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SQLite – Java | 小熊教程

SQLite – Java

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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 
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