java - 为什么我无法从可执行 JAR 文件插入或更新 SQLite 数据库？

Question

我有一个作为可执行 JAR 文件部署的应用程序。最初，这个 JAR 文件将与 MySQL 数据库通信，但最近我决定改用 SQLite。但是，在测试时我发现从 JAR 文件运行应用程序时无法插入或更新数据库。

我正在使用来自以下网站的 JDBC 驱动程序:http://zentus.com/sqlitejdbc/index.html

我必须采取解决方法吗？

该驱动程序在我的 Eclipse 环境中测试时工作得很好，但似乎不能在 JAR 文件中独立工作。任何帮助将不胜感激。

下面是我正在做的代码片段:

public abstract class AbstractDataUpdator implements DataUpdator{

    protected String description;
    public String[] fieldsToSelect;
    protected String queryString;
    protected String updateString;
    protected String tableName;
    protected String whereStatement;
    protected String groupByStatement;
    protected String orderByStatement;
    protected ResultSet queryResultSet;
    protected Connection connection;
    protected PreparedStatement preparedStatement;
    protected Statement statement;
    protected Database db;
    protected String uri, username, password;
    protected int dbIndex = 0;
    protected static int numInstances = 0;
    protected String countQueryString;
    protected int maxLookupNo = 0;
    protected boolean preparedStatementAlreadyCreated = false;

    AbstractDataUpdator(String description ){
        this.description = description;
        //this.fieldsToSelect = fieldsToSelect;
        //this.tableName = tableName;
        //setupDatabase(databaseName, serverName);

        numInstances++;

    }

    public void setupDatabase(String databaseName, String serverName) {
        // MySQL
        //uri = "jdbc:mysql://"+serverName+"/"+databaseName;

        // SQLite
        uri = "jdbc:sqlite:myfirst_sqlite_db";

        // If there is already a database object in the pool with this information we want to use that object
        // instead of creating another one.
        dbIndex = DatabasePool.getInstance().getIndexOfDatabaseWithThisInfo(uri, username, password);
        if( dbIndex == -1 ){
            db = new Database( uri, username, password );

        }else{
            db = DatabasePool.getInstance().getDatabaseAt(dbIndex);
        }

        try {
            connection = db.getConnection().getConnection();
            connection.setAutoCommit(true);
            statement = connection.createStatement();

        } catch (SQLException e) {
            System.out.println("SQL error occured in setupDatabase() --> "+e.getMessage());
            e.printStackTrace();
        }
    }

    public String executeUpdate(){

        //System.out.println(updateString);

        try {

            if( updateString != null){
                statement.executeUpdate( updateString );
                return null;
            }
            return "update string is null";

        } catch (SQLException e) {
            System.out.println("SQL error occured in executeUpdate()"+e.getMessage());
            return e.getMessage();

        }catch (OutOfMemoryError e){
            System.out.println("out of memory due to execute update function!!!!");
            return e.getMessage();

        }

    }
}

Answer 1

However, while testing I found that I can't insert into or update the database when running my application from the JAR file.

没有。应用程序运行时类路径上的 Jars 内的条目无法更新。 jar 通常是锁着的。

因此，只读数据库可以部署在 Jar 中。为了更新，数据库首先需要扩展到文件系统。