Struts 2 攔截器

interceptor(攔截器)是一種可以在請求處理之前或者之後執行的Struts 2元件。攔截器是Struts 2的重要特性，Struts 2框架絕大多數功能都是通過攔截器來完成的。

1.攔截器類:

public class MyTimerInterceptor extends AbstractInterceptor {

	@Override
	public String intercept(ActionInvocation invocation) throws Exception {
		// 1。執行Action之前的工作:獲取開始執行時間
		long startTime =
 
 System.currentTimeMillis();
		System.out.println("執行Action之前的工作，開始時間:" + startTime);
		// 執行後續攔截器或Action
		String result = invocation.invoke();
		// 3.執行Action之後的工作，計算並輸出執行時間
		long endTime = System.currentTimeMillis();
		long execTime = endTime - startTime;
		System.out.println("ִ執行Action後的工作,結束時間" + endTime)
 
;
		System.out.println("總共時間:" + execTime);
		return result;
	}

}

攔截器的配置

通過<interceptor/》元素定義攔截器
通過<interceptot-ref/》元素使用攔截器

<package name="default" namespace="/" extends="struts-default">
		<!-- 攔截器 -->
		<interceptors>
			<!-- action的執行用時 -->
			<interceptor name=
 
"myTimer" class="util.MyTimerInterceptor" />		
		</interceptors>
		<action name="login" class="userAction" method="login">
			<result name="success">main.jsp</result>
			<result name="error">login.jsp</result>
			<result name="input">login.jsp</result>
			<interceptor-ref name="myTimer"></interceptor-ref>
			<interceptor-ref name="defaultStack"></interceptor-ref>
		</action>

定義攔截器棧

<interceptors>
			<!-- action的執行用時 -->
			<interceptor name="myTimer" class="util.MyTimerInterceptor" />
			<interceptor name="myAuthorization" class="util.AuthorizationInterceptot" />
			<interceptor-stack name="myStack">
				<interceptor-ref name="myAuthorization" />
				<interceptor-ref name="defaultStack" />
			</interceptor-stack>
		</interceptors>

自定義攔截器

許可權驗證檢查攔截器

public class AuthorizationInterceptot extends AbstractInterceptor {
	
	public String intercept(ActionInvocation invocation) {
		Map session = invocation.getInvocationContext().getSession();
		User user = (User) session.get("USER");
		if (user == null) {
			return Action.SUCCESS;
		} else {
			return Action.ERROR;
		}
	}
}

配置檔案

<package name="default" namespace="/" extends="struts-default">
		<!-- 攔截器 -->
		<interceptors>
			<!-- action的執行用時 -->
			<!-- 定義許可權驗證攔截器 -->
			<interceptor name="myAuthorization" class="util.AuthorizationInterceptot" />
			<interceptor-stack name="myStack">
				<interceptor-ref name="myAuthorization" />
				<interceptor-ref name="defaultStack" />
			</interceptor-stack>
		</interceptors>
		<!-- 定義預設攔截器 -->
		<default-interceptor-ref name="myStack" />
		<default-action-ref name="defaultAction" />
		<!-- 定義全域性結果 -->
		<global-results>
			<result name="login" type="redirect">
				/login.jsp
			</result>
		</global-results>
</package>

注意：指定預設攔截器後，action中可省略攔截器的引用

檔案上傳

準備commons-fileupload-x.x.x.jar和commons-io-x.x.x.jar
1.jsp中

 <s:form action="upload.action" enctype="multipart/form-data"
		method="post">
		<s:textfield name="title" lable="標題" />
		<br />
		<s:file name="upload" lable="選擇檔案" />
		<br />
		<s:submit name="submit" value="上傳檔案" />
	</s:form>

2.檔案上傳的action

public class UploadAction extends ActionSupport {
	private File upload; // 獲取提交的檔案
	private String uploadContentType; // 封裝上傳檔案的型別
	private String uploadFileName; // 服裝上傳檔名稱
	private String savePath; // 獲取檔案的路徑

	public String execute() throws Exception {
		byte[] buffer = new byte[1024];
		//讀取檔案
			FileInputStream fis = new FileInputStream(getUpload());
			//儲存問津
			FileOutputStream fos = new FileOutputStream(getSavePath() + "\\"+ this.getUploadFileName());
			int length = fis.read(buffer);
			while (length > 0) {
				fos.write(buffer, 0, length);
				length = fis.read(buffer);
			}
			fis.close();
			fos.flush();
			fos.close();
		}

		return SUCCESS;
	}
	public String getSavePath() {
		return ServletActionContext.getServletContext().getRealPath(savePath);
	}
}

3.Strut.xml

<action name="upload" class="action.UploadAction">
			<param name="savePath">/upload</param>
			<result name="success">/upload_success.jsp</result>
		</action>

4.success.jsp

你所上傳的檔案是:
	<s:property value="uploadFileName" />
	
	檔案型別:
	<s:property value="uploadContentType" />

多檔案上傳

action

private File[] upload; // 獲取提交的檔案
	private String[] uploadContentType; // 封裝上傳檔案的型別
	private String[] uploadFileName; // 服裝上傳檔名稱
	private String savePath; // 獲取檔案的路徑

	public String execute() throws Exception {
		byte[] buffer = new byte[1024];
		for (int i = 0; i < upload.length; i++) {
			FileInputStream fis = new FileInputStream(getUpload()[i]);
			FileOutputStream fos = new FileOutputStream(getSavePath() + "\\"
					+ this.getUploadFileName()[i]);
			int length = fis.read(buffer);
			while (length > 0) {
				fos.write(buffer, 0, length);
				length = fis.read(buffer);
			}
			fis.close();
			fos.flush();
			fos.close();
		}

		return SUCCESS;
	}
	public String getSavePath() {
		return ServletActionContext.getServletContext().getRealPath(savePath);
	}

檔案下載

1.jsp

<a href="download.action?fileName=334.jpg">點選下載</a>

2.struts.xml

<action name="download" class="action.FileDownAction">
			<param name="inputPath">/upload</param>
			<!-- <result name="success">/upload_success.jsp</result> -->
			<result name="success" type="stream">
				<param name="contentType">application/octet-stream</param>
				<param name="inputName">inputStream</param>
				<param name="contentDisposition">
					attachment;filename="${fileName}"
				</param>
				<param name="bufferSize">4096</param>
			</result>

		</action>

3.action

private String inputPath; // 讀取下載檔案的目錄
	private String fileName; // 下載檔案的檔名
	@SuppressWarnings("unused")
	private InputStream inputStream; // 讀取下載檔案的輸入流
	private String conetntType; // 下載檔案的型別

	public InputStream getInputStream() throws FileNotFoundException {
		String path = ServletActionContext.getServletContext().getRealPath(
				inputPath);
		return new BufferedInputStream(new FileInputStream(path + "\\"
				+ fileName));
	}

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

stream結果型別的配置引數

contentType檔案型別