add jdbc batchinsert demo

tests/examples/JDBC/JDBCDemo/pom.xml

@@ -17,7 +17,7 @@
         <dependency>
             <groupId>com.taosdata.jdbc</groupId>
             <artifactId>taos-jdbcdriver</artifactId>
-            <version>2.0.34</version>
+            <version>2.0.35</version>
         </dependency>
     </dependencies>
 

tests/examples/JDBC/JDBCDemo/src/main/java/com/taosdata/example/BatchInsert.java

+package com.taosdata.example;
+
+import java.sql.*;
+import java.util.*;
+
+public class BatchInsert {
+
+    private static final String host = "127.0.0.1";    
+    private static final String user = "root";
+    private static final String password = "taosdata";
+
+
+    private static final String dbname = "test";
+    private static final String stbname = "stb";
+    private static final int tables= 100;
+    private static final int rows = 500;
+    private static final long ts = 1604877767000l;
+
+    private Connection conn;
+    
+    private void init() {
+        // final String url = "jdbc:TAOS://" + host + ":6030/?user=" + user + "&password=" + password;
+        final String url = "jdbc:TAOS-RS://" + host + ":6041/?user=" + user + "&password=" + password;
+        
+        // get connection
+        try {
+            Properties properties = new Properties();
+            properties.setProperty("charset", "UTF-8");
+            properties.setProperty("locale", "en_US.UTF-8");
+            properties.setProperty("timezone", "UTC-8");
+            System.out.println("get connection starting...");
+            conn = DriverManager.getConnection(url, properties);
+            if (conn != null){
+                System.out.println("[ OK ] Connection established.");
+            }
+            
+            Statement stmt = conn.createStatement();
+
+            stmt.execute("drop database if exists " + dbname);
+            stmt.execute("create database if not exists " + dbname);
+            stmt.execute("use " + dbname);
+            stmt.execute("create table " + dbname + "." + stbname + "(ts timestamp, col int) tags(id int)");
+
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+    }
+
+    private String generateSql() {
+        StringBuilder sb = new StringBuilder();
+        Random rand = new Random();
+        sb.append("insert into ");
+        for (int i = 0; i < tables; i++) {
+            sb.append(dbname + ".tb" + i + " using " + dbname + "." + stbname + " tags(" + i +  ") values");
+            for (int j = 0; j < rows; j++) {
+                sb.append("(");
+                sb.append(ts + j);
+                sb.append(",");
+                sb.append(rand.nextInt(1000));
+                sb.append(") ");
+            }
+        }
+        return sb.toString();
+    }
+
+    private void executeQuery(String sql) {        
+        try (Statement stmt = conn.createStatement()) {
+            long start = System.currentTimeMillis();
+            stmt.execute(sql);
+            long end = System.currentTimeMillis();
+            
+            System.out.println("insert " + tables * rows + " records, cost " + (end - start)+ "ms");
+        } catch (SQLException ex) {
+            ex.printStackTrace();
+        }
+    }
+
+    public static void main(String[] args) {
+        BatchInsert bi = new BatchInsert();
+
+        String sql = bi.generateSql();
+        bi.init();
+        bi.executeQuery(sql);
+    }
+
+
+}