An Introduction to Ethereum Jdbc Driver: Principles and Functionality
Introduction to Ethereum JDBC driver: Principles and functions
Overview:
Ethereum JDBC driver is a driver used to connect and interact Ethereum blockchain in Java applications.It provides access to Ethereum through the JDBC (Java database connection) interface, enabling developers to read and write the Ethereum directly from the Java code.This article will introduce the principles and functions of the Ethereum JDBC driver, and provide some Java code examples to help readers understand.
principle:
The Ethereum JDBC driver is built based on the JDBC specification. It uses the standard interface and method provided by JDBC to achieve access to Ethereum.It establishes a connection with the Ethereum node and sends JSON-RPC requests to perform operations related to Ethereum.The Ethereum JDBC driver encapsulates these operations as the Java method so that developers can interact with Ethereum by calling these methods.
Function:
1. Connect the Ethereum node: Ethereum JDBC driver allows developers to connect to Ethereum nodes through the URL, port, and authentication information of the specified node.
2. Execute query operation: Developers can use the Ethereum JDBC driver to perform various query operations, such as obtaining account balance, querying transaction history records, etc.
3. Send transaction: Ethereum JDBC driver provides the function of sending transactions, enabling developers to send Ethereum transactions from the Java code.
4. Contract deployment and call: Ethereum JDBC driver allows developers to deploy and call smart contracts.Developers can use Java code to write smart contracts and deploy them into the Ethereum network through the Ethereum JDBC driver.
Example code:
Here are some Java code examples of the Ethereum JDBC driver to help readers understand how they use.
1. Connect Ethereum node:
String url = "jdbc:ethereum://localhost:8545";
Properties props = new Properties();
props.put("user", "username");
props.put("password", "password");
Connection conn = DriverManager.getConnection(url, props);
2. Query account balance:
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("SELECT balance FROM accounts WHERE address = '0x123456789'");
while (rs.next()) {
BigInteger balance = rs.getBigInteger("balance");
System.out.println ("Account balance:" + Balance);
}
3. Send Ethereum transaction:
String sql = "INSERT INTO transactions (from, to, value) VALUES ('0x111111111', '0x222222222', 100)";
Statement stmt = conn.createStatement();
int rowsAffected = stmt.executeUpdate(sql);
System.out.println ("transaction has been sent, the number of influence:" + ROWSAffect);
4. Call the smart contract method:
CallableStatement cstmt = conn.prepareCall("{? = CALL invoke_contract(?, ?)}");
cstmt.registerOutParameter(1, Types.VARCHAR);
cstmt.setString(2, contractAddress);
cstmt.setString(3, methodName);
boolean result = cstmt.execute();
String output = cstmt.getString(1);
System.out.println ("contract call result:" + output);
Summarize:
The Ethereum JDBC driver provides a simple way to connect and interact Ethereum from the Java application.Through the JDBC interface, developers can easily perform query operations, send transactions and call smart contracts.This article briefly introduces the principles and functions of the Ethereum JDBC driver, and provides some Java code example for readers for reference.
