SQLite - Java

安装

在 Java 程序中使用 SQLite 之前，我们需要确保机器上已经有 SQLite JDBC Driver 驱动程序和 Java。可以查看 Java 教程了解如何在计算机上安装 Java。现在，我们来看看如何在机器上安装 SQLite JDBC 驱动程序。

• 从 sqlite-jdbc 库下载 sqlite-jdbc-(VERSION).jar 的最新版本。

• 在您的 class 路径中添加下载的 jar 文件 sqlite-jdbc-(VERSION).jar，或者在 -classpath 选项中使用它，这将在后面的实例中进行讲解。

在学习下面部分的知识之前，您必须对 Java JDBC 概念有初步了解。如果您还未了解相关知识，那么建议您可以先花半个小时学习下 JDBC 教程相关知识，这将有助于您学习接下来讲解的知识。

连接数据库

下面的 Java 程序显示了如何连接到一个现有的数据库。如果数据库不存在，那么它就会被创建，最后将返回一个数据库对象。

import java.sql.*;



public class SQLiteJDBC

{

  public static void main( String args[] )

  {

    Connection c = null;

    try {

      Class.forName("org.sqlite.JDBC");

      c = DriverManager.getConnection("jdbc:sqlite:test.db");

    } catch ( Exception e ) {

      System.err.println( e.getClass().getName() + ": " + e.getMessage() );

      System.exit(0);

    }

    System.out.println("Opened database successfully");

  }

}

现在，让我们来编译和运行上面的程序，在当前目录中创建我们的数据库 test.db。您可以根据需要改变路径。我们假设当前路径下可用的 JDBC 驱动程序的版本是 sqlite-jdbc-3.7.2.jar。

$javac SQLiteJDBC.java

$java -classpath ".:sqlite-jdbc-3.7.2.jar" SQLiteJDBC

Open database successfully

如果您想要使用 Windows 机器，可以按照下列所示编译和运行您的代码：

$javac SQLiteJDBC.java

$java -classpath ".;sqlite-jdbc-3.7.2.jar" SQLiteJDBC

Opened database successfully

创建表

下面的 Java 程序将用于在先前创建的数据库中创建一个表：

import java.sql.*;



public class SQLiteJDBC

{

  public static void main( String args[] )

  {

    Connection c = null;

    Statement stmt = null;

    try {

      Class.forName("org.sqlite.JDBC");

      c = DriverManager.getConnection("jdbc:sqlite:test.db");

      System.out.println("Opened database successfully");



      stmt = c.createStatement();

      String sql = "CREATE TABLE COMPANY " +

                   "(ID INT PRIMARY KEY     NOT NULL," +

                   " NAME           TEXT    NOT NULL, " + 

                   " AGE            INT     NOT NULL, " + 

                   " ADDRESS        CHAR(50), " + 

                   " SALARY         REAL)"; 

      stmt.executeUpdate(sql);

      stmt.close();

      c.close();

    } catch ( Exception e ) {

      System.err.println( e.getClass().getName() + ": " + e.getMessage() );

      System.exit(0);

    }

    System.out.println("Table created successfully");

  }

}

上述程序编译和执行时，它会在 test.db 中创建 COMPANY 表，最终文件列表如下所示：

-rw-r--r--. 1 root root 3201128 Jan 22 19:04 sqlite-jdbc-3.7.2.jar

-rw-r--r--. 1 root root    1506 May  8 05:43 SQLiteJDBC.class

-rw-r--r--. 1 root root     832 May  8 05:42 SQLiteJDBC.java

-rw-r--r--. 1 root root    3072 May  8 05:43 test.db

INSERT 操作

下面的 Java 代码显示了如何在上面创建的 COMPANY 表中创建记录：

import java.sql.*;



public class SQLiteJDBC

{

  public static void main( String args[] )

  {

    Connection c = null;

    Statement stmt = null;

    try {

      Class.forName("org.sqlite.JDBC");

      c = DriverManager.getConnection("jdbc:sqlite:test.db");

      c.setAutoCommit(false);

      System.out.println("Opened database successfully");



      stmt = c.createStatement();

      String sql = "INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) " +

                   "VALUES (1, 'Paul', 32, 'California', 20000.00 );"; 

      stmt.executeUpdate(sql);



      sql = "INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) " +

            "VALUES (2, 'Allen', 25, 'Texas', 15000.00 );"; 

      stmt.executeUpdate(sql);



      sql = "INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) " +

            "VALUES (3, 'Teddy', 23, 'Norway', 20000.00 );"; 

      stmt.executeUpdate(sql);



      sql = "INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) " +

            "VALUES (4, 'Mark', 25, 'Rich-Mond ', 65000.00 );"; 

      stmt.executeUpdate(sql);



      stmt.close();

      c.commit();

      c.close();

    } catch ( Exception e ) {

      System.err.println( e.getClass().getName() + ": " + e.getMessage() );

      System.exit(0);

    }

    System.out.println("Records created successfully");

  }

}

上述程序编译和执行时，它会在 COMPANY 表中创建给定记录，并会显示以下两行：

Opened database successfully

Records created successfully

SELECT 操作

下面的 Java 程序显示了如何从前面创建的 COMPANY 表中获取并显示记录：

import java.sql.*;



public class SQLiteJDBC

{

  public static void main( String args[] )

  {

    Connection c = null;

    Statement stmt = null;

    try {

      Class.forName("org.sqlite.JDBC");

      c = DriverManager.getConnection("jdbc:sqlite:test.db");

      c.setAutoCommit(false);

      System.out.println("Opened database successfully");



      stmt = c.createStatement();

      ResultSet rs = stmt.executeQuery( "SELECT * FROM COMPANY;" );

      while ( rs.next() ) {

         int id = rs.getInt("id");

         String  name = rs.getString("name");

         int age  = rs.getInt("age");

         String  address = rs.getString("address");

         float salary = rs.getFloat("salary");

         System.out.println( "ID = " + id );

         System.out.println( "NAME = " + name );

         System.out.println( "AGE = " + age );

         System.out.println( "ADDRESS = " + address );

         System.out.println( "SALARY = " + salary );

         System.out.println();

      }

      rs.close();

      stmt.close();

      c.close();

    } catch ( Exception e ) {

      System.err.println( e.getClass().getName() + ": " + e.getMessage() );

      System.exit(0);

    }

    System.out.println("Operation done successfully");

  }

}

上述程序编译和执行时，它会产生以下结果：

Opened database successfully

ID = 1

NAME = Paul

AGE = 32

ADDRESS = California

SALARY = 20000.0



ID = 2

NAME = Allen

AGE = 25

ADDRESS = Texas

SALARY = 15000.0



ID = 3

NAME = Teddy

AGE = 23

ADDRESS = Norway

SALARY = 20000.0



ID = 4

NAME = Mark

AGE = 25

ADDRESS = Rich-Mond

SALARY = 65000.0



Operation done successfully

UPDATE 操作

下面的 Java 代码显示了如何使用 UPDATE 语句来更新任何记录，然后从 COMPANY 表中获取并显示更新的记录：

import java.sql.*;



public class SQLiteJDBC

{

  public static void main( String args[] )

  {

    Connection c = null;

    Statement stmt = null;

    try {

      Class.forName("org.sqlite.JDBC");

      c = DriverManager.getConnection("jdbc:sqlite:test.db");

      c.setAutoCommit(false);

      System.out.println("Opened database successfully");



      stmt = c.createStatement();

      String sql = "UPDATE COMPANY set SALARY = 25000.00 where ID=1;";

      stmt.executeUpdate(sql);

      c.commit();



      ResultSet rs = stmt.executeQuery( "SELECT * FROM COMPANY;" );

      while ( rs.next() ) {

         int id = rs.getInt("id");

         String  name = rs.getString("name");

         int age  = rs.getInt("age");

         String  address = rs.getString("address");

         float salary = rs.getFloat("salary");

         System.out.println( "ID = " + id );

         System.out.println( "NAME = " + name );

         System.out.println( "AGE = " + age );

         System.out.println( "ADDRESS = " + address );

         System.out.println( "SALARY = " + salary );

         System.out.println();

      }

      rs.close();

      stmt.close();

      c.close();

    } catch ( Exception e ) {

      System.err.println( e.getClass().getName() + ": " + e.getMessage() );

      System.exit(0);

    }

    System.out.println("Operation done successfully");

  }

}

上述程序编译和执行时，它会产生以下结果：

Opened database successfully

ID = 1

NAME = Paul

AGE = 32

ADDRESS = California

SALARY = 25000.0



ID = 2

NAME = Allen

AGE = 25

ADDRESS = Texas

SALARY = 15000.0



ID = 3

NAME = Teddy

AGE = 23

ADDRESS = Norway

SALARY = 20000.0



ID = 4

NAME = Mark

AGE = 25

ADDRESS = Rich-Mond

SALARY = 65000.0



Operation done successfully

DELETE 操作

下面的 Java 代码显示了如何使用 DELETE 语句删除任何记录，然后从 COMPANY 表中获取并显示剩余的记录：

import java.sql.*;



public class SQLiteJDBC

{

  public static void main( String args[] )

  {

    Connection c = null;

    Statement stmt = null;

    try {

      Class.forName("org.sqlite.JDBC");

      c = DriverManager.getConnection("jdbc:sqlite:test.db");

      c.setAutoCommit(false);

      System.out.println("Opened database successfully");



      stmt = c.createStatement();

      String sql = "DELETE from COMPANY where ID=2;";

      stmt.executeUpdate(sql);

      c.commit();



      ResultSet rs = stmt.executeQuery( "SELECT * FROM COMPANY;" );

      while ( rs.next() ) {

         int id = rs.getInt("id");

         String  name = rs.getString("name");

         int age  = rs.getInt("age");

         String  address = rs.getString("address");

         float salary = rs.getFloat("salary");

         System.out.println( "ID = " + id );

         System.out.println( "NAME = " + name );

         System.out.println( "AGE = " + age );

         System.out.println( "ADDRESS = " + address );

         System.out.println( "SALARY = " + salary );

         System.out.println();

      }

      rs.close();

      stmt.close();

      c.close();

    } catch ( Exception e ) {

      System.err.println( e.getClass().getName() + ": " + e.getMessage() );

      System.exit(0);

    }

    System.out.println("Operation done successfully");

  }

}

上述程序编译和执行时，它会产生以下结果：

Opened database successfully

ID = 1

NAME = Paul

AGE = 32

ADDRESS = California

SALARY = 25000.0



ID = 3

NAME = Teddy

AGE = 23

ADDRESS = Norway

SALARY = 20000.0



ID = 4

NAME = Mark

AGE = 25

ADDRESS = Rich-Mond

SALARY = 65000.0



Operation done successfully