java后台生成echarts图片

由于最近项目需要在java后台生成echarts图片，花时间研究了下这个，顺便分享下；

1.首先需要先下载echarts本地服务器；

　　　可以去官网下载也可以直接去我的网盘下载，也可以去这个官网下载最新的 https://www.jianshu.com/p/dfc28fd7d786

　　（1）网盘:链接：https://pan.baidu.com/s/1kTZ9JWsU48PTTG809HurRA 提取码：b69t

　　（2）获取后放入本地解压到例如D:/TEST下

D:\TEST\phantomjs-2.1.1-windows\bin\phantomjs.exe D:\TEST\saintlee-echartsconvert-master\echartsconvert\echarts-convert.js  -s -p 6666

解压之后可以使用cmd命令启动这个服务,输入以上命令出现 echarts-convert server start success. [pid]=10500 提示即启动成功；

2.此服务启动成功后就是代码了

　　以下是springboot项目整体结构了采用了Maven导包方式，需要utils下和pom文件需要导入相应的包
　　

　　(1)导入pom.xml包

  　　　<dependency>
            <groupId>org.freemarker</groupId>
            <artifactId>freemarker</artifactId>
            <version>2.3.28</version>
      </dependency>
      <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
            <version>4.5.7</version>
      </dependency>
        <!-- 阿里JSON解析器 -->
     <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.68</version>
    </dependency>

　　　　<!-- pool 对象池 -->
　　　　<dependency>
  　　 　　<groupId>org.apache.commons</groupId>
   　　　　<artifactId>commons-pool2</artifactId>
　　　　</dependency>

　　（2）3个工具类分别如下，根据需求可自行修改逻辑

package com.lxp.demo.utils;/**
 * @projectName: ruoyi
 * @packageName: com.rmis.common.utils.chart
 * @className: HttpUtil
 * @description: ${description}
 * @author: hrs
 * @date: 2020-07-16 15:25
 */
 
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;
 
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
 
 
public class HttpUtil {
    public static String post(String url, Map<String, String> 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<NameValuePair> nameValuePairs = new ArrayList<>();
        if (params != null) {
            for (Map.Entry<String, String> 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;
    }
}

package com.lxp.demo.utils;/**
 * @projectName: ruoyi
 * @packageName: com.rmis.common.utils.chart
 * @className: FreemarkerUtil
 * @description: ${description}
 * @author: hrs
 * @date: 2020-07-16 15:26
 */
 
import freemarker.template.Configuration;
import freemarker.template.Template;
import freemarker.template.TemplateException;
 
import java.io.IOException;
import java.io.StringWriter;
import java.io.UnsupportedEncodingException;
import java.util.Map;
 
/**
 * @author msh
 * @date2020/7/16
 */
public class FreemarkerUtil {
 
  private static final String path = FreemarkerUtil.class.getClassLoader().getResource("").getPath();
 
    public static String generateString(String templateFileName, String templateDirectory, Map<String, Object> datas)
            throws IOException, TemplateException {
        Configuration configuration = new Configuration(Configuration.VERSION_2_3_0);
        // 设置默认编码
        configuration.setDefaultEncoding("UTF-8");
 
        //获取模板地址
        configuration.setClassForTemplateLoading(FreemarkerUtil.class,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();
        }
    }
}

package com.lxp.demo.utils;
 
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
 
import freemarker.template.TemplateException;
import org.apache.http.client.ClientProtocolException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import sun.misc.BASE64Decoder;
 
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
 
/**
 * @author msh
 * @date2020/7/16
 */
public class EchartsUtil {
    /**
     * 临时文件夹路径
     */
    public static final String TEMP_FILE_PATH = "D:/tempFile/";
    private static final String SUCCESS_CODE = "1";
    private static final Logger logger = LoggerFactory.getLogger(EchartsUtil.class);
 
    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<String, String> params = new HashMap<>();
        params.put("opt", option);
        String response = HttpUtil.post("http://localhost:6666", 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;
    }
 
    public static void getImage(Map<String, Object> datas) throws IOException {
        // 生成option字符串
        String option = null;
        try {
            if (!datas.containsKey("ftl")){
                logger.error("没有指定生成图表的模板！");
            }
            option = FreemarkerUtil.generateString((String) datas.get("ftl"), "/template", datas);
        } catch (TemplateException e) {
            logger.error(e.getMessage());
        }
        // 根据option参数
        String base64 = generateEchartsBase64(option);
        File file = new File(TEMP_FILE_PATH);
        if(!file.exists()) {
            // 如果不存在就创建文件
            file.mkdir();
        }
 
        BASE64Decoder decoder = new BASE64Decoder();
        try (OutputStream out = new FileOutputStream(TEMP_FILE_PATH+"test.jpg")){
            // 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();
        }
    }
}

　以上是所有工具类的代码，解释基本都有，最后还需要一个echarts图模板 option.ftl 如下:

{
    title: {
        text: '功率调节计算'
    },
    tooltip: {
        trigger: 'axis'
    },
    legend: {
        data: ['AO', 'AO*']
    },
    xAxis: {
        type: 'category',
        boundaryGap: false,
        data:  ${aohour}
    },
    yAxis: {
        type: 'value'
    },
    series: [
        {
            name: 'AO',
            type: 'line',
            stack: '总量',
            data: ${aoList},
            smooth : true
        },
        {
            name: 'AO*',
            type: 'line',
            stack: '总量',
            data: ${aoxList},
            smooth : true
        },
 
 
    ]
}

　　(3)最后一部是执行EchartUtils的测试方法

public static void main(String[] args) {
       //制造数据
       List<String> aoxList = new ArrayList<>();
       aoxList.add("2");  aoxList.add("4");  aoxList.add("7");aoxList.add("9");  aoxList.add("10");  aoxList.add("9");
       aoxList.add("8");  aoxList.add("8");  aoxList.add("7");
       List<String> aoList = new ArrayList<>();
       aoList.add("1");  aoList.add("4");  aoList.add("7");aoList.add("9");  aoList.add("10");  aoList.add("10");
       aoList.add("10");  aoList.add("10");  aoList.add("10");
       List<String> aohour = new ArrayList<>();
       aohour.add("1");aohour.add("2");aohour.add("3");aohour.add("4");aohour.add("5");aohour.add("6");aohour.add("7");
       aohour.add("8");aohour.add("9");
       // 模板参数
       HashMap<String, Object> datas = new HashMap<>();
       //aohour、aoList、aoxList对应模板/template/option.ftl中的x和y轴的名字,模板可自行修改，
       //ftl 为设置模板的名字。路径在/templates下
       datas.put("aoxList", JSON.toJSONString(aoxList));
       datas.put("aoList", JSON.toJSONString(aoList));
       datas.put("aohour", JSON.toJSONString(aohour));
       datas.put("ftl", "option.ftl");
       try {
           EchartsUtil.getImage(datas);
       } catch (IOException e) {
           e.printStackTrace();
       }
 
   }