【Echarts】散点图点击散点加载对应的图片（ajax传值&获取流）

" class="reference-link">效果图：点击每个散点，右边的图片会变成对应的~（10000个点）

需求说明：因为图片较多，直接放在项目里，项目启动时要加载很久。所以尝试把图片放在本地/服务器上，当点击一个散点的时候，再去请求图片地址，即不点就不被加载。

对应z_data.json文件：这个文件是学长强化学习的数据，看起来很长…就用到了0-x坐标，1-y坐标，3-对应图片序号。

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前端 demo.html:

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>散点图</title>
    <script src="https://cdn.staticfile.org/echarts/4.3.0/echarts.min.js"></script>
    <script src="https://cdn.bootcss.com/jquery/3.2.1/jquery.js"></script>
    <script src="/jquery.base64.js" type="text/javascript"></script>
</head>
<body>
<div id="main" style="width: 1000px;height:600px;float:left"></div>
<img id="img" src="state-0.png" style="float:right"/>
<script type="text/javascript">
    var myChart = echarts.init(document.getElementById('main'));
    myChart.setOption({
        title: {
            text: 'BreakoutScatter',
            left: 'center',
            top: 0
        },
        xAxis: {},
        yAxis: {},
        series: [{
            data: [],
            type: 'scatter'
        }]
    });
    //加载数据
    $.get('z_data.json').done(function (data) {
        var option = {
            visualMap: {
                min: 0,
                max: 1000,
                dimension: 1,
                orient: 'vertical',
                right: 10,
                top: 'center',
                text: ['HIGH', 'LOW'],
                calculable: true,
                inRange: {
                    color: ['#eccb5e', '#f22424']
                }
            },
            tooltip: {
                trigger: 'item',
                axisPointer: {
                    type: 'cross'
                }
            },
            xAxis: [{
                type: 'value'
            }],
            yAxis: [{
                type: 'value'
            }],
            series: [{
                name: 'price-area',
                type: 'scatter',
                symbolSize: 7,
                data: data.data
            }]
        };
        myChart.setOption(option);
    });
    //点击事件
    myChart.on('click', function (params) {
        console.log(params.data[3]-1);
        $.ajax({
            url:"/getImg",
            type : 'GET',
            data:{"path_index":params.data[3]-1},
            //dataType : 'json',
            success: function(data){
                console.log(data.result);
                var ImgUrl="data:image/jpeg;base64,"+data.result;
                $("#img").attr('src',ImgUrl); //修改图片地址
            },
        })
    })
</script>
</body>
</html>

后端 demoController:

package com.example.breakout.Controller;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.servlet.ModelAndView;
import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.image.BufferedImage;
import java.io.*;
import java.net.URLDecoder;
import java.util.HashMap;
import java.util.Map;
@Controller
public class demoController {
    @RequestMapping("/demo")
    public String show(){
        return "demo";
    }
    @GetMapping("/getImg")
    @ResponseBody
    public Map<String,Object> getImage(@RequestParam String path_index) throws Exception{
        System.out.println("path_index: "+path_index); //得到图片序号
        byte[] imageContent ;
        Map<String,Object> resultMap = new HashMap<String, Object>();
        String path = "C:\\Users\\10846\\Desktop\\test_circle\\state-"+path_index+".png";
        imageContent = fileToByte(new File(path));
        resultMap.put("result", imageContent);
        return resultMap;
    }
    //转换成byte流
    public static byte[] fileToByte(File img) throws Exception {
        byte[] bytes = null;
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        try {
            BufferedImage bi;
            bi = ImageIO.read(img);
            ImageIO.write(bi, "png", baos);
            bytes = baos.toByteArray();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            baos.close();
        }
        return bytes;
    }
}