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先在下图文件夹中导入相应的jar包，其中第一个红框中的是使用json数据必须导入的两个包，上面5个jar包也是json包，看情况添加，第二个红框是用JDBC连接MySQL数据库必须的包。
连接MySQL的工具类：
package com.XXXXXX.util;
import java.sql.Connection;
import java.sql.DriverManager;
public class MysqlUtil
{
private static Connection conn = null; //数据库连接
private static String server = "localhost"; //服务ip
private static String port = "3306"; //服务端口
public static String dbname = "XXXXX"; //数据库名
private static String user = "root"; //数据库用户名
private static String pass = "XXXXX"; //数据库密码
private static String drivername = "com.mysql.jdbc.Driver"; //MySql驱动类名
private static String url = "jdbc:mysql://" + server + ":" + port + "/" + dbname + "?user=" + user + "&password=" + pass + "&useUnicode=true&characterEncoding=UTF-8"; //连接地址
public static Connection getConn()
{
try
{
Class.forName(drivername).newInstance(); //加载JDBC驱动
conn = DriverManager.getConnection(url); //建立连接
} catch (Exception e)
{
e.printStackTrace();
}
return conn;
}
}服务端上的查询Servlet：
package com.XXXXX.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
import com.webmappoi.util.MysqlUtil;
public class GetPoiInfoServlet extends HttpServlet
{
/**
*
*/
private static final long serialVersionUID = 1L;
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
/*
* response.setContentType("text/html"); PrintWriter out =
* response.getWriter();out.println(
* "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
* out.println("<HTML>");
* out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
* out.println(" <BODY>"); out.print(" This is ");
* out.print(this.getClass()); out.println(", using the GET method");
* out.println(" </BODY>"); out.println("</HTML>"); out.flush();
* out.close();
*/
this.doPost(request, response);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to
* post.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
JSONArray array = new JSONArray();
Connection con = null;
PreparedStatement ps = null;
ResultSet rs = null;
String sql = "select * from university";
try
{
con = MysqlUtil.getConn();
ps = con.prepareStatement(sql);
rs = ps.executeQuery();
while (rs.next())
{
JSONObject temp = new JSONObject().element("id", rs.getInt("U_ID")).element("point", rs.getString("U_Point")).element("title", rs.getString("U_Title")).element("address", rs.getString("U_Addr")).element("tel", rs.getString("U_Tel"));
array.add(temp);
}
out.print(array.toString()); //将array对象传到前端
System.out.println(array.toString());
out.flush();
out.close();
} catch (SQLException e)
{
e.printStackTrace();
} finally
{
try
{
//依次关闭连接
if (rs != null)
{
rs.close();
rs = null;
}
if (ps != null)
{
ps.close();
ps = null;
}
if (con != null)
{
con.close();
con = null;
}
} catch (SQLException e)
{
e.printStackTrace();
}
}
}
}前端js接收array对象并解析：
$.getJSON("./servlet/GetPoiInfoServlet",function(json)
{
for(var i=0;i<json.length;i++)
{
//var json = eval(json);
//console.log(JSON.stringify(json));
//获取经纬度
ulng = parseFloat(json[i].point.split(",")[0]); //以,分割成数组
ulat = parseFloat(json[i].point.split(",")[1]);
var uid = parseFloat(json[i].id);
var title = json[i].title;
var address = json[i].address;
var point = json[i].point;
var tel = json[i].tel;
}
});/********************************************************************
getJSON函数所接收的数据就是json格式，所以可以不用eval函数转化。function中参数json就是后台Servlet传来的array对象。getJSON函数还有一个问题就是，用它从前端传数据到后台时，如果有中文的话，传到后台的数据就会乱码。（网上有解决办法，但我没试过，我就用post方法将就了，post方法不会乱码，但是在接收是需要用eval函数转化。）
********************************************************************/
前端js中封装表单成json数据：
function GetJsonData()
{
var json =
{
"point": GID("point").value,
"title": GID("title").value,
"address": $("#address").val(),
"tel": $("#tel").val()
};
return json;
}前端js中封装document.getElementById方法：
function GID(id)
{
return document.getElementById(id);
}前端js中用Jquery post方法提交表单json数据：
function post()
{
/*$("#status").html("正在提交数据，请勿关闭当前窗口...");
var url = GID("form1").action;
//alert(JSON.stringify(GetJsonData()));
$.ajax(
{
type: "POST",
//url: "./servlet/AddPoiDataServlet",
url: url,
//contentType: "application/json; charset=utf-8",
data: {data: JSON.stringify(GetJsonData())},
//dataType: "json",
success: function (json)
{
if (json.length > 0)
{
alert("提交成功！");
}
},
error: function (json)
{
$("#status").html("提交数据失败！");
}
});*/
var url = GID("form1").action;
//alert(url);
$("#status").html("正在提交数据，请勿关闭当前窗口...");
$.post(url,{data:JSON.stringify(GetJsonData())},function (msg)
{
//alert("提交成功！");
$("#status").html("提交成功！");
});
}/*******************************************************************************
JSON.stringify()函数是为了将json数据字符串化。Jquery ajax和post方法都能将表单传到后端，post方法封装了ajax，用起来更简单。
******************************************************************************/
后台Servlet接收前端传来的json数据并保存到MySQL数据库中：
//System.out.println("地名:" + request.getParameter("title") + "<br>");
JSONObject json = JSONObject.fromObject(request.getParameter("data")); //获取前端传来的data
System.out.println(json.toString());
Connection con = null;
PreparedStatement ps = null;
int result = 0;
String sql = "insert into university(U_Point,U_Title,U_Addr,U_Tel) values(?,?,?,?)";
try
{
con = MysqlUtil.getConn();
ps = con.prepareStatement(sql);
ps.setString(1, json.getString("point"));
ps.setString(2, json.getString("title"));
ps.setString(3, json.getString("address"));
ps.setString(4, json.getString("tel"));
result = ps.executeUpdate();
out.print(json.toString());
System.out.println(json.toString());
out.flush();
out.close();
} catch (SQLException e)
{
e.printStackTrace();
} finally
{
try
{
if (ps != null)
{
ps.close();
ps = null;
}
if (con != null)
con.close();
con = null;
} catch (SQLException e)
{
e.printStackTrace();
}
}其它的修改，删除Servlet：
删除servlet：
String sql = "delete from university where U_ID=?";
try
{
con = MysqlUtil.getConn();
ps = con.prepareStatement(sql);
ps.setInt(1, json.getInt("id"));
result = ps.executeUpdate();
json.put("result", true);
out.print(json.toString());
System.out.println(json.toString());
out.flush();
out.close();
}修改servlet：
String sql = "update university set U_Title=?,U_Addr=?,U_Tel=? where U_Point=?";
try
{
con = MysqlUtil.getConn();
ps = con.prepareStatement(sql);
ps.setString(1, json.getString("title"));
ps.setString(2, json.getString("address"));
ps.setString(3, json.getString("tel"));
ps.setString(4, json.getString("point"));
result = ps.executeUpdate();
//json.put("result", true);
out.print(json.toString());
System.out.println(json.toString());
out.flush();
out.close();
}模糊查询：
前端js传输查询条件并接受后台查询数据库之后传过来的json数据：
function selectInfo() //模糊查询
{
var json =
{
"title": GID("info").value
};
//alert(JSON.stringify(json));
$.post("./servlet/SelectPoiInfoServlet",{data:JSON.stringify(json)},function(json)
{
for(var i=0;i<json.length;i++)
{
var json = eval(json);
//获取经纬度
ulng = parseFloat(json[i].point.split(",")[0]);
ulat = parseFloat(json[i].point.split(",")[1]);
var uid = parseFloat(json[i].id);
var title = json[i].title;
var address = json[i].address;
var point = json[i].point;
var tel = json[i].tel;
}
});
} /*****************************************************************************************
这里不能用getJSON方法，因为如果前端传过来json数据有中文，到后台就会乱码，所以就用post方法。
******************************************************************************************/
后台模糊查询的servlet：
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
JSONObject json = JSONObject.fromObject(request.getParameter("data"));
System.out.println(json.toString());
JSONArray array = new JSONArray();
Connection con = null;
PreparedStatement ps = null;
ResultSet rs = null;
String sql = "select * from university where U_Title like ?";
try
{
con = MysqlUtil.getConn();
ps = con.prepareStatement(sql);
ps.setString(1, "%" + json.getString("title") + "%");
rs = ps.executeQuery();
while (rs.next())
{
JSONObject temp = new JSONObject().element("id", rs.getInt("U_ID")).element("point", rs.getString("U_Point")).element("title", rs.getString("U_Title")).element("address", rs.getString("U_Addr")).element("tel", rs.getString("U_Tel"));
array.add(temp);
}
out.print(array.toString()); //将array对象传到前端
System.out.println(array.toString());
out.flush();
out.close();
}关于模糊查询：
参考JDBC 模糊查询 传参问题，附文如下：
错误写法：String sql = “select * from tableName where column like ‘%?%’”;
这样写，？是不能传参进来的，因为编译的时候？没被编译成传参标识，所以执行时会抛出SQLException。
正确写法有两种：
1、String sql = “select * from tableName where column like ‘%” + columnValue + “%’”; //可以直接将变量值写进sql语句
2、String sql = “select * from tableName where column like ?”; //可以利用jdbc的传参函数传进
PreparedStatement ps = conn.PreparedStatement(sql);
ps.setString(1, “%” + columnValue + “%”);
其中遇到的问题：
1. 使用自己安装的jdk时会报错（如下图），只有用Myeclipse自带的版本才可以。
我所使用的JDK版本及MyEclipse的JDK版本如下：
只有选中下面那个Sun JDK 1.6.0_13才不会报错，不知道why？
2. 在Servlet中修改doPost()或doGet()方法，发布到浏览器时，仍出现This is class XXXXXXXX, using the POST method的字样，如图：
解决办法是：重启Tomcat，重新发布。
参考资料：
[1] http://blog.163.com/jackswu@yeah/blog/static/140629123201161810168361/
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原文地址：http://blog.csdn.net/qq_20828113/article/details/51302203
