Hacker and Geeker's Way

//这里我们定义跟之前认证api相同的url，但方法是POST
@RequestMapping(value = "/index", method = RequestMethod.POST)
   public
   @ResponseBody
   //3个校验消息真实性的参数，还有一个request实体body，里面是xml文本
   ResponseEntity<String> receive(@RequestParam("signature") String signature,
                                  @RequestParam("timestamp") String timestamp,
                                  @RequestParam("nonce") String nonce,
                                  @RequestBody String body) throws Exception {
       log.info("receive message start");
       log.info(String.format("signature:%s, timestamp:%s, nonce:%s", signature, timestamp, nonce));

       //先校验消息的真实性，如果校验失败，则返回400
       if (!wechatAuth(signature, timestamp, nonce)) {
           log.info("wechat auth failed");
           return new ResponseEntity<String>("wechat auth failed.", HttpStatus.BAD_REQUEST);
       }

       log.info(String.format("body:%s", body));
       //我们定义了一个util来解析xml，将其转换为一个object
       TextMessage requestMessage = XmlUtil.toTextMessage(body);
       log.info(String.format("requestMessage:%s", requestMessage));

       TextMessage textMessage = null;
       String msgType = requestMessage.getMsgType();
       String toUserName = requestMessage.getToUserName();
       String fromUserName = requestMessage.getFromUserName();
       //判断消息类型，如果是event，且事件类型为subscribe，则新建一个文本消息
       if (MessageType.event.name().equals(msgType)) {
           if (EventType.subscribe.name().equals(requestMessage.getEvent())) {
               String message = "感谢您关注我的公众账号[愉快]";
               textMessage = new TextMessage(toUserName, fromUserName,
                       MessageType.text.name(), message, TimeUtil.currentSeconds());
           }
       }

       //将文本消息转换为xml文本
       String responseMessage = XmlUtil.toXml(textMessage);
       HttpHeaders responseHeaders = new HttpHeaders();
       //设置返回实体的编码，不设置的话可能会变成乱码
       responseHeaders.add("Content-Type", "text/html; charset=utf-8");
       log.info(String.format("response message: %s", responseMessage));
       log.info("receive message finish");
       return new ResponseEntity<String>(responseMessage, responseHeaders, HttpStatus.OK);
   }

import com.zzm.wechat.model.TextMessage;
import org.apache.commons.io.IOUtils;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
import java.io.StringReader;
import java.io.StringWriter;

public class XmlUtil {

    public static String toXml(TextMessage textMessage) throws Exception {
        if (textMessage == null) return "";

        JAXBContext context = JAXBContext.newInstance(TextMessage.class);
        Marshaller m = context.createMarshaller();
        m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        m.setProperty(Marshaller.JAXB_FRAGMENT, true);

        StringWriter sw = new StringWriter();
        m.marshal(textMessage, sw);
        return sw.toString();
    }

    public static TextMessage toTextMessage(String xml) throws Exception {
        JAXBContext jaxbContext = JAXBContext.newInstance(TextMessage.class);
        Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
        StringReader reader = new StringReader(xml);
        TextMessage textMessage = (TextMessage) jaxbUnmarshaller.unmarshal(reader);
        IOUtils.closeQuietly(reader);
        return textMessage;
    }
}

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

//定义命名空间，如果不写的话，xml会以类名开头: <TextMessage>...</TextMessage>，写了就会以xml开头: <xml>...</xml>
@XmlRootElement(name = "xml")
public class TextMessage {
    private String fromUserName;
    private String toUserName;
    private String msgType;
    private int funcFlag = 0;
    private String content;
    private String event;
    private long createTime;

    public TextMessage() {
    }

    public TextMessage(String fromUserName, String toUserName, String msgType, String content, long createTime) {
        this.fromUserName = fromUserName;
        this.toUserName = toUserName;
        this.msgType = msgType;
        this.content = content;
        this.createTime = createTime;
    }

    public String getToUserName() {
        return toUserName;
    }

    //定义xml子项的名称，不写这个annotation的话，转换后的xml是: <toUserName>xxx</toUserName>，首字母变小写了，会导致消息传输错误
    @XmlElement(name = "ToUserName")
    public void setToUserName(String toUserName) {
        this.toUserName = toUserName;
    }

    //other setter and getter

    @Override
    public String toString() {
        //...
    }
}