }
    // getter && setter
    public String getResult() {
        return result;
    }
    public void setResult(String result) {
        this.result = result;
    }  

} 

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
    "http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>
    <package name="test" extends="struts-default">
        <result-types>
            <result-type name="string" class="test.StringResultType"></result-type>
        </result-types>  

        <action name="myAction" class="test.MyAction" >
            <result name="ajaxResponse" type="string">
                <param name="stringName">result</param>
            </result>
        </action>
    </package>
</struts> 

这里定义返回Action的String  result变量，即“abc”。