echarts基础使用

1、新建web项目

2、给定初始化dom(记得引入echarts、jquery文件）

<div id="main" style="height:400px;width:600px"></div>

3、写入echarts主题

<script type="text/javascript">
                var myChart = echarts.init(document.getElementById('main')); 
                myChart.setOption ({
                    title:{
                    	text:'异步数据加载'
                    },
                    legend: {
                        data:['销量']
                    },
                    xAxis : 
                        {
                            data:[]     
                        }
                    ,
                    yAxis : {},
                    series : [
                        {
                            "name":"销量",
                            "type":"bar",   
                            data:[]
                        }
                    ]
                })
         myChart.showLoading();	//上部分为echarts基本实现，下部分为ajax异步获取数据
         var names=[];
         var nums=[];
		 $.ajax({
               type : "post",
               async : true,
               url : "bar.do",  //重点说明！！这个url是后续servlet的映射地址，请相对应。
               data : {},
               dataType : "json",
               success : function(result) {
                          if (result) {
                                  for(var i=0;i<result.length;i++){
                                    names.push(result[i].name);
                                  }
                                  for(var i=0;i<result.length;i++){
                                    nums.push(result[i].num);
                                  }
                     			  myChart.hideLoading();
                     			  myChart.setOption({
                     			  	xAxis:{data:names},
                     			  	series:[{
                     			  		name:'销量',
                     			  		data: nums
                     			  	}]
                     			  })
                           }
                        },
                        error : function(errorMsg) {
				             //请求失败时执行该函数
				         alert("图表请求数据失败!");
				         myChart.hideLoading();
				       }
              
            });       

    </script>

4、声明一个实体类 barBean.java

public class barBean {
	public String name;
	public Integer num;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Integer getNum() {
		return num;
	}
	public void setNum(Integer num) {
		this.num = num;
	}
}

5、数据库连接类 DBUtil.java

public class DBUtil {
	public static Connection getConncetion(){
		Connection conn = null;
		try {
			Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
			String url="jdbc:sqlserver://localhost:1433;DatabaseName=test";
			String user="sa";
			String password="88888888";
			conn=DriverManager.getConnection(url, user, password);
		} catch (SQLException e) {
				// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			System.out.println("连接失败");
			e.printStackTrace();
		}
		return conn;
	}

}

6、barDao.java

public class barDao {
	public ArrayList<barBean> select_all(){
		Connection conn=null;
		Statement stmt = null;
		ResultSet rst = null;
		try {		
		conn=DBUtil.getConncetion();	
		stmt=conn.createStatement();
		String sql = "select * from bar";
		rst=stmt.executeQuery(sql);
		ArrayList<barBean> array = new ArrayList<barBean>();
		while(rst.next()){
			barBean bar = new barBean();
			bar.setName(rst.getString("name"));
			bar.setNum(rst.getInt("num"));
			array.add(bar);
		}
		stmt.close();
		rst.close();
		conn.close();
		return array;
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			System.out.println("读取失败");
			return new ArrayList<barBean>();
		}
		
	}
}

7、数据库数据

8、barServlet.java

public class barServlet extends HttpServlet {


	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		barDao bardao = new barDao();
	    ArrayList<barBean> array = bardao.select_all();
		ObjectMapper mapper = new ObjectMapper();    //提供java-json相互转换功能的类
        String json = mapper.writeValueAsString(array);//将list中的对象转换为Json格式的数组
        System.out.println(json);
        //将json数据返回给客户端
        response.setContentType("text/html; charset=utf-8");
        response.getWriter().write(json);    
	}

}

9、web.xml

  <servlet>
  		<servlet-name>barServlet</servlet-name>
  		<servlet-class>echart.barServlet</servlet-class> //**class地址为包.类名**
  </servlet>
  <servlet-mapping>
  		<servlet-name>barServlet</servlet-name>
  		<url-pattern>/bar.do</url-pattern>
  </servlet-mapping>

 

 

运行截图：

 

转载自：https://blog.csdn.net/qq_25827785/article/details/103498558