如何在Java后台生成Echarts图片

一、准备环境（主要以Centos7环境为准，通过Phantomjs和EChartsConvert工具实现具体功能）

1、下载Phantomjs

官网下载：http://phantomjs.org/download.html

image.png
国内镜像：http://npm.taobao.org/dist/phantomjs

2、部署Phantomjs到服务器

(1)、将从官网下载的包phantomjs-2.1.1-linux-x86_64.tar.bz2上传到服务器/usr/local/phantomjs目录之下，通过以下命令进行解压

tar -jxvf phantomjs-2.1.1-linux-x86_64.tar.bz2

解压时可能会出现以下错误提示

tar (child): bzip2: Cannot exec: No such file or directory
tar (child): Error is not recoverable: exiting now
tar: Child returned status 2
tar: Error is not recoverable: exiting now

出现该错误，使用以下命令安装bzip2插件，安装完成后再解压

yum install -y bzip2

完成解压后进入/usr/local/phantomjs/phantomjs-2.1.1-linux-x86_64/bin目录，通过./phantomjs -v 命令，查看phantomjs 是否能使用，如果能正常使用，则会输出对应phantomjs版本号，但此处提示以下错误信息

./phantomjs: error while loading shared libraries: libfontconfig.so.1: cannot open shared object file: No such file or directory

提示该错误信息，需要安装安装fontconfig和freetype依赖，其实phantomjs界面有对应的提示，运行phantomjs需要fontconfig依赖，通过以下命令，安装依赖

yum install fontconfig freetype2

安装依赖完成之后，再到/usr/local/phantomjs/phantomjs-2.1.1-linux-x86_64/bin目录下，执行./phantomjs -v 命令，可看到如下内容，则说明安装成功

image.png

（2）、将/usr/local/phantomjs/phantomjs-2.1.1-linux-x86_64/bin添加到环境变量,将export PATH=$PATH:/usr/local/phantomjs/phantomjs-2.1.1-linux-x86_64/bin放到profile文件最后一行，最后重新加载环境变量

vi /etc/profile

export PATH=$PATH:/usr/local/phantomjs/phantomjs-2.1.1-linux-x86_64/bin

source /etc/profile

（3）、安装字体（一定要进行字体安装，否则会导致导出的图片中文无法正常显示）

yum install bitmap-fonts bitmap-fonts-cjk

3、下载EChartsConvert并运行项目

下载地址：https://gitee.com/saintlee/echartsconvert

1、将下载好的包上传到服务器；
2、在echarts-convert.js同级目录下，运行命令phantomjs echarts-convert.js -s
3、如果控制台出现echarts-convert server start success. [pid]=xxxx则表示启动成功，默认端口9090；
4、也可以通过phantomjs echarts-convert.js -s -p 8080的方式，直接指定端口号

二、在项目中添加以下Maven依赖

        
            org.freemarker
            freemarker
            2.3.23
        

        
            com.alibaba
            fastjson
            1.2.48
        

        
            org.apache.httpcomponents
            httpclient
            4.5.12

三、编写工具类

(1)、Http工具类

package com.framework.pie.poi.echarts;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import org.apache.http.HttpEntity;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

public class HttpUtil {

    public static String post(String url, Map params, String charset)
            throws ClientProtocolException, IOException {
        String responseEntity = "";

        // 创建CloseableHttpClient对象
        CloseableHttpClient client = HttpClients.createDefault();

        // 创建post方式请求对象
        HttpPost httpPost = new HttpPost(url);

        // 生成请求参数
        List nameValuePairs = new ArrayList<>();
        if (params != null) {
            for (Entry entry : params.entrySet()) {
                nameValuePairs.add(new BasicNameValuePair(entry.getKey(), entry.getValue()));
            }
        }

        // 将参数添加到post请求中
        httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs, charset));

        // 发送请求，获取结果（同步阻塞）
        CloseableHttpResponse response = client.execute(httpPost);

        // 获取响应实体
        HttpEntity entity = response.getEntity();
        if (entity != null) {
            // 按指定编码转换结果实体为String类型
            responseEntity = EntityUtils.toString(entity, charset);
        }

        // 释放资源
        EntityUtils.consume(entity);
        response.close();

        return responseEntity;
    }
}

(2)、Freemarker工具类

package com.framework.pie.poi.echarts;

import java.io.File;
import java.io.IOException;
import java.io.StringWriter;
import java.util.Map;

import freemarker.template.Configuration;
import freemarker.template.Template;
import freemarker.template.TemplateException;

public class FreemarkerUtil {
    private static final String path = FreemarkerUtil.class.getClassLoader().getResource("").getPath();

    public static String generateString(String templateFileName, String templateDirectory, Map datas)
            throws IOException, TemplateException {
        Configuration configuration = new Configuration(Configuration.VERSION_2_3_0);

        // 设置默认编码
        configuration.setDefaultEncoding("UTF-8");

        // 设置模板所在文件夹
        configuration.setDirectoryForTemplateLoading(new File(path + templateDirectory));

        // 生成模板对象
        Template template = configuration.getTemplate(templateFileName);

        // 将datas写入模板并返回
        try (StringWriter stringWriter = new StringWriter()) {
            template.process(datas, stringWriter);
            stringWriter.flush();
            return stringWriter.getBuffer().toString();
        }
    }
}

(3)、Echarts工具类

package com.framework.pie.poi.echarts;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import org.apache.http.client.ClientProtocolException;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;

public class EchartsUtil {
    private static String url = "http://192.168.199.138:9090";
    private static final String SUCCESS_CODE = "1";

    public static String generateEchartsBase64(String option) throws ClientProtocolException, IOException {
        String base64 = "";
        if (option == null) {
            return base64;
        }
        option = option.replaceAll("\\s+", "").replaceAll("\"", "'");

        // 将option字符串作为参数发送给echartsConvert服务器
        Map params = new HashMap<>();
        params.put("opt", option);
        String response = HttpUtil.post(url, params, "utf-8");

        // 解析echartsConvert响应
        JSONObject responseJson = JSON.parseObject(response);
        String code = responseJson.getString("code");

        // 如果echartsConvert正常返回
        if (SUCCESS_CODE.equals(code)) {
            base64 = responseJson.getString("data");
        }
        // 未正常返回
        else {
            String string = responseJson.getString("msg");
            throw new RuntimeException(string);
        }

        return base64;
    }
}

(4)、柱形图option.ftl(用的springboot项目，直接将模板放置到resources中template文件夹中)

{
    title: {
        text:'${title}',
        x:'middle',
        textAlign:'center'
    },
    xAxis: {
        type: 'category',
        data: ${categories}
    },
    yAxis: {
        type: 'value'
    },
    series: [{
        data: ${values},
        type: 'bar'
    }]
}

折线图

{
    title: {
        text: '折线图测试'
    },
    tooltip : {
        trigger: 'axis'
    },
    legend: {
        data: ['国家级', '省级', '州市级']
    },
    xAxis: [
        {
            type: 'category',
            boundaryGap: false,
            data: ['2019上半年', '2019下半年', '2020上半年', '2020下半年', '2021上半年', '2021下半年'],
            axisLabel: {
                interval:0,
                rotate:30,
            }
        }
    ],
    yAxis: [
        {
            type: 'value'
        }
    ],
    series: [
        {
            name: '国家级',
            type: 'line',
            stack: 'Total',
            data: [120, 132, 101, 134, 90, 230, 210]
        },
        {
            name: '省级',
            type: 'line',
            stack: 'Total',
            data: [220, 182, 191, 234, 290, 330, 310]
        },
        {
            name: '州市级',
            type: 'line',
            stack: 'Total',
            data: [150, 232, 201, 154, 190, 330, 410]
        }
    ]
}

饼图

{
    tooltip: {
        trigger: 'item',
        formatter: '{a} 
{b}: {c} ({d}%25)'
    },
    legend: {
        orient: 'vertical',
        left: 10,
        data: ['直接访问', '邮件营销', '联盟广告', '视频广告', '搜索引擎']
    },
    series: [
        {
            name: '访问来源',
            type: 'pie',
            radius: ['50%25', '70%25'],
            avoidLabelOverlap: false,
            label: {
                show: false,
                position: 'center'
            },
            emphasis: {
                label: {
                    show: true,
                    fontSize: '30',
                    fontWeight: 'bold'
                }
            },
            labelLine: {
                show: false
            },
            data: [
                {value: 335, name: '直接访问'},
                {value: 310, name: '邮件营销'},
                {value: 234, name: '联盟广告'},
                {value: 135, name: '视频广告'},
                {value: 1548, name: '搜索引擎'}
            ]
        }
    ]
}

(5)、测试类信息

package com.framework.pie.poi.echarts;

import com.alibaba.fastjson.JSON;
import freemarker.template.TemplateException;
import org.apache.http.client.ClientProtocolException;
import sun.misc.BASE64Decoder;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.HashMap;

public class TestEcharts02 {
    public static void main(String[] args) throws ClientProtocolException, IOException, TemplateException {
        // 变量
        String title = "水果";
        String[] categories = new String[] { "苹果", "香蕉", "西瓜" };
        int[] values = new int[] { 3, 2, 1 };

        // 模板参数
        HashMap datas = new HashMap<>();
        datas.put("categories", JSON.toJSONString(categories));
        datas.put("values", JSON.toJSONString(values));
        datas.put("title", title);


        // 生成option字符串
        String option = FreemarkerUtil.generateString("option.ftl", "template/echarts", datas);

        // 根据option参数
        String base64 = EchartsUtil.generateEchartsBase64(option);

        System.out.println("BASE64:" + base64);
        generateImage(base64, "E:/export/echarts001.png");
    }

    public static void generateImage(String base64, String path) throws IOException {
        BASE64Decoder decoder = new BASE64Decoder();
        try (OutputStream out = new FileOutputStream(path)){
            // 解密
            byte[] b = decoder.decodeBuffer(base64);
            for (int i = 0; i < b.length; ++i) {
                if (b[i] < 0) {
                    b[i] += 256;
                }
            }
            out.write(b);
            out.flush();
        }
    }
}

四、效果图

echarts001.png

echarts6.png

echarts8.png

五、需要注意的问题

饼图绘制不了，request时就卡住的问题，程序一直卡在如下界面，不会往下执行