js脚本中执行java后台代码方法解析

使用场景：关闭页面弹窗时执行sql语句。

其实js里执行sql语句有多种方式。

方式一：直接在js代码里调用sql语句，原则上不能使用，因为这将sql直接暴露在客户端，安全性极差。

方式二：在js里运用ajax技术，调用后台方法执行sql语句。

方式三：运用dwr框架，其实是对ajax技术进行了封装。

一、首先编写一个dwr.xml文件

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 2.0//EN" "http://www.getahead.ltd.uk/dwr//dwr20.dtd">
<dwr>
  <allow>
    <!-- 对呼叫类型的操作 -->
    <create javascript="CallTypeOpDwr" creator="new">
      <param name="class"
        value="cn.etcom.jfgl.tel.fee.callType.CallTypeOpDwr" />
      <include method="addCallType" />
      <include method="modifyCallType" />
      <include method="deleteCallType" />
      <include method="updateSp" />
    </create>

  </allow>
  <!-- 用户信息管理操作中用到的map配置 -->
  <signatures>
    <![CDATA[
      import java.util.List;
      import cn.etcom.jfgl.customer.tel.userInfo.UserInfoManageOpDwr;
      UserInfoManageOpDwr.addUsersInfo(String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,Map<String,String>);
      UserInfoManageOpDwr.addUserInfo(String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,String,Map<String,String>);
      ]]>
  </signatures>
</dwr>

二、在web.xml文件里配置servlet

<!-- DWR相关配置 -->
  <servlet>
    <servlet-name>dwr-invoker</servlet-name>
    <servlet-class>uk.ltd.getahead.dwr.DWRServlet</servlet-class>
    <init-param>
      <param-name>debug</param-name>
      <param-value>false</param-value>
    </init-param>
    <init-param>
      <param-name>
        allowGetForSafariButMakeForgeryEasier
      </param-name>
      <param-value>true</param-value>
    </init-param>
    <init-param>
      <param-name>crossDomainSessionSecurity</param-name>
      <param-value>false</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>dwr-invoker</servlet-name>
    <url-pattern>/dwr/*</url-pattern>
  </servlet-mapping>

三、写一个普通的JAVA类

package cn.etcom.jfgl.tel.fee.callType;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.http.HttpServletRequest;

import org.json.JSONException;
import org.json.JSONObject;

import cn.etcom.common.utility.DBUtil;
import cn.etcom.common.utility.RsHandler;
import cn.etcom.common.utility.SqlActuator;
import cn.etcom.common.utility.StringUtil;

/*******************************************************************************
 *
 * @author 刘彦宁 2011-08-12
 *
 */
// 处理呼叫类型的dwr
public class CallTypeOpDwr {

  /***************************************************************************
   * DWR 方法，执行存储过程。
   *
   */
  public String updateSp() {
    String sql = "exec Pub_Sp_UpdateFieldMemo ?";
    Connection conn = DBUtil.getConnection();
    PreparedStatement psmt = null;
    try {
      psmt = conn.prepareStatement(sql);
      psmt.setString(1, "CALL");
      boolean a = psmt.execute();
      DBUtil.close(null, psmt, conn);
      conn = DBUtil.getConnection();
      psmt = conn.prepareStatement(sql);
      psmt.setString(1, "USER");
      boolean b = psmt.execute();
      System.out.println(a);
      System.out.println(b);
      System.out.println("关闭弹窗执行存储过程 >> "+sql);
    } catch (SQLException e) {
      e.printStackTrace();
    }finally {
      DBUtil.close(null, psmt, conn);
    }
    return null;
  }
}

四、写一个JSP页面，主要导入engine.js和相应的java类映射的js文件，然后编写js即可调用

//以下为jsp的引入js文件部分
<script type="text/javascript">
  //设置根路径，放在 tab.js 前
  var glbRootPath = "<%=basePath%>";
</script>
<script src="<%=basePath%>js/lhgdialog/lhgcore.min.js" type="text/javascript"></script>
<script src="<%=basePath%>js/lhgdialog/lhgdialog.js" type="text/javascript"></script>

五、js文件里调用后台代码

var basePath = "";
  if(typeof(glbRootPath) != "undefined"){
    basePath = glbRootPath;
    document.write("<script type='text/javascript' src='"+basePath+"\/dwr\/engine.js'><\/script><script type='text/javascript' src='"+basePath+"\/dwr\/interface\/CallTypeOpDwr.js'><\/script>");
  }
/*
中间省略若干代码
*/
.
.
.
if(typeof(glbRootPath) != "undefined"&&$(this).parent().children().eq(0).text()=="呼叫类型设置"){
        console.log("进来了");
        DWREngine.setAsync(false);
        CallTypeOpDwr.updateSp();
      }

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