在 Java 程序中使用 SQLite 之前，我們需要確保機器上已經(jīng)有 SQLite JDBC Driver 驅動程序和 Java。可以查看 Java 教程了解如何在計算機上安裝 Java?，F(xiàn)在，我們來看看如何在機器上安裝 SQLite JDBC 驅動程序。
在學習下面部分的知識之前，您必須對 Java JDBC 概念有初步了解。如果您還未了解相關知識，那么建議您可以先花半個小時學習下 JDBC 教程相關知識，這將有助于您學習接下來講解的知識。
下面的 Java 程序顯示了如何連接到一個現(xiàn)有的數(shù)據(jù)庫。如果數(shù)據(jù)庫不存在，那么它就會被創(chuàng)建，最后將返回一個數(shù)據(jù)庫對象。
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");
}
}現(xiàn)在，讓我們來編譯和運行上面的程序，在當前目錄中創(chuàng)建我們的數(shù)據(jù)庫 test.db。您可以根據(jù)需要改變路徑。我們假設當前路徑下可用的 JDBC 驅動程序的版本是 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 機器，可以按照下列所示編譯和運行您的代碼：
$javac SQLiteJDBC.java
$java -classpath ".;sqlite-jdbc-3.7.2.jar" SQLiteJDBC
Opened database successfully下面的 Java 程序將用于在先前創(chuàng)建的數(shù)據(jù)庫中創(chuàng)建一個表：
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");
}
}上述程序編譯和執(zhí)行時，它會在 test.db 中創(chuàng)建 COMPANY 表，最終文件列表如下所示：
-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下面的 Java 代碼顯示了如何在上面創(chuàng)建的 COMPANY 表中創(chuàng)建記錄：
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");
}
}上述程序編譯和執(zhí)行時，它會在 COMPANY 表中創(chuàng)建給定記錄，并會顯示以下兩行：
Opened database successfully
Records created successfully下面的 Java 程序顯示了如何從前面創(chuàng)建的 COMPANY 表中獲取并顯示記錄：
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");
}
}上述程序編譯和執(zhí)行時，它會產(chǎn)生以下結果：
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下面的 Java 代碼顯示了如何使用 UPDATE 語句來更新任何記錄，然后從 COMPANY 表中獲取并顯示更新的記錄：
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");
}
}上述程序編譯和執(zhí)行時，它會產(chǎn)生以下結果：
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下面的 Java 代碼顯示了如何使用 DELETE 語句刪除任何記錄，然后從 COMPANY 表中獲取并顯示剩余的記錄：
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");
}
}上述程序編譯和執(zhí)行時，它會產(chǎn)生以下結果：
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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