基于echarts ajax数据库读取数据库_基于echarts+ajax数据库读取数据并返回前端

更新时间:2020-09-13    来源:php与数据库    手机版     字体:

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1.echarts的官网上的demo,都是直接写死的随机数据,没有和数据库的交互,所以就自己写了一下,ok,我们开始一步一步走一遍整个流程吧。

就以官网最简单的那个小demo来做修改吧。官网上的小demo的效果图如下:(很熟悉,有没有)


2.按照echarts的使用方法新建一个echarts.html文件。为ECharts准备一个具备大小(宽高)的Dom(讲的有点细,熟悉的朋友直接跳过)



   
    ECharts
   
   

新建<script>标签引入符合AMD规范的加载器,如esl.js,引入jquery为等一下AJAX发送POST请求做准备


<script src="echarts/esl.js"></script>
 <script src="echarts/jquery.min.js"></script>

路径配置

// 路径配置
 require.config({
            paths:{
                ‘echarts‘ : ‘echarts/echarts‘,
                ‘echarts/chart/bar‘ : ‘echarts/echarts‘
            }
 });

最后是使用:以下代码是官网上的,红色部分的data数据等一下我们修改一下从数据库中去读取


 // 使用
        require(
            [
                ‘echarts‘,
                ‘echarts/chart/bar‘ // 使用柱状图就加载bar模块,按需加载
            ],
            function (ec) {
                // 基于准备好的dom,初始化echarts图表
                var myChart = ec.init(document.getElementById(‘main‘));
                
                var option = {
                    tooltip: {
                        show: true
                    },
                    legend: {                        data:[‘销量‘]
                    },
                    xAxis : [
                        {                            type : ‘category‘,                            data : ["衬衫","羊毛衫","雪纺衫","裤子","高跟鞋","袜子"]
                        }
                    ],
                    yAxis : [
                        {                            type : ‘value‘
                        }
                    ],
                    series : [
                        {
                            "name":"销量",
                            "type":"bar",                            "data":[5, 20, 40, 10, 10, 20]
                        }
                    ]
                };
        
                // 为echarts对象加载数据
                myChart.setOption(option);
            }
        );
整个前段页面的代码如下:主要就是修改了option中的xAxis的data和series中的data,这2个data在官网的demo中都是直接写死的,这里我们采用AJAX发送post请求:



   
    ECharts
   
    <script src="echarts/esl.js"></script>
    <script src="echarts/jquery.min.js"></script>
   
   
    <script type="text/javascript">
        // 路径配置        require.config({
            paths:{
                ‘echarts‘ : ‘echarts/echarts‘,                ‘echarts/chart/bar‘ : ‘echarts/echarts‘
            }
        });        // 使用        require(
            [                ‘echarts‘,                ‘echarts/chart/bar‘ // 使用柱状图就加载bar模块,按需加载            ],
            drewEcharts
        );         function drewEcharts(ec) {                // 基于准备好的dom,初始化echarts图表                myChart = ec.init(document.getElementById(‘main‘));
                var option = {
                    tooltip: {
                        show: true
                    },
                    legend: {                        data:[‘销量‘]
                    },
                    xAxis : [
                        {
                            type : ‘category‘,
                            data : (function(){                                    var arr=[];
                                        $.ajax({                                        type : "post",
                                        async : false, //同步执行                                        url : "bar.do",                                        data : {},
                                        dataType : "json", //返回数据形式为json                                        success : function(result) {                                        if (result) {                                               for(var i=0;i                                                   console.log(result[i].name);
                                                  arr.push(result[i].name);
                                                }   
                                        }
                                        
                                    },
                                    error : function(errorMsg) {
                                        alert("不好意思,大爷,图表请求数据失败啦!");
                                        myChart.hideLoading();
                                    }
                                   })                                   return arr;
                                })()
                        }
                    ],
                    yAxis : [
                        {                            type : ‘value‘
                        }
                    ],
                    series : [
                        {                            "name":"销量",                            "type":"bar",                            "data":(function(){                                        var arr=[];
                                        $.ajax({                                        type : "post",
                                        async : false, //同步执行                                        url : "bar.do",                                        data : {},
                                        dataType : "json", //返回数据形式为json                                        success : function(result) {                                        if (result) {                                               for(var i=0;i                                                   console.log(result[i].num);
                                                  arr.push(result[i].num);
                                                } 
                                        }
                                    },
                                    error : function(errorMsg) {
                                        alert("不好意思,大爷,图表请求数据失败啦!");
                                        myChart.hideLoading();
                                    }
                                   })                                  return arr;
                            })()
                            
                        }
                    ]
                };              
                // 为echarts对象加载数据                 myChart.setOption(option);       
            }    </script>
3.在前一步中AJAX的POST请求的路径是 url : "bar.do" 在web.xml中配置以下映射如下图:


    helloBar
    com.helloBar
 

 
  helloBar
  /bar.do
 

这样,通过bar.do就会找到com这个包下面的helloBar这个servlet.这个servlet的主要作用是向数据库读取数据并返回给前段页面,这里我用的是局部数据源去链接,关于局部数据源怎么连这里我就不讲述了,不会的同学可以在我的博客中找到。当然也可以使用最基本的JDBC去连接。

public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //创建了一个bardao的对象,barDAO主要是对数据库的连接和对数据库的操作
        barDAO bardao=new barDAO();
        //调用bardao的select_all()方法把从数据库中读取所有的数据返回的是一个ArrayList,ArrayList里面放的是一个barBean
        ArrayList array = bardao.select_all();
        //设置返回时的编码格式
        response.setContentType("text/html; charset=utf-8");
        //调用JSONArray.fromObject方法把array中的对象转化为JSON格式的数组
        JSONArray json=JSONArray.fromObject(array);
        System.out.println(json.toString());
        //返回给前段页面
        PrintWriter out = response.getWriter(); 
        out.println(json); 
        out.flush(); 
        out.close();  
}
数据库的bar表格式如下图:


barBean的代码:

import java.io.Serializable;
import java.sql.Date;
public class barBean {
    private String name;
    private int num;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getNum() {
        return num;
    }
    public void setNum(int num) {
        this.num = num;
    }
    
}
barDAO的代码:
public class barDAO {
        private static InitialContext context = null;
        private DataSource dataSource = null;
        private static final String SELECT_ALL = "SELECT*FROM bar ";
        public barDAO(){
            try{
                if(context == null){
                    context = new InitialContext();
                }                dataSource = (DataSource)context.lookup("java:comp/env/jdbc/sampleDS");
            }catch(NamingException e2){
                
            }
        }
        public Connection getConnection(){
            Connection conn = null;
            try{
                conn = dataSource.getConnection();
            }catch(SQLException e){}
            return conn;
        } 
        public ArrayList select_all()
        {
             Connection conn = null;
             PreparedStatement pstmt = null;
             ResultSet rst = null;
            try{
                conn = dataSource.getConnection();
                pstmt = conn.prepareStatement(SELECT_ALL);
                rst = pstmt.executeQuery();
                ArrayList array = new ArrayList();
                while(rst.next())
                {
                    barBean bar = new barBean();
                    bar.setName(rst.getString("name"));
                    bar.setNum(rst.getInt("num"));
                    array.add(bar);
                }
                pstmt.close();
                rst.close();
                return array;
            }catch(SQLException e){
                System.out.println("Error occured at barDAO->select_all()");
                return new ArrayList();
            }finally{
                try{
                    conn.close();
                }catch(SQLException e){
                    System.out.println("Error occured at closing connection in barDAO");
                }
            }
        }
}

4.前段的页面在确认ajax请求success以后,读取返回后的数组的内容。就可以显示了。

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