Struts2：二

SSH

Struts2
结果类型

Struts2 中的视图称为结果, 有很多类型, 可以在 struts-default.xml 中看到其定义:

<result-types>    <result-type name="chain" class="com.opensymphony.xwork2.ActionChainResult"/>    <result-type name="dispatcher" class="org.apache.struts2.result.ServletDispatcherResult" default="true"/>    <result-type name="freemarker" class="org.apache.struts2.views.freemarker.FreemarkerResult"/>    <result-type name="httpheader" class="org.apache.struts2.result.HttpHeaderResult"/>    <result-type name="redirect" class="org.apache.struts2.result.ServletRedirectResult"/>    <result-type name="redirectAction" class="org.apache.struts2.result.ServletActionRedirectResult"/>    <result-type name="stream" class="org.apache.struts2.result.StreamResult"/>    <result-type name="velocity" class="org.apache.struts2.result.VelocityResult"/>    <result-type name="xslt" class="org.apache.struts2.views.xslt.XSLTResult"/>    <result-type name="plainText" class="org.apache.struts2.result.PlainTextResult" />    <result-type name="postback" class="org.apache.struts2.result.PostbackResult" /></result-types>

默认结果类型是 dispatcher, 由类 ServletDispatcherResult 负责处理.

重定向类型 redirect

重定向类型 redirect 由 ServletRedirectResult 类负责解析:

使用步骤如下:

编写控制器:

public class DocAction {    public String execute(){        System.out.println("DocAction");         return "success";    }}

配置 struts.xml

<package name="day02" namespace="/day02"    extends="struts-default">    <!-- 重定向测试 -->    <action name="doc" class="ssh.day02.DocAction">        <result name="success" type="redirect">             http://doc.tedu.cn        </result>    </action>           </package>

测试.

重定向到其他 控制器 redirectAction

重定向到其他控制器的处理类: ServletActionRedirectResult

使用步骤:

配置struts.xml

<!-- 重定向到其他控制器 --><action name="add" class="ssh.day02.DocAction">    <result name="success"         type="redirectAction">        <param name="actionName">list</param>        <param name="namespace">/demo</param>       </result></action>

测试

Stream 类型结果

Http协议支持多种媒体类型数据下载功能, 重要响应头是Content-Type:

Struts2 利用Stream 类型的结果封装了HTTP的下载功能:

使用步骤:

声明控制器:

public class LogoAction {    private String type;    private InputStream img;    public String getType() {        return type;    }    public void setType(String type) {        this.type = type;    }    public InputStream getImg() {        return img;    }    public void setImg(InputStream img) {        this.img = img;    }    public String execute() throws IOException{        type = "image/png";        img = createPngImage("Hello");        return "success";    }    private InputStream createPngImage(String msg)         throws IOException{        BufferedImage image = new BufferedImage(            200, 100, BufferedImage.TYPE_3BYTE_BGR);        image.setRGB(100, 50, 0xffff00);        Graphics2D g = image.createGraphics();        g.setColor(new Color(0xffff00));         g.drawString(msg, 20, 40);         //将 image 编码为 png数据(byte数组)        ByteArrayOutputStream out =                 new ByteArrayOutputStream();        ImageIO.write(image, "png", out);        out.close();        byte[] data = out.toByteArray();        return new ByteArrayInputStream(data);     }}

配置struts.xml

<!-- 动态生成图片 --><action name="logo" class="ssh.day02.LogoAction">    <result name="success" type="stream">        <param name="contentType">${type}</param>        <param name="inputName">img</param>    </result></action>

测试

在网页中展示动态图片:

<h2>显示图片</h2><img alt="" src="day02/logo.do">

动态下载图片

配置struts.xml

<!-- 下载图片 --><action name="download-logo"     class="ssh.day02.LogoAction">    <result name="success" type="stream">        <param name="contentType">${type}</param>        <param name="inputName">img</param>        <param name="contentDisposition">            attachment;filename="logo.png"        </param>    </result></action>

在页面中设置下载链接

<h2>下载图片</h2><a href="day02/download-logo.do">下载</a> 

测试

动态下载Excel

只要将上述图片下载案例是图片API更换为Excel API, 就可以实现下载Excel功能:

导入Excel API

<dependency>  <groupId>org.apache.poi</groupId>  <artifactId>poi-ooxml</artifactId>  <version>3.16</version></dependency>

声明控制器

public class ExcelAction {    private String type;    private InputStream excel;    public String getType() {        return type;    }    public void setType(String type) {        this.type = type;    }    public InputStream getExcel() {        return excel;    }    public void setExcel(InputStream excel) {        this.excel = excel;    }    public String execute() throws IOException{        //type 来自 tomcat/conf/web.xml        type = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";        excel = createExcel();        return "success";    }    private InputStream createExcel() throws IOException {        //创建工作簿        XSSFWorkbook workbook=new XSSFWorkbook();        //在工作簿中创建工作表        XSSFSheet sheet = workbook.createSheet();        //在工作表里面创建行        XSSFRow row0 = sheet.createRow(0);        XSSFRow row1 = sheet.createRow(1);        XSSFRow row2 = sheet.createRow(2);        //在行中创建单元格(cell)        XSSFCell cell = row0.createCell(0);        cell.setCellValue("编号");         row0.createCell(1).setCellValue("姓名");         row0.createCell(2).setCellValue("数量");          //添加数据        row1.createCell(0).setCellValue(1);        row1.createCell(1).setCellValue("范传奇");        row1.createCell(2).setCellValue(1);        row2.createCell(0).setCellValue(2);        row2.createCell(1).setCellValue("李某");        row2.createCell(2).setCellValue(2);        ByteArrayOutputStream out=                new ByteArrayOutputStream();        workbook.write(out);        out.close();        byte[] data = out.toByteArray();        return new ByteArrayInputStream(data);     }}配置 struts.xml<!-- 下载Excel文件 --><action name="download-excel"     class="ssh.day02.ExcelAction">    <result name="success" type="stream">        <param name="contentType">${type}</param>        <param name="inputName">excel</param>        <param name="contentDisposition">            attachment;filename="demo.xlsx"        </param>    </result></action>

添加下载链接:

<h2>下载Excel</h2><a href="day02/download-excel.do">下载</a> 

测试

JSON Result

Struts2 利用插件支持了 JSON 类型的 Result

<dependency>  <groupId>org.apache.struts</groupId>  <artifactId>struts2-json-plugin</artifactId>  <version>2.5.12</version></dependency>

在插件配置文件struts-plugin.xml中可以看到:

<package name="json-default" extends="struts-default">    <result-types>        <result-type name="json" class="org.apache.struts2.json.JSONResult"/>        <result-type name="jsonActionRedirect" class="org.apache.struts2.json.JSONActionRedirectResult"/>    </result-types>

只需要继承 “json-default” 就可以同时使用 json Result和struts-default 中声明的Result了.

默认情况下 JSON Result 会将控制器的全部Bean属性转换为JSON对象属性发送到浏览器:

案例:

声明控制器

public class JsonAction {    private String name;    private int age;    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }    public String execute(){        name = "Tom";        age = 10;        return "success";    }}

配置 struts.xml

<package name="test" namespace="/test"    extends="json-default">    <action name="json" class="ssh.day02.JsonAction">        <result name="success" type="json"></result>    </action></package>

测试

为了更加灵活的发送JSON数据, 经常用一个JavaBean封装JSON数据, 并且只发送这个一个属性到客户端:

案例步骤:

声明JavaBean, JsonResult 类

public class JsonResult {    private static final int SUCCESS=1;    private static final int ERROR=0;    /**状态*/    private int state;    /**对应状态的消息*/    private String message;    /**具体业务数据*/    private Object data;    /**此构造方法应用于data为null的场景*/    public JsonResult(){        this.state=SUCCESS;//1        this.message="OK";    }    /**有具体业务数据返回时,使用此构造方法*/    public JsonResult(Object data){        this();        this.data=data;    }    /**出现异常以后要调用此方法封装异常信息*/    public JsonResult(Throwable t){        this.state=ERROR;        this.message=t.getMessage();    }    public Object getData() {        return data;    }    public int getState() {        return state;    }    public String getMessage() {        return message;    }    public void setState(int state) {        this.state = state;    }}

声明控制器

public class JsonResultAction {    private String name;    private int age;    private JsonResult jsonResult;    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }    public JsonResult getJsonResult() {        return jsonResult;    }    public void setJsonResult(JsonResult jsonResult) {        this.jsonResult = jsonResult;    }    public String execute(){        name = "Tom";        age = 10;        String[] names = {"Andy","Mac","John","Jerry"};        jsonResult = new JsonResult(names);        return "success";    }}

配置 struts.xml

<!-- 利用JsonResult封装数据发送到浏览器客户端 --><action name="json3"     class="ssh.day02.JsonResultAction">    <result name="success" type="json">        <param name="root">jsonResult</param>    </result></action>

测试

整合 Struts2 和 Spring

整合Struts2 和 Spring的目的是将Spring作为Struts2控制器工厂管理控制器对象.

Struts2 提供的插件 struts2-spring-plugin 完成这个功能.

具体步骤:

导入struts2-spring-plugin

<dependency>  <groupId>org.apache.struts</groupId>  <artifactId>struts2-spring-plugin</artifactId>  <version>2.5.12</version></dependency>

添加Spring配置文件: spring-struts2.xml

<?xml version="1.0" encoding="UTF-8"?><beans     xmlns="http://www.springframework.org/schema/beans"     xmlns:p="http://www.springframework.org/schema/p"    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"     xmlns:context="http://www.springframework.org/schema/context"    xmlns:tx="http://www.springframework.org/schema/tx"    xmlns:mvc="http://www.springframework.org/schema/mvc"    xsi:schemaLocation="         http://www.springframework.org/schema/beans          http://www.springframework.org/schema/beans/spring-beans-4.1.xsd         http://www.springframework.org/schema/mvc          http://www.springframework.org/schema/mvc/spring-mvc-4.1.xsd          http://www.springframework.org/schema/tx          http://www.springframework.org/schema/tx/spring-tx-4.1.xsd          http://www.springframework.org/schema/context         http://www.springframework.org/schema/context/spring-context-4.1.xsd" >      <context:component-scan         base-package="ssh.day02"/></beans>

利用 ContextLoaderListener 初始化Spring容器:

<!-- 利用ContextLoaderListener初始化Spring容器 -->  <listener>    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>  </listener>  <context-param>     <param-name>contextConfigLocation</param-name>     <param-value>classpath:spring-*.xml</param-value>  </context-param>

创建 控制器:

@Controller//BeanID: demoActionpublic class DemoAction {    public String execute(){        System.out.println("Hello World!");        return "success";    }}

配置 struts.xml

<!-- 利用Spring管理控制器对象 class=BeanID --><action name="demo" class="demoAction">    <result name="success">        /WEB-INF/jsp/ok.jsp    </result></action>

测试.

Struts2 提供了拦截器, 其运行机制与Servlet Filter类似:

编写一个拦截器:

@Componentpublic class ExceptionInterceptor implements Interceptor {    public void destroy() {    }    public void init() {    }    public String intercept(ActionInvocation inv)            throws Exception {        try{            //执行后续的控制器            String val = inv.invoke();            return val;        }catch(Exception e){            e.printStackTrace();            Object act=inv.getAction();            if(act instanceof JsonAction){                JsonAction action=(JsonAction)act;                action.setJsonResult(new JsonResult(e));                return JsonAction.JSON;            }            throw e;        }    }}

拦截器配置时候,必须将和系统拦截器组成拦截器栈一起使用才行:

<interceptors>    <interceptor name="exp"         class="exceptionInterceptor"/>    <interceptor-stack name="myStack">        <interceptor-ref name="completeStack"/>        <interceptor-ref name="exp"></interceptor-ref>    </interceptor-stack></interceptors><default-interceptor-ref name="myStack"/>

Struts2的核心功能是由一组拦截器实现的, 如果不带上系统拦截器, 则无法使用系统的功能!!