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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。

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" SQLiteJDBCOpen 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" SQLiteJDBCOpened 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 successfullyRecords 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 successfullyID = 1NAME = PaulAGE = 32ADDRESS = CaliforniaSALARY = 20000.0ID = 2NAME = AllenAGE = 25ADDRESS = TexasSALARY = 15000.0ID = 3NAME = TeddyAGE = 23ADDRESS = NorwaySALARY = 20000.0ID = 4NAME = MarkAGE = 25ADDRESS = Rich-MondSALARY = 65000.0Operation 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 successfullyID = 1NAME = PaulAGE = 32ADDRESS = CaliforniaSALARY = 25000.0ID = 2NAME = AllenAGE = 25ADDRESS = TexasSALARY = 15000.0ID = 3NAME = TeddyAGE = 23ADDRESS = NorwaySALARY = 20000.0ID = 4NAME = MarkAGE = 25ADDRESS = Rich-MondSALARY = 65000.0Operation 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 successfullyID = 1NAME = PaulAGE = 32ADDRESS = CaliforniaSALARY = 25000.0ID = 3NAME = TeddyAGE = 23ADDRESS = NorwaySALARY = 20000.0ID = 4NAME = MarkAGE = 25ADDRESS = Rich-MondSALARY = 65000.0Operation done successfully