八、Sling Servlet的使用

八、Sling Servlet的使用

这一章介绍如何使用SlingServlet开发AEM的HTTP接口，从AEM后端实现翻译功能。

编写Servlet

使用@Component注解声明是一个Servlet服务，sling.servlet.methods参数声明HTTP请求方法，sling.servlet.paths参数声明HTTP请求路径

package com.adobe.aem.guides.wknd.core.servlet;import lombok.extern.slf4j.Slf4j;
import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.NameValuePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
import org.apache.sling.api.SlingHttpServletRequest;
import org.apache.sling.api.SlingHttpServletResponse;
import org.apache.sling.api.servlets.HttpConstants;
import org.apache.sling.api.servlets.SlingAllMethodsServlet;
import org.osgi.service.component.annotations.Component;import javax.servlet.Servlet;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;import static org.osgi.framework.Constants.SERVICE_DESCRIPTION;@Slf4j
@Component(service = Servlet.class, property = {SERVICE_DESCRIPTION + "= Servlet to translate","sling.servlet.methods=" + HttpConstants.METHOD_GET,"sling.servlet.paths=" + "/bin/translate"
})
public class TranslateServlet extends SlingAllMethodsServlet {private static final String YOUDAO_URL = "https://openapi.youdao.com/api";private static final String APP_KEY = "应用ID";private static final String APP_SECRET = "应用密钥";@Overrideprotected void doGet(final SlingHttpServletRequest request, final SlingHttpServletResponse response)throws IOException {String q = request.getRequestParameter("content").toString();Map<String, String> params = new HashMap<>();String salt = String.valueOf(System.currentTimeMillis());params.put("from", "en");params.put("to", "zh-CHS");params.put("signType", "v3");String curtime = String.valueOf(System.currentTimeMillis() / 1000);params.put("curtime", curtime);String signStr = APP_KEY + truncate(q) + salt + curtime + APP_SECRET;String sign = getDigest(signStr);params.put("appKey", APP_KEY);params.put("q", q);params.put("salt", salt);params.put("sign", sign);params.put("vocabId", "");/* 处理结果 */String result = requestForHttp(YOUDAO_URL, params);// 设置返回数据类型为json，编码格式为UTF-8response.setContentType("application/json;charset=utf-8");PrintWriter writer = response.getWriter();writer.print(result);writer.close();}public static String requestForHttp(String url, Map<String, String> params) throws IOException {/* 创建HttpClient */CloseableHttpClient httpClient = HttpClients.createDefault();/* httpPost */HttpPost httpPost = new HttpPost(url);List<NameValuePair> paramsList = new ArrayList<>();for (Map.Entry<String, String> en : params.entrySet()) {String key = en.getKey();String value = en.getValue();paramsList.add(new BasicNameValuePair(key, value));}httpPost.setEntity(new UrlEncodedFormEntity(paramsList, "UTF-8"));CloseableHttpResponse httpResponse = httpClient.execute(httpPost);try {Header[] contentType = httpResponse.getHeaders("Content-Type");log.info("Content-Type:" + contentType[0].getValue());if ("audio/mp3".equals(contentType[0].getValue())) {//如果响应是wavHttpEntity httpEntity = httpResponse.getEntity();ByteArrayOutputStream baos = new ByteArrayOutputStream();httpResponse.getEntity().writeTo(baos);byte[] result = baos.toByteArray();EntityUtils.consume(httpEntity);//合成成功String file = "合成的音频存储路径" + System.currentTimeMillis() + ".mp3";byte2File(result, file);} else {/* 响应不是音频流，直接显示结果 */HttpEntity httpEntity = httpResponse.getEntity();String json = EntityUtils.toString(httpEntity, "UTF-8");EntityUtils.consume(httpEntity);log.info(json);return json;}} finally {try {if (httpResponse != null) {httpResponse.close();}} catch (IOException e) {log.info("## release resouce error ##" + e);}}return "";}/*** 生成加密字段*/public static String getDigest(String string) {if (string == null) {return null;}char[] hexDigits = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};byte[] btInput = string.getBytes(StandardCharsets.UTF_8);try {MessageDigest mdInst = MessageDigest.getInstance("SHA-256");mdInst.update(btInput);byte[] md = mdInst.digest();int j = md.length;char[] str = new char[j * 2];int k = 0;for (byte byte0 : md) {str[k++] = hexDigits[byte0 >>> 4 & 0xf];str[k++] = hexDigits[byte0 & 0xf];}return new String(str);} catch (NoSuchAlgorithmException e) {return null;}}/*** @param result 音频字节流* @param file   存储路径*/private static void byte2File(byte[] result, String file) {File audioFile = new File(file);FileOutputStream fos = null;try {fos = new FileOutputStream(audioFile);fos.write(result);} catch (Exception e) {log.error(e.getMessage(), e);} finally {if (fos != null) {try {fos.close();} catch (IOException e) {e.printStackTrace();}}}}public static String truncate(String q) {if (q == null) {return null;}int len = q.length();return len <= 20 ? q : (q.substring(0, 10) + len + q.substring(len - 10, len));}
}

使用postman测试，需要添加认证信息，在postman中接口访问正常，但在AEM页面中会出现下面的问题

出现的问题及解决办法

接口403问题

打开Adobe Experience Manager Web Console - Configuration配置页，搜索CSRF，打开配置添加Servlet地址/bin/translate，保存即可

中文乱码问题

需要在Servlet中设置返回数据的编码格式及数据类型

// 设置返回数据类型为json，编码格式为UTF-8
response.setContentType("application/json;charset=utf-8");
response.getWriter().print(result);

页面及JS修改

页面修改

<sly data-sly-use.model="com.adobe.aem.guides.wknd.core.models.Translate"><h1>类名: ${model.className}h1><div class="cmp-translate" appId="${model.appId}" appKey="${model.appKey}"><input id="trans-content" type="text" placeholder="请输入需要翻译的英文内容" ><button onclick="transByServlet()">翻译button><br><span id="result">span>div>
sly>

js修改

transByServlet = function() {var query = $('#trans-content').val();$.ajax({url: '/bin/translate?content=' + query,type: 'get',success: function (data) {var translation = data.translation$('#result').html('翻译结果：' + translation);}});
}

完整效果

SlingServlet的使用就介绍完了，下一章介绍Scheduler的使用。

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