import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import java.sql.*;
import java.util.*;
public class Main {
public static void main(String[] args) {
Connection conn = null;
User user = null;
Gson gson = new Gson();
try {
# JDK6 之前的版本需要加载驱动
# new com.mysql.jdbc.Driver();
# 连接数据库
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/dbname?" +
"useSSL=false&useUnicode=true&characterEncoding=UTF8", "root", "root");
# 使用 prepareStatement 查询数据库
PreparedStatement preStatement = conn.prepareStatement("select * from tables");
ResultSet res = preStatement.executeQuery();
List<User> users = new ArrayList<User>();
while (res.next()) {
user = new User();
user.setId(Integer.parseInt(res.getString("id")));
user.setUser(res.getString("user"));
users.add(user);
}
# 导出为 json
String strJson = gson.toJson(users);
System.out.println(strJson);
} catch (SQLException e) {
e.printStackTrace();
} finally {
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
}
# 用到的类
public class User {
private int id;
private String user;
@Override
public String toString() {
return "User{" +
"id=" + id +
", user='" + user + '\'' +
'}';
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUser() {
return user;
}
public void setUser(String user) {
this.user = user;
}
}