📌  相关文章
📜  JSP API(1)

📅  最后修改于: 2023-12-03 14:43:35.152000             🧑  作者: Mango

JSP API

JavaServer Pages (JSP) API is a collection of Java classes and interfaces that provides a standard way to develop dynamic web applications using Java technology. JSP pages are server-side web pages that are compiled into Java servlets. JSP provides a simple and convenient way to embed dynamic content in static web pages using special tags.

Overview of JSP API

JSP API includes several major packages:

  • javax.servlet.jsp: Contains classes and interfaces for developing JSP pages and communicating with the servlet container.
  • javax.servlet.jsp.el: Contains classes and interfaces for Expression Language, which is used in JSP pages to access and manipulate data.
  • javax.servlet.jsp.tagext: Contains classes and interfaces for defining custom JSP tags.
  • javax.servlet.jsp.jstl: Contains classes and interfaces for JavaServer Pages Standard Tag Library (JSTL), which provides a set of common tags for web application development.
  • javax.servlet.jsp.jstl.core: Contains classes and interfaces for the core JSTL tags, such as forEach, if, choose, and set.
  • javax.servlet.jsp.tagext.tagfile: Contains classes and interfaces for defining JSP fragment files that can be reused across multiple JSP pages.
  • javax.servlet.jsp.tagext.simpletag: Contains classes and interfaces for defining simple tags that generate dynamic content.
JSP API Example

Here is an example of a JSP page using JSP API to access database and display data dynamically:

<%@ page import="java.sql.*" %>
<html>
<head><title>Customer List</title></head>
<body>
<%
    // Connect to database
    Class.forName("com.mysql.jdbc.Driver");
    Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb", "root", "password");
    Statement stmt = conn.createStatement();

    // Execute SQL query
    String sql = "SELECT * FROM customers";
    ResultSet rs = stmt.executeQuery(sql);

    // Display customer list
    out.print("<table>");
    while (rs.next()) {
        out.print("<tr><td>" + rs.getString("name") + "</td><td>" + rs.getString("email") + "</td><td>" + rs.getString("phone") + "</td></tr>");
    }
    out.print("</table>");

    // Close database connection
    rs.close();
    stmt.close();
    conn.close();
%>
</body>
</html>

In this example, JSP API is used to:

  • Import the java.sql package to connect to a database.
  • Retrieve a connection object from the DriverManager and create a statement object to execute a SQL query.
  • Retrieve a result set object from the statement and iterate through the rows to display data using HTML tags.
  • Close the result set, statement, and database connection.
Conclusion

JSP API is an essential tool for developing dynamic web applications using Java technology. It provides a powerful and flexible way to embed dynamic content in static web pages using special tags, access and manipulate data using Expression Language, define custom tags, and use JSTL for common web application tasks. As a Java developer, mastering JSP API is an important skill that can help you build robust and scalable web applications.