Java 写一个供别人访问的http接口

1.引入jar包

2.读取发送过来的请求参数，判断参数是否正确

3.根据参数，查询所需要的信息

4.返回给请求端信息

例子：

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.sf.json.JSONObject;

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.methods.ByteArrayRequestEntity;
import org.apache.commons.httpclient.methods.EntityEnclosingMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.methods.RequestEntity;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.struts2.ServletActionContext;

import cn.com.speed.busdevelop.action.account.AccountAction;
import cn.com.speed.busdevelop.po.Account;
import cn.com.speed.busdevelop.service.AccountService;
import cn.com.speed.busdevelop.service.impl.AccountServiceImpl;

import com.sdicons.json.mapper.JSONMapper;
import com.sdicons.json.mapper.MapperException;

/*
     * pos管理系统接口
     * 查询省经理下的所有拓展人员
     */
    public String queryListCount() throws Exception{
    	log.info("查询省经理下的所有拓展人员");
		HttpServletRequest request = ServletActionContext.getRequest();
		HttpServletResponse response = ServletActionContext.getResponse();
		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
		response.setContentType("application/json;charset=UTF-8");
		
		BufferedReader reader = new BufferedReader(new InputStreamReader(
                request.getInputStream()));
		
		StringBuffer strBuf = new StringBuffer("");
		 String lines;
         while ((lines = reader.readLine()) != null) {
             lines = new String(lines.getBytes(), "utf-8");
             strBuf.append(lines);
         }
		
		Map map = new HashMap();
//		//协议参数
//		String cid = request.getParameter("cid");
//		String cmd = request.getParameter("cmd");
//		String version = request.getParameter("version");
//		String returnType = request.getParameter("returnType");
//		//业务参数
//		String userId = request.getParameter("userId");
		
		//协议参数
		String cid = JSONObject.fromObject(strBuf).getString("cid");
		String cmd = JSONObject.fromObject(strBuf).getString("cmd");
		String version = JSONObject.fromObject(strBuf).getString("version");
		String returnType = JSONObject.fromObject(strBuf).getString("returnType");
		//业务参数
		String userId = JSONObject.fromObject(strBuf).getString("userId");
		
		String returnVerify = JSONObject.fromObject(strBuf).getString("verify");
		
		
		map.put("cid", cid);//系统标识
		map.put("cmd", cmd);//命令字
		map.put("version",version);//接口版本
		map.put("returnType", returnType);//报文格式
//		map.put("userId", userId);
		
		String param = null;
        try {
        	param = JSONMapper.toJSON(map).render(false);
		} catch (MapperException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		log.info("参数："+param);
		
//		String returnVerify = request.getParameter("verify");
		String key = "123456789";
		InterfaceCheck check = new InterfaceCheck();
		String verify = check.checkPos(userId,key);
		
		Map resultMap = new HashMap();
		String jsonStr = null;
		Writer writer = response.getWriter();
		if(!verify.equals(returnVerify)){
			resultMap.put("result", null);
			resultMap.put("resultCode", "1");//失败
			resultMap.put("resultDesc","协议参数不正确，请求失败！");//结果描述
			try {
				jsonStr = JSONMapper.toJSON(resultMap).render(false);
			} catch (MapperException e) {
				e.printStackTrace();
			}
			log.info("返回的参数"+jsonStr);
			writer.write(jsonStr);
			return "";
		}
		System.out.println("==============================");
		System.out.println(userId);
		System.out.println("==============================");
		
		Map<String, Object> retMap = new HashMap<String, Object>();
		
		String errorMsg = "";
		List<Account> list = null;
		try {
			AccountService service = new AccountServiceImpl();
			list = service.queryListAccount(userId);
			if(list!=null){
				for (int i = 0; i < list.size(); i++) {
					Account account = list.get(i);
					retMap.put("userId", account.getUserId());
					retMap.put("userName", account.getUserName());
				}
			}
			
		} catch (Exception e1) {
			errorMsg = errorMsg + e1.getMessage();
		}
		resultMap.put("result", retMap);
		resultMap.put("resultCode", "0");
		resultMap.put("resultDesc", "拓展人员列表查询成功！");
		//转换成json
		try {
			jsonStr = JSONMapper.toJSON(resultMap).render(false);
		} catch (MapperException e) {
			e.printStackTrace();
		}
		try {
			log.info("返回的参数"+jsonStr);
			writer.write(jsonStr);
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (writer != null) {
				try {
					writer.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
		return "";
    }