EasyUI+JSP之java讀取數據庫后JSON格式數據的返回及調用

做作業工程中遇到一些問題，特此記錄一下

解決的問題：使用EasyUI框架搭建簡單學生管理系統（數據庫增刪改查）操作時配合JSP，不知道如何把從數據庫獲得的數據封裝成JSON格式並傳回前端JSP並進行展示

解決工具：Servlet、MVC設計模式

1.數據封裝

//連接數據庫
      Connection connection=null;
      String driverName="com.microsoft.sqlserver.jdbc.SQLServerDriver";//SQL數據庫引擎
      String dbURL="jdbc:sqlserver://localhost:1433;DatabaseName=tjl";//數據源  ！！！注意若出現加載或者連接數據庫失敗一般是這里出現問題
      String Name="sa";
      String Pwd="19990713";
      ResultSet rs=null;
      //定義JSON數組，用於保存從數據庫查出來的數據
      JSONArray array = new JSONArray();
        
      try{
      Class.forName(driverName);
      connection=DriverManager.getConnection(dbURL,Name,Pwd);
      System.out.println("連接數據庫成功");
      }catch(Exception e){
       e.printStackTrace();
         System.out.println("連接失敗");
         }
        Statement stmt = null;
        try {
            stmt = connection.createStatement();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        /*//增刪改操作
        String sql_1="insert into student values('990403','佩奇','男','12','1','2101')";
        int count_1 = 0;
        try {
            count_1 = stmt.executeUpdate(sql_1);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }//返回值表示增刪改幾條數據
        //處理結果
        if(count_1>0){
            System.out.println("更新成功!");
        }*/
        //查詢操作
        String sql_2="select * from student";
        try {
            rs = stmt.executeQuery(sql_2);
            // 獲取列數
            ResultSetMetaData metaData = rs.getMetaData();
            int columnCount = metaData.getColumnCount();
            while (rs.next()) {
                JSONObject jsonObj = new JSONObject();
               
                // 遍歷每一列
                for (int i = 1; i <= columnCount; i++) {
                    String columnName =metaData.getColumnLabel(i);
                    String value = rs.getString(columnName);
                    jsonObj.put(columnName, value);
                    
                } 
                array.put(jsonObj); 
            }
        } catch (SQLException e1) {
            e1.printStackTrace();
        }

2.Servlet基礎知識

 

 

3.在Ecplise內創建Servlet

在您所創建的WEB項目的src目錄右鍵新建，如圖，選擇Servlet，如果有版本選項，選擇3.0版本，系統會自動創建映射和基本都代碼格式

 

4.完整代碼

 

package com.jwglxt.data;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;

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 org.json.JSONArray;
import org.json.JSONObject;


@WebServlet("/getStudent")
public class getStudent extends HttpServlet {
    
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      //設置編碼格式
      request.setCharacterEncoding("UTF-8"); 
      response.setCharacterEncoding("utf-8");
      response.setContentType("text/json; charset=utf-8");
      //連接數據庫
      Connection connection=null;
      String driverName="com.microsoft.sqlserver.jdbc.SQLServerDriver";//SQL數據庫引擎
      String dbURL="jdbc:sqlserver://localhost:1433;DatabaseName=tjl";//數據源  ！！！注意若出現加載或者連接數據庫失敗一般是這里出現問題
      String Name="sa";
      String Pwd="19990713";
      ResultSet rs=null;
      //定義JSON數組，用於保存從數據庫查出來的數據
      JSONArray array = new JSONArray();
        
      try{
      Class.forName(driverName);
      connection=DriverManager.getConnection(dbURL,Name,Pwd);
      System.out.println("連接數據庫成功");
      }catch(Exception e){
       e.printStackTrace();
         System.out.println("連接失敗");
         }
        Statement stmt = null;
        try {
            stmt = connection.createStatement();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        /*//增刪改操作
        String sql_1="insert into student values('990403','佩奇','男','12','1','2101')";
        int count_1 = 0;
        try {
            count_1 = stmt.executeUpdate(sql_1);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }//返回值表示增刪改幾條數據
        //處理結果
        if(count_1>0){
            System.out.println("更新成功!");
        }*/
        //查詢操作
        String sql_2="select * from student";
        try {
            rs = stmt.executeQuery(sql_2);
            // 獲取列數
            ResultSetMetaData metaData = rs.getMetaData();
            int columnCount = metaData.getColumnCount();
            while (rs.next()) {
                JSONObject jsonObj = new JSONObject();
               
                // 遍歷每一列
                for (int i = 1; i <= columnCount; i++) {
                    String columnName =metaData.getColumnLabel(i);
                    String value = rs.getString(columnName);
                    jsonObj.put(columnName, value);
                    
                } 
                array.put(jsonObj); 
            }
        } catch (SQLException e1) {
            e1.printStackTrace();
        }
        //關閉
        try {
            if(rs!=null) rs.close();
            stmt.close();
            connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        PrintWriter out = response.getWriter();
        out.println(array);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

}

 

 

 

5.EasyUI引用數據

 

參考文章：https://blog.csdn.net/qq_38313548/article/details/85966603