add java query example

docs-cn/06-insert-data/01-sql-writing.mdx

@@ -118,6 +118,6 @@ TDengine 也提供了支持参数绑定的 Prepare API，与 MySQL 一样，这
 
 :::note
 
-只有使用本地驱动方式连接连接，才能使用动态绑定工具。
+只有使用本地驱动方式连接连接，才能使用动态绑定功能。
 
 :::

docs-cn/06-insert-data/_java_stmt.mdx

 ```java
-{{#include docs-examples/java/src/main/java/com/taos/example/StmtInsertExample.java:insert}}
+{{#include docs-examples/java/src/main/java/com/taos/example/StmtInsertExample.java}}
 ```

docs-cn/07-query-data/_java.mdx

+```java
+{{#include docs-examples/java/src/main/java/com/taos/example/RestQueryExample.java}}
+```

docs-cn/07-query-data/index.mdx

@@ -123,25 +123,25 @@ Query OK, 5 row(s) in set (0.001521s)
 
 <Tabs defaultValue="java" groupId="lang">
   <TabItem label="Java" value="java">
-    <JavaStmt />
+    <JavaQuery />
   </TabItem>
   <TabItem label="Python" value="python">
-    <PyStmt />
+    <PyQuery />
   </TabItem>
   <TabItem label="Go" value="go">
-    <GoStmt />
+    <GoQuery />
   </TabItem>
   <TabItem label="Rust" value="rust">
-    <RustStmt />
+    <RustQuery />
   </TabItem>
   <TabItem label="Node.js" value="nodejs">
-    <NodeStmt />
+    <NodeQuery />
   </TabItem>
   <TabItem label="C#" value="csharp">
-    <CsStmt />
+    <CsQuery />
   </TabItem>
   <TabItem label="C" value="c">
-    <CStmt />
+    <CQuery />
   </TabItem>
 </Tabs>
 
@@ -177,4 +177,3 @@ Query OK, 5 row(s) in set (0.001521s)
 只有使用本地驱动方式连接连接，才能使用异步查询功能。
 
 :::
-

docs-examples/java/src/main/java/com/taos/example/RestQueryExample.java

+package com.taos.example;
+
+import java.sql.*;
+
+public class RestQueryExample {
+    private static Connection getConnection() throws SQLException {
+        String jdbcUrl = "jdbc:TAOS-RS://localhost:6041/power?user=root&password=taosdata";
+        return DriverManager.getConnection(jdbcUrl);
+    }
+
+    private static void printRow(ResultSet rs) throws SQLException {
+        ResultSetMetaData meta = rs.getMetaData();
+        for (int i = 1; i <= meta.getColumnCount(); i++) {
+            String value = rs.getString(i);
+            System.out.print(value);
+            System.out.print("\t");
+        }
+        System.out.println();
+    }
+
+    private static void printColName(ResultSet rs) throws SQLException {
+        ResultSetMetaData meta = rs.getMetaData();
+        for (int i = 1; i <= meta.getColumnCount(); i++) {
+            String colLabel = meta.getColumnLabel(i);
+            System.out.print(colLabel);
+            System.out.print("\t");
+        }
+        System.out.println();
+    }
+
+    private static void processResult(ResultSet rs) throws SQLException {
+        printColName(rs);
+        while (rs.next()) {
+            printRow(rs);
+        }
+    }
+
+    private static void queryData() throws SQLException {
+        try (Connection conn = getConnection()) {
+            try (Statement stmt = conn.createStatement()) {
+                ResultSet rs = stmt.executeQuery("SELECT AVG(voltage) FROM meters GROUP BY location");
+                processResult(rs);
+            }
+        }
+    }
+
+    public static void main(String[] args) throws SQLException {
+        queryData();
+    }
+}
+
+// possible stdout:
+// avg(voltage)	location
+// 222.0	Beijing.Haidian
+// 219.0	Beijing.Chaoyang

docs-examples/java/src/main/java/com/taos/example/StmtInsertExample.java

@@ -14,9 +14,18 @@ import java.util.Arrays;
 import java.util.List;
 
 public class StmtInsertExample {
-    private static Connection getConnection() throws SQLException {
-        String jdbcUrl = "jdbc:TAOS://localhost:6030?user=root&password=taosdata";
-        return DriverManager.getConnection(jdbcUrl);
+    private static ArrayList<Long> tsToLongArray(String ts) {
+        ArrayList<Long> result = new ArrayList<>();
+        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS");
+        LocalDateTime localDateTime = LocalDateTime.parse(ts, formatter);
+        result.add(localDateTime.toInstant(ZoneOffset.of("+8")).toEpochMilli());
+        return result;
+    }
+
+    private static <T> ArrayList<T> toArray(T v) {
+        ArrayList<T> result = new ArrayList<>();
+        result.add(v);
+        return result;
     }
 
     private static List<String> getRawData() {
@@ -32,21 +41,11 @@ public class StmtInsertExample {
         );
     }
 
-    private static ArrayList<Long> tsToLongArray(String ts) {
-        ArrayList<Long> result = new ArrayList<>();
-        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS");
-        LocalDateTime localDateTime = LocalDateTime.parse(ts, formatter);
-        result.add(localDateTime.toInstant(ZoneOffset.of("+8")).toEpochMilli());
-        return result;
-    }
-
-    private static <T> ArrayList<T> toArray(T v) {
-        ArrayList<T> result = new ArrayList<>();
-        result.add(v);
-        return result;
+    private static Connection getConnection() throws SQLException {
+        String jdbcUrl = "jdbc:TAOS://localhost:6030?user=root&password=taosdata";
+        return DriverManager.getConnection(jdbcUrl);
     }
 
-    // ANCHOR: insert
     private static void createTable(Connection conn) throws SQLException {
         try (Statement stmt = conn.createStatement()) {
             stmt.execute("CREATE DATABASE power KEEP 3650");
@@ -68,7 +67,7 @@ public class StmtInsertExample {
                     pst.setTagString(0, ps[5]);
                     pst.setTagInt(1, Integer.valueOf(ps[6]));
                     // bind values
-                    pst.setTimestamp(0, tsToLongArray(ps[1]));
+                    pst.setTimestamp(0, tsToLongArray(ps[1])); //ps[1] looks like: 2018-10-03 14:38:05.000
                     pst.setFloat(1, toArray(Float.valueOf(ps[2])));
                     pst.setInt(2, toArray(Integer.valueOf(ps[3])));
                     pst.setFloat(3, toArray(Float.valueOf(ps[4])));
@@ -78,7 +77,6 @@ public class StmtInsertExample {
             }
         }
     }
-    // ANCHOR_END: insert
 
     public static void main(String[] args) throws SQLException {
         insertData();