/**
* Tencent is pleased to support the open source community by making MSEC available.
*
* Copyright (C) 2016 THL A29 Limited, a Tencent company. All rights reserved.
*
* Licensed under the GNU General Public License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License. You may
* obtain a copy of the License at
*
* https://opensource.org/licenses/GPL-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the
* License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
* either express or implied. See the License for the specific language governing permissions
* and limitations under the License.
*/
package msec.org;
import org.apache.log4j.Logger;
import org.codehaus.jackson.map.ObjectMapper;
import org.json.JSONObject;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.nio.charset.Charset;
/**
*
* msec console这个项目的所有异步json请求都是由这个servlet来处理的
* 该类主要是利用java反射机制，自动根据json请求里制定的handleClass来动态
* 执行后台的java bean，准确的说是执行后台java bean的exec函数。并自动实现
* json字符串与java类之间的序列化和反序列化
*/
@WebServlet(name = "JsonRPCServlet")
public class JsonRPCServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
//应答一个包含错误信息的json字符串给前端
private void errorResponse(HttpServletResponse resp, String message)
{
resp.setCharacterEncoding("UTF-8");
resp.setContentType("application/json; charset=utf-8");
Logger logger = Logger.getLogger(JsonRPCServlet.class);
JsonRPCResponseBase r = new JsonRPCResponseBase();
r.setMessage(message);
r.setStatus(100);
try {
PrintWriter out = resp.getWriter();
String s = new ObjectMapper().writeValueAsString(r);
logger.error(s);
out.println(s);
}
catch (Exception e){logger.error(e);}
}
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
Logger logger = Logger.getLogger(JsonRPCServlet.class);
req.setCharacterEncoding("UTF-8");
//从http请求里获取完整的json字符串
//json字符串是http请求的一个form字段
String request_string = req.getParameter("request_string");
int maxLen = request_string.length();
if (maxLen > 10240) { maxLen = 10240;}
logger.info("request_string:" + request_string.substring(0, maxLen));
//ObjectManager和JSONObject两个都是 json与java类之间的转换工具
ObjectMapper objectMapper = new ObjectMapper();
JSONObject jsonObject = new JSONObject(request_string);
String handleClassStr = jsonObject.getString("handleClass");
JSONObject requestBodyObj = jsonObject.getJSONObject("requestBody");
logger.info("requestBody:" + requestBodyObj.toString());
try
{
//加载handleClass字段指定的类，并创建它的实例
Class<?> clazz = Class.forName(handleClassStr);
JsonRPCHandler handler = (JsonRPCHandler) clazz.newInstance();
//将http的上下文信息传给该实例，以方便在业务逻辑处理的时候访问
handler.setHttpRequest(req);
handler.setHttpResponse(resp);
handler.setServlet(this);
//获取类的所有成员方法，遍历找到exec函数
Method[] methods = clazz.getMethods();
boolean execFound = false;
for (int i = 0; i <methods.length ; i++) {
if (methods[i].getName().equals("exec")) {
execFound = true;
//获取exec的参数列表，要求只能有一个参数
Class<?>[] paramTypes = methods[i].getParameterTypes();
if (paramTypes.length != 1)
{
errorResponse(resp, "handle class's exec() method's param number is not 1!");
return;
}
//将json字符串的requestBody部分映射到一个java类的实例，作为exec函数的参数
Object exec_request = objectMapper.readValue(requestBodyObj.toString(), paramTypes[0]);
//检查exec 函数的返回类型，要求继承自JsonRPCResponseBase
/*
Class<?> returnType = methods[i].getReturnType();
String superClass = returnType.getSuperclass().getName();
if (superClass == null || !superClass.equals("msec.org.JsonRPCResponseBase"))
{
errorResponse(resp, "method exec() should return a class extending JsonRPCResponseBase.");
return;
}
*/
//调用exec函数，如果返回非空，就序列化为json字符串返回
//特殊场景下，例如文件下载等，exec 会返回null，不需要给前端返回json字符串
try {
Object exec_result = methods[i].invoke(handler, exec_request);
if (exec_result != null) {
String s = objectMapper.writeValueAsString(exec_result);//�����ص�bean���л�Ϊjson�ַ���
resp.setCharacterEncoding("UTF-8");
resp.setContentType("application/json; charset=utf-8");
PrintWriter out = resp.getWriter();
out.println(s);
maxLen = s.length();
if (maxLen > 10240) { maxLen = 10240;}
logger.info("response:" + s.substring(0, maxLen));
out.close();
}
return;
} catch (InvocationTargetException e) {
logger.error(e);
logger.error(e);
}
}
}
if (!execFound)
{
errorResponse(resp, "handleClass has NOT method named exec()");
return;
}
} catch (ClassNotFoundException e)
{
logger.error(e);
logger.error(e);
errorResponse(resp, "ClassNotFoundException:" + e.toString());
return;
} catch (InstantiationException e)
{
logger.error(e);
logger.error(e);
errorResponse(resp, "InstantiationException:" + e.toString());
;
return;
} catch (IllegalAccessException e)
{
logger.error(e);
logger.error(e);
errorResponse(resp, "IllegalAccessException:" + e.toString());
return;
}
}
}